Thursday, September 25, 2014
Moore 139

Head TA Network

Wednesday, November 5, 2014
Center for Student Services 360 (Workshop Space)

HALF TIME: A Mid-Quarter Meetup for TAs

Friday, April 10, 2015
Center for Student Services 360 (Workshop Space)

Ombudsperson Training

Friday, October 3, 2014
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TA Training

Frederick B. Thompson



Frederick Burtis Thompson, professor of applied philosophy and computer science, emeritus, passed away on May 27, 2014. The research that Thompson began in the 1960s helped pave the way for today's "expert systems" such as IBM's supercomputer Jeopardy! champ Watson and the interactive databases used in the medical profession. His work provided quick and easy access to the information stored in such systems by teaching the computer to understand human language, rather than forcing the casual user to learn a programming language.

Indeed, Caltech's Engineering & Science magazine reported in 1981 that "Thompson predicts that within a decade a typical professional [by which he meant plumbers as well as doctors] will carry a pocket computer capable of communication in natural language."

"Natural language," otherwise known as everyday English, is rife with ambiguity. As Thompson noted in that same article, "Surgical reports, for instance, usually end with the statement that 'the patient left the operating room in good condition.' While doctors would understand that the phrase refers to the person's condition, some of us might imagine the poor patient wielding a broom to clean up."

Thompson cut through these ambiguities by paring "natural" English down to "formal" sublanguages that applied only to finite bodies of knowledge. While a typical native-born English speaker knows the meanings of 20,000 to 50,000 words, Thompson realized that very few of these words are actually used in any given situation. Instead, we constantly shift between sublanguages—sometimes from minute to minute—as we interact with other people.

Thompson's computer-compatible sublanguages had vocabularies of a few thousand words—some of which might be associated with pictures, audio files, or even video clips—and a simple grammar with a few dozen rules. In the plumber's case, this language might contain the names and functions of pipe fittings, vendors' catalogs, maps of the city's water and sewer systems, sets of architectural drawings, and the building code. So, for example, a plumber at a job site could type "I need a ¾ to ½ brass elbow at 315 South Hill Avenue," and, after some back-and-forth to clarify the details (such as threaded versus soldered, or a 90-degree elbow versus a 45), the computer would place the order and give the plumber directions to the store.

Born on July 26, 1922, Thompson served in the Army and worked at Douglas Aircraft during World War II before earning bachelor's and master's degrees in mathematics at UCLA in 1946 and 1947, respectively. He then moved to UC Berkeley to work with logician Alfred Tarski, whose mathematical definitions of "truth" in formal languages would set the course of Thompson's later career.

On getting his PhD in 1951, Thompson joined the RAND (Research ANd Development) Corporation, a "think tank" created within Douglas Aircraft during the war and subsequently spun off as an independent organization. It was the dawn of the computer age—UNIVAC, the first commercial general-purpose electronic data-processing system, went on sale that same year. Unlike previous machines built to perform specific calculations, UNIVAC ran programs written by its users. Initially, these programs were limited to simple statistical analyses; for example, the first UNIVAC was bought by the U.S. Census Bureau. Thompson pioneered a process called "discrete event simulation" that modeled complex phenomena by breaking them down into sequences of simple actions that happened in specified order, both within each sequence and in relation to actions in other, parallel sequences.

Thompson also helped model a thermonuclear attack on America's major cities in order to help devise an emergency services plan. According to Philip Neches (BS '73, MS '77, PhD '83), a Caltech trustee and one of Thompson's students, "When the team developed their answer, Fred was in tears: the destruction would be so devastating that no services would survive, even if a few people did. . . . This kind of hard-headed analysis eventually led policy makers to a simple conclusion: the only way to win a nuclear war is to never have one." Refined versions of these models were used in 2010 to optimize the deployment of medical teams in the wake of the magnitude-7.0 Haiti earthquake, according to Neches. "The models treated the doctors and supplies as the bombs, and calculated the number of people affected," he explains. "Life has its ironies, and Fred would be the first to appreciate them."

In 1957, Thompson joined General Electric Corporation's computer department. By 1960 he was working at GE's TEMPO (TEchnical Military Planning Operation) in Santa Barbara, where his natural-language research began. "Fred's first effort to teach English to a computer was a system called DEACON [for Direct English Access and CONtrol], developed in the early 1960s," says Neches.

