1,902 research outputs found

    A whole systems energy study - the Glasgow energy operator

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    Deep decarbonisation of local energy systems requires consideration of the contributions from multiple energy resources and networks, which may not be achievable by separate Network Operators acting in isolation. In this paper, the concept of the Local Energy System Operator (LESO) is introduced, acting to bridge between different Distribution Network Operators with a Whole System view of energy provision, and able to utilise assets in both electricity and gas networks. The LESO concept is demonstrated using a model representing the electricity and gas networks of the Glasgow City Council Area, and illustrates the ability of the LESO to optimise dispatch of assets across multiple carriers to achieve specific objectives in costs and emissions intensity, and to coordinate local investment in networks between DNOs. This bridging role is particularly appropriate to local municipalities such as Glasgow which have set ambitious near-term targets for emissions reduction, while not having direct control over the cost and emissions associated with upstream energy provision. Scenarios representing different future upstream energy system evolutionary pathways (such as mass electrification and gas grid decarbonisation) are simulated and indicate the means by which local emissions reduction may be achieved in both operational and planning timescales via joint dispatch/planning of electricity and gas networks in order to avoid stranded assets and unnecessary sunk costs. Within operational timescales, hybrid systems such as heat networks may be dispatched to make optimal use of network headroom, which can then further inform the level of emissions reduction which will be realised through specific volumes of network investment, and where they might best be directed. The inability of the LESO to control upstream emissions means that the rate of decarbonisation is still constrained by the emissions intensity of transmission-connected energy resources – however, as there is no implicit central planning role in deregulated energy markets, a local coordinating role is seen as key to making best use of heterogeneous regional and local energy systems, and interfacing with centralised actors to best realised the energy transition

    Paying clinicians to join clinical trials : a review of guidelines and interview study of trialists

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    Background: The motivations of clinicians to participate in clinical trials have been little studied. This project explored the potential role of payment for participation in publicly funded clinical trials in the UK. The aims were to review relevant guidelines and to collate and analyse views of clinical trialists on the role of payments and other factors that motivated clinicians to join clinical trials. Methods: Review of guidelines governing payments to clinicians for recruitment to trials. Semistructured interviews with a range of NHS clinical trial leaders, analysed using qualititative methods. Results: While UK guidelines had little to say specifically on payments linked to recruitment, all payments have become highly regulated and increasingly transparent. Interview participants believed that expenses arising from research should be covered. Payments in excess of expenses were seen as likely to increase participation but with the risk of reducing quality. Motivations such as interest in the topic, the scope for patients to benefit and intellectual curiosity were considered more important. Barriers to involvement included bureaucracy and lack of time. Discussion: Limited scope exists for paying clinicians over-and-above the cost of their time to be involved in research. Most trialists favour full payment of all expenses related to research. Conclusion: Payment of clinicians beyond expenses is perceived to be a less important motivating factor than researching important, salient questions, and facilitating research by reducing bureaucracy and delay

    Chiral extrapolation of lattice moments of proton quark distributions

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    We present the resolution of a long-standing discrepancy between the moments of parton distributions calculated from lattice QCD and their experimental values. We propose a simple extrapolation formula for the moments of the nonsinglet quark distribution u-d, as a function of quark mass, which embodies the general constraints imposed by the chiral symmetry of QCD. The inclusion of the leading nonanalytic behavior leads to an excellent description of both the lattice data and the experimental values of the moments.Comment: 9 pages, 1 figure, to appear in Physical Review Letter

    dbar/ubar Asymmetry and the Origin of the Nucleon Sea

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    The Drell-Yan cross section ratios, σ(p+d)/σ(p+p)\sigma(p+d)/\sigma(p+p), measured in Fermilab E866, have led to the first determination of dˉ(x)/uˉ(x)\bar d(x) / \bar u(x), dˉ(x)uˉ(x)\bar d(x) - \bar u(x), and the integral of dˉ(x)uˉ(x)\bar d(x) - \bar u(x) for the proton over the range 0.02x0.3450.02 \le x \le 0.345. The E866 results are compared with predictions based on parton distribution functions and various theoretical models. The relationship between the E866 results and the NMC measurement of the Gottfried integral is discussed. The agreement between the E866 results and models employing virtual mesons indicates these non-perturbative processes play an important role in the origin of the dˉ\bar d, uˉ\bar u asymmetry in the nucleon sea.Comment: 5 pages, 3 figures, ReVTe

