Friday, April 4, 2014
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Tuesday, April 1, 2014
Center for Student Services 360 (Workshop Space)

Spring Head TA Lunch

Lessons from the 1994 Northridge Quake

Current Earthquake Research at Caltech

Since the magnitude 6.7 Northridge earthquake 20 years ago (January 17, 1994), researchers at the California Institute of Technology (Caltech) have learned much more about where earthquakes are likely to happen, and how danger to human life and damage to property might be mitigated when they do occur.

"The Northridge quake really heralded the beginning of a new era in earthquake research, not only in southern California, but worldwide," says Michael Gurnis, John E. and Hazel S. Smits Professor of Geophysics, and director of the Seismological Laboratory at Caltech.

In the years just prior to the Northridge earthquake, Caltech launched a program called TERRAscope supported by the Whittier foundations, which placed high-quality seismic sensors near where earthquakes occur. The Northridge earthquake was, in effect, the first test of TERRAscope in which Caltech scientists could infer the distribution of an earthquake rupture on subsurface faults and directly measure the associated motion of the ground with greater accuracy. "With a modern digital seismic network, the potential of measuring ground shaking in real time presented itself," says Gurnis. "The real time view also gave first responders detailed maps of ground shaking so that they could respond to those in need immediately after a quake," adds Egill Hauksson, senior research associate at Caltech.

To give us this new view of earthquakes, Caltech collaborated with the U.S. Geological Survey (USGS) and the California Geological Survey to form TriNet, through which a vastly expanded network of instrumentation was put in place across southern California. Concurrently, a new network of continuously operated GPS stations was permanently deployed by a group of geophysicists under the auspices of the Southern California Earthquake Center, funded by the USGS, NASA, NSF, and the Keck Foundation. GPS data are used to measure displacements as small as 1 millimeter per year between stations at any two locations, making it possible to track motions during, between, and after earthquakes. Similar and even larger networks of seismometers and GPS sensors have now been deployed across the United States, especially EarthScope, supported by the NSF, and in countries around the world by various respective national agencies like the networks deployed by the Japanese government.

Initially, says Gurnis, there were not many large earthquakes to track with the new dense network of broadband seismic instruments and GPS devices. That all changed in December 2004 with the magnitude 9.3 earthquake and resulting tsunami that struck the Indian Ocean off the west coast of Sumatra, Indonesia. Quite abruptly, Caltech scientists had an enormous amount of information coming in from the instrumentation in Indonesia previously deployed by the Caltech Techtonics Observatory with support from the Gordon and Betty Moore Foundation. By the time the magnitude 9.0 Tohoku-Oki earthquake hit northern Japan in 2011, the Seismological Laboratory at Caltech had developed greatly expanded computing power capable of ingesting massive amounts of seismic and geodetic data. Within weeks of the disaster, a team led by Caltech professor of geophysics Mark Simons using data from GPS systems installed by the Japanese had produced extensive measurements of ground motion, as well as earthquake models constrained by this data, that provided new insight into the mechanics of plate tectonics and fault ruptures.

The Tohoku-Oki earthquake was unprecedented: scientists estimate that over 50 meters of slip on the subsurface fault occurred during the devastating earthquake. Currently, scientists at Caltech and the Jet Propulsion Laboratory are prototyping new automated systems for exploiting the wealth of GPS and satellite imaging data to rapidly provide disaster assessment and situational awareness as events occur around the globe. "We are now at a juncture in time where new observational capabilities and available computational power will allow us to provide critical information with unprecedented speed and resolution," says Simons.

Earthquakes are notable—and, for many, particularly upsetting—because they have always come without warning. Earthquakes do in fact happen quickly and unpredictably, but not so much so that early-warning systems are impossible. In a Moore Foundation-supported collaboration with UC Berkeley, the University of Washington, and the USGS, Caltech is developing a prototype early-warning system that may provide seconds to tens of seconds of warning to people in areas about to experience ground shaking, and minutes of warning to people potentially in the path of a tsunami. Japan invested heavily in an earthquake early-warning system after the magnitude 6.9 Kobe earthquake that occurred January 17, 1995, on the one-year anniversary of the Northridge earthquake, and the system performed well during the Tohoku-Oki earthquake. "It was a major scientific and technological accomplishment," says Gurnis. "High-speed rail trains slowed and stopped as earthquake warnings came in, and there were no derailments as a result of the quake."

