A Faster Implementation of Online Run-Length Burrows-Wheeler Transform

Run-length encoding Burrows-Wheeler Transformed strings, resulting in Run-Length BWT (RLBWT), is a powerful tool for processing highly repetitive strings. We propose a new algorithm for online RLBWT working in run-compressed space, which runs in $O(n\lg r)$ time and $O(r\lg n)$ bits of space, where $n$ is the length of input string $S$ received so far and $r$ is the number of runs in the BWT of the reversed $S$. We improve the state-of-the-art algorithm for online RLBWT in terms of empirical construction time. Adopting the dynamic list for maintaining a total order, we can replace rank queries in a dynamic wavelet tree on a run-length compressed string by the direct comparison of labels in a dynamic list. The empirical result for various benchmarks show the efficiency of our algorithm, especially for highly repetitive strings.Comment: In Proc. IWOCA201

Mediation, translation and local ecologies: understanding the impact of policy levers on FE colleges

This article reports the views of managers and tutors on the role of policy ‘levers’ on teaching, learning, and inclusion in colleges of Further Education (FE) in our research project, ‘The impact of policy on learning and inclusion in the Learning and Skills Sector (LSS)’.i Using data from five research visits conducted over two years in eight FE learning sites, we explore the processes by which colleges ‘mediate’ and ‘translate’ national policy levers and how this affects their ability to respond to local need. The paper tentatively develops three related concepts/metaphors to explain the complexity of the policy/college interface – ‘the process of mediation’, ‘acts of translation’ and ‘local ecologies’. We found that policy levers interacted with a complex set of national, local and institutional factors as colleges responded to pressures from the external environment and turned these into internal plans, systems and practices. We conclude by suggesting that national policy-makers, who design national policy levers, may not be fully aware of these complexities and we make the case for the benefits of greater local control over policy levers, where these interactions are better understood

Detection of antihydrogen annihilations with a Si-micro-strip and pure CsI detector

In 2002, the ATHENA collaboration reported the creation and detection of cold (~15 K) antihydrogen atoms [1]. The observation was based on the complete reconstruction of antihydrogen annihilations, simultaneous and spatially correlated annihilations of an antiproton and a positron. Annihilation byproducts are measured with a cylindrically symmetric detector system consisting of two layers of double sided Si-micro-strip modules that are surrounded by 16 rows of 12 pure CsI crystals (13 x 17.5 x 17 mm^3). This paper gives a brief overview of the experiment, the detector system, and event reconstruction. Reference 1. M. Amoretti et al., Nature 419, 456 (2002).Comment: 7 pages, 5 figures; Proceedings for the 8th ICATPP Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications (Como, Italy October 2003) to be published by World Scientific (style file included

Positron plasma diagnostics and temperature control for antihydrogen production

Production of antihydrogen atoms by mixing antiprotons with a cold, confined, positron plasma depends critically on parameters such as the plasma density and temperature. We discuss non-destructive measurements, based on a novel, real-time analysis of excited, low-order plasma modes, that provide comprehensive characterization of the positron plasma in the ATHENA antihydrogen apparatus. The plasma length, radius, density, and total particle number are obtained. Measurement and control of plasma temperature variations, and the application to antihydrogen production experiments are discussed.Comment: 5 pages, 4 figures, to be published in Phys. Rev. Let

Three Dimensional Annihilation Imaging of Antiprotons in a Penning Trap

We demonstrate three-dimensional annihilation imaging of antiprotons trapped in a Penning trap. Exploiting unusual feature of antiparticles, we investigate a previously unexplored regime in particle transport; the proximity of the trap wall. Particle loss on the wall, the final step of radial transport, is observed to be highly non-uniform, both radially and azimuthally. These observations have considerable implications for the production and detection of antihydrogen atoms.Comment: Invited Talk at NNP03, Workshop on Non-Neutral Plasmas, 200

ATHENA -- First Production of Cold Antihydrogen and Beyond

Atomic systems of antiparticles are the laboratories of choice for tests of CPT symmetry with antimatter. The ATHENA experiment was the first to report the production of copious amounts of cold antihydrogen in 2002. This article reviews some of the insights that have since been gained concerning the antihydrogen production process as well as the external and internal properties of the produced anti-atoms. Furthermore, the implications of those results on future prospects of symmetry tests with antimatter are discussed.Comment: Proc. of the Third Meeting on CPT and Lorentz Symmetry, Bloomington (Indiana), USA, August 2004, edited by V. A. Kostelecky (World Scientific, Singapore). 10 pages, 5 figures, 1 table. Author affiliations cor

Short-term variability of solar wind number density, speed and dynamic pressure as a function of the interplanetary magnetic field components: A survey over two solar cycles

The variability of hourly values of solar wind number density, number density variation, speed, speed variation and dynamic pressure with IMF Bz and magnitude |B| has been examined for the period 1965–1986. We wish to draw attention to a strong correlation in number density and number density fluctuation with IMF Bz characterised by a symmetric increasing trend in these quantities away from Bz = 0 nT. The fluctuation level in solar wind speed is found to be relatively independent of Bz. We infer that number density and number density variability dominate in controlling solar wind dynamic pressure and dynamic pressure variability. It is also found that dynamic pressure is correlated with each component of IMF and that there is evidence of morphological differences between the variation with each component. Finally, we examine the variation of number density, speed, dynamic pressure and fluctuation level in number density and speed with IMF magnitude |B|. Again we find that number density variation dominates over solar wind speed in controlling dynamic pressure

The School Sport Co-ordinator Programme: Changing the Role of the Physical Education Teacher?

Over the last decade or so, young people have increasingly become a focus of UK sport policy. Fuelled in part by concerns such as the increasing levels of childhood inactivity and obesity, and the lack of international success in sport, a plethora of policy initiatives aimed at young people have been developed. In April 2000, the government published its sport strategy document, A Sporting Future for All, pulling together all the threads of recent policies, and in it, restating its commitment to youth sport, sport in education, excellence and sport in the community. One such policy initiative, the School Sport Co-ordinator programme, is the focus of this paper. The School Sport Co-ordinator programme, currently being introduced into schools in England, is an initiative that involves two government departments (sport and education) and a number of other agencies, reflecting the government's current agenda to ensure 'joined up policy' thinking. It aims to develop opportunities for youth sport through co-ordinated links between PE and sport in schools, both within and outside of the formal curriculum, with those in local community sports settings. The essence of the School Sport Co-ordinator programme is to free up nominated teachers in schools from teaching to allow them time for development activities, specifically to encourage schools and community sports providers to work in partnership. This paper draws on data from an ongoing research project examining the implementation of one School Sport Co-ordinator partnership, 'northbridge'. Drawing on in-depth interviews, it explores the perceptions of the newly established School Sport Co-ordinators of their changing role. The paper highlights some of the initial tensions and challenges for them in their task of working across different educational and sporting contexts