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

Casimir Energy and Entropy between perfect metal Spheres

We calculate the Casimir energy and entropy for two perfect metal spheres in the large and short separation limit. We obtain nonmonotonic behavior of the Helmholtz free energy with separation and temperature, leading to parameter ranges with negative entropy, and also nonmonotonic behavior of the entropy with temperature and with the separation between the spheres. The appearance of this anomalous behavior of the entropy is discussed as well as its thermodynamic consequences.Comment: 10 pages and 8 figures. Accepted for publication in the Proceedings of the tenth conference on Quantum Field Theory under the influence of external conditions - QFEXT'1

Preliminary results of passive microwave snow experiment during February and March 1978

The purpose of the experiment was to determine if remote microwave sensing of snowpack data could be used to predict runoff, thereby allowing more efficient management of the water supply. A four-frequency microwave radiometer system was attached to a truck-mounted aerial lift and was used to gather data on snowpacks at three different sites in the Colorado Rocky Mountains. Ground truth data measurements (density, temperature, grain size, hardness, and free-liquid water content) were taken at each site corresponding to each microwave scan

Using resource graphs to represent conceptual change

We introduce resource graphs, a representation of linked ideas used when reasoning about specific contexts in physics. Our model is consistent with previous descriptions of resources and coordination classes. It can represent mesoscopic scales that are neither knowledge-in-pieces or large-scale concepts. We use resource graphs to describe several forms of conceptual change: incremental, cascade, wholesale, and dual construction. For each, we give evidence from the physics education research literature to show examples of each form of conceptual change. Where possible, we compare our representation to models used by other researchers. Building on our representation, we introduce a new form of conceptual change, differentiation, and suggest several experimental studies that would help understand the differences between reform-based curricula.Comment: 27 pages, 14 figures, no tables. Submitted for publication to the Physical Review Special Topics Physics Education Research on March 8, 200

Probabilistic Cloning of Coherent States without a Phase Reference

We present a probabilistic cloning scheme operating independently of any phase reference. The scheme is based solely on a phase-randomized displacement and photon counting, omitting the need for non-classical resources and non-linear materials. In an experimental implementation, we employ the scheme to clone coherent states from a phase covariant alphabet and demonstrate that the cloner is capable of outperforming the hitherto best-performing deterministic scheme. An analysis of the covariances between the output states shows that uncorrelated clones can be approached asymptotically. An intriguing feature is that the trade-off between success rate and achieved fidelity can be optimized even after the cloning procedure

Atmospheric fluctuations below 0.1 Hz during drift-scan solar diameter measurements

Measurements of the power spectrum of the seeing in the range 0.001-1 Hz have been performed in order to understand the criticity of the transits' method for solar diameter monitoring.Comment: 3 pages, 3 figures, proc. of the Fourth French-Chinese meeting on Solar Physics Understanding Solar Activity: Advances and Challenges, 15 - 18 November, 2011 Nice, Franc

A ferrovia no Vale do Itajaí

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Urbanismo, História e Arquitetura da CidadeO tema desta dissertação é uma análise dos fatos históricos relacionados ao processo de implantação e à posterior desativação da EFSC no Vale do Itajaí, destacando os principais agentes do processo e a conseqüência de suas ações no domínio geográfico e social. Esta pesquisa tem sua relevância social e acadêmica como instrumento de pesquisa e de memória baseado na organização dos fatos históricos desencadeados em torno dos transportes no Vale do Itajaí, com foco para o transporte ferroviário, uma vez que há pouca publicação e pesquisa sobre a EFSC. O trabalho foi referenciado pela análise das relações sociais sob os conceitos de Santos (1991), de fatos históricos registrados em periódicos, documentos escritos, fotográficos e cartográficos, entrevistas e, quando necessário, pela busca da contextualização dentro dos acontecimentos nacionais e internacionais, para melhor esclarecimento dos fatos em escala local e regional. Além disso, esta pesquisa usou como referência a análise e os conceitos de Mumford, em sua obra A Cidade na História, abordando o processo de transformações urbanas decorrente do desenvolvimento das cidades e seus principais agentes. Conceitos de outros autores, como Villaça, Lefebvre e Halbwachs são igualmente suportes teóricos deste trabalho. A ferrovia fez parte dos planos das lideranças locais, desde as primeiras décadas de história da fundação dos núcleos urbanos na região da bacia do Itajaí, como questão básica para o desenvolvimento econômico da região. The theme of this thesis is an analysis of historical facts related to the process of implantation and further disabling of EFSC (Estrada de Ferro Santa Catarina) in the region of Vale do Itajaí, State of Santa Catarina, highlighting the main agents of the case and the consequences of their actions both on geographical and social domain. This research has a social and academic relevance as a tool for further search and memory since it presents the organization of historical facts regarding transport in the region of Vale do Itajaí, with a focus on railway transportation, especially EFSC, from which little research sources and publications can be found. The work is referenced by an analysis of social relations according to the concepts of Santos (1991); historical facts recorded in journals, written, photographic, cartographic documents; and interviews. It includes, also, some search on the context of national and international events in order to offer a better understanding of the facts in a local and regional scale. Additionally, this research used as a reference to the concepts shown an analysis registered by Mumford in his book "A Cidade na História", around the process of urban transformations resulting from the development of cities and their key players. Concepts of other authors, as Villaça, Lefebvre and Halbwachs are also devices of this theoretical work. The railway took part of the local leaders' plans since the first decades of the history of the foundation of urban areas located at the basin of the Itajaí River. It was, at that time, a basic need for the economic development of the region