Closer to home, Caltech professor of geophysics Robert Clayton has aided local earthquake detection by distributing wallet-sized seismometers to residents of the greater Pasadena area to keep in their homes. The seismometers are attached to a USB drive on each resident's computer, which is to remain on at all times. The data from these seismometers serve two functions: they record seismic activity on a detailed block-by-block scale, and, in the event of a large earthquake, they can help identify areas that are hardest hit. One lesson learned in the Northridge earthquake was that serious damage can occur far from the epicenter of an earthquake. The presence of many seismometers could help first responders to find the worst-affected areas more quickly after an earthquake strikes.

Caltech scientists have also been playing a leading role in the large multi-institutional Salton Seismic Imaging Project. The project is mapping the San Andreas fault and discovering additional faults by setting off underground explosions and underwater bursts of compressed air and then measuring the transmission of the resulting sound waves and vibrations through sediment. According to Joann Stock, professor of geology and geophysics at Caltech, knowing the geometry of faults and the composition of nearby sediments informs our understanding of the types of earthquakes that will occur in the future, and the reaction of the local sediment to ground shaking.

In addition, Caltech scientists learned much through simulating—via both computer modeling and physical modeling techniques—how earthquakes occur and what they leave in their aftermath.

Computer simulations of how buildings respond during earthquakes recently allowed Caltech professors Thomas Heaton, professor of engineering seismology, and John Hall, professor of civil engineering, to estimate the decrease in building safety caused by the existence of defective welds in steel-frame structures, a problem identified after the Northridge earthquake. Researchers simulated the behavior of different 6- and 20-story building models in a variety of potential earthquake scenarios created by the Southern California Earthquake Center for the Los Angeles and San Francisco areas. The study showed that defective welds make a building significantly more susceptible to collapse and irreparable damage, and also found that stiffer, higher-strength buildings perform better than more flexible, lower-strength designs.

Caltech professor of mechanical engineering and geophysics Nadia Lapusta recently used computer simulations of numerous earthquakes to determine what role "creeping" fault slip might play in earthquake events. It has been known for some time that, in addition to the rapid displacements that trigger earthquakes, land also slips very slowly along fault lines, a process that was thought to stop incoming earthquake rupture. Instead, Lapusta's models show that these "stable segments" may become seismically active in an earthquake, accelerating and even strengthening its motions. Lapusta hypothesizes that this was one factor behind the severity of the 2011 Tohoku-Oki earthquake. Taking advantage of advances in computer modeling, Lapusta and her colleague Jean-Philippe Avouac, Earle C. Anthony Professor of Geology at Caltech, have created a comprehensive model of a fault zone, including both its earthquake activity and its behavior in seismically quiet times.

Physical modeling of earthquakes is carried out at Caltech via collaborative efforts between the Divisions of Geological and Planetary Sciences and of Engineering and Applied Science. A series of experiments conducted by Ares Rosakis, the Theodore von Kármán Professor of Aeronautics and Mechanical Engineering, and collaborators including Lapusta and Hiroo Kanamori, the John E. and Hazel S. Smits Professor of Geophysics, Emeritus, used polymer plates to simulate land masses. Stresses were then created at various angles to the fault lines between the plates to set off earthquake-like activity. The motion in the polymer plates was measured by laser vibrometers while a high-speed camera recorded the movements in detail, yielding unprecedented data on the propagation of seismic waves. Researchers learned that strike-slip faults like the San Andreas may rupture in more than one direction (it was previously believed that these faults had a preferred direction), and that in addition to sliding along a fault, ruptures may occur in a "self-healing" pulselike manner in which a seismic wave "crawls" down a fault line. A third study drew conclusions about how faults will behave—in either a classic cracklike sliding rupture or in a pulselike rupture—depending on the angle at which compression forces strike the fault.

"Northridge was a devastating earthquake for Los Angeles, and there was a massive amount of damage," Gurnis says, "But in some sense, we stepped up to the plate after Northridge to determine what we could do better. And as a result we have ushered in an era of dense, high-fidelity geophysical networks on top of hazardous faults. We've exploited these networks to better understand how earthquakes occur, and we've pushed the limits such that we are now at the dawn of a new era of earthquake early warning in the United States. That's because of Northridge."

