Elementary Scattering Theory

The opportunities for doing scattering experiments at synchrotron and neutron facilities have grown rapidly in recent years and are set to continue to do so into the foreseeable future. This text provides a basic understanding of how these techniques enable the structure and dynamics of materials to be studied at the atomic and molecular level. Although mathematics cannot be avoided in a theoretical discussion, the aim has been to write a book that most scientists will still find approachable. To this end, the first two chapters are devoted to providing a tutorial background in the mathematics and physics that are implicitly assumed in other texts. Thereafter, the philosophy has been one of keeping things as simple as possible

Elementary Scattering Theory

The opportunities for doing scattering experiments at synchrotron and neutron facilities have grown rapidly in recent years and are set to continue to do so into the foreseeable future. This text provides a basic understanding of how these techniques enable the structure and dynamics of materials to be studied at the atomic and molecular level. Although mathematics cannot be avoided in a theoretical discussion, the aim has been to write a book that most scientists will still find approachable. To this end, the first two chapters are devoted to providing a tutorial background in the mathematics and physics that are implicitly assumed in other texts. Thereafter, the philosophy has been one of keeping things as simple as possible

Measurement Invariance, Entropy, and Probability

We show that the natural scaling of measurement for a particular problem defines the most likely probability distribution of observations taken from that measurement scale. Our approach extends the method of maximum entropy to use measurement scale as a type of information constraint. We argue that a very common measurement scale is linear at small magnitudes grading into logarithmic at large magnitudes, leading to observations that often follow Student's probability distribution which has a Gaussian shape for small fluctuations from the mean and a power law shape for large fluctuations from the mean. An inverse scaling often arises in which measures naturally grade from logarithmic to linear as one moves from small to large magnitudes, leading to observations that often follow a gamma probability distribution. A gamma distribution has a power law shape for small magnitudes and an exponential shape for large magnitudes. The two measurement scales are natural inverses connected by the Laplace integral transform. This inversion connects the two major scaling patterns commonly found in nature. We also show that superstatistics is a special case of an integral transform, and thus can be understood as a particular way in which to change the scale of measurement. Incorporating information about measurement scale into maximum entropy provides a general approach to the relations between measurement, information and probability

General heatbath algorithm for pure lattice gauge theory

A heatbath algorithm is proposed for pure SU(N) lattice gauge theory based on the Manton action of the plaquette element for general gauge group N. Comparison is made to the Metropolis thermalization algorithm using both the Wilson and Manton actions. The heatbath algorithm is found to outperform the Metropolis algorithm in both execution speed and decorrelation rate. Results, mostly in D=3, for N=2 through 5 at several values for the inverse coupling are presented.Comment: 9 pages, 10 figures, 1 table, major revision, final version, to appear in PR

Is sex ratio at birth an appropriate measure of prenatal sex-selection? Findings of a theoretical model and its application to India

Son preference and prenatal sex selection against females have resulted in significant sex ratio at birth (SRB) imbalances well documented in several Asian countries, including India and China. The SRB bias is generally used as indicator for the extent and trends of prenatal sex selection against females. Decreasing fertility levels are expected to increase sex selection and thus SRB bias, since desiring fewer children increases the risk for families to remain sonless (fertility squeeze effect). We developed and employ mathematical models linking family size, birth order and childbearing strategies with population SRB bias. We show that SRB bias can increase despite fewer sex selection interventions occurring, inconsistent with the expectation of the fertility squeeze effect. We show that a disproportionality effect of fertility reduction amplifies SRB bias, in addition to the fertility squeeze effect, making SRB bias an inaccurate indicator for changes in sex selection practices within a population. We propose to use sex selection propensity (proportion of couples intervening) to measure behavioural change and evaluate policies targeting sex selection practices. We apply our findings to India, showing for instance that sex selection propensity in Punjab and Delhi was lower than in Rajasthan or Uttar Pradesh, despite significantly higher SRB bias in the former. While we observe a continuous overall increase in the SRB over the 2005-2010 period in India, our results indicate that prenatal sex selection propensity started declining during that period

Application of a Bayesian Method to Absorption Spectral-Line Finding in Simulated ASKAP Data

The large spectral bandwidth and wide field of view of the Australian SKA Pathfinder radio telescope will open up a completely new parameter space for large extragalactic HI surveys. Here we focus on identifying and parametrising HI absorption lines which occur in the line of sight towards strong radio continuum sources. We have developed a method for simultaneously finding and fitting HI absorption lines in radio data by using multi-nested sampling, a Bayesian Monte Carlo algorithm. The method is tested on a simulated ASKAP data cube, and is shown to be reliable at detecting absorption lines in low signal-to-noise data without the need to smooth or alter the data. Estimation of the local Bayesian evidence statistic provides a quantitative criterion for assigning significance to a detection and selecting between competing analytical line-profile models.Comment: 8 pages, 5 figures and 1 table; accepted for publication in PAS

