Ditch Day, one of Caltech's oldest traditions, is happening today, May 26. During this annual spring rite—the timing of which is kept secret until the last minute—seniors ditch their classes and vanish from campus. Before they go, however, they leave behind complex, carefully planned out puzzles and challenges—known as "stacks"—designed to occupy the underclassmen and prevent them from wreaking havoc on the seniors' unoccupied rooms.

Follow the action on Caltech's Facebook, Twitter, Snapchat (search for "CaltechEdu"), and Instagram pages as the undergraduates tackle the puzzles left for them to solve around campus. Join the conversation by sharing your favorite Ditch Day memories and using #CaltechDitchDay in your tweets and postings.

As a chemistry major at the University of Minnesota, Kelsey Boyle kept a laser-like focus on her core classes, which left little room to explore the life sciences. Despite her interest, during her senior year, "I was afraid to take a biochemistry class because I didn't know if I had the background," she says. Looking back, Boyle—now a fourth-year graduate student in a bioinorganic chemistry laboratory at Caltech—says she wishes there had been more opportunities to explore different fields in college.

Boyle and fellow fourth-year graduate student Rebekah Silva have found a way to offer Caltech undergraduates just that kind of opportunity: a low-stakes way to explore topics in chemistry that pique their interest. The pair, both of whom hold student leadership positions at the Caltech Center for Teaching, Learning, and Outreach (CTLO), launched a reinvented course this spring: Chemistry 101.

Read more in Caltech magazine.

Caltech senior Andrew Romine isn't just majoring in chemistry and business, economics, and management. He also majors in creativity. Because of Caltech's small size and favorable proportion of graduate students to undergraduates, Romine built a close relationship with the members of a small group of researchers in a lab that was practically his second home.

"In order to do research, you have to be immensely creative because you're thinking of something no one else has thought of before," Romine says. "Once you get someone who's creative enough to break the boundary of knowledge in chemistry, you suddenly have a whole new field. Caltech is one of the best places at doing that."

Romine learned that one of those field-shaping people—Nobel laureate Robert H. Grubbs—was on Caltech's faculty. And he learned Grubbs' door was wide open to him as an undergraduate.

Read more on the Break Through campaign website.

As a gaggle of wide-eyed elementary school students crowd in for a view, first-year geophysics graduate student Celeste Labedz plunges her gloved hands into a basin overflowing with carbon dioxide fog.

With the children's help moments earlier, she had combined ingredients including water and dry ice to demonstrate how comets form. Now she pulls out the finished product: a fist-sized chunk of ice flecked with dirt and trailing streamers of white mist.

"Whoa!" one student cries. "Can we make another one?"

Labedz's visit to Field Elementary School in Pasadena on May 18 was part of the Science Night program that brings more than 30 Caltech volunteers—undergraduate, graduate, and postdoctoral scholars in physics, chemistry, biology, geology, astronomy, and engineering—to conduct science demonstrations for students at 11 schools across Pasadena and the San Gabriel Valley.

Started in 2013, the program originally targeted three area schools, but grew rapidly as parents and teachers spread the word about the events, and more schools invited Caltech to partner with them, says Mitch Aiken, associate director for educational outreach in Caltech's Center for Teaching, Learning, and Outreach.

Aiken says the program helps expand Catech's community involvement and provides benefits not only to local schools and their students, but also to the Institute and its students. "Through these events, our students and researchers are contributing to elevating overall science literacy while improving their own ability to explain complex topics to diverse audiences. That's critical to their success as they prepare for careers in industry, research, and academia."

More than 200 parents and students attended the recent event, which also featured hands-on demonstrations of gyroscopes, super-cooled magnets, and gravity-wave detectors.

"Many parents and students told me this was the best night of the year," says Daniel Bagby, principal of Field Elementary. "The presenters were so passionate about their field—and it was contagious. Students wanted to show me what they were learning and the sheer joy they were experiencing was truly palpable."

Arian Jadbabaie, a first-year physics graduate student who says he volunteers for Science Night about twice a month, spent the evening at Field demonstrating how gyroscopes work. Having visitors stand atop a spinnable disk, he invited them to grip a bike tire by handles attached to the sides its center axis. With the wheel spinning, participants tilted it right and left and suddenly found themselves turning on the disk, frequently prompting surprised laughter.

