Addressing student models of energy loss in quantum tunnelling

We report on a multi-year, multi-institution study to investigate student reasoning about energy in the context of quantum tunnelling. We use ungraded surveys, graded examination questions, individual clinical interviews, and multiple-choice exams to build a picture of the types of responses that students typically give. We find that two descriptions of tunnelling through a square barrier are particularly common. Students often state that tunnelling particles lose energy while tunnelling. When sketching wave functions, students also show a shift in the axis of oscillation, as if the height of the axis of oscillation indicated the energy of the particle. We find inconsistencies between students' conceptual, mathematical, and graphical models of quantum tunnelling. As part of a curriculum in quantum physics, we have developed instructional materials to help students develop a more robust and less inconsistent picture of tunnelling, and present data suggesting that we have succeeded in doing so.Comment: Originally submitted to the European Journal of Physics on 2005 Feb 10. Pages: 14. References: 11. Figures: 9. Tables: 1. Resubmitted May 18 with revisions that include an appendix with the curriculum materials discussed in the paper (4 page small group UW-style tutorial

Productive resources in students’ ideas about energy: An alternative analysis of Watts’ original interview transcripts

For over 30 years, researchers have investigated students’ ideas about energy with the intent of reforming instructional practice. In this pursuit, Watts contributed an influential study with his 1983 paper “Some alternative views of energy” [Phys. Educ. 18, 213 (1983)]. Watts’ “alternative frameworks” continue to be used for categorizing students’ non-normative ideas about energy. Using a resources framework, we propose an alternate analysis of student responses from Watts’ interviews. In our analysis, we show how students’ activated resources about energy are disciplinarily productive. We suggest that fostering seeds of scientific understandings in students’ ideas about energy may play an important role in their development of scientific literacy

Students Talk about Energy in Project- Based Inquiry Science

We examine the types of emergent language eighth grade students in rural Maine middle schools use when they discuss energy in their first experiences with Project-Based Inquiry Science: Energy, a research-based curriculum that uses a specific language for talking about energy. By comparative analysis of the language used by the curriculum materials to students’ language, we find that students’ talk is at times more aligned with a Stores and Transfer model of energy than the Forms model supported by the curriculum

Trialkylphosphine-mediated synthesis of 2-Acyl furans from ynenones

A novel reaction for the synthesis of 2-acyl furans is reported. The reaction is believed to proceed by sequential addition of a trialkylphosphine to an ynenone, 5-exo-dig cyclization to form the furan, and oxidation of the resulting phosphonium ylide with molecular oxygen. Many common functional groups are tolerated during the reaction, and the products are obtained in good to excellent yield under the mild conditions. This methodology offers efficient access to biologically important compounds, including fused polycyclic compounds and furaldehydes, from simple starting materials

Collaborative Project: Developing a tutorial approach to enhance student learning of intermediate mechanics

There is a need among science students for increased conceptual and mathematical understanding in courses beyond the introductory level. Future scientists, future secondary science teachers, and future engineers who take these courses must create an effective bridge between the mathematical reasoning emphasized in most physics classes and the physical intuition that will guide their future work. Using past success as a template, the collaborating PI\u27s are developing Intermediate Mechanics Tutorials, a set of at least 23 tutorials, including pencil-and-paper conceptual tutorials (15), mathematical tutorials (4), and computer-based tutorials (4), for the purpose of enhancing instruction in intermediate mechanics. Each tutorial is accompanied by a pretest (ungraded quiz), homework problems, and post-tests (exam questions). Tutorials are designed to allow flexible implementation in lecture, studio, laboratory, or seminar courses. Intellectual Merit: Tutorial materials act as supplements to (rather than replacements of) regular lecture instruction. Materials address specific difficulties students have when learning the physics. Having the materials in place allows for greater understanding of what student difficulties in intermediate mechanics are, as well as providing data about the difficulties. Physics education research (PER) data not only can enhance future versions of these materials but also can help instructors using other similar materials in their classes.Broader impact: A coherent set of materials is being created for teaching intermediate mechanics more effectively. These materials can reach future scientists, teachers, and future university faculty. The research-based development work can inform other ongoing PER investigations. Dissemination to interested physics faculty members can help them learn about and utilize innovative teaching methods