    An Alternative Method to Obtain the Quark Polarization of the Nucleon

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    An alternate method is described to extract the quark contribution to the spin of the nucleon directly from the first moment of the deuteron structure function, g1dg^d_1. It is obtained without recourse to the use of input on the nucleon wave function from hyperon decays involving the flavor symmetry parameters, F and D. The result for the quark polarization of the nucleon, ΔΣN,\Delta\Sigma_ N, is in good agreement with the values of the singlet axial current matrix element, a0a_0, obtained from recent next-to-leading order analyses of current proton, neutron and deuteron data.Comment: 7 pages, 1 figur

    Progress in neutrino oscillation searches and their implications

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    Neutrino Oscillation, in which a given flavour of neutrino transforms into another is a powerful tool for probing small neutrino masses. The intrinsic neutrino properties involved are neutrino mass squared difference Δm2\Delta m^2 and the mixing angle in vacuum θ\theta. In this talk I will summarize the progress that we have achieved in our search for neutrino oscillation with special emphasis on the recent results from the Sudbury Neutrino Observatory (SNO) on the measurement of solar neutrino fluxes. I will outline the current bounds on the neutrino masses and mixing parameters and discuss the major physics goals of future neutrino experiments in the context of the present picture.Comment: Plenary Talk, WHEPP-7, January 2002, published in Pramana, Vol. 60, 261, 200

    Polarized light-flavor antiquarks from Drell-Yan processes of h+\vec{N}\to\vec{l^{+-}} + l^{-+} + X

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    We propose a formula to determine the first moment of difference between the polarized uˉ\bar u- and dˉ\bar d-quarks in the nucleon, {\it i.e.} ΔuˉΔdˉ\Delta\bar u-\Delta \bar d from the Drell-Yan processes in collisions of unpolarized hadrons with longitudinally polarized nucleons by measuring outgoing lepton helicities. As coefficients in the differential cross section depend on the uu- and dd-quark numbers in the unpolarized hadron beam, the difference ΔuˉΔdˉ\Delta\bar u-\Delta\bar d can be independently tested by changing the hadron beam. Moreover, a formula for estimating the KK-factor in Drell-Yan processes is also suggested.Comment: 10 pages, 1 figur

    Do we expect light flavor sea-quark asymmetry also for the spin-dependent distribution functions of the nucleon?

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    After taking account of the scale dependence by means of the standard DGLAP evolution equation, the theoretical predictions of the chiral quark soliton model for the unpolarized and longitudinally polarized structure functions of the nucleon are compared with the recent high energy data. The theory is shown to explain all the qualitative features of the experiments, including the NMC data for F2p(x)F2n(x)F_2^p (x) - F_2^n (x), F2n(x)/F2p(x)F_2^n (x) / F_2^p (x), the Hermes and NuSea data for dˉ(x)uˉ(x)\bar{d}(x) - \bar{u}(x), the EMC and SMC data for g1p(x)g_1^p(x), g1n(x)g_1^n(x) and g1d(x)g_1^d(x). Among others, flavor asymmetry of the longitudinally polarized sea-quark distributions is a remarkable prediction of this model, i.e., it predicts that Δdˉ(x)Δuˉ(x)=Cxα[dˉ(x)uˉ(x)]\Delta \bar{d}(x) - \Delta \bar{u}(x) = C x^{\alpha} [ \bar{d}(x) - \bar{u}(x)] with a sizable negative coefficient C2.0C \simeq -2.0 (and α0.12\alpha \simeq 0.12) in qualitative consistency with the recent semi-phenomenological analysis by Morii and Yamanishi.Comment: 14pages, including 5 eps_figures with epsbox.sty, late
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