A B S T R A C TBy a combination of radiative lifetimes measured using the fast-beam-laser method and experimental branching ratios deduced from Fourier transform spectrometer spectra, it has been possible to derive experimental f-values for Lu ii lines observed in the visible and nearultraviolet regions. These data are compared with relativistic Hartree±Fock calculations, taking core polarization effects into account, and a set of additional oscillator strengths of astrophysical interest is presented.

Propagation through silicon-on-insulator (SOI) waveguide structures of 1.53 μm, 100 fs laser pulses with peak powers up to 400 W is studied experimentally and theoretically. The dominant nonlinear effects are two-photon absorption and self-phase modulation. The two-photon absorption coefficient and the nonlinear refractive index of Si obtained in this work are β2=0.9 cm/GW and n2=0.7×10−13 cm2/W, respectively. At high intensities, free carriers generated by two-photon absorption are demonstrated to have a significant influence on pulse spectra and transmitted power. The figure of merit for all-optical switching obtained in this work (T=1.8) indicates that a switch based on a SOI waveguide structure might be possible at 1.55 μm.

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Assigning open textbooks in college and university courses can help students save money on increasingly expensive commercial textbooks, and recent research shows that this savings can often be achieved with little to no sacrifice in textbook quality or student learning outcomes. We add to this body of research by examining the use of an open textbook in an introductory physics course at a large research university in Canada that enrols approximately 800-900 students per year. In this course, the instructors revised an open textbook and combined it with other learning resources onto a single website, whereas more than one source of learning materials was used previously. We used the COUP framework to structure our analysis, focusing on cost, outcomes, use, and perceptions in relation to the open textbook assigned in the course. Through the use of a survey of students and data about student learning outcomes in the form of final exam and course grades, and shifts on the pre-/post-Colorado Learning Attitudes about Science Survey, we show that student savings by moving to an open textbook were accompanied by little change in learning outcomes. We also show that the vast majority of survey respondents perceived the open textbook to be of the same or better quality than commercial textbooks used in their other courses.Further, many of them appreciated the fact that the textbook was customized to this particular coursewhich is made possible by the use of a textbook with an open license.