Low-temperature behavior of the statistics of the overlap distribution in Ising spin-glass models

Using Monte Carlo simulations, we study in detail the overlap distribution for individual samples for several spin-glass models including the infinite-range Sherrington-Kirkpatrick model, short-range Edwards-Anderson models in three and four space dimensions, and one-dimensional long-range models with diluted power-law interactions. We study three long-range models with different powers as follows: the first is approximately equivalent to a short-range model in three dimensions, the second to a short-range model in four dimensions, and the third to a short-range model in the mean-field regime. We study an observable proposed earlier by some of us which aims to distinguish the "replica symmetry breaking" picture of the spin-glass phase from the "droplet picture," finding that larger system sizes would be needed to unambiguously determine which of these pictures describes the low-temperature state of spin glasses best, except for the Sherrington-Kirkpatrick model which is unambiguously described by replica symmetry breaking. Finally, we also study the median integrated overlap probability distribution and a typical overlap distribution, finding that these observables are not particularly helpful in distinguishing the replica symmetry breaking and the droplet pictures.Comment: 11 pages, 6 figure

Kerncraft: A Tool for Analytic Performance Modeling of Loop Kernels

Achieving optimal program performance requires deep insight into the interaction between hardware and software. For software developers without an in-depth background in computer architecture, understanding and fully utilizing modern architectures is close to impossible. Analytic loop performance modeling is a useful way to understand the relevant bottlenecks of code execution based on simple machine models. The Roofline Model and the Execution-Cache-Memory (ECM) model are proven approaches to performance modeling of loop nests. In comparison to the Roofline model, the ECM model can also describes the single-core performance and saturation behavior on a multicore chip. We give an introduction to the Roofline and ECM models, and to stencil performance modeling using layer conditions (LC). We then present Kerncraft, a tool that can automatically construct Roofline and ECM models for loop nests by performing the required code, data transfer, and LC analysis. The layer condition analysis allows to predict optimal spatial blocking factors for loop nests. Together with the models it enables an ab-initio estimate of the potential benefits of loop blocking optimizations and of useful block sizes. In cases where LC analysis is not easily possible, Kerncraft supports a cache simulator as a fallback option. Using a 25-point long-range stencil we demonstrate the usefulness and predictive power of the Kerncraft tool.Comment: 22 pages, 5 figure

Revision of the amphiamerican genus Mysidium Dana, 1852 (Crustacea: Mysida: Mysidae), with descriptions of two new species and the establishment of two new subgenera

Revised definitions are given for the genus Mysidium Dana, 1852, and its eight previously known species, based on material from Curacao, Bonaire and SE-Brazil, along with the evaluation of published data. Type material of Diamysis columbiae Zimmer, 1915, M. cubanense Bacescu & Ortiz, 1984 and M. rubroculatum Bacescu & Ortiz, 1984 is examined. A lectotype is designated for D. columbiae Zimmer, 1915, a senior synonym of Mysidium columbiae (Zimmer, 1915). Two new species are described, M. triangulare Wittmann sp. nov. from Curacao and M. antillarun Wittmann sp. nov. from Curacao and Bonaire. Known ranges arc extended by first records of M. cubanense from Curacao and Bonaire and of M. integrum W.M. Tattersall, 1951 from SE Brazil. Three morphologically different groups are established at the subgeneric level: (1) the nominotypical subgenus Mysidium Dana, 1852 with M. gracile (Dana, 1852), M. integrum, M. cubanense, M. rubroculatum and M. triangulare sp. nov. from the West Atlantic plus M. rickettsi Harrison & Bowman, 1987 from the East Pacific; (2) Occimysidium Wittmann subgen. nov. represented only by M. pumae Ortiz, Hendrickx & Winfield, 2017 from the Pacific coast of Mexico; and finally (3) Orientomysidium Wittmann subgen. nov. comprising M. columbiae and M. antillarum sp. nov. from the West Atlantic. The poorly known M. iliffei Bacescu, 1991 is not assigned to any subgenus. A key to the resulting three subgenera and ten nominal species of the genus Mysidium is given.info:eu-repo/semantics/publishedVersio