Thompson arrived at Caltech in 1965 with a joint professorship in engineering and the humanities. "He advised the computer club as a canny way to recruit a small but dedicated cadre of students to work with him," Neches recalls. In 1969, Thompson began a lifelong collaboration with Bozena Dostert, a senior research fellow in linguistics who died in 2002. The collaboration was personal as well as professional; their wedding was the second marriage for each.

Although Thompson's and Dostert's work was grounded in linguistic theory, they moved beyond the traditional classification of words into parts of speech to incorporate an operational approach similar to computer languages such as FORTRAN. And thus they created REL, for Rapidly Extensible Language. REL's data structure was based on "objects" that not only described an item or action but allowed the user to specify the interval for which the description applied. For example:

                        Object: Mary Ann Summers

                        Attribute: driver's license

                        Value: yes

                        Start time: 1964

                        End time: current

"This foreshadowed today's semantic web representations," according to Peter Szolovits (BS '70, PhD '75), another of Thompson's students.

In a uniquely experimental approach, the Thompsons tested REL on complex optimization problems such as figuring out how to load a fleet of freighters—making sure the combined volumes of the assorted cargoes didn't exceed the capacities of the holds, distributing the weights evenly fore and aft, planning the most efficient itineraries, and so forth. Volunteers worked through various strategies by typing questions and commands into the computer. The records of these human-computer interactions were compared to transcripts of control sessions in which pairs of students attacked the same problem over a stack of paperwork face-to-face or by communicating with each other from separate locations via teletype machines. Statistical analysis of hundreds of hours' worth of seemingly unstructured dialogues teased out hidden patterns. These patterns included a five-to-one ratio between complete sentences—which had a remarkably invariant average length of seven words—and three-word sentence fragments. Similar patterns are heard today in the clipped cadences of the countdown to a rocket launch.

The "extensible" in REL referred to the ease with which new knowledge bases—vocabulary lists and the relationships between their entries—could be added. In the 1980s, the Thompsons extended REL to POL, for Problem Oriented Language, which had the ability to work out the meanings of words not in its vocabulary as well as coping with such human frailties as poor spelling, bad grammar, and errant punctuation—all on a high-end desktop computer at a time when other natural-language processors ran on room-sized mainframe machines.

"Fred taught both the most theoretical and the most practical computer science courses at the Institute long before Caltech had a formal computer science department. In his theory class, students proved the equivalence of a computable function to a recursive language to a Turing machine. In his data analysis class, students got their first appreciation of the growing power of the computer to handle volumes of data in novel and interesting ways," Neches says. "Fred and his students pioneered the arena of 'Big Data' more than 50 years ahead of the pack." Thompson co-founded Caltech's official computer science program along with professors Carver Mead (BS '56, MS '57, PhD '60) and Ivan Sutherland (MS '60) in 1976.

Adds Remy Sanouillet (MS '82, PhD '94), Thompson's last graduate student, "In terms of vision, Fred 'invented' the Internet well before Al Gore did. He saw, really saw, that we would be asking computers questions that could only be answered by fetching pieces of information stored on servers all over the world, putting the pieces together, and presenting the result in a universally comprehensible format that we now call HTML."

Thompson was a member of the scientific honorary society Sigma Xi, the Association for Symbolic Logic, and the Association for Computing Machinery. He wrote or coauthored more than 40 unclassified papers—and an unknown number of classified ones.

Thompson is survived by his first wife, Margaret Schnell Thompson, and his third wife, Carmen Edmond-Thompson; two children by his first marriage, Mary Ann Thompson Arildsen and Scott Thompson; and four grandchildren.

Plans for a celebration of Thompson's life are pending.

Douglas Smith
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Frederick B. Thompson (1922–2014)
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Tuesday, July 29, 2014
Center for Student Services 360 (Workshop Space)

Intro to Course Design Workshop

DOE Awards $15 Million to Caltech's Solar Energy Research

The United States Department of Energy (DOE) announced on Wednesday that it will be awarding $15.2 million to Caltech's Light-Material Interactions in Energy Conversion (LMI) program, one of 32 Energy Frontier Research Centers (EFRCs) nationwide that will receive a combined $100 million over the next four years to pursue innovative energy research.

The LMI-EFRC is directed by Harry Atwater, the Howard Hughes Professor of Applied Physics and Materials Science, and is a collaborative partnership of researchers in photonics (the generation, manipulation, and detection of light) at Caltech, Lawrence Berkeley National Laboratory, the University of Illinois at Urbana-Champaign, Stanford University, and Harvard University.

