Reid on knowledge and justification in Physical Education

[FIRST PARAGRAPHS] To my knowledge, very little has been written on the educational justification of PE activities for the last decade. Since PE now does have a place on the National Curriculum, albeit arguably a minor one, the justification issue does seem to have been put on the back burner by the profession. In a recent and welcome addition to the literature, Reid revisits the debate, outlining two ‘conventional assumptions’ made by what he calls the ‘new orthodoxy’ in PE: 1. The ‘early Hirstian’ account3, which sees knowledge as propositional, and education as academic. When applied to PE, this suggests: 2. The distinction between practical performance and the ‘theory’ related to it - i.e. the propositional knowledge of Human Movement Science (HMS). The paper is a critique of these two assumptions, and a defence of the claim that PE ‘can indeed satisfy the knowledge requirements of education; but ... without making claims to academic significance’ (p95)

A new photon recoil experiment: towards a determination of the fine structure constant

We report on progress towards a measurement of the fine structure constant to an accuracy of $5\times 10^{-10}$ or better by measuring the ratio of the Planck constant to the mass of the cesium atom. Compared to similar experiments, ours is improved in three significant ways: (i) simultaneous conjugate interferometers, (ii) multi-photon Bragg diffraction between same internal states, and (iii) an about 1000 fold reduction of laser phase noise to -138 dBc/Hz. Combining that with a new method to simultaneously stabilize the phases of four frequencies, we achieve 0.2 mrad effective phase noise at the location of the atoms. In addition, we use active stabilization to suppress systematic effects due to beam misalignment.Comment: 12 pages, 9 figure

Probabilistic Inference for Fast Learning in Control

We provide a novel framework for very fast model-based reinforcement learning in continuous state and action spaces. The framework requires probabilistic models that explicitly characterize their levels of confidence. Within this framework, we use flexible, non-parametric models to describe the world based on previously collected experience. We demonstrate learning on the cart-pole problem in a setting where we provide very limited prior knowledge about the task. Learning progresses rapidly, and a good policy is found after only a hand-full of iterations

Characterization and comparison of smokeless powders by on-line two-dimensional liquid chromatography

Smokeless powders (SPs) are one of the most commonly used propellants for ammunition but can also be abused as energetic material in improvised explosive devices (IEDs) such as pipe bombs. After a shooting or explosion, unburnt or partially burnt particulates may be observed which can be used for forensic investigation. SPs comprise mainly nitrocellulose (NC) and additives. Therefore, the characterization of both NC and the additives is of significant forensic importance. Typically, the identification, classification, and chemical profiling of smokeless powders are based exclusively on the analysis of the additives. In this study, information regarding the NC base component was combined with the chemical analysis of the additives using two-dimensional liquid chromatography (2D-LC). The system combines size-exclusion chromatography (SEC) and reversed-phase liquid chromatography (RPLC) in an on-line heart-cut 2D-LC configuration. In the first dimension, the NC is characterized by its molecular-weight distribution (MWD) while being separated from the additives. The additives are then transferred to the second-dimension separation using a novel analyte-transfer system. In the second dimension, the additives are separated to obtain a detailed profile of the low-molecular-mass compounds in the SP. With this approach, the MWD of the NC and the composition of the additives in SP have been obtained within an hour. A discrimination power of 90.53% was obtained when studying exclusively the NC MWD, and 99.47% for the additive profile. This novel combination enables detailed forensic comparison of intact SPs. Additionally, no extensive sample preparation is required, making the developed method less labor intensive

What's wrong with the scrum laws in rugby union? - Judgment, truth and refereeing

Officiating and the role of officials in sport are crucial and often decisive factors in sports contests. Notable contributions in philosophy of sport include Collins (2012), Russell (1997; 1999), McFee (2011) & Mumford (2006) have brought a sharp philosophical focus to highlight that justice and desert of sport contests, in part, rely on officiating truths (performances) that arise from an appropriate admixture of epistemic (judgments) and metaphysical (actions) ingredients. This paper provides a rigorous and original philosophical analysis of the problems of obeying the rules and of applying the rules of sport. The paper focuses on a particular phase of play in rugby union, namely the scrum. It is fair to say that the scrum has become a focus of criticism and bewilderment. Elite televised rugby is damaged as a spectacle because too much time is wasted setting and re-setting scrums. Furthermore, our trust in the fairness of games is eroded because the scrum is a ‘lottery’ when it comes to officiating. In this paper, we identify two fundamental structural problems which contribute to the scrum controversy. First, drawing on Mumford (2006) and Collins (2012) we argue that officials cannot make reliable judgments about scrums because they cannot see what they need to see. Secondly, we argue that players cannot follow the laws of the scrum even if they have a strong desire to do so. Laws which can’t be followed are, according to Fuller (2000) defective. Consequently, the scrum is not only potentially dangerous but also flawed in terms of its capacity to actualize an intended part of the game

Basis Expansion in Natural Actor Critic Methods

International audienceIn reinforcement learning, the aim of the agent is to find a policy that maximizes its expected return. Policy gradient methods try to accomplish this goal by directly approximating the policy using a parametric function approximator; the expected return of the current policy is estimated and its parameters are updated by steepest ascent in the direction of the gradient of the expected return with respect to the policy parameters. In general, the policy is defined in terms of a set of basis functions that capture important features of the problem. Since the quality of the resulting policies directly depend on the set of basis func- tions, and defining them gets harder as the complexity of the problem increases, it is important to be able to find them automatically. In this paper, we propose a new approach which uses cascade-correlation learn- ing architecture for automatically constructing a set of basis functions within the context of Natural Actor-Critic (NAC) algorithms. Such basis functions allow more complex policies be represented, and consequently improve the performance of the resulting policies. We also present the effectiveness of the method empirically

Production of Eta-Mesons in Collisions of Nucleons and Delta-Resonances

We calculate the cross section for the production of $\eta$-mesons via \mbox{$\Delta N \to N N \eta$} in a relativistic One-Boson-Exchange-Model. Using this cross section we then determine the probability for the production of an $\eta$-meson by a $\Delta$-resonance moving in nuclear matter. The result is compared to prescriptions in BUU-calculations in which \et-production proceeds both through a direct channel and through the sequential process $\Delta \to N \pi ; \pi N \to N \eta$.Comment: revised version: large parts have been rewritten, there are two new figures. A discusion of effects of multi-body reactions of the intermediate pion on our results has been adde

Coherent matter wave inertial sensors for precision measurements in space

We analyze the advantages of using ultra-cold coherent sources of atoms for matter-wave interferometry in space. We present a proof-of-principle experiment that is based on an analysis of the results previously published in [Richard et al., Phys. Rev. Lett., 91, 010405 (2003)] from which we extract the ratio h/m for 87Rb. This measurement shows that a limitation in accuracy arises due to atomic interactions within the Bose-Einstein condensate