"My favorite part of the demonstrations is the look of amazement on the kids' faces when they see how the world is so much stranger than what they've seen or imagined," he says. "In those moments, I feel like I'm on the same level as they are, regardless of what additional technical knowledge I might have."

Taking a break from her comet-making demonstration, Labedz agrees: "When kids are excited about what they're hearing, you can see it. Sometimes they can't keep it to themselves and start bouncing around. It's awesome to see that learning can have that kind of effect on a kid."

Theater Arts at Caltech presents six undergraduate and graduate students telling stories about their personal struggles and their passion for science in an event titled "Telling Tales in Toxic Times." Tickets are free; donations to Theater Arts at Caltech are encouraged. View a brief video sneak peek of the storytellers' preparation for the showcase here.
Friday, June 9, 7:30 p.m., Ramo Auditorium 

Sonola (soon to be BS '17) opted for the bold move and enrolled at Caltech, for both the change of scenery and the academic challenge. Scholarships made that move possible. At Caltech, he found a community of like-minded undergraduate scholars who encourage and motivate one another. And he put his heart into supporting his peers—including serving as president of Fleming House.

"One of the better parts of the house system is that you're surrounded by people who have gone through the exact same thing as you," says Sonola, who pursues an option in chemical engineering with a minor in computer science. "Anytime you face a struggle, odds are someone right next to you has had the same struggle."

Read more on the Break Through campaign website.

When she found out she got into Caltech and received a full scholarship, Bianca Lepe (BS '16) screamed—and her mom cried.

To learn more about Bianca's road to and through Caltech, visit The Caltech Effect, the e-magazine of the Break Through campaign.

Glenn Price joined Caltech last fall as band director and director of performing and visual arts. He came to Pasadena with a resume that included time spent conducting in more than 30 countries as well as full-time positions in both Canada and the United States.

This Friday will be Price's first time conducting the Caltech Convocation Brass and Percussion Ensemble for the Institute's 123rd annual commencement ceremony, held on the lawn in front of Beckman Auditorium.

Several months ago, we caught up with Price to find out his initial impressions of Caltech and his vision for his new role. Hear what he had to say on the Caltech magazine website.

Why haven't insects multiplied enough to eat all the leaves on every tree—that is, why do trees stay green? How are atoms taken from inorganic materials to make living matter? What is the fastest rate at which a cell can divide?

These are some of the "puzzles" posed to undergraduate students in the introductory course Bi 1: Principles of Biology, taught this year by Rob Phillips, the Fred and Nancy Morris Professor of Biophysics and Biology in the divisions of Engineering and Applied Science and Biology and Biological Engineering.

As part of the Caltech undergraduate core curriculum, every student must fulfill a biology requirement. Many do so by taking Bi 1. The challenge facing Phillips was, in his own words: "What is the best way to teach biology to 220 non-biology majors?"

"I believe the most fascinating subject of our time is the quantitative study of living matter, trying to understand the living part of the world with the same precision as we have understood the inorganic world," he says. "Many students think of biology as a subject that is all about a variety of facts. I reject this viewpoint and in teaching this class I aimed to find an alternative to the 'death by powerpoint' approach."

Instead of a traditional encyclopedic approach where students learn about the broad sweep of facts that have been accumulated about the living world, Phillips decided to focus the course on what he calls the "broad guiding principles of biology," including lectures on biogeography (the study of the geographic distribution of species), the role of predators' ecosystems, evolution, the fossil record, photosynthesis, gene regulation, and how probability informs our understanding of biological mechanisms.

"I wanted to cultivate a sense of wonder," he says. "I want students to be observers of nature, and not necessarily adhere to manmade, artificial divisions of biological topics." Thus, each lecture began with a so-called puzzle. These were not rhetorical questions—they could be solved with techniques from biology, computer science, mathematics, chemistry, and physics. Homework questions were similar, requiring order-of-magnitude calculations made using both data and intuition to solve problems such as "how many sea otters does a killer whale need to eat every day?" to illustrate how keystone species—predators that hold ecosystems together—work.

Students were also encouraged to go outside to observe and reflect on the natural world. While this was not a formal assignment, Phillips suggested that the students think of sentences beginning with "I wonder…" and try to figure out what physical constraints set the scale of different objects in the natural world—such as, what sets the scale of how tall a tree can be, how long it took whales to evolve, or how far a bird can fly without eating.