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Cynthia Eller
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Friday, January 24, 2014
Beckman Institute Auditorium

2014 Frontiers in Nano Science and Technology

New Department of Medical Engineering Added by the Caltech Division of Engineering and Applied Science

Caltech's Division of Engineering and Applied Science (EAS) has added a new department to its roster: the Department of Medical Engineering (MedE). MedE joins EAS's existing departments of Aerospace; Applied Physics and Materials Science; Computing and Mathematical Sciences; Electrical Engineering; Environmental Science and Engineering; and Mechanical and Civil Engineering. Like these other departments, MedE pulls together faculty from a broad range of specialties, both within EAS and outside it, to create an interdisciplinary program that aims to aid collaboration and provide graduate education in a critical area of engineering that directly and positively impacts human health and well-being.

MedE was formed to take advantage of Caltech's commitment to basic science, using this focus as a stepping-stone to finding fresh avenues to developing diagnostic tools, medical devices, and treatment options, in an approach sometimes known as translational, or "bench-to-bedside," medicine. Ares Rosakis, Theodore von Kármán Professor of Aeronautics and Mechanical Engineering and Booth Leadership Chair of the EAS division, explains that the MedE department was formed "in response to the desire of many of our faculty and of local research hospitals and medical foundations to engage jointly in engineering-centric technology development efforts for medical applications." To that end, the MedE department is already partnering with the Keck School of Medicine of USC, UCLA's Geffen School of Medicine, City of Hope, the UCSF School of Medicine, and Huntington Memorial Hospital, among others.

Combined with the newly established Division of Biology and Biological Engineering at Caltech, MedE positions Caltech to become an even more dynamic force in the field of bioengineering. As Vice Provost and Hans W. Liepmann Professor of Aeronautics and Bioinspired Engineering Morteza Gharib explains, "Medical engineering is top-down. We look at the problems that are currently challenging to the field and try to come up with devices and techniques to help clinicians do their job better or make breakthroughs. Biological engineering is bottom-up. It tries to understand how biology works and then builds upon that to get to the point where it can contribute to the field. Basically we're looking at the same wall from two different sides." Bringing the two sides together, says Gharib, "will not only help coordinate scientific work at Caltech but will also give outsiders a more accurate impression of how we at Caltech are taking a multifaceted approach to the challenges of bioengineering across disciplines."

"Caltech really has an opportunity here," says Yu-Chong Tai, Anna L. Rosen Professor of Electrical Engineering and Mechanical Engineering and executive officer of the new MedE department. "There are more than 60 accredited biomedical engineering programs in the United States, and there are about 100 biomedical programs at various universities and institutes. A lot of the work we want to do has to rely on deep engineering, which is our strength at Caltech. That's why our intention is to build the Caltech medical engineering department in a way that is rooted in really first-class engineering, moving from that base toward medical applications."

The expertise the MedE faculty bring to the department is deep and varied. In the field of diagnostics, Tai's research uses microelectromechanical and nanoelectromechanical systems (MEMS/NEMS) technologies to produce high-performance liquid chromatography (HPLC) on a chip and blood labs on a chip. Similar technologies are deployed for therapeutic treatments, such as the creation of miniature or micro implant devices including spinal neural stimulators, ECG implants, retinal prosthetic devices, intraocular lenses, and increasingly precise drug delivery systems. Gharib is looking into the use of nanoscale carbon-tube medical adhesives and painless nanoscale needles, and is also exploring the hemodynamics and wave dynamics of large blood vessels and embryonic heart flow with an eye toward cardiovascular medical applications. Joel Burdick, Richard L. and Dorothy M. Hayman Professor of Mechanical Engineering and Bioengineering, has been focusing his expertise in robotics to help patients suffering from paralysis. He and his colleagues have developed a rehabilitation technology that could lead to the successful repair of paralyzing spinal-cord injuries. Azita Emami, Professor of Electrical Engineering, and her team are designing high-performance, low-power, minimally invasive implantable and wearable medical devices for neural recording, neural stimulation, and drug delivery.

The medical engineering department is currently offering MS and PhD degrees, seeking to train a new generation of engineers to close the gap between engineering and medicine. The MedE department will cooperate with existing research centers at Caltech such as the Donna and Benjamin M. Rosen Bioengineering Center and the Center for Bioinspired Engineering. To learn more about the MedE department, visit its website at http://www.mede.caltech.edu, or read an overview of the department's faculty and their ambitions for the new MedE program in the Fall 2013 issue of EAS's ENGenious magazine (http://eas.caltech.edu/engenious/ten/eas_feature).

