97 research outputs found

    A new Palma Vecchio in the Chapter Hall Museum, Birgu : some observations on the domestic Sacra Conversazione in Venice

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    A painting attributed to the sixteenth-century Venetian school was recently published in Birgu - A Maltese Maritime City.! The work in question. The Virgin and Child with St. Peter and a Donor (PI. 1), is owned by the Chapter Hall Museum, Birgu. 2 It can now be considered as a new addition to the oeuvre of Jacopo Negretti, called Palma il Vecchio (c.1485-1528). This article describes the process of authetification through both the style and technique of the painting.peer-reviewe

    X-ray diffraction studies of muscle : observations on the anterior byssus retractor muscle of Mytilus edulis and the insect flight muscle from Sarcophaga bullata

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    The interfilament spacing of the anterior byssus retractor muscle from Mytilus edulis was studied as the muscle was extended. It was found that variations in this spacing were very small and consistent with the hypothesis that the interfilament spacing was independent of the extension of the muscle. It was observed that the interfilament spacing was dependent on the osmolarity of the bathing medium. In concentrated solutions of the artificial seawater, the interfilament spacing decreased; while in dilute solutions of artificial seawater, it was observed that the interfilament spacing was increasing. X-ray diffraction patterns were obtained from fresh, and glutaraldehyde fixed, specimens of insect flight muscle from Sarcophaga bullata. There patterns were in general agreement with previous X-ray diffraction studies of insect flight muscle. A reflexion G at 93A was observed and interpreted as arising from diffraction in the mitochondria. Specimens of dried insect flight muscle produced a diffraction pattern consisting of arc and ring reflexions. This was interpreted as suggesting an ordered arrangement of cristae, in the mitochondria from these muscles

    Thresholds of biodiversity and ecosystem function in a forest ecosystem undergoing dieback

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    Ecological thresholds, which represent points of rapid change in ecological properties, are of major scientific and societal concern. However, very little research has focused on empirically testing the occurrence of thresholds in temperate terrestrial ecosystems. To address this knowledge gap, we tested whether a number of biodiversity, ecosystem functions and ecosystem condition metrics exhibited thresholds in response to a gradient of forest dieback, measured as changes in basal area of living trees relative to areas that lacked recent dieback. The gradient of dieback was sampled using 12 replicate study areas in a temperate forest ecosystem. Our results provide novel evidence of several thresholds in biodiversity (namely species richness of ectomycorrhizal fungi, epiphytic lichen and ground flora); for ecological condition (e.g. sward height, palatable seedling abundance) and a single threshold for ecosystem function (i.e. soil respiration rate). Mechanisms for these thresholds are explored. As climate-induced forest dieback is increasing worldwide, both in scale and speed, these results imply that threshold responses may become increasingly widespread

    Experiences and perceptions of people with headache: a qualitative study

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    BACKGROUND: Few qualitative studies of headache have been conducted and as a result we have little in-depth understanding of the experiences and perceptions of people with headache. The aim of this paper was to explore the perceptions and experiences of individuals with headache and their experiences of associated healthcare and treatment. METHODS: A qualitative study of individuals with headache, sampled from a population-based study of chronic pain was conducted in the North-East of Scotland, UK. Seventeen semi-structured interviews were conducted with adults aged 65 or less. Interviews were analysed using the Framework approach utilising thematic analysis. RESULTS: Almost every participant reported that they were unable to function fully as a result of the nature and unpredictability of their headaches and this had caused disruption to their work, family life and social activities. Many also reported a negative impact on mood including feeling depressed, aggressive or embarrassed. Most participants had formed their own ideas about different aspects of their headache and several had searched for, or were seeking, increased understanding of their headache from a variety of sources. Many participants reported that their headaches caused them constant worry and anguish, and they were concerned that there was a serious underlying cause. A variety of methods were being used to manage headaches including conventional medication, complementary therapies and self-developed management techniques. Problems associated with all of these management strategies emerged. CONCLUSION: Headache has wide-ranging adverse effects on individuals and is often accompanied by considerable worry. The development of new interventions or educational strategies aimed at reducing the burden of the disorder and associated anxiety are needed

    Inclusive jet cross sections and dijet correlations in D±D^{*\pm} photoproduction at HERA

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    Inclusive jet cross sections in photoproduction for events containing a DD^* meson have been measured with the ZEUS detector at HERA using an integrated luminosity of 78.6pb178.6 {\rm pb}^{-1}. The events were required to have a virtuality of the incoming photon, Q2Q^2, of less than 1 GeV2^2, and a photon-proton centre-of-mass energy in the range 130<Wγp<280GeV130<W_{\gamma p}<280 {\rm GeV}. The measurements are compared with next-to-leading-order (NLO) QCD calculations. Good agreement is found with the NLO calculations over most of the measured kinematic region. Requiring a second jet in the event allowed a more detailed comparison with QCD calculations. The measured dijet cross sections are also compared to Monte Carlo (MC) models which incorporate leading-order matrix elements followed by parton showers and hadronisation. The NLO QCD predictions are in general agreement with the data although differences have been isolated to regions where contributions from higher orders are expected to be significant. The MC models give a better description than the NLO predictions of the shape of the measured cross sections.Comment: 43 pages, 12 figures, charm jets ZEU

    Dissociation of virtual photons in events with a leading proton at HERA

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    The ZEUS detector has been used to study dissociation of virtual photons in events with a leading proton, gamma^* p -> X p, in e^+p collisions at HERA. The data cover photon virtualities in two ranges, 0.03<Q^2<0.60 GeV^2 and 2<Q^2<100 GeV^2, with M_X>1.5 GeV, where M_X is the mass of the hadronic final state, X. Events were required to have a leading proton, detected in the ZEUS leading proton spectrometer, carrying at least 90% of the incoming proton energy. The cross section is presented as a function of t, the squared four-momentum transfer at the proton vertex, Phi, the azimuthal angle between the positron scattering plane and the proton scattering plane, and Q^2. The data are presented in terms of the diffractive structure function, F_2^D(3). A next-to-leading-order QCD fit to the higher-Q^2 data set and to previously published diffractive charm production data is presented

    Study of deep inelastic inclusive and diffractive scattering with the ZEUS forward plug calorimeter

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    Deep inelastic scattering and its diffractive component, ep -> e'gamma*p ->e'XN, have been studied at HERA with the ZEUS detector using an integrated luminosity of 4.2 pb-1. The measurement covers a wide range in the gamma*p c.m. energy W (37 - 245 GeV), photon virtuality Q2 (2.2 - 80 GeV2) and mass Mx. The diffractive cross section for Mx > 2 GeV rises strongly with W; the rise is steeper with increasing Q2. The latter observation excludes the description of diffractive deep inelastic scattering in terms of the exchange of a single Pomeron. The ratio of diffractive to total cross section is constant as a function of W, in contradiction to the expectation of Regge phenomenology combined with a naive extension of the optical theorem to gamma*p scattering. Above Mx of 8 GeV, the ratio is flat with Q2, indicating a leading-twist behaviour of the diffractive cross section. The data are also presented in terms of the diffractive structure function, F2D(3)(beta,xpom,Q2), of the proton. For fixed beta, the Q2 dependence of xpom F2D(3) changes with xpom in violation of Regge factorisation. For fixed xpom, xpom F2D(3) rises as beta -> 0, the rise accelerating with increasing Q2. These positive scaling violations suggest substantial contributions of perturbative effects in the diffractive DIS cross section.Comment: 87 pages, 25 figure
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