"I found that doing the actual computations gave me a much more solid understanding of biology than just memorizing facts," says Sophia Coplin, a freshman computer science major. "We were using programming and statistical mechanics and other science to calculate the size of a bacterium, how evolution works, how a cell uses energy on a molecular level—all kinds of things. We were really thinking hard about and solving biological problems."

"I believe that biology is a forum for all scientists," says Phillips, who received an ASCIT (Associated Students of the California Institute of Technology) Teaching Award for his work. "Especially here at Caltech, where we don't steer clear of math and chemistry and physics to solve problems. Many of the greatest problems facing humanity, both in terms of curiosity and in terms of impact on our civilization, have to do with understanding the workings of the living world. Bi 1 as a course has the capacity to bring a huge set of brilliant students into thinking about subjects that they may have thought were not of interest to them."

Senior Soon Wei Daniel Lim has been named as the winner of the 2017 Library Friends' Senior Thesis Prize. Established in 2010, the Thesis Prize is intended to encourage undergraduates to complete a formal work of scholarship as a capstone project for their undergraduate career and to recognize sophisticated in-depth use of library and archival research. For their achievement, recipients of the $1,200 prize are listed in the commencement program. This year's prizes were announced and awarded at a reception at Alumni House on Wednesday, May 24 with students, alumni, Friends of the Caltech Libraries, library staff, and faculty present.

Lim's thesis, titled "Revolution in large-area curved surface lithography: Nanofilm sculpting by thermocapillary modulation," is based on experimental research he conducted over two years in the laboratory of Professor of Applied Physics, Aeronautics, and Mechanical Engineering Sandra M. Troian. The work describes a method he developed to sculpt high-quality microlens arrays and, potentially, other micro-optical components out of polymer nanofilms using laser illumination.

"Writing a thesis was a very cathartic experience," Lim says. "Over time you start to accumulate all of this knowledge in your head, and it's very satisfying and challenging to actually get it all out onto paper. I used basically every library resource. It was particularly liberating to have access to DocuServe, which allowed me to access very uncommon and specialized publications."

"Our group has been working on thermocapillary sculpting of nanofilms for several years now in the hope of designing and fabricating fully integrated, polymeric photonic circuits in a single step via a thermal projection technique," says Troian. "Daniel advanced this concept by demonstrating an inverse projection method, which imbues the sculpting process with far greater versatility. Daniel is an exceptional student—a rare combination of superb talent, tremendous drive, utmost professionalism, and entrepreneurial chops. I have a strong inkling he will someday become one of Caltech's famed alumni. It has been sheer delight working with him."

Earlier this year, Lim received the 2017 American Physical Society Ken Hass Outstanding Student Paper Award in recognition of industrial applications of the laser illumination technique described in his thesis. After graduation, Lim will spend a gap year doing research in his home country of Singapore, after which he will attend Harvard University to begin work on a PhD in applied physics.

Caltech faculty nominate seniors whose theses they deem to be deserving of the prize. Nominated students then supply a research narrative that explains their research methodology, detailing not only the sources they used but the way they obtained access to them.

Other finalists for the prize were Adrian Ray Avalani for his thesis in English, Moriah Bischann for her thesis in aerospace, Bella Guo for her thesis in computer science, Shannon Wang for her thesis in physics, and Aaron Young for his thesis in physics.

Mark Kozlowski, a fourth-year graduate student in chemistry, might not sell his soul for science, fame, and fortune—but he has given a lot of thought to why a researcher could be tempted.

Kozlowski collaborated with Theater Arts at Caltech (TACIT) for more than a year to hone a manuscript and then stage a performance of his comedy Faustus, PhD, about a struggling graduate student who makes a deal with the Devil to learn which experiments will bring him success.

Read more in Caltech magazine.

Campus eateries have switched to new summer hours, and Dining Services officials say they have plans to enliven the dining experience with a varied menu and some literal magic.

Jonathan Webster, senior director of dining services, says the Chandler menu will feature smoked meats, fresh pastas, seasonal vegetables and sides, as well as new dinner specials and varied grill and pizza offerings.

In addition, Chandler will feature Magic Castle magicians performing from 5–7:30 p.m. on Mondays in July starting July 10.