The DOE received more than 200 proposals for EFRCs. Caltech is among 22 centers whose initial funding, granted in 2009, is being extended for another four years. During its first funding period, among other accomplishments, LMI-EFRC fabricated complex three-dimensional photonic nanostructure and light absorbers; created a solar cell with world-record-breaking efficiency; and developed the printing-based mechanical assembly of microscale solar cells.

"In recent years the solar energy landscape has been fundamentally altered with the recent growth of a large worldwide photovoltaics industry," says Atwater. "The most important area for basic research advances is now in enumerating the scientific principles and methods for achieving the highest conversion efficiencies. There is a new era emerging in which the science of nanoscale light management plays a critical role in enabling energy conversion to surpass traditional limits. This is where the Light-Material Interactions EFRC has focused its effort and is making advances."

LMI-EFRC will be using its new DOE award to address opportunities for high-efficiency solar energy conversion, with a goal of making scientific discoveries that will enable utilization of the entire visible and infrared solar resource.

"We are proud of the accomplishments of Professor Atwater, his colleagues, postdocs, and students in the Light-Material Interactions effort and are gratified that this effort will go beyond its great accomplishments to date through the renewed funding from the DOE," says Peter Schröder, deputy chair of the Division of Engineering and Applied Science and the Shaler Arthur Hanisch Professor of Computer Science and Applied and Computational Mathematics. "Harry exemplifies the best tradition of engineering at Caltech, creating the interface between fundamental science advances and their realization through engineering for the benefit of society at large."

According to the United States Department of Energy, "transforming the way we generate, supply, transmit, store, and use energy will be one of the defining challenges for America and the globe in the 21st century. At its heart, the challenge is a scientific one. Important as they are, incremental advances in current energy technologies will not be sufficient. History has demonstrated that radically new technologies arise from disruptive advances at the science frontiers. The Energy Frontier Research Centers program aims to accelerate such transformative discovery." 

Energy Secretary Ernest Moniz, in announcing the awards, said, "Today, we are mobilizing some of our most talented scientists to join forces and pursue the discoveries and breakthroughs that will lay the foundation for our nation's energy future."

Cynthia Eller
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Ravichandran Receives Murray Lecture Award

Guruswami (Ravi) Ravichandran, the John E. Goode, Jr., Professor of Aerospace and professor of mechanical engineering, and director of the Graduate Aerospace Laboratories (GALCIT), has received the 2014 William M. Murray Award from the Society for Experimental Mechanics (SEM), "for pioneering contributions in experimental mechanics of deformation, damage and failure of materials under multiaxial dynamic loading."

Ravichandran's research group explores the properties of materials ranging from biomaterials to bulk metallic glasses, adhesives, and polymers. As winner of the Murray Award, Ravichandran delivered a lecture to the SEM annual conference on June 3, 2014, titled "Three-Dimensional Quantitative Visualization: Application to Studying Cell-Matrix Interactions." The lecture will be published in a forthcoming volume of SEM's official journal, Experimental Mechanics.

"I was greatly honored to give the 2014 William M. Murray Lecture of the Society for Experimental Mechanics," says Ravichandran. "I consider this award to be a recognition of the collective work carried out by my research group (students, postdocs, and visitors) over the last 25 years in mechanics of materials. My research has benefited from the truly interdisciplinary and highly collaborative environment at Caltech, and from the appreciation and support for cutting-edge experimental work in the Graduate Aerospace Laboratories (GALCIT)."

The Murray Award is the highest honor given by the SEM, the leading professional society in experimental solid mechanics. Ravichandran is currently president-elect of the society, and will be its president in 2015‑16.

Past Caltech winners of the Murray Award include Wolfgang G. Knauss (1995) and Ares J. Rosakis (2005).

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Maria I. Lopez Wins Schmitt Staff Prize

Maria I. Lopez, lead options administrator in Computing and Mathematical Sciences in the Division of Engineering and Applied Science at Caltech, is this year's winner of the Thomas W. Schmitt Annual Staff Prize. Lopez has been working at Caltech since 1996. Since 2003, she has served in a variety of capacities within computer science: as secretary to the department head, administrator for the Center for the Mathematics of Information, and most recently as the option administrator for Caltech students who are pursuing concentrations in computer science.

"Lopez is in charge of the organization of annual classes taken by more than 2,000 undergraduate and graduate students," says one of the anonymous individuals who nominated Lopez for the prize. "Computer science is the largest option on campus, so as option rep administrator, Lopez is in charge of about 200 students a year. Maria gets thanked in every thesis defense that I attend. Her positive attitude has been quite contagious among her peers: she literally invigorated her colleagues to play as a team . . . I do not think it is an exaggeration to state that she is the energy source of the whole department."