Bayesian curve fitting for lattice gauge theorists

A new method of extracting the low-lying energy spectrum from Monte Carlo estimates of Euclidean-space correlation functions which incorporates Bayesian inference is described and tested. The procedure fully exploits the information present in the correlation functions at small temporal separations and uses this information in a way consistent with fundamental probabilistic hypotheses. The computed errors on the best-fit energies include both statistical uncertainties and systematic errors associated with the treatment of contamination from higher-lying stationary states. Difficulties in performing the integrals needed to compute these error estimates are briefly discussed.Comment: 7 pages, 6 figures, 2 tables, uses espcrc2. Talk presented at the Workshop on Lattice Hadron Physics, Colonial Club Resort, Cairns, Australia, July 9-18, 200

Teacher Perceptions of Project Based Learning in the Secondary Classroom

This study examines teacher perceptions of their experiences with Project Based Learning (PBL) at a secondary school in Western Canada. This PBL initiative included English language arts, mathematics, science, and digital literacy courses and all the grade nines at this large secondary school. This article reports on two teacher focus group interviews that were part of a larger mixed-methods study (Creswell & Plano Clark, 2007). Results provide specific details regarding conditions for the successful implementation of PBL, challenges and support for current research into PBL, and areas of additional needed research.Cette étude se penche sur les perceptions qu’ont les enseignants de leurs expériences avec l’apprentissage axé sur les projets (PBL—project based learning) dans une grande école secondaire dans l’Ouest canadien. Cette initiative d’apprentissage actif par les projets impliquait les cours d’anglais, de mathématiques, de sciences et de littératie numérique, ainsi que les tous les élèves de la 9e année. Cet article porte sur un élément de cette étude à méthodologie mixte (Creswell & Plano Clark, 2007), soit deux groupes de discussion/entrevues avec des enseignants. Les résultats fournissent des détails sur les conditions nécessaires à la mise en œuvre réussie du PBL, les défis qui en découlent, l’appui pour la recherche actuelle et les domaines qui restent à étudier plus en profondeur

Moving from EDID Words to Policy Action: A Case Study of a Teacher Education Program’s Admissions Policy Reform

Regardless of the commitments that universities and teacher education programs (TEPs) have publicly stated regarding equity, diversity, inclusion, or decolonization (EDID), rarely do these commitments impact their admission policies or practices. Through examining a small program’s efforts at implementing EDID change over a three-year period, this article provides critical reflections, questions, and action steps for TEPs looking to move beyond talking about the importance of EDID, to actually altering policies and procedures to address systemic change. Utilizing the concepts of “equity in” and “equity through” admissions, intake variables (Multiple Mini Interview [MMI], Program Preparation, GPA) were analyzed quantitatively and used in this beginning participatory action research project. Results illustrate the benefits of the MMI, the need for program admissions to account for capacities in relation to anti-racism directly, rather than just generally referring to equity, and the need for admission practices to reflect an appreciation of the complexities around identity and ethics.Quels que soient les engagements publics pris par les universités et les programmes de formation des enseignants en matière d’équité, de diversité, d’inclusion et de décolonisation (EDID), il est rare que ceux-ci se traduisent en impacts sur leurs politiques ou pratiques d’admission. En examinant les efforts déployés par un petit programme pour implanter les changements EDID sur une période de trois ans, cet article présente des réflexions critiques, des questionnements et des actions à entreprendre afin que les programmes de formation des enseignants puissent dépasser les discours sur l’importance de l’EDID en modifiant réellement leurs politiques et procédures dans une perspective de changement systémique. En utilisant les concepts d’« équité dans » et d’« équité par » les admissions, les variables d’admission (minientretiens multiples [MEM], programme de préparation, moyenne générale) ont été analysées quantitativement et utilisées dans l’amorce de ce projet de recherche-action participative. Les résultats montrent les avantages des MEM, ainsi que la nécessité pour les admissions aux programmes d’adopter des pratiques qui tiennent compte de leur capacité à soutenir directement la lutte contre le racisme — plutôt que de se contenter des notions générales d’équité — et qui reflètent une appréciation des complexités entourant l’identité et l’éthique

Syllepse et antanaclase : procédés rhétoriques dans le slogan publicitaire

This study concentratres upon the lexical strategies that include figures and rhetorical devices like metaphor or metonymy and their functioning in advertising messages. The identified figures of rhetoric are used to support and increase advertising effectiveness and are responsible for creativity in advertising