Summer hours (in effect through Sept. 19):

Broad Café: Weekdays, 7:30 a.m.–2:30 p.m.

Red Door Marketplace: Weekdays, 7:30 a.m.–10 p.m.; weekends, noon–10 p.m.

Chandler Café: Weekdays, 7 a.m.–3:30 p.m. and 5–7:30 p.m. (Dinner hours only through Aug. 25)

The Associated Students of Caltech (ASCIT) and Caltech's Graduate Student Council (GSC) on June 14 announced the honorees of their annual teaching awards, celebrating professors, TAs, and mentors for outstanding teaching in the 2016–17 academic year.

Based on voting by undergraduates, the ASCIT Teaching Awards honored professors Paul Asimow (MS '93, PhD '97), the Eleanor and John R. McMillan Professor of Geology and Geochemistry; Rob Phillips, the Fred and Nancy Morris Professor of Biophysics and Biology; Adam Wierman, professor of computing and mathematical sciences; and Evan Kirby, assistant professor of astronomy. The TAs honored were Chinmay Nirkhe (BS '17) and graduate students Dylan Freas (CCE), Eugene Tang (PMA), and Todd Norton (PMA).

The GSC's Teaching and Mentoring Awards, which honor those who have "made an extraordinary impact on graduate students," went to a professor, a TA, and a mentor; two honorable mentions were named as well.

Xie Chen, assistant professor of theoretical physics, won the teaching award; Michael Wong (MS '14), a graduate student in GPS, won the TA award; and Beverley McKeon, the Theodore von Karman Professor of Aeronautics, won the mentoring award. The two honorable mentions went to Heather Knutson, professor of planetary science; and Laura Flower Kim, associate director of International Student Programs.

Artworks created by members of the Caltech community will go on display Friday, July 21, at Lake Avenue Church in Pasadena to accompany a summer chamber music concert celebrating the nation's immigrants.

Fifteen pieces of art, selected from the 75 pieces displayed in Chandler Café as part of this year's Caltech Art Competition, will be featured on stage during the concert—and in the lobby before and after the performance. They will be displayed for limited periods of time over the weekend before returning to Chandler on July 24.

The artworks—large pieces that include photographs, paintings, and a collage—were created by a diverse group of students, staff, and faculty from countries across the world and echo the theme of the concert, which focuses on inclusiveness and the nation's immigrant community.

The concert highlights European immigrants coming through Ellis Island in the early 1900s and will include performances of chamber music those immigrants would have heard on both sides of their journey, including pieces by Johannes Brahms and American immigrants George Gershwin, Curt Weill, and Irving Berlin.

The event marks the first of several off-campus displays of Caltech art that are being coordinated by the Graduate Student Council's Arts Committee and Caltech Dining, with the aim of building additional support on campus for the arts and better integrating Caltech into the local Pasadena community.

The free concert (donations will be accepted) will take place at Lake Avenue Church, 393 N. Lake Ave. in Pasadena. Doors open at 7 p.m. for the 7:30 p.m. performance; the exhibit will be on view Friday, July 21 from 7–7:30 p.m. and 9–9:30 p.m.; Saturday, July 22 from 6:15–6:45 p.m.; and Sunday, July 23 from 8:30 a.m.–12:30 p.m.

Most people think about time throughout the day, but Sean Carroll, research professor of physics at Caltech, notes that very few people appreciate just how "weird" time is.

Carroll points out that in space, for instance, you can go from point A to point B and back again—but once you leave a given point in time, you can never return to that moment. Speaking to a packed Hameetman Auditorium on July 6, he told the crowd, "You could say, 'This is the most boring lecture I've ever heard. I will get up and walk away.' But you cannot choose to have not come to the lecture. Right? You cannot make a choice right now about the past. Why is that?"

Carroll's 45-minute lecture was part of the weekly Innovation Speaker Series science and technology talks presented each Thursday through August 3 by Summer App Space, a summer program that teaches programming to Los Angeles-area students and teachers while at the same time, they get paid to do fun space-related projects. The speaker series, which features entrepreneurs, researchers, and technologists from Caltech and elsewhere, aims to showcase the ways in which people with science- and space-related backgrounds and education can help change the world.

