Integrated chronological control on an archaeologically significant Pleistocene river terrace sequence: the Thames-Medway, eastern Essex, England

Late Middle Pleistocene Thames-Medway deposits in eastern Essex comprise both large expanses of Palaeolithic artefact-bearing river sands/gravels and deep channels infilled with thick sequences of fossiliferous fine-grained estuarine sediments that yield valuable palaeoenvironmental information. Until recently, chronological control on these deposits was limited to terrace stratigraphy and limited amino-acid racemisation (AAR) determinations. Recent developments in both this and optically stimulated luminescence (OSL) dating make them potentially powerful tools for improving the chronological control on such sequences. This paper reports new AAR analyses and initial OSL dating from the deposits in this region. These results will help with ongoing investigation of patterns of early human settlement. Using AAR, the attribution by previous workers of the interglacial channel deposits to both MIS 11 (Tillingham Clay) and MIS 9 (Rochford and Shoeburyness Clays) is reinforced. Where there are direct stratigraphic relationships between AAR and OSL as with the Cudmore Grove and Rochford Clays and associated gravels, they agree well. Where OSL dating is the only technique available, it seems to replicate well, but must be treated with caution since there are relatively few aliquots. It is suggested on the basis of this initial OSL dating that the gravel deposits date from MIS 8 (Rochford and Cudmore Grove Gravels) and potentially also MIS 6 (Dammer Wick and Barling Gravels). However, the archaeological evidence from the Barling Gravel and the suggested correlations between this sequence and upstream Thames terraces conflict with this latter age estimate and suggest that it may need more investigation

The ZEPLIN II dark matter detector: data acquisition system and data reduction

ZEPLIN-II is a two-phase (liquid/gas) xenon dark matter detector searching for WIMP-nucleon interactions. In this paper we describe the data acquisition system used to record the data from ZEPLIN-II and the reduction procedures which parameterise the data for subsequent analysis.Comment: 11 pages, 10 figure

The ZEPLIN II dark matter detector: data acquisition system and data reduction

ZEPLIN-II is a two-phase (liquid/gas) xenon dark matter detector searching for WIMP-nucleon interactions. In this paper we describe the data acquisition system used to record the data from ZEPLIN-II and the reduction procedures which parameterise the data for subsequent analysis.Comment: 11 pages, 10 figure

Limits on spin-dependent WIMP-nucleon cross-sections from the first ZEPLIN-II data

The first underground data run of the ZEPLIN-II experiment has set a limit on the nuclear recoil rate in the two-phase xenon detector for direct dark matter searches. In this paper the results from this run are converted into the limits on spin-dependent WIMP-proton and WIMP-neutron cross-sections. The minimum of the curve for WIMP-neutron cross-section corresponds to 0.07 pb at a WIMP mass of around 65 GeV.Comment: 12 pages, 2 figures, to be published in Physics Letters

Topical Issues for Particle Acceleration Mechanisms in Astrophysical Shocks

Particle acceleration at plasma shocks appears to be ubiquitous in the universe, spanning systems in the heliosphere, supernova remnants, and relativistic jets in distant active galaxies and gamma-ray bursts. This review addresses some of the key issues for shock acceleration theory that require resolution in order to propel our understanding of particle energization in astrophysical environments. These include magnetic field amplification in shock ramps, the non-linear hydrodynamic interplay between thermal ions and their extremely energetic counterparts possessing ultrarelativistic energies, and the ability to inject and accelerate electrons in both non-relativistic and relativistic shocks. Recent observational developments that impact these issues are summarized. While these topics are currently being probed by astrophysicists using numerical simulations, they are also ripe for investigation in laboratory experiments, which potentially can provide valuable insights into the physics of cosmic shocks.Comment: 13 pages, no figures. Invited review, accepted for publication in Astrophysics and Space Science, as part of the HEDLA 2006 conference proceeding

University continuing education in a neoliberal landscape: developments in England and Aotearoa New Zealand

This paper explores how changing higher education policies and funding, influenced by neoliberalism, are impacting on university adult and continuing education in England and Aotearoa New Zealand. The downhill trajectory of English university continuing education in the first decade of the twenty-first century is compared with the apparent buoyancy of the situation in New Zealand during the same period. The paper discusses some of the contextual factors which may have contributed to sustaining continuing education in New Zealand, against the tide of developments elsewhere, and in spite its subjection to the influence of neoliberal policies since the 1980s. These factors include: an ethos of public dissemination of knowledge, an acknowledgement of the universities’ role as ‘critic and conscience’ of society, a broad commitment to educational equality and an approach which has been strategic as well as pragmatic. The paper describes developments in one New Zealand continuing education department between 2006 and 2010 as it experiences further institutional and political change. The author concludes that, in spite of having demonstrated considerable resilience, the current structures and activities of continuing education departments in New Zealand are as fragile as they have been shown to be in England. Possible responses to the current situation are discussed and ‘radical hope’ (Brookfield 2005) is advocated as the university-based adult educators’ response in difficult times. Radical hope, founded on critical theory, involves recognising and challenging the assumptions of neoliberalism, as well as critical praxis (Carr and Kemmis 1986), and a reaffirmation on the part of academics and adult educators of the political nature of adult education (Freire 1972; Crowther et al 2005; Martin 2008; Wallace 2008)