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Cynthia Eller
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A New View into Cardiovascular Disease

About a third of American adults suffer from cardiovascular diseases, which are the underlying cause of about one in three deaths in the U.S. In 2010, cardiovascular diseases generated direct and indirect costs of approximately $503 billion. New techniques to detect these diseases early and provide ongoing health information could significantly reduce such unacceptable human and financial costs. Such new techniques are in development with support from the Caltech Innovation Initiative, a philanthropically funded internal grant program designed to provide research funds to high-risk but potentially high-reward projects that could produce disruptive technologies with practical applications in the marketplace.

Caltech's Mory Gharib—a professor of aeronautics and bioinspired engineering, and an expert in cardiac mechanics and bioinspired medical devices—is developing a new method and device for easy, low-cost, and early diagnosis of cardiovascular diseases.

Clinicians could gain a wealth of information by analyzing the waveform of the patient's arterial pulse if they could retrieve the information easily enough. But current approaches to this analysis require simultaneous measurement of pressure and flow waves in the same location, which would be difficult if not impossible in clinical settings.

In the second year of a Caltech Innovation Initiative grant, the Gharib group is conceiving a new way to collect this information through noninvasive measurements that medical staff or patients themselves could easily perform. The technology extracts information by using anatomical knowledge and new methods in applied mathematics to extrapolate from intrinsic frequencies observed in arterial pressure waves or in wall displacement. Only a single waveform is needed, representing either pressure or flow—the two no longer need to be measured simultaneously in order to access the rich information they can provide.

For the first time, patients could have an easy, low-cost way to get information on the health of their hearts and arteries.

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Materials that Change on Demand

The discovery of new materials with novel properties often spurs leaps in science and technology. One of the most promising advances under way now is the creation of "tunable" materials. Caltech aerospace engineer Dennis Kochmann, who works on the modeling and fabrication of novel materials, is using Caltech Innovation Initiative support to design materials whose performance can be altered on demand. The Caltech Innovation Initiative, a philanthropically funded internal grant program, is designed to provide research funds to high-risk but potentially high-reward projects that could produce disruptive technologies with practical applications in the marketplace.

Kochmann started where many research groups are now — focusing on composite materials that change when you add or remove heat. Engineers are designing composites in which a stiff matrix holds phase-transforming inclusions. When an outside force acts to change their phase, the change in the inclusions can change the host material's properties. By using temperature to trigger phase transformation in a tin-barium-titanate composite, Kochmann found that he could increase the material's stiffness and damping (its ability to absorb and attenuate vibration) by orders of magnitude. But he saw that the precise temperature requirements of thermally tunable materials rendered them useless for most practical purposes. So he took a new approach.  

With Caltech Innovation Initiative seed-funding, Kochmann is working to design, fabricate, and test new types of composites with specially designed inclusions that change phase at the push of a button — through application of an electric field rather than changes in temperature. In particular, he wants to create stiff, structural materials that absorb vibration well. The rare combination of high stiffness and high damping would open new possibilities in engineering and science.

Kochmann's new idea could enable many possible outcomes, such as machine beds that isolate lab or factory equipment from vibration, strong and stable aircraft wings, and buildings that better withstand earthquakes.

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From Lab-on-a-Chip to Lab-in-the-Body: The Role of Nanotechnology in the Miniaturization of Medical Diagnostic Tools

Watson Lecture Preview

Fictional inventor Wayne Szalinsky built a shrink ray while wearing a Caltech hoodie in the film Honey, I Shrunk the Kids. And a shrunken sub and its five-person crew cleared a blood clot deep inside someone's brain in Fantastic Voyage. Now Axel Scherer, Caltech's Bernard Neches Professor of Electrical Engineering, Applied Physics and Physics, is miniaturizing medical equipment without benefit of a shrink ray. He'll tell us how to make a sensor small enough to be injected into an artery at 8 p.m. on Wednesday, November 6, in Caltech's Beckman Auditorium. Admission is free.

 

Q: What do you do?

