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Impact of sputtering parameters on titanium dioxide thin films for nonlinear nanophotonics, at Photonics West 2011 (San Francisco, CA), Monday, January 24, 2011:
talk_1707.pdf
We have identified titanium dioxide (TiO2) as a promising material for on-chip nonlinear optical devices. Its high refractive index and large intrinsic nonlinearity can strongly enhance confinement and non-linear interactions. In this study we optimize our deposition process to lower the linear losses in planar waveguides. We deposit titanium oxide thin films by RF reactive sputtering titanium onto oxidized silicon wafers in an argon/oxygen environment. The oxygen partial pressure in the chamber has a large impact on the deposition rate and the film composition. We investigate the composition... Read more about Impact of sputtering parameters on titanium dioxide thin films for nonlinear nanophotonics
Plasmon-enhanced ultrafast laser cell transfection, at Photonics West 2011 (San Francisco, CA), Sunday, January 23, 2011:
talk_1700.pdf
We present a method for transfecting biological cells using ultrafast plasmons excited on large areas of bio-compatible, nano-pyramid substrates. This technique does not employ any potentially toxic chemical transfection reagents or metallic nanoparticles. Leveraging the field enhancement supported by these pyramidal plasmonic nanostructures, we generate localized, transient pores in the membranes of large numbers of cells at a rate of approximately 10^4 per second. Diffusion through these pores enables the delivery of functional short interfering RNA (siRNA) molecules into the cells. We... Read more about Plasmon-enhanced ultrafast laser cell transfection
An Evaluation of Effectiveness of Short Physics Workshops for In-service Teachers, at American Association of Physics Teachers Winter Meeting 2011 (Jacksonville, FL), Monday, January 10, 2011
There is compelling evidence that Peer Instruction improves students’ ability to complete both conceptual and traditional computational physics problems. We used Peer Instruction during a four-week long (120 hours) retraining course for in-service teachers of grades 7-12 in Korea. The goal of this study is to investigate if Peer Instruction can be used to improve the participating teachers’ conceptual understanding of introductory physics concepts. To this end we pre- and post-tested the teachers using the Force Concept Inventory and The Conceptual Survey of Electricity and Magnetism.... Read more about An Evaluation of Effectiveness of Short Physics Workshops for In-service Teachers
Low-loss TiO2 planar waveguides for nanophotonic applications, at IEEE Photonics Society Annual Meeting, IEEE Photonics Society (Denver, CO), Tuesday, November 9, 2010:
talk_1705.pdf
We deposit TiO2 planar waveguides on oxidized silicon substrates by reactive sputtering. The films exhibit Raman spectra consistent with an amorphous or anatase phase and have losses as low as 0.4 dB/cm at 826 nm.
Infrared absorption limits of femtosecond laser doped silicon – effect of dopant types and thermal treatments, at Black Silicon Symposium (Albany, NY), Friday, August 20, 2010
Silicon doped with non-equilibrium concentrations of chalcogen exhibits strong sub-bandgap photon absorption. In this work, we investigate mid-infrared absorption of femtosecond laser doped silicon. Fourier transform infrared spectroscopy could shed light on energy levels of dopant states or bands. We study samples doped with sulfur, selenium and tellurium. In addition, we also investigate the effect of annealing temperature. Preliminary results suggest that near-unity absorption of sulfur doped silicon extends to mid-infrared. However, absorption decreases for photons with energy less than... Read more about Infrared absorption limits of femtosecond laser doped silicon – effect of dopant types and thermal treatments
Gender, mental rotations, and introductory physics, at Portland, OR, Thursday, July 22, 2010
In this talk we examine an often-cited claim for gender differences in STEM participation: cognitive differences on tests of spatial ability explain achievement differences in physics. We specifically investigate the role of mental rotations in physics achievement and problem-solving, viewing mental rotations as a tool that students can use on physics problems. We first look at student survey results for lower-level introductory students, finding a small, but significant correlation between performance on a mental rotations test and course achievement. In contrast, we find no such... Read more about Gender, mental rotations, and introductory physics
Assessing and Enhancing Student Learning in the Advanced Physics Lab, at AAPT Summer Meeting, 2010 (Portland, Oregon), Monday, July 19, 2010
Efforts to reform instructional physics labs--by defining measurable goals and improving student learning--have led to several innovations (i.e. rubrics for enhanced formative assessment) at the introductory level. However, researchers have yet to explore similar innovations in advanced laboratory courses. In an effort to fill this void, we investigated the observable aspects of student learning, culled from submitted written work and discussions between students and faculty, in light of specific changes to the advanced lab course (clear statement of learning goals, better-defined activities... Read more about Assessing and Enhancing Student Learning in the Advanced Physics Lab
Academic Physicists' Introductory Teaching Improvement Efforts at Major Research Universities, at American Association of Physics Teachers Summer Meeting 2010 (Portland, OR, USA), Saturday, July 17, 2010
There is no shortage of PER literature describing research-based, instructional strategies for improving teaching in introductory college physics courses. [1] It remains, however, that most physics faculty with visions of improved teaching based on such strategies must overcome significant barriers, including a reward system structured to direct faculty attention toward research and away from pedagogy. [2] Barriers to teaching improvement are compounded at major research universities (MRUs), where science faculty must balance extreme demands for research productivity with their teaching... Read more about Academic Physicists' Introductory Teaching Improvement Efforts at Major Research Universities

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