Causality and classical dispersion relations

We explore the consequences of relativistic causality and covariant stability for short-wavelength dispersion relations in classical systems. For excitations described by a finite number of partial differential equations, as is the case in relativistic hydrodynamics, we give causality and covariant stability constraints on the excitation's frequency at large momenta.Comment: 16 pages, 1 figure. v2: reference added, small clarification

Schools and their communities: pupil and teacher perceptions of community action

In England over the last two decades, there has been a growing interest in the role of English schools in developing, facilitating and supporting young people’s community participation. A number of policy initiatives have sought to build the capacity and opportunities for youth participation. Research suggests, however, that pupils and schools are often prohibited by significant barriers from becoming involved with community activities, particularly those which might occur beyond the school environment itself. In March 2010 the UK Labour government launched a Youth Community Action initiative for England, piloted across five local authorities, which aimed to involve young people of 14-16 years-of-age in community action. Following the UK general election in May 2010, the Conservative-Liberal Democrat coalition government terminated these pilots but was quick to announce the launch and piloting of a National Citizen Service for 16-19 year olds in England. Purpose Drawing on research conducted with participants in one Youth Community Action pilot project, the aim of this study was to explore the perceptions and understandings of young people regarding their involvement in community action activities and how this compared to the perceptions and understandings of the teachers responsible for co-ordinating such activities. Sample In the final synthesis, the sample comprised 614 pupil questionnaires, representing a response rate of 24 percent of the pupils in the 9 participating schools. 11 semi-structured interviews and one focus group interview were conducted with pupils in 6 of the schools, with a further 8 semi-structured interviews conducted with teachers in these 6 schools. Design and methods A questionnaire was administered to pupils participating in the Youth Community Action pilot, enabling an exploration of self-reported behavioural attitudes and perceptions. The data collected was analysed thematically, with an identification of common themes in responses. In addition, factor analysis and a series of Chi² tests of association were carried out. The use of semi-structured interviews, the data from which were analysed thematically, enabled a qualitative exploration of pupils’ and teachers’ self-reported perceptions of community action activities. Results The findings of our questionnaires report that those pupils who know more about their local neighbourhood and community are likely to report greater levels of concern for what happens within it. This suggests that pupils’ learning about their neighbourhoods and community is likely to be beneficial toward developing affective attachments to them. For the pupils in our data-set, simply possessing pro-social behaviours and attitudes was not a sufficient or necessary condition for their community awareness and involvement. It suggests that, at least for a notable number of pupils, active engagement in the community requires cultivation and learning beyond pro-social behaviours. The semi-structured interviews report that pupils identify the school as the key source of information about community engagement opportunities, but also indicate that there is a marked difference in the activities which teachers identify their pupils as having undertaken, and the ability of pupils to vocalise these themselves. A further notable finding was a focus on the practical (time, distance, age-constraints) and social (peer-pressure) barriers to community action activities to the exclusion of specifically educational (lack of understanding and skills) barriers. Conclusions Results from this study suggest that schools represent an important source for pupils’ community involvement, but that in our sample pupils often lack the vocabulary with which to explain the extent and nature of such engagement. Pupils and teachers identify a range of barriers to and benefits of community involvement, but these do not include a lack of understanding or skills. The research raises important questions in the context of recent policy trends in England

Two-Dimensional Magnetic Resonance Tomographic Microscopy using Ferromagnetic Probes

We introduce the concept of computerized tomographic microscopy in magnetic resonance imaging using the magnetic fields and field gradients from a ferromagnetic probe. We investigate a configuration where a two-dimensional sample is under the influence of a large static polarizing field, a small perpendicular radio-frequency field, and a magnetic field from a ferromagnetic sphere. We demonstrate that, despite the non-uniform and non-linear nature of the fields from a microscopic magnetic sphere, the concepts of computerized tomography can be applied to obtain proper image reconstruction from the original spectral data by sequentially varying the relative sample-sphere angular orientation. The analysis shows that the recent proposal for atomic resolution magnetic resonance imaging of discrete periodic crystal lattice planes using ferromagnetic probes can also be extended to two-dimensional imaging of non-crystalline samples with resolution ranging from micrometer to Angstrom scales.Comment: 9 pages, 11 figure

The contribution of teacher education to universities: a case study for international teacher educators

This paper reports on the initial stage of a research project which aims to develop deeper understanding of the contribution teacher education, as a sub-discipline within Education, makes to Higher Education in England. The study is located in the intersection between the domains of teacher education and higher education scholarship, which in England represents a contested and ambiguous professional space. Tensions between competing accountability measures, pulling away from university-based to exclusively school-based teacher education, are exacerbated by proposed policy changes arising from the government's recent market review. Findings drawn from analysis of qualitative data from a national survey are discussed in the context of Elizabeth Povinelli's critique of late liberalism and previous scholarship on the nature of teacher educators’ work. Evidence from the study demonstrates numerous benefits to higher education of hosting teacher education departments, including contributions to standard metrics, regional development and knowledge exchange within a strategic social justice agenda. However, teacher educators themselves may find articulating these benefits difficult, because of marginalisation from the dominant ways of achieving and accounting for excellence in the modern university. These findings offer a cautionary tale to international colleagues whose governments may be embarking on equivalent paths of teacher education reform

