Presentations

    Laser-induced microexplosions: Ultrafast physics with clinical applications, at Physics Colloquium, Texas A&M University (College Station, TX), Thursday, February 18, 1999:
    Recently there has been much interest in using femtosecond laser pulses in surgical applications. For example, femtosecond lasers could replace the nanosecond systems currently used for opthalmic photodisruption, providing improved surgical precision and adding versatility. In surgical applications, it is the high intensity of femtosecond laser pulses that is exploited. By tightly focusing these short pulses, the intensity becomes high enough to cause nonlinear absorption inside a transparent material (such as the vitreous humor). The absorption produces a hot plasma inside the sample that is... Read more about Laser-induced microexplosions: Ultrafast physics with clinical applications
    Laser-induced microexplosions: creating stellar conditions on an optical bench, at Condensed Matter Seminar, Old Dominion University (Norfolk, VA), Friday, April 9, 1999:
    Using femtosecond laser pulses we study the effects of intense laser radiation on transparent materials. By tightly focusing these laser pulses below the surface of transparent materials, we initiate highly nonlinear absorption processes which produce a dense, highly-excited plasma inside the sample. The high density, tightly-confined plasma leads to a micron-sized explosion within the material, with temperatures and pressures approaching stellar conditions. We have recently shown that it is possible to create internal submicron-sized structures by optically initiating microexplosions inside... Read more about Laser-induced microexplosions: creating stellar conditions on an optical bench
    Quick as a Flash: Observing Ultrafast Laser-Induced Dynamics in Semiconductors, at Physics Colloquium, University of Massachusetts at Lowell (Lowell, MA), Wednesday, April 21, 1999:
    We track laser-induced phase changes in materials on ultrafast time scales by measuring the material's dielectric function (from near-UV to near-IR) with 100-fs time resolution. Experiments on GaAs excited with intense femtosecond pulses reveal details of the ultrafast electron and lattice dynamics at large excited carrier densities. Future experiments will use our technique to measure the plasma dynamics during femtosecond laser-induced breakdown of transparent materials, a process which has been shown to have several potential applications in micro-machining and data storage.
    Peer Instruction: Turning a lecture into a seminar, at Physics Colloquium, University of California San Diego (San Diego, CA), Thursday, May 6, 1999:
    Education is more than just transfer of information, yet that is mostly what happens in large introductory courses - instructors present material (even though this material might be readily available in printed form) 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 fields such as physics, in which learning consists primarily of developing new thinking skills, this is disastrous. Students get frustrated because their study strategies are inappropriate, and thus... Read more about Peer Instruction: Turning a lecture into a seminar
    Interactions of Femtosecond Laser Pulses with Transparent Materials, at Physics colloquium, University of Massachusetts at Lowell (Lowell, MA), Wednesday, April 12, 2000:
    Usually when light goes through a piece of glass, nothing happens to either the light nor the glass, i.e. the glass is transparent. With a powerfull femtosecond laser pulse, however, both the laser light and the glass can be changed. We study the interaction of intense, femtosecond laser pulses with bulk transparent materials. The intensity of a tightly-focused, femtosecond laser pulse can be high enough to cause nonlinear absorption of laser energy by the transparent material. When enough energy is deposited, permanent material change results. The absorption and therefore the material... Read more about Interactions of Femtosecond Laser Pulses with Transparent Materials
    Memorization or Understanding: Are we teaching the right thing?, at Physics Colloquium, MIT (Cambridge, MA), Thursday, September 21, 2000:
    Education is more than just transfer of information, yet that is what is mostly done in large introductory courses -- instructors present material (even though this material might be readily available in printed form) and for students the main purpose of lectures is to take down as many notes as they can. Few students have the ability, motivation, and discipline to synthesize all the information delivered to them. Yet synthesis is perhaps the most important -- and most elusive -- aspect of education. Students get frustrated because they are unable to grasp simple concepts. Instructors get... Read more about Memorization or Understanding: Are we teaching the right thing?
    Understanding or Memorization: Are we Teaching the Right Thing?, at Physics Colloquium, Massachusetts Institute of Technology (Cambridge, MA), Thursday, September 21, 2000:
    Education is more than just transfer of information, yet that is what is mostly done in large introductory courses -- instructors present material (even though this material might be readily available in printed form) and for students the main purpose of lectures is to take down as many notes as they can. Few students have the ability, motivation, and discipline to synthesize all the information delivered to them. Yet synthesis is perhaps the most important -- and most elusive -- aspect of education. Students get frustrated because they are unable to grasp simple concepts. Instructors get... Read more about Understanding or Memorization: Are we Teaching the Right Thing?
    Memorization or Understanding: Are we teaching the right thing?, at Physics Colloquium, University of Missouri-Rolla (Rolla, MI), Thursday, April 12, 2001:
    Education is more than just transfer of information, yet that is what is mostly done in large introductory courses -- instructors present material (even though this material might be readily available in printed form) and for students the main purpose of lectures is to take down as many notes as they can. Few students have the ability, motivation, and discipline to synthesize all the information delivered to them. Yet synthesis is perhaps the most important -- and most elusive -- aspect of education. Students get frustrated because they are unable to grasp simple concepts. Instructors get... Read more about Memorization or Understanding: Are we teaching the right thing?
    Classroom Demonstrations: More Than Just Entertainment?, at Physics Colloquium, Calvin College (Grand Rapids, MI), Thursday, September 27, 2001
    Classroom demonstrations in science courses 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 manner of presentation of demonstrations affects their... Read more about Classroom Demonstrations: More Than Just Entertainment?
    Classroom Demonstrations: Learning Tools or Entertainment?, at Physics colloquium, Swarthmore College (Swarthmore, PA), Friday, April 19, 2002:
    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?

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