Magnetic field relaxation in ferromagnetic Ising systems

We analyze the thermal magnetization reversal processes in magnetic grains. Two experiments are carried out: swtiching time and switching field experiments. In both cases, we find that the simulated behavior is coherent with existing experimental data (the streched exponent of the switching time experiment increases with the temperature and is superior to unity; there exists a master curve for the switching field experiment). Moreover, we simulated magnetic grains in a region of parameters where no experimental data are available. We find that the relaxation time distribution $P(\ln{\tau})$ is gaussian, and we find the existence of a strong field regime.Comment: 9 pages, 7 figures, J.M.M.

Wireless Keypads - A New Classroom Technology Using Enhanced Multiple-Choice Questions

This article discusses the advantages of using wireless keypads in the Lecture/classroom. This new technology requires multiple-choice (MC) questions to mate with the keypad entry features of these devices. The format of the traditional MC response is constrained to five choices and only one best response is allowed. For this reason, we propose enhancements to the traditional MC question. This enhanced MC question allows as many as ten answers. The answers can vary in their degree of correctness and can be assigned partial credit. By combining wireless keypads and multiple-choice questions, we can readily perform both formative and summative assessments of student learning. Examples and classroom applications are presented.Comment: pdf file, 8 pages,

Heterogeneous multireference alignment: a single pass approach

Multireference alignment (MRA) is the problem of estimating a signal from many noisy and cyclically shifted copies of itself. In this paper, we consider an extension called heterogeneous MRA, where $K$ signals must be estimated, and each observation comes from one of those signals, unknown to us. This is a simplified model for the heterogeneity problem notably arising in cryo-electron microscopy. We propose an algorithm which estimates the $K$ signals without estimating either the shifts or the classes of the observations. It requires only one pass over the data and is based on low-order moments that are invariant under cyclic shifts. Given sufficiently many measurements, one can estimate these invariant features averaged over the $K$ signals. We then design a smooth, non-convex optimization problem to compute a set of signals which are consistent with the estimated averaged features. We find that, in many cases, the proposed approach estimates the set of signals accurately despite non-convexity, and conjecture the number of signals $K$ that can be resolved as a function of the signal length $L$ is on the order of $\sqrt{L}$.Comment: 6 pages, 3 figure

Constitutional Procedure for the Reform of the Supreme Court of Canada

L'auteur nous trace l'évolution de la Cour suprême du Canada créée en 1875 ainsi que des implications pour cette Cour, de la venue de la Loi constitutionnelle de1982, spécialement des articles 41(d) et 42(l)(d). Il exprime son point de vue quant au nombre de juges qui doivent siéger, aux quotas régionaux, aux méthodes de sélection. Il examine aussi la question de savoir si la Cour suprême doit continuer d'être le tribunal général d'appel au Canada ou si elle devrait se spécialiser en droit public et constitutionnel

The Fiercest Debate: Cecil A. Wright, the Benchers and Legal Education in Ontario 1923-1957

In the dozen years after the end of the Second World War, long-standing conflicts about the nature of education for the legal profession in Ontario became especially acute. Fortunately, climax and successful compromise came in 1957. In that year the Law Society of Upper Canada, which had controlled legal education and admission to practice from the early days of the Colony of Upper Canada, gave up its monopoly of legal education and conceded an equal position in this respect to Ontario universities willing and able to enter the field. Several were, and promptly did so. Indeed the University of Toronto was already there. For many decades it had been teaching law, but the Law Society refused proper recognition to the University of Toronto law degrees for purposes of admission to the legal profession in the Province

Preparation, characterization, and electrical properties of epitaxial NbO2 thin film lateral devices

Epitaxial NbO2 (110) films, 20 nm thick, were grown by pulsed laser deposition on Al2O3 (0001) substrates. The Ar/O2 total pressure during growth was varied to demonstrate the gradual transformation between NbO2 and Nb2O5 phases, which was verified using x-ray diffraction, x-ray photoelectron spectroscopy, and optical absorption measurements. Electric resistance threshold switching characteristics were studied in a lateral geometry using interdigitated Pt top electrodes in order to preserve the epitaxial crystalline quality of the films. Volatile and reversible transitions between high and low resistance states were observed in epitaxial NbO2 films, while irreversible transitions were found in case of Nb2O5 phase. Electric field pulsed current measurements confirmed thermally-induced threshold switching.Comment: This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics D: Applied Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0022-3727/48/33/33530