A: There's a fantastic scene in Star Trek: The Next Generation where a silicon-based life form calls Captain Picard "you ugly bag of mostly water," which is a really bad insult. But it's true—we are bags of skin containing mostly water, and if we know what's in the water, we can tell whether we're going to be sick. Most health care today is after the fact, which is very inefficient. Your body reacts to some problem—you run a fever or feel dizzy, or whatever—and if it doesn't go away, you go to the emergency room, and someone tries to figure out what's happened. 

So, our goal is to build tiny chemical laboratories that will function inside the body and allow you to know there's a problem before you get symptoms, and you can seek treatment before the damage is done. For example, we work with Eric Topol, a cardiologist at the Scripps Research Institute, who has developed a test that will give you two or three days' warning that you're going to suffer a heart attack. 

Building something small enough to inject is the easy part. In order to sample the water in your bag, we have to evade your natural defenses. The human body assumes that anything it can't recognize must be bad, so it seals that thing off to protect you. That's how we deal with splinters, for example. And the blood stream has all sorts of cells whose entire function is to isolate and destroy foreign objects, so anything we want to introduce into the body we have to somehow camouflage or else build it small enough that it can't be recognized by the immune system.  

 

Q: Why are you doing this? 

A: The world needs cheap, readily available health care. Traditionally, every new medical technology increases the cost of care, so the PCR thermal cycling apparatus that Eric would use for molecular diagnostics in a hospital setting and my DVD player are both rather complicated, but I can get a DVD player for $49.95, and medical instruments are $49,000. We need to figure out how to make them inexpensively the same way we do for consumer electronics. This is something I think can be done as a cottage industry in a university environment. A few people working together can build a device, and if it works for a single person, or maybe a couple of hundred, then you just feed it into the manufacturing system. I see the implantable devices we want to build as a step along a continuum of more and more capable point-of-care instruments that will ultimately move the point of care out of the hospital to wherever the patient is. 

 

Q: How did you get into this line of work? 

A: I came to Caltech from Bell Labs in 1993, and since then, my lab has miniaturized things like communications systems, optical spectroscopic systems, and microfluidic systems. And then one day I asked myself, "What do I really want to do with my miniaturization capabilities?" Also, this academic year Caltech has started a new option in medical engineering. The idea is to harness our engineering capabilities by starting with a medical problem, or set of problems, and working backward to design fundamentally new solutions rather than trying to adapt things that were designed for other purposes. The Institute is saying, "This is something society needs, and we're going to educate the people who will be doing this for the next 30 or 40 years." It's a fantastic opportunity to be relevant in health care without opening a medical school. 

 

Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at Caltech's iTunes U site.

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Douglas Smith
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A New Device to Advance Glaucoma Research and Treatment

Glaucoma, the leading cause of blindness, affects some 70 million people, including four million Americans. As Americans age, the problem is expected to worsen in the U.S. There's stronger hope of progress in the fight against glaucoma, thanks to funding from the Caltech Innovation Initiative, a philanthropically funded internal grant program designed to provide research funds to high-risk but potentially high-reward projects that could produce disruptive technologies with practical applications in the marketplace. With Caltech Innovation Initiative seed funds, Caltech electrical engineer Hyuck Choo is developing a device that could accelerate progress on glaucoma research in addition to helping patients monitor their own optical health.

The key research and clinical tool for glaucoma is intraocular pressure (IOP) monitoring. But presently available IOP monitoring technologies are so cumbersome and limited that researchers studying animal models have to use anesthesia and extreme care to achieve acceptable accuracies, and patients can only get periodic snapshots of their pressure at their doctor's office. So far, most approaches to this problem have focused on development of microelectronic implantable sensors, but the sensors are too big for more than 90 percent of the animal species used in glaucoma research. Glaucoma patients themselves may object to such large sensors (1–3 mm in diameter) because of their visibility and interference with eye function.

Choo has pioneered a new approach, using precise nanophotonic engineering to create an implantable IOP monitoring system 10 to 30 times smaller than previously used sensors. In the first year of Caltech Innovation Initiative support, his group has completed the first device simulations and designs, developed a fabrication process, and begun fabrication. They have also built a measurement setup and obtained initial measurements that correspond with their expectations.

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Tuesday, December 10, 2013
Noyes 153 (J. Holmes Sturdivant Lecture Hall)

Advice for Future New Faculty: Caltech Postdoc Association Event

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