During his lecture, Carroll led an audience that included middle- and high-school students—as well as Caltech students, staff, and faculty, who are welcome to attend these public talks—on a tour of physics, quantum mechanics, and cosmology that examined what science can tell us about the origins of existence. Covering theories that delved into what happened before the Big Bang and what might occur when the universe ends, he also discussed how time might frame our perspective of the universe.

"Is any of this true?" he asked, referring to what happened before the Big Bang. "Who knows? I don't know. That's why we do physics. Physics is not about solving problems that you can see the solution to in the back of the book. It's about asking questions we don't know the answers to, suggesting possibilities, figuring out what those possibilities predict, and going out and collecting data and seeing which one is right."

• • •

The Innovation Speaker Series will feature two speakers each Thursday, one at 8 a.m. and one at 8:45 a.m., in Hameetman Auditorium. The schedule for the remaining lectures is as follows:

Thursday, July 20:

• 8 a.m.: Adam Lichtl, founder and CEO of Delta Brain Inc.
• 8:45 a.m.:  Solange Ramírez, associate staff scientist at the NASA Exoplanet Science Institute

Thursday, July 27

• 8 a.m.: Theoretical astrophysicist Jorge Moreno
• 8:45 a.m.:  Silicon Valley entrepreneur and Westworld actress Talulah Riley

Thursday, August 3

• 8 a.m.: Caltech postdoc and member of the 2017 NASA astronaut class Jessica Watkins
• 8:45 a.m.: Jessie Christiansen, Caltech astronomer at the NASA Exoplanet Science Institute

On July 11, workers dissected Caltech's 400-year-old Engelman oak, which died last year. The wood will be preserved for several uses including: research rounds for GPS paleoclimatology research; historic rounds for display of key science and Caltech milestones; construction of a communal table for the new Red Door Café; and development donor gifts and recognition pieces.

Read more about the history of the oak in Caltech magazine.

The last remaining occupant in the Winnett Student Center—the Caltech Store—will be closing its doors beginning July 17 and relocating to a temporary location on the first floor of Millikan Library. The move is part of a larger, multi-month effort to vacate Winnett so that the existing building can be demolished to make way for the construction of a new campus hub, called the Hameetman Center.

The Caltech Store, which sells clothing, souvenirs, office materials, Apple computers, and computer supplies, is planning to re-open in the lobby of Millikan Library the week of July 24, says manager Karyn Seixas. The store's new operating hours will be 9 a.m. to 5:30 p.m., Monday through Friday.

The Hameetman Center, named in honor of Caltech trustee Fred Hameetman (BS '62) and his wife, Joyce, is scheduled to open in fall 2018. Exterior demolition of Winnett, which has served as the central gathering place for Caltech's community for more than 50 years, is anticipated to begin in mid-August. Over the next month, the building and construction team plans to start clearing and breaking down the interior of the building, in preparation for the complete demolition of the facility, says Greg Norden, the project manager for the Hameetman Center.

The Caltech Store is just the latest of the relocations of offices and services that were once housed in Winnett. This spring, the Red Door moved to share a space with the campus convenience store, creating the Red Door Marketplace, which will ultimately be housed in the Hameetman Center; Caltech's Ticket Office was moved permanently to the Keith Spaulding Building of Business Services, next to the Post Office Center.

While access to areas in close proximity to the building site may be limited throughout the construction process, Norden says that they are working to maintain clear and easy passage for pedestrians. For instance, the pedestrian access along the east side of the building will be maintained to allow movement from the Olive Walk to the Red Door Marketplace, Chandler Dining, and the ATM, which will be relocated in August just south of the Red Door Marketplace. San Pasqual Walk will remain open and the grove of sycamore trees with dining tables will remain available for outdoor seating and use. Similarly, the fire lane along the west of the site will be maintained for emergency access.

Ongoing updates on the construction and its progress will be provided on Caltech Today.

Caltech sustainability efforts paid dividends in fiscal year 2016, cutting water use by 11 percent and trash generation by 5 percent while increasing hazardous material recycling by 11 percent compared to the previous year.

Those highlights, reported by Caltech Sustainability in its "Annual Sustainability Update 2016" report were among dozens of metrics showing the Institute's progress in reducing its environmental footprint. The report also highlighted areas where improvements could be made, such as increasing carpool usage and reducing greenhouse gas emissions.

John Onderdonk, director of sustainability programs, says that "progress in the last year has been steady and really strengthened long-term positive trends."