The contribution of Teacher education to universities:a case study for international teacher educators

This paper reports on the initial stage of a research project which aims to develop deeper understanding of the contribution teacher education, as a sub-discipline within Education, makes to Higher Education in England. The study is located in the intersection between the domains of teacher education and higher education scholarship, which in England represents a contested and ambiguous professional space. Tensions between competing accountability measures, pulling away from university-based to exclusively school-based teacher education, are exacerbated by proposed policy changes arising from the government's recent market review. Findings drawn from analysis of qualitative data from a national survey are discussed in the context of Elizabeth Povinelli's critique of late liberalism and previous scholarship on the nature of teacher educators’ work. Evidence from the study demonstrates numerous benefits to higher education of hosting teacher education departments, including contributions to standard metrics, regional development and knowledge exchange within a strategic social justice agenda. However, teacher educators themselves may find articulating these benefits difficult, because of marginalisation from the dominant ways of achieving and accounting for excellence in the modern university. These findings offer a cautionary tale to international colleagues whose governments may be embarking on equivalent paths of teacher education reform.<br/

Current CONtrolled Transmit And Receive Coil Elements (C2ONTAR) for Parallel Acquisition and Parallel Excitation Techniques at High-Field MRI

A novel intrinsically decoupled transmit and receive radio-frequency coil element is presented for applications in parallel imaging and parallel excitation techniques in high-field magnetic resonance imaging. Decoupling is achieved by a twofold strategy: during transmission elements are driven by current sources, while during signal reception resonant elements are switched to a high input impedance preamplifier. To avoid B0 distortions by magnetic impurities or DC currents a resonant transmission line is used to relocate electronic components from the vicinity of the imaged object. The performance of a four-element array for 3 T magnetic resonance tomograph is analyzed by means of simulation, measurements of electromagnetic fields and bench experiments. The feasibility of parallel acquisition and parallel excitation is demonstrated and compared to that of a conventional power source-driven array of equivalent geometry. Due to their intrinsic decoupling the current-controlled elements are ideal basic building blocks for multi-element transmit and receive arrays of flexible geometry

Sheep Updates 2006 - part 4

This session covers seven papers from different authors: MANAGEMENT 1. Wool and meat traits in Merino flocks in different regions, K.G. Geenty, A.A. Swan, A.J. Smith, J.L. Smith, Sheep CRC and CSIRO Livestock Industries, Armidale 2. Fat score or Condition score? - It all depends on what you want to do! Chris Oldham, Department of Agriculture and Food Western Australia 3. Sheep worm control - the latest for Western Australia, RG Woodgate, RA Love, E Dobbe, HM Hoult, J Pearson, S Hill, A van Burgel and RB Besier, Department of Agriculture and Food Western Australia PASTURES 4. Rethinking pasture production - STEPS to greater productivity with perennials, R. Warburton, Farmer, Mobrup, WA, L. Mathwin, Farmer Kojonup WA, D. Rogers, E. Crossley, Department of Agriculture and Food Western Australia 5. Sheep Returnes from Saltland Pastures, Allan Herbert, Department of Agriculture and Food Western Australia 6. Pasture legumes and grasses from saline land, Phil Nichols, Tony Albertsen, Darryl McClements, Department of Agriculture and Food Western Australia, & Cooperative Research Centre for Plant-based Management of Dryland Salinity MERINO INNOVATION DAY 7. Towards \u27clean, green and ethical\u27 sheep production, Graeme Martin, Penny Hawken, Carolina Viñoles, Beth Paganoni and Dominique Blache, School of Animal Biology, Faculty of Natural & Agricultural Sciences, The University of Western Australi

Mississippi River and Sea Surface Height Effects on Oil Slick Migration

Millions of barrels of oil escaped into the Gulf of Mexico (GoM) after the 20 April, 2010 explosion of Deepwater Horizon (DH). Ocean circulation models were used to forecast oil slick migration in the GoM, however such models do not explicitly treat the effects of secondary eddy-slopes or Mississippi River (MR) hydrodynamics. Here we report oil front migration that appears to be driven by sea surface level (SSL) slopes, and identify a previously unreported effect of the MR plume: under conditions of relatively high river discharge and weak winds, a freshwater mound can form around the MR Delta. We performed temporal oil slick position and altimeter analysis, employing both interpolated altimetry data and along-track measurements for coastal applications. The observed freshwater mound appears to have pushed the DH oil slick seaward from the Delta coastline. We provide a physical mechanism for this novel effect of the MR, using a two-layer pressure-driven flow model. Results show how SSL variations can drive a cross-slope migration of surface oil slicks that may reach velocities of order km/day, and confirm a lag time of order 5–10 days between mound formation and slick migration, as observed form the satellite analysis. Incorporating these effects into more complex ocean models will improve forecasts of slick migration for future spills. More generally, large SSL variations at the MR mouth may also affect the dispersal of freshwater, nutrients and sediment associated with the MR plume