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Lasers Aim to Replace Scalpels in Cutting-Edge Biopsy Technique

05-16-19

Professor Lihong Wang and Postdoctoral Scholar Dr. Junhui Shi have developed a new imaging technique that uses pulses from two kinds of lasers to take pictures of microscopic biological structures. This new approach, called ultraviolet-localized mid-infrared photoacoustic microscopy, or ULM-PAM, develops images of the microscopic structures found in a piece of tissue by bombarding the sample with both infrared and ultraviolet laser light. "Because ultraviolet light and infrared have different properties, we had to find special mirrors and glass that could focus both," Dr. Shi says. "And because no camera exists that can see both, we had to develop ways to see if they were correctly focused." [Caltech story]

Tags: EE research highlights MedE Lihong Wang postdocs Junhui Shi

Levitating Objects with Light

03-18-19

Ognjen Ilic, postdoctoral scholar in Professor Harry Atwater’s laboratory, and colleagues have designed a way to levitate and propel objects using only light, by creating specific nanoscale patterning on the objects' surfaces. "We have come up with a method that could levitate macroscopic objects," says Professor Atwater, who is also the director of the Joint Center for Artificial Photosynthesis. "There is an audaciously interesting application to use this technique as a means for propulsion of a new generation of spacecraft. We're a long way from actually doing that, but we are in the process of testing out the principles." [Caltech story]

Tags: APhMS research highlights Harry Atwater postdocs Ognjen Ilic

Best Paper Award

03-13-19

Professor Pietro Perona along with Caltech alumni David Hall and Steve Branson have won the 2018 U. V. Helava Best Paper Award from the ISPRS Journal of Photogrammetry and Remote Sensing. Their paper “From Google Maps to a fine-grained catalog of street trees” was selected for the award. The jury described the work in the paper as “innovative, and applicable for large areas of tree classification and inventories. The developed methodology would affect practices of urban tree management globally.” [Read the paper]

Tags: EE honors Pietro Perona alumni postdocs David Hall Steve Branson

Microscopic Devices That Control Vibrations Could Allow Smaller Mobile Devices

12-12-18

Chiara Daraio, Professor of Mechanical Engineering and Applied Physics, and colleagues have developed phononic devices that include parts that vibrate extremely fast, moving back and forth up to tens of millions of times per second. The devices were developed by creating silicon nitride drums that are just 90 nanometers thick. The drums are arranged into grids, with different grid patterns having different properties. Professor Daraio, along with former Caltech postdoctoral scholar Jinwoong Cha, have shown that arrays of these drums can act as tunable filters for signals of different frequencies and can act like one-way valves for high-frequency waves. [Caltech story]

Tags: research highlights Chiara Daraio MCE APh postdocs Jinwoong Cha

Nailing It: Caltech Engineers Help Show That InSight Lander Probe Can Hammer Itself Into Martian Soil

11-26-18

Professor José Andrade’s research team including Postdoctoral researchers Ivan Vlahinic and Jason Marshall have helped the InSight Mars lander boldly go where no one has gone before: beneath the surface of Mars. InSight is equipped with two main instrument packages: a seismometer for studying how seismic waves (for example, from marsquakes and meteorite impacts) travel through the planet and a "mole" that will burrow into the ground, dragging a tether with temperature sensors behind it to measure how temperatures change with depth on the planet. These instruments will tell scientists about Mars's interior structure (similar to the way an ultrasound lets doctors "see" inside a human body) and also about the heat flow from the planet's interior. When designing the mole the engineers at JPL wanted to be certain that it would be capable of reaching the necessary depth, and so they called on Professor Andrade, an expert on the physics of granular materials. He was able to develop new computer models that helped the JPL team predict the mole's effectiveness in Martian soil. Unless the mole encounters an obstacle, Andrade is confident that it will be successful. [Caltech story]

Tags: research highlights MCE Jose Andrade postdocs Ivan Vlahinic Jason Marshall

President Rosenbaum Highlights Postdocs as "Unsung Heroes"

09-24-18

In a letter to the Caltech community during National Postdoc Appreciation Week, the Caltech President emphasizes the role this key group plays at the Institute. He stated, “Caltech's mission of world-leading research and education depends crucially on our postdoctoral scholars. Although their time at Caltech may be short, they quickly become vital parts of the Institute's intellectual fabric.” [President’s Letter] [EAS Postdoc Resource Page]

Tags: APhMS EE GALCIT MedE MCE CMS ESE Thomas Rosenbaum postdocs

Dragonfly Larvae Inspire New Designs for Prosthetic Heart Valves

07-17-18

Professor Mory Gharib and postdoctoral researcher Chris Roh (MS '13, PhD '17) have studied the design and control of the jets that dragonfly larvae use to propel themselves to re-design health values. "The current heart valve design is a one-size-fits-all, where no patient-specific design is considered, and this causes many post-transplant complications," Dr. Roh says. "We believe that an intentionally off-centered opening of the heart valve to more closely match the patient's original blood flow will be an important design parameter that can be adjusted based on each patient's heart morphology." [Caltech story]

Tags: research highlights GALCIT MedE Morteza Gharib Chris Roh postdocs

No Motor, No Battery, No Problem

05-15-18

Chiara Daraio, Professor of Mechanical Engineering and Applied Physics, and colleagues have developed robots capable of self-propulsion without using any motors, servos, or power supply. Instead, these first-of-their-kind devices paddle through water as the material they are constructed from deforms with temperature changes. "Combining simple motions together, we were able to embed programming into the material to carry out a sequence of complex behaviors," says Caltech postdoctoral scholar Osama R. Bilal, who is co-first author of the PNAS paper is titled "Harnessing bistability for directional propulsion of soft, untethered robots." [Caltech story]

Tags: research highlights Chiara Daraio MCE APh postdocs Osama Bilal

Solving Pieces of the Genetic Puzzle

05-09-18

Postdoctoral scholar Nathan Belliveau working in the laboratory of Professor Rob Phillips has applied a method called Sort-Seq to mutate small pieces of noncoding regions in E. coli and determined which regions contain binding sites. Binding sites are the locations where specialized proteins that are involved in transcription—the first step in the process of gene expression—attach to DNA. "Humans have such a wide variety of cells—muscle cells, neurons, photoreceptors, blood cells, to name a few," says Professor Phillips. "They all have the same DNA, so how do they each turn out so differently? The answer lies in the fact that genes can be regulated—turned on or off, dialed up and dialed down—differently in different tissues. Until now, there have been no general principles to help us understand how this regulation was encoded." [Caltech story]

Tags: research highlights Rob Phillips APh postdocs Nathan Belliveau

Professor Hou Receives SIAM Outstanding Paper Prize

04-09-18

Yizhao T. (Thomas) Hou, Charles Lee Powell Professor of Applied and Computational Mathematics, and his former postdoc Dr. Guo Luo are recipients of the Society for Industrial and Applied Mathematics (SIAM) 2018 Outstanding Paper Prize for their paper entitled Toward the Finite-Time Blowup of the 3D Axisymmetric Euler Equations: A Numerical Investigation. The prizes are given for outstanding papers published in SIAM journals during the three years prior to the year of the award. [Read the paper]

Tags: honors CMS Thomas Hou postdocs Guo Luo