53 research outputs found

    Twisted Electromagnetic Modes and Sagnac Ring-Lasers

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    A new approximation scheme, designed to solve the covariant Maxwell equations inside a rotating hollow slender conducting cavity (modelling a ring-laser), is constructed. It is shown that for well-defined conditions there exist TE and TM modes with respect to the longitudinal axis of the cavity. A twisted mode spectrum is found to depend on the integrated Frenet torsion of the cavity and this in turn may affect the Sagnac beat frequency induced by a non-zero rotation of the cavity. The analysis is motivated by attempts to use ring-lasers to measure terrestrial gravito-magnetism or the Lense-Thirring effect produced by the rotation of the Earth.Comment: LaTeX 31 pages, 3 Figure

    The British Male Voice Choir: A History and Contemporary Assessment

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    Secular male voice choral singing in Britain as a self-regulated, self-financed musical and social organization is the basis of this study. The opening chapters examine the form, repertoire and composers of, respectively, the catch and the glee, in the context of the gentlemen's meetings at which the music was performed. Whether at the catch-singing in the homes of late seventeenth century Oxford clergy or at the Georgian club where glees (with alto lead) held sway, it was educated men from the upper and middle strata of British society who were involved and in terms of organization and repertoire, these meetings are presented as antecedents of what, in the early years of the present century, became the male voice choir. The influences of protestant churches, changing social conditions, musical fashion, choral competitions and education are shown to combine in widening the social range within choir membership leading to public popularity and, through improved standardst,of respect from the music profession during the first half of this century. The involvement of choirs in competitions is examined in detail in Chapter 4, this area of activity providing an enormous stimulus to their musical and social well-being. The chronological structure is completed with comment on post-war musical retrenchment and partial ossification. Chapter 5 also reviews the detailed statistics on contemporary British male choirs collected in the author's national survey carried out over a three-yeapr eriod( 1988-91 ). The repertoire of original music is discussed in the subsequent chapter, supported by 64 illustrations with reference made to 250 works by over 120 composers. Finally, a comparative study places current British male choir work within a European context. Discussion on the future concentrates on problems of recruitment and implications for the survival of this neglected arm of the British choral scene

    Implications of climate change for agricultural productivity in the early twenty-first century

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    This paper reviews recent literature concerning a wide range of processes through which climate change could potentially impact global-scale agricultural productivity, and presents projections of changes in relevant meteorological, hydrological and plant physiological quantities from a climate model ensemble to illustrate key areas of uncertainty. Few global-scale assessments have been carried out, and these are limited in their ability to capture the uncertainty in climate projections, and omit potentially important aspects such as extreme events and changes in pests and diseases. There is a lack of clarity on how climate change impacts on drought are best quantified from an agricultural perspective, with different metrics giving very different impressions of future risk. The dependence of some regional agriculture on remote rainfall, snowmelt and glaciers adds to the complexity. Indirect impacts via sea-level rise, storms and diseases have not been quantified. Perhaps most seriously, there is high uncertainty in the extent to which the direct effects of CO2 rise on plant physiology will interact with climate change in affecting productivity. At present, the aggregate impacts of climate change on global-scale agricultural productivity cannot be reliably quantified

    Quantitative trace analysis of a broad range of antiviral drugs in poultry muscle using column-switch liquid chromatography coupled to tandem mass spectrometry

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    A liquid chromatography–tandem mass spectrometry method for the analysis of seven antiviral drugs, zanamivir, ribavirin, oseltamivir, oseltamivir carboxylate, amantadine, rimantadine and arbidol, in poultry muscle is reported. The antiviral drugs were extracted from the homogenized poultry muscle sample using methanol. The extract was purified using tandem solid-phase extraction combining a cation exchange cartridge and a phenylboronic acid cartridge. To prevent excessive matrix effects, the analytes were separated from the matrix constituents using a column-switch liquid chromatography system combining a reversed-phase and a Hypercarb analytical column. Detection was carried out using tandem mass spectrometry. The method was fully validated according to 2002/657/EC [1] and proved to be adequate for quantification and confirmation of zanamivir and ribavirin at 10 Όg kg−1, oseltamivir, oseltamivir carboxylate, amantadine and rimantadine at levels below 1.0 Όg kg−1 and for qualitative confirmatory analysis of arbidol at levels below 1 Όg kg−1

    Translocator protein is a marker of activated microglia in rodent models but not human neurodegenerative diseases

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    Microglial activation plays central roles in neuroinflammatory and neurodegenerative diseases. Positron emission tomography (PET) targeting 18 kDa Translocator Protein (TSPO) is widely used for localising inflammation in vivo, but its quantitative interpretation remains uncertain. We show that TSPO expression increases in activated microglia in mouse brain disease models but does not change in a non-human primate disease model or in common neurodegenerative and neuroinflammatory human diseases. We describe genetic divergence in the TSPO gene promoter, consistent with the hypothesis that the increase in TSPO expression in activated myeloid cells depends on the transcription factor AP1 and is unique to a subset of rodent species within the Muroidea superfamily. Finally, we identify LCP2 and TFEC as potential markers of microglial activation in humans. These data emphasise that TSPO expression in human myeloid cells is related to different phenomena than in mice, and that TSPO-PET signals in humans reflect the density of inflammatory cells rather than activation state.Published versionThe authors thank the UK MS Society for financial support (grant number: C008-16.1). DRO was funded by an MRC Clinician Scientist Award (MR/N008219/1). P.M.M. acknowledges generous support from Edmond J Safra Foundation and Lily Safra, the NIHR Senior Investigator programme and the UK Dementia Research Institute which receives its funding from DRI Ltd., funded by the UK Medical Research Council, Alzheimer’s Society, and Alzheimer’s Research UK. P.M.M. and D.R.O. thank the Imperial College Healthcare Trust-NIHR Biomedical Research Centre for infrastructure support and the Medical Research Council for support of TSPO studies (MR/N016343/1). E.A. was supported by the ALS Stichting (grant “The Dutch ALS Tissue Bank”). P.M. and B.B.T. are funded by the Swiss National Science Foundation (projects 320030_184713 and 310030_212322, respectively). S.T. was supported by an “Early Postdoc.Mobility” scholarship (P2GEP3_191446) from the Swiss National Science Foundation, a “Clinical Medicine Plus” scholarship from the Prof Dr. Max CloĂ«tta Foundation (Zurich, Switzerland), from the Jean et Madeleine Vachoux Foundation (Geneva, Switzerland) and from the University Hospitals of Geneva. This work was funded by NIH grants U01AG061356 (De Jager/Bennett), RF1AG057473 (De Jager/Bennett), and U01AG046152 (De Jager/Bennett) as part of the AMP-AD consortium, as well as NIH grants R01AG066831 (Menon) and U01AG072572 (De Jager/St George-Hyslop)
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