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Below-band gap absorption in microstructured silicon, at Optical Society of America Annual Meeting (Providence, RI), Tuesday, October 24, 2000:
talk_360.pdf
We report two remarkable properties of silicon surfaces that are microstructured with laser-assisted etching: the absorptance for wavelengths between 0.25 and 2.5 micrometers is 97% or more, and photoelectrons are produced at 1.3 micrometers. We also report chemical and structural analysis of the microstructured material.
Ultrafast Phase Transition Dynamics in GeSb Films, at Nonlinear Optics 2000, Optical Society of America (Kaua'i, HI, USA), Tuesday, August 8, 2000:
talk_362.pdf
We measure the femtosecond time resolved dielectric function of a-GeSb after excitation with an ultrashort laser pulse. The results reveal an ultrafast transition to a new non-thermodynamic phase which is not c-GeSb as previously believed.
Photodisruption in turbid tissues with ultrashort laser pulses, at Photonics West 2000 (San Jose, CA), Tuesday, January 25, 2000:
talk_331.pdf
We investigate the potential of femtosecond laser pulses for photodusruptive surgery on the surface and in the bulk of turbid tissue. Human epidermis cultures, mouse skin, and pig skin were used as tissue models. We use nonlinear absorption of tightly focused 100-fs laser pulses to vaporize tissue in the focal volume. By focusing the pulse in the bulk of the skin, we can vaporize 10-µm diameter regions up to 100 µm beneath the surface with minimal damage to the surrounding tissue. This technique offers exciting possibilities for clinical dermatology applications, such as tattoo removal and... Read more about Photodisruption in turbid tissues with ultrashort laser pulses
Oscillator-only micromachining of transparent materials, at Photonics West 2000 (San Jose, CA), Monday, January 24, 2000:
talk_325.pdf
By focusing femtosecond laser pulses with high numerical-aperture microscope objectives, we achieve the intensities required for bulk damage in transparent materials with energies in the range of modern laser oscillators. When a femtosecond laser pulse is tightly focused inside a transparent material, energy deposition occurs only at the focus, where the laser intensity is high enough to cause absorption through nonlinear processes. When enough energy is deposited, a localized change in the index of refraction is produced, i.e. the material is damaged. By scanning the focus through the sample... Read more about Oscillator-only micromachining of transparent materials
Factors That Make Peer Instruction Work: A 700-User Survey, at 2000 AAPT Winter Meeting (Kissimmee, FL), Tuesday, January 18, 2000:
talk_309.pdf
Peer Instruction, a teaching strategy in which lectures are interspersed with short, conceptual questions (""ConcepTests""), is used widely in introductory physics and other classes at the college and secondary school levels. Although anecdotal evidence suggests that many instructors achieve success, there has been no previous systematic study of the factors contributing to the effectiveness of Peer Instruction. We administered a comprehensive survey of nearly 700 Peer Instruction users worldwide, gathering data on implementation and outcomes in a wide variety of settings and institutions. We... Read more about Factors That Make Peer Instruction Work: A 700-User Survey
ConcepTests in Introductory Physics: What Do Students Get Out of Them?, at American Association of Physics Teachers Winter 2000 Meeting (Kissimmee, FL), Tuesday, January 18, 2000:
talk_316.pdf
ConcepTests (conceptual questions asked during class) are designed to allow the students to think about material that has just been presented, as well as to help the instructor assess students' understanding. Ideally, roughly half of the class answers a ConcepTest correctly on their own; after next discussing their answers with their fellow students, many more agree on the correct answer. We report on students' ability, long after a ConcepTest is asked in class, to explain the answer to a free-response exam question different from the ConcepTest, but involving the same underlying ideas.... Read more about ConcepTests in Introductory Physics: What Do Students Get Out of Them?
Confusion: Students' Perception vs. Reality, at American Association of Physics Teachers Winter 2000 Meeting (Kissimmee, FL), Tuesday, January 18, 2000:
talk_317.pdf
Should an instructor be discouraged when students say ""I'm confused""? This is a crucial issue for educational reform, because students often report feeling more confused when they are asked to think more for themselves. We report on an analysis of the relationship between perceived confusion and understanding in introductory physics. We asked 200 students during one semester to indicate what, if anything, they found difficult or confusing in their pre-class reading assignment and correlated their responses to answers they provided on questions on corresponding topics. Preliminary results... Read more about Confusion: Students' Perception vs. Reality
Classroom demonstrations: education or entertainment?, at American Association of Physics Teachers Winter 2000 Meeting (Kissimmee, FL), Tuesday, January 18, 2000:
talk_328.pdf
Classroom demonstrations have two important purposes: to increase student understanding of physical concepts and to enhance interest in the subject matter. Do demonstrations in fact achieve the first of these goals? Does the manner of presentation determine the effectiveness of demonstrations as teaching tools? To answer these questions, we presented several demonstrations to different sections of an introductory physics course in different ways: (1) students were asked to predict the outcome before the demonstration, (2) students were shown the demonstration and told how it works (... Read more about Classroom demonstrations: education or entertainment?
Black Silicon, at XI International Symposium Ultrafast Phenomena in Spectroscopy, Academia Sinica (Taipei, Taiwan), Monday, October 25, 1999:
talk_354.pdf

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