Seeing Earth's Orbit in the Stars: Parallax and Aberration

During the 17th century the idea of an orbiting and rotating Earth became increasingly popular, but opponents of this view continued to point out that the theory had observable consequences that had never, in fact, been observed. Why, for instance, had astronomers failed to detect the annual parallax of the stars that must occur if Earth orbits the Sun? To address this problem, astronomers of the 17th and18th centuries sought to measure the annual parallax of stars using telescopes. None of them succeeded. Annual stellar parallax was not successfully measured until 1838, when Friedrich Bessel detected the parallax of the star 61 Cygni. But the early failures to detect annual stellar parallax led to the discovery of a new (and entirely unexpected) phenomenon: the aberration of starlight. This paper recounts the story of the discovery of stellar aberration. It is accompanied by a set of activities and computer simulations that allow students to explore this fascinating historical episode and learn important lessons about the nature of science.Comment: 10 pages, 5 figures, submitted to The Physics Teache

Introductory Physics In Biological Context: An Approach To Improve Introductory Physics For Life Science Students

We describe restructuring the introductory physics for life science students (IPLS) course to better support these students in using physics to understand their chosen fields. Our courses teach physics using biologically rich contexts. Specifically, we use examples in which fundamental physics contributes significantly to understanding a biological system to make explicit the value of physics to the life sciences. This requires selecting the course content to reflect the topics most relevant to biology while maintaining the fundamental disciplinary structure of physics. In addition to stressing the importance of the fundamental principles of physics, an important goal is developing students\u27 quantitative and problem solving skills. Our guiding pedagogical framework is the cognitive apprenticeship model, in which learning occurs most effectively when students can articulate why what they are learning matters to them. In this article, we describe our courses, summarize initial assessment data, and identify needs for future research. (C) 2014 American Association of Physics Teachers

Initial Interest, Goals, And Changes In CLASS Scores In Introductory Physics For Life Sciences

To examine the effect of extensive life science applications on student attitudes to learning physics, we analyzed CLASS data from life science students in introductory physics. We compare the same students\u27 responses from the first semester, taught with a standard syllabus, to the second semester, taught with extensive life science applications (IPLS). Although first semester responses become less favorable (pre to post), IPLS responses show an increase in favorable and a decrease in unfavorable responses. This is noteworthy because improvement is rarely observed without direct attention to attitudes/beliefs, and suggests IPLS courses are one possible approach to improving attitudes. Finally, we analyzed CLASS responses by gender, major, students\u27 stated goals in taking physics, and initial interest in physics; initial interest was determined from CLASS items chosen based on the Four-Phase Model of Interest Development. Most notably, we find that in the IPLS course, students identified as having low interest initially had the greatest gains

Density of States and NMR Relaxation Rate in Anisotropic Superconductivity with Intersecting Line Nodes

We show that the density of states in an anisotropic superconductor with intersecting line nodes in the gap function is proportional to $E log (\alpha \Delta_0 /E)$ for $|E| << \Delta_0$, where $\Delta_0$ is the maximum value of the gap function and $\alpha$ is constant, while it is proportional to $E$ if the line nodes do not intersect. As a result, a logarithmic correction appears in the temperature dependence of the NMR relaxation rate and the specific heat, which can be observed experimentally. By comparing with those for the heavy fermion superconductors, we can obtain information about the symmetry of the gap function.Comment: 7 pages, 4 PostScript Figures, LaTeX, to appear in J. Phys. Soc. Jp

Teaching the electrical origins of the electrocardiogram: An introductory physics laboratory for life science students

We present the design, pedagogical logic, and assessment of a laboratory and supporting materials that integrate a clinical academic cardiologist\u27s understanding of the origins of the electrocardiogram (ECG) with a physics educator\u27s insights into how to teach the underlying physics at the introductory level to life science students. In this article, we explain the choices made throughout the design process, connect a more advanced treatment of the physics to our approach, and present our assessment of the curriculum. Before the laboratory, students learn the cellular origins of the electric dipole potential produced by the heart on the body\u27s surface, including a simple physical model for the electrical activity of excitable cells, and learn to interpret the measured voltages of an ECG as probing components of the heart\u27s time-varying electric dipole moment. In the laboratory, students measure their own ECGs and analyze the data accordingly; they animate their data to display their own heart\u27s dipole moment for a single heartbeat. Our results from the assessment of student understanding and attitudes indicate that although students find the content challenging, nearly all students find it at least moderately interesting, and for about a quarter of the students in the course, this lab plays a highly meaningful part in connecting physics to medicine

Hypernatural Numbers as Ultrafilters

In this paper we present a use of nonstandard methods in the theory of ultrafilters and in related applications to combinatorics of numbers

Behavioral Inhibition as a Risk Factor for the Development of Childhood Anxiety Disorders: A Longitudinal Study

This longitudinal study examined the additive and interactive effects of behavioral inhibition and a wide range of other vulnerability factors in the development of anxiety problems in youths. A sample of 261 children, aged 5 to 8 years, 124 behaviorally inhibited and 137 control children, were followed during a 3-year period. Assessments took place on three occasions to measure children’s level of behavioral inhibition, anxiety disorder symptoms, other psychopathological symptoms, and a number of other vulnerability factors such as insecure attachment, negative parenting styles, adverse life events, and parental anxiety. Results obtained with Structural Equation Modeling indicated that behavioral inhibition primarily acted as a specific risk factor for the development of social anxiety symptoms. Furthermore, the longitudinal model showed additive as well as interactive effects for various vulnerability factors on the development of anxiety symptoms. That is, main effects of anxious rearing and parental trait anxiety were found, whereas behavioral inhibition and attachment had an interactive effect on anxiety symptomatology. Moreover, behavioral inhibition itself was also influenced by some of the vulnerability factors. These results provide support for dynamic, multifactorial models for the etiology of child anxiety problems

Friedel oscillations induced by non-magnetic impurities in the two-dimensional Hubbard model

We study the interplay of correlations and disorder using an unrestricted Slave-Boson technique in real space. Within the saddle-point approximation, we find Friedel oscillations of the charge density in the vicinity of a nonmagnetic impurity, in agreement with numerical simulations. The corresponding amplitudes are suppressed by repulsive interactions, while attractive correlations lead to a charge-density-wave enhancement. In addition, we investigate the spatial dependence of the local magnetic moment and the formation of a magnetic state at the impurity site.Comment: 9 pages, RevTeX, includes 8 figure

Quantum gravitational corrections to black hole geometries

We calculate perturbative quantum gravity corrections to eternal two-dimensional black holes. We estimate the leading corrections to the AdS_2 black hole entropy and determine the quantum modification of N-dimensional Schwarzschild spacetime.Comment: 15 pages, 6 figures. Revised version: Introduction and conclusion expanded, section II reshaped, references added. Accepted for publication in Phys. Rev.