Invited

Femtosecond laser micromachining, at MIT Center for Integrated Photonic Systems Annual Meeting, MIT (Cambridge, MA, USA), Thursday, May 3, 2007:
When femtosecond laser pulses are focused tightly into a transparent material, the intensity in the focal volume can become high enough to cause nonlinear absorption of laser energy. The absorption, in turn, can lead to permanent structural or chemical changes. Such changes can be used for micromachining bulk transparent materials. Applications include data storage and the writing of waveguides and waveguide splitters in bulk glass, fabrication of micromechanical devices in polymers, and subcellular photodisruption inside single cells.
Probing cell mechanics with femtosecond laser pulses, at Photonics West 2007 (San Jose, CA), Sunday, January 21, 2007:
We use femtosecond laser pulses to selectively disrupt the cytoskeleton of a living cell and probe its mechanical properties. Our nanosurgery setup is based on a home-built fluorescence microscope with an integrated femtosecond laser. We severed single actin bundles inside live cells to probe the local dynamics of the cytoskeleton and correlate it to global changes in cell shape. Simultaneous cutting and imaging allows us to study immediate cellular response with several hundred-nanometer spatial and less than 500-ms time resolution. The targeted actin bundle retracts rapidly after laser... Read more about Probing cell mechanics with femtosecond laser pulses
Using short bursts of photons to manipulate biological matter at the nanoscale, at Winter Colloquium on the Physics of Quantum Electronics (Snowbird, UT), Friday, January 5, 2007:
We use femtosecond laser pulses to manipulate sub-cellular structures inside live and fixed cells. Using only a few nanojoules of laser pulse energy, we are able to selectively disrupt individual mitochondria in live bovine capillary epithelial cells, and cleave single actin fibers in the cell cytoskeleton network of fixed human fibro-blast cells. We have also used the technique to micromanipulate the neural network of C. Elegans, a small nematode. Our laser scalpel can snip individual axons without causing any damage to surrounding tissue, allowing us to study the function of individual... Read more about Using short bursts of photons to manipulate biological matter at the nanoscale
Femtosecond laser micromachining, at 1st International Workshop on Multiphoton Processes in Glass and Glassy Materials, University of Sydney (Sydney, Australia), Monday, December 11, 2006:
When femtosecond laser pulses are focused tightly into a transparent material, the intensity in the focal volume can become high enough to cause nonlinear absorption of laser energy. The absorption, in turn, can lead to permanent structural or chemical changes. Such changes can be used for micromachining bulk transparent materials. Applications include data storage and the writing of waveguides and waveguide splitters in bulk glass, fabrication of micromechanical devices in polymers, and subcellular photodisruption inside single cells.
Active learning and interactive lectures, at AAPT New Faculty Workshop, American Center for Physics (College Park, MD), Friday, October 27, 2006:
I thought I was a good teacher until I discovered my students were just memorizing information rather than learning to understand the material. Who was to blame? The students? The material? I will explain how I came to the agonizing conclusion that the culprit was neither of these. It was my teaching that caused students to fail! I will show how I have adjusted my approach to teaching and how it has improved my students' performance significantly.
Classroom Demonstrations: Learning Tools or Entertainment?, at Biennial Conference on Chemical Education, Purdue University (West Lafayette, IN), Wednesday, August 2, 2006:
Classroom science demonstrations are intended to serve two important purposes: to increase students' interest in the material being covered and to improve students' understanding of the underlying scientific concepts. Student end-of-semester evaluations typically praise demonstrations as one of the most interesting parts of a course, suggesting that demonstrations accomplish the first objective. What about the second? Do demonstrations effectively help students learn the underlying concepts? We examined whether the mode of presentation of demonstrations affects their effectiveness as teaching... Read more about Classroom Demonstrations: Learning Tools or Entertainment?
The scientific approach to teaching: Research as a basis for course design, at 2006 Cottrell Scholars Meeting (Tucson, AZ), Saturday, July 8, 2006:
Discussions of teaching -- even some publications -- abound with anecdotal evidence. Our intuition often supplants a systematic, scientific approach to finding out what works and what doesn't work. Yet, research is increasingly demonstrating that our gut feelings about teaching are often wrong. In this talk I will discuss some research my group has done on gender issues in science courses and on the effectiveness of classroom demonstrations.
Interactive Teaching: Turning a Large Lecture into a Seminar, at Symposium on Technology in Undergraduate Education, Harvard University (Cambridge, MA 02138), Friday, June 16, 2006:
Education is more than just transfer of information, yet that is mostly what happens in large introductory courses -- instructors present material and students take down as many notes as they can. This format tends to reinforce the idea that learning is about acquiring information rather than gaining new ways of thinking. In undergraduate science, however, learning consists primarily of developing new thinking skills; this mismatch between instruction and learning leads to students misunderstanding what science is, as well as frustration for both students and instructors. The problem has a... Read more about Interactive Teaching: Turning a Large Lecture into a Seminar
Subcellular surgery and nanosurgery, at CIMIT/Lester Wolfe Workshop on Femtosecond Microscopy & Microsurgery, Wellman Center for Photomedicine (Boston, MA), Tuesday, April 18, 2006:
We use femtosecond laser pulses to manipulate sub-cellular structures inside live and fixed cells. Using only a few nanojoules of laser pulse energy, we are able to selectively disrupt individual mitochondria in live bovine capillary epithelial cells, and cleave single actin fibers in the cell cytoskeleton network of fixed human fibro-blast cells. We have also used the technique to micromanipulate the neural network of C. Elegans, a small nematode. Our laser scalpel can snip individual axons without causing any damage to surrounding tissue, allowing us to study the function of individual... Read more about Subcellular surgery and nanosurgery

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