12,019 research outputs found

    The shape of the Δ\Delta baryon in a covariant spectator quark model

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    Using a covariant spectator quark model that describes the recent lattice QCD data for the Δ\Delta electromagnetic form factors and