For her part, Lopez counts herself lucky to work with such a wonderful group of people. "My first job on campus was in faculty records, and then I moved to admissions and worked with prospective students. These were good experiences, but I think I've found my place in computer science. It's a great department. We have great leadership, great support, and wonderful coworkers. My supervisor, Jerolyn Chittum, always gives us the proper tools. If you want to take a class to better yourself, she's very supportive. And our director, Mathieu Desbrun, is just amazing."

Another anonymous individual who nominated Lopez for the Schmitt Prize notes her "independent initiative" and "unflapping professionalism and cheer." Indeed, Lopez stands poised to step into all kinds of situations, to be of use wherever she can. As Lopez explains, "I really enjoy interacting with people, and it's nice to work with people from multicultural backgrounds. For everyone, but especially for our international students, I like to emphasize an open door policy: stop by and say hello, come on in. If it's not my area, I'll find out who you can talk to. I just want to be of service. We're here because of the students, so I try to make it warm and inviting for them." Because Lopez works with incoming students, she often knows individuals throughout their Caltech careers, and she delights in meeting their families and watching them grow and change during their time here.

"Caltech is a great place to work," says Lopez. "When I first started, a friend of mine was introducing me to other staff, and they all said, 'Oh, I've worked here 17 years, or 20 years, or 12 years.' Now it's me saying, 'Oh, I've been here 18 years.' My whole job is different each term, so it's always interesting."

The Schmitt Prize was established in 2007 through the initiative of Thomas W. Schmitt, former associate vice president for human resources. Schmitt proposed the idea of a staff prize to senior administrators, and it was eventually funded by Ted Jenkins, Caltech alumnus (BS '65, MS '66) and trustee, who spent his professional career in the semiconductor industry. Both men were on hand to help award the prize at the 59th annual staff service awards on June 2.

Part of the excitement of the Schmitt Prize is that potential recipients do not know in advance who will receive the award. As Schmitt remarks, "I think Caltech does a better job of including staff as part of the community than any other place I know of." Jenkins is equally enthusiastic about the staff at Caltech. "One of the things that resonated with me when Tom first mentioned the idea to me was that the faculty get all kinds of awards, while staff are mainly recognized for seniority alone," says Jenkins. "Our faculty are the best and the brightest, but they can't do it by themselves. They need the environment and that comes from the staff."

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Miniature Truss Work

Fancy Erector Set? Nope. The elaborate fractal structure shown at right (with a close-up below) is many, many times smaller than that and is certainly not child's play. It is the latest example of what Julia Greer, professor of materials science and mechanics, calls a fractal nanotruss—nano because the structures are made up of members that are as thin as five nanometers (five billionths of a meter); truss because they are carefully architected structures that might one day be used in structural engineering materials.

Greer's group has developed a three-step process for building such complex structures very precisely. They first use a direct laser writing method called two-photon lithography to "write" a three-dimensional pattern in a polymer, allowing a laser beam to crosslink and harden the polymer wherever it is focused. At the end of the patterning step, the parts of the polymer that were exposed to the laser remain intact while the rest is dissolved away, revealing a three-dimensional scaffold. Next, the scientists coat the polymer scaffold with a continuous, very thin layer of a material—it can be a ceramic, metal, metallic glass, semiconductor, "just about anything," Greer says. In this case, they used alumina, or aluminum oxide, which is a brittle ceramic, to coat the scaffold. In the final step they etch out the polymer from within the structure, leaving a hollow architecture.

Taking advantage of some of the size effects that many materials display at the nanoscale, these nanotrusses can have unusual, desirable qualities. For example, intrinsically brittle materials, like ceramics, including the alumina shown, can be made deformable so that they can be crushed and still rebound to their original state without global failure.

"Having full control over the architecture gives us the ability to tune material properties to what was previously unattainable with conventional monolithic materials or with foams," says Greer. "For example, we can decouple strength from density and make materials that are both strong (and tough) as well as extremely lightweight. These structures can contain nearly 99 percent air yet can also be as strong as steel. Designing them into fractals allows us to incorporate hierarchical design into material architecture, which promises to have further beneficial properties."

The members of Greer's group who helped develop the new fabrication process and created these nanotrusses are graduate students Lucas Meza and Lauren Montemayor and Nigel Clarke, an undergraduate intern from the University of Waterloo.

Kimm Fesenmaier
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