Tunable beam displacer

We report the implementation of a tunable beam displacer, composed of a polarizing beam splitter (PBS) and two mirrors, that divides an initially polarized beam into two parallel beams whose separation can be continuously tuned. The two output beams are linearly polarized with either vertical or horizontal polarization and no optical path difference is introduced between them. The wavelength dependence of the device as well as the maximum separation between the beams achievable is limited mainly by the PBS characteristics.Comment: 3 pages, 2 figure

Are There Lasting Effects of a Schema Based Learning System in Interior Design Studio?

Gallini (1989) argues that, “the ability to combine a collection of problems into a meaningful representation, or schema facilitates learning” (p. 244). In a previous study, it was found that introducing a schema-based learning system in the design studio assisted novice designers in a structured, purposeful process, where they began to see patterns of information and use these patterns to develop and refine their design solutions. Their design solutions proved to be significantly better than the other students who did not utilize the instructional interventions. But, does this instructional intervention have any lasting effects with this same group of students? Do these skills transfer to new or novel tasks after a period of time ? The aim of this study is to measure the lasting effects of this learning tool by following this group of students through a new set of transfer tasks approximately one year after the original instructional intervention. Like the previous year study, the effectiveness characteristics were examined from four main areas of a design project: 1) organization of information, 2) categorization of information, 3) application of theory, and 4) overall design. The following research questions were addressed: 1. What are the lasting effects of the schema-based learning tools after one year from the initial implementation of the instructional intervention? Or, what are the problem solving transfer effects of the instructional intervention? 2. Do students, who use these schema-based learning tools, develop projects that are more organized, categorized, more theoretically-based, and have better overall designs, than students who do not use such learning tools

The Utility of a Bright-line Rule in Copyright Law: Freeing Judges from Aesthetic Controversy and Conceptual Separability in Leicester v. Warner Bros.

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An Imaging Fabry-Perot System for the Robert Stobie Spectrograph on the Southern African Large Telescope

We present the design of the Fabry-Perot system of the Robert Stobie Spectrograph on the 10-meter class Southern African Large Telescope and its characterization as measured in the laboratory. This system provides spectroscopic imaging at any desired wavelength spanning a bandpass 430 - 860 nm, at four different spectral resolving powers ranging from 300 to 9000. Our laboratory tests revealed a wavelength dependence of the etalon gap and parallelism with a maximum variation between 600 - 720 nm that arises because of the complex structure of the broadband multi-layer dielectric coatings. We also report an unanticipated optical effect of this multi-layer coating structure that produces a significant, and wavelength dependent, change in the apparent shape of the etalon plates. This change is caused by two effects: the physical non-uniformities or thickness variations in the coating layers, and the wavelength dependence of the phase change upon refection that can amplify these non-uniformities. We discuss the impact of these coating effects on the resolving power, finesse, and throughput of the system. This Fabry-Perot system will provide a powerful tool for imaging spectroscopy on one of the world's largest telescopes.Comment: 17 pages, 14 figures, accepted for publication in The Astronomical Journa

Riccati parameter modes from Newtonian free damping motion by supersymmetry

We determine the class of damped modes \tilde{y} which are related to the common free damping modes y by supersymmetry. They are obtained by employing the factorization of Newton's differential equation of motion for the free damped oscillator by means of the general solution of the corresponding Riccati equation together with Witten's method of constructing the supersymmetric partner operator. This procedure leads to one-parameter families of (transient) modes for each of the three types of free damping, corresponding to a particular type of %time-dependent angular frequency. %time-dependent, antirestoring acceleration (adding up to the usual Hooke restoring acceleration) of the form a(t)=\frac{2\gamma ^2}{(\gamma t+1)^{2}}\tilde{y}, where \gamma is the family parameter that has been chosen as the inverse of the Riccati integration constant. In supersymmetric terms, they represent all those one Riccati parameter damping modes having the same Newtonian free damping partner modeComment: 6 pages, twocolumn, 6 figures, only first 3 publishe

The politics of prisoner legal rights

The article begins by locating human rights law within the current political context before moving on to critically review judicial reasoning on prisoner legal rights since the introduction of the Human Rights Act 1998. The limited influence of proportionality on legal discourses in England and Wales is then explored by contrasting a number of judgments since October 2000 in the domestic courts and European Court of Human Rights (ECtHR). The article concludes with a discussion of the implications of the restricted interpretation of legal rights for penal reform and proposes an alternative radical rearticulation of the politics of prisoner human rights

Hong-Ou-Mandel interferometer with cavities: theory

We study the number of coincidences in a Hong-Ou-Mandel interferometer exit whose arms have been supplemented with the addition of one or two optical cavities. The fourth-order correlation function at the beam-splitter exit is calculated. In the regime where the cavity length are larger than the one-photon coherence length, photon coalescence and anti-coalescence interference is observed. Feynman's path diagrams for the indistinguishable processes that lead to quantum interference are presented. As application for the Hong-Ou-Mandel interferometer with two cavities, it is discussed the construction of an optical XOR gate

Rolling of asymmetric disks on an inclined plane

In a recent papers, Turner and Turner (2010 {\em Am. J. Phys.} {\bf 78} 905-7) and Jensen (2011 {\em Eur. J. Phys.} {\bf 32} 389-397) analysed the motion of asymmetric rolling rigid bodies on a horizontal plane. These papers addressed the common misconception that the instantaneous point of contact of the rolling body with the plane can be used to evaluate the angular momentum $\mathbf L$ and the torque $\boldsymbol\tau$ in the equation of motion $d\mathbf L/dt = \boldsymbol\tau$. To obtain the correct equation of motion, the "phantom torque" or various rules that depend on the motion of the point about which $\mathbf L$ and $\boldsymbol\tau$ are evaluated were discussed. In this paper, I consider asymmetric disks rolling down an inclined plane and describe the most basic way of obtaining the correct equation of motion; that is, to choose the point about which $\mathbf L$ and $\boldsymbol\tau$ are evaluated that is stationary in an inertial frame