Classical Robustness of Quantum Unravellings

We introduce three measures which quantify the degree to which quantum systems possess the robustness exhibited by classical systems when subjected to continuous observation. Using these we show that for a fixed environmental interaction the level of robustness depends on the measurement strategy, or unravelling, and that no single strategy is maximally robust in all ways.Comment: 8 Pages, 2 figures, Version 2. Minor changes to wording for clarification and some references added. Accepted for publication in Europhysics Letter

Precision microwave dielectric and magnetic susceptibility measurements of correlated electronic materials using superconducting cavities

We analyze microwave cavity perturbation methods, and show that the technique is an excellent, precision method to study the dynamic magnetic and dielectric response in the $GHz$ frequency range. Using superconducting cavities, we obtain exceptionally high precision and sensitivity for measurements of relative changes. A dynamic electromagnetic susceptibility $\tilde{\zeta}(T)=\zeta ^{\prime}+i\zeta ^{\prime \prime}$ is introduced, which is obtained from the measured parameters: the shift of cavity resonant frequency $\delta f$ and quality factor $Q$. We focus on the case of a spherical sample placed at the center of a cylindrical cavity resonant in the $TE_{011}$ mode. Depending on the sample characteristics, the magnetic permeability $\tilde{\mu}$, the dielectric permittivity $\tilde{\epsilon}$ and the complex conductivity $\tilde{\sigma}$ can be extracted from $\tilde{\zeta}_{H}$. A full spherical wave analysis of the cavity perturbation is given. This analysis has led to the observation of new phenomena in novel low dimensional materials.Comment: 16 pages, 5 figure

Portfolios as assessment for learning: A case study of pre-service Foundation Phase teacher education students

South African Foundation Phase teacher education programmes are criticised for not delivering critical and creative students who can rightfully take their place in an ever-changing world. Moreover, the demand for developing teacher education programmes that are of high quality and lead to meaningful development of teachers as well as several national and institutional teacher education policy changes has led to revisions to approaches to assessment. The aim of this article is to indicate how portfolios can be used as a reflective learning tool in assessment. A qualitative exploratory case study is presented where Foundation Phase teacher education portfolios were analysed thematically to establish whether portfolios promote learning through students’ engagement in reflection. We argue that student reflections through portfolios have the potential of enhancing the process of thinking about learning, thereby encouraging students to think about more than just their marks, but also their personal development and growth. An analysis of the data showed that students developed the ability to reflect as they progressed through the portfolio, albeit superficially. There were strong indicators that the portfolio tasks enabled different levels of reflection and learning. We found that the students had not developed the ability to assess their own teaching or learning, and it made us realise that we need to do more probing for such critical thinking about the way we implement the portfolio task. Portfolios hold much value for summative assessment purposes, but it is important to acknowledge its value to enable assessment for learning. Therefore, a mind shift is needed towards alternative uses of portfolios in teacher education programmes as well as how they can be used for sustainable assessment. The construction of learning portfolios with an explicit focus on learning could bring about important changes for Foundation Phase teacher education students, as it enables them to become more aware of their own learning and growth and could serve as a form of professional development for pre-service teachers that could also serve them well when practising as in-service professionals

An Empirical Analysis of Racial Categories in the Algorithmic Fairness Literature

Recent work in algorithmic fairness has highlighted the challenge of defining racial categories for the purposes of anti-discrimination. These challenges are not new but have previously fallen to the state, which enacts race through government statistics, policies, and evidentiary standards in anti-discrimination law. Drawing on the history of state race-making, we examine how longstanding questions about the nature of race and discrimination appear within the algorithmic fairness literature. Through a content analysis of 60 papers published at FAccT between 2018 and 2020, we analyze how race is conceptualized and formalized in algorithmic fairness frameworks. We note that differing notions of race are adopted inconsistently, at times even within a single analysis. We also explore the institutional influences and values associated with these choices. While we find that categories used in algorithmic fairness work often echo legal frameworks, we demonstrate that values from academic computer science play an equally important role in the construction of racial categories. Finally, we examine the reasoning behind different operationalizations of race, finding that few papers explicitly describe their choices and even fewer justify them. We argue that the construction of racial categories is a value-laden process with significant social and political consequences for the project of algorithmic fairness. The widespread lack of justification around the operationalization of race reflects institutional norms that allow these political decisions to remain obscured within the backstage of knowledge production.Comment: 13 pages, 2 figures, FAccT '2

A Systematic Approach to Delay Functions

We present a systematic introduction to a class of functions that provide fundamental solutions for autonomous linear integer-order and fractional-order delay differential equations. These functions, referred to as delay functions, are defined through power series or fractional power series, with delays incorporated into their series representations. Using this approach, we have defined delay exponential functions, delay trigonometric functions and delay fractional Mittag-Leffler functions, among others. We obtained Laplace transforms of the delay functions and demonstrated how they can be employed in finding solutions to delay differential equations. Our results, which extend and unify previous work, offer a consistent framework for defining and using delay functions