For example, he notes that the Institute has made significant progress in reducing demand for and increasing efficiency in energy and water use. Recent achievements in those areas have included: installation of a direct chilled-water loop to connect the campus's central and satellite utility plants to improve cooling in campus buildings; installing dedicated tree irrigation systems; installing low-flow urinals campus-wide; overhauling the 10-megawatt gas turbine in the central plant to bolster efficiency; and upgrading fuel cells providing 2 megawatts to boost their efficiency and reduce carbon emissions.

Here are some other highlights from the report:

• Caltech now derives 88 percent of its own power needs from on-campus sources—and those on-campus sources are 15 percent cleaner than power provided by the municipal utility;
• Water features including the Gene Pool and the Watson Lab fountain have been outfitted with systems to use recycled water from air conditioning condensation, saving as much as 200,000 gallons of water annually;
• The campus now recycles 34 percent of its waste, a 3 percent increase over the previous year;
• In 2016, the campus installed 61 Level 2 electric vehicle charging stations around campus; the stations are free to use for campus electric vehicle owners as part of a research project led by Steven Low, professor of computer science and electrical engineering, to determine how the Institute can best integrate large numbers of electric vehicles into the campus power grid. The 300-kilowatt stations can fully charge an electric vehicle in about five hours.

Onderdonk says the biggest challenge remaining is further reducing greenhouse gas emissions, which have plateaued—partly as a result of increased energy demands due to new building construction and research as well as from reliance on natural gas combustion to generate electricity and heat on campus. To address that challenge, the Institute approved an energy resource plan in April that aims to significantly decarbonize the campus's electrical supply by 2025 through the deployment of on- and off-site renewable energy projects.

The annual report—which details the goals, successes, and challenges facing the Institute in terms of sustainability—can be found at http://www.caltech.edu/content/2016-report-institute-sustainability-released.

Onderdonk says the report underscores the depth and breadth of the campus's continuing efforts to reduce its environmental impact. "Having detailed metrics and meaningful initiatives across multiple key areas—energy, water, materials, built environment, transportation, and emissions—is rare and certainly shows our commitment to transparency and sustained progress," he says.

The Caltech Store reopened on Monday, July 24, after moving to its new (albeit temporary) location on campus—in the lobby of Millikan Library. The move was made to allow for the demolition of the existing Winnett Student Center and the subsequent construction of a new campus hub, the Hameetman Center, on that same site.

Current plans are for the Caltech Store to be part of the Hameetman Center's retail space when the building opens in the fall of 2018.

"Student Affairs would like to thank the offices of the president and provost, Development and Institute Relations, and the Division of Chemistry and Chemical Engineering for allowing us to use their respective spaces during this transition period as well as for their patience during the construction phase," says Joe Shepherd, Caltech's vice president for student affairs.

The Caltech Store's new operating hours will be 9 a.m. to 5:30 p.m., Monday through Friday.

Workers have erected fencing and scaffolding around the Winnett Student Center to prepare for abatement of any hazardous materials in the building before its demolition.

The demolition of Winnett is expected to begin at the end of August, and construction of the Hameetman Center, which will replace Winnett as a new campus hub, should begin as soon as that demolition is complete, says Greg Norden, the project manager for the new Hameetman Center.

Key services previously available at Winnett have been moved to various locations as follows:

• the Caltech SAS Store has been temporarily relocated to the lobby of Millikan Library;
• the Red Door Café is now temporarily located in Chandler Dining Hall, sharing space with the C-Store in what is now called the Red Door Marketplace, and;
• the Ticket Office has been moved permanently to the Keith Spalding Building of Business Services, next to the post office;
• the ATM remains in its current location and is still accessible from a path west of the construction site. The ATM will remain in place until about August 11, 2017, when it will be moved to its new location south of the Red Door Marketplace;
• the prayer room formerly located in the basement of Winnett is now located in the Center for Student Services, Room 248.

The Hameetman Center, named in honor of Caltech trustee Fred Hameetman (BS '62) and his wife, Joyce, is scheduled to open in late 2018. It will feature a large public lounge, an expanded Red Door Marketplace, Caltech SAS Store, music rehearsal facilities, student club rooms, multipurpose room, and conference room.

For questions about the project, contact Dimitris Sakellariou, assistant vice president for student affairs operations, at dimitris@caltech.edu.