102,177 research outputs found

    Interaction of martensitic microstructures in adjacent grains

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    It is often observed that martensitic microstructures in adjacent polycrystal grains are related. For example, micrographs of Arlt exhibit propagation of layered structures across grain boundaries in the cubic-to-tetragonal phase transformation in BaTiO3\rm BaTiO_3. Such observations are related to requirements of compatibility of the deformation at the grain boundary. Using a generalization of the Hadamard jump condition, this is explored in the nonlinear elasticity model of martensitic transformations for the case of a bicrystal with suitably oriented columnar geometry, in which the microstructure in both grains is assumed to involve just two martensitic variants, with a planar or non-planar interface between the grains.Comment: 6 pages, 1 figure, submitted to ICOMAT 2017 Proceeding

    Testing QCD Sum Rules on the Light-Cone in D->(pi,K) l nu Decays

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    We compare the predictions for the form factors f_+^{D->pi,K}(0) from QCD sum rules on the light-cone with recent experimental results. We find f_+^{D->pi}(0) = 0.63\pm 0.11, f_+^{D->K}(0) = 0.75\pm 0.12 and f_+^{D->pi}(0)/f_+^{D->K}(0)= 0.84\pm 0.04 in very good agreement with experiment. Although the uncertainties of the form factors themselves are larger than the current experimental errors and difficult to reduce, their ratio is determined much more accurately and with an accuracy that matches that of experiment.Comment: 12 page

    The influence of banner advertisements on attention and memory: human faces with averted gaze can enhance advertising effectiveness

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    Research suggests that banner advertisements used in online marketing are often overlooked, especially when positioned horizontally on webpages. Such inattention invariably gives rise to an inability to remember advertising brands and messages, undermining the effectiveness of this marketing method. Recent interest has focused on whether human faces within banner advertisements can increase attention to the information they contain, since the gaze cues conveyed by faces can influence where observers look. We report an experiment that investigated the efficacy of faces located in banner advertisements to enhance the attentional processing and memorability of banner contents. We tracked participants’ eye movements when they examined webpages containing either bottom-right vertical banners or bottom-centre horizontal banners. We also manipulated facial information such that banners either contained no face, a face with mutual gaze or a face with averted gaze. We additionally assessed people’s memories for brands and advertising messages. Results indicated that relative to other conditions, the condition involving faces with averted gaze increased attention to the banner overall, as well as to the advertising text and product. Memorability of the brand and advertising message was also enhanced. Conversely, in the condition involving faces with mutual gaze, the focus of attention was localised more on the face region rather than on the text or product, weakening any memory benefits for the brand and advertising message. This detrimental impact of mutual gaze on attention to advertised products was especially marked for vertical banners. These results demonstrate that the inclusion of human faces with averted gaze in banner advertisements provides a promising means for marketers to increase the attention paid to such adverts, thereby enhancing memory for advertising information

    Time-dependent CP Asymmetry in B->K* gamma as a (Quasi) Null Test of the Standard Model

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    We calculate the dominant Standard Model contributions to the time-dependent CP asymmetry in B0->K*0 gamma, which is O(1/mb) in QCD factorisation. We find that, including all relevant hadronic effects, in particular from soft gluons, the asymmetry S is very small, S=-0.022\pm 0.015^{+0}_{-0.01}, and smaller than suggested recently from dimensional arguments in a 1/mb expansion. Our result implies that any significant deviation of the asymmetry from zero, and in particular a confirmation of the current experimental central value, S_{HFAG}=-0.28\pm 0.26, would constitute a clean signal for new physics.Comment: 14 pages, 1 figure, discussions on further power corrections adde

    Determination of alpha_s from F_2^p at HERA

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    We compute the proton structure function F_2^p at small x and large Q^2 at next-to-leading order in alpha_s(Q^2), including summations of all leading and subleading logarithms of Q^2 and 1/x in a way consistent with momentum conservation. We perform a detailed comparison to the 1993 HERA data, and show that they may be used to determine alpha_s(M_Z^2)=0.120 pm 0.005(exp) pm 0.009(th). The theoretical error is dominated by the renormalization and factorization scheme ambiguities.Comment: 24 pages, TeX with harvmac and epsf, 10 figures in compressed postscript. Final (published) versio

    Double Asymptotic Scaling '96

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    We review recent HERA data on the structure function F_2 at small x and large Q^2. We show that the salient features of the data are revealed by comparing them to the double asymptotic scaling behaviour which F_2 is predicted to satisfy in perturbative QCD.Comment: 5 pages, LaTeX with espcrc2.sty (included), 11 figures included by epsfi

    Can we trust small x resummation?

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    We review the current status of small x resummation of evolution of parton distributions and of deep-inelastic coefficient functions. We show that the resummed perturbative expansion is stable, robust upon different treatments of subleading terms, and that it matches smoothly to the unresummed perturbative expansions, with corrections which are of the same order as the typical NNLO ones in the HERA kinematic region. We discuss different approaches to small x resummation: we show that the ambiguities in the resummation procedure are small, provided all parametrically enhanced terms are included in the resummation and properly matched.Comment: 12 pages, 12 figures; LaTeX with espcrc2.sty. Talk given at the 2008 Ringberg workshop "New Trends in HERA Physics

    A method for putting chiral fermions on the lattice

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    We describe a method to put chiral gauge theories on the lattice. Our method makes heavy use of the effective action for chiral fermions in the continuum, which is in general complex. As an example we discuss the chiral Schwinger model.Comment: 4 pages, HLRZ 92-8

    A new model for procuring e-books

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    This paper draws on a recent ground-breaking tender for e-books for higher education libraries in the UK. The strategy for the tender was informed by standard procurement practice and by the experience of acquiring other e-resources, particularly journals under the so-called big deal. Both are examined as background to the discussion of e-books in general and the tender in particular

    What's the 'big deal', and why is it bad deal for universities?

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    At first sight the “big (or all-you-can-eat) deal” seems excellent value for libraries and their users, and represents the shining possibilities of the electronic age. A more thorough-going evaluation, however, exposes dangers for universities, their funders and publishers. This paper examines the big deal in the light of fundamental market conditions and suggests alternative models for procuring electronic resources. The roles and strengths of the players in the information supply chain are defined and traditional hard-copy procurement is analysed in terms of these roles and the concepts of authority, branding and monopoly. The fundamentals of procuring electronic resources and prevalent purchasing models are discussed in terms of the same roles and concepts. The advantages of the big deal are laid out - access to resources, low unit costs etc. The dangers are also discussed. These arise mainly from the publishers’ position as monopolists. The possible long-term effects, on library budgets and academic publishing, of dealing with monopoly suppliers are examined. Means of avoiding or minimising these dangers – consortia, alternative publishing methods, new economic models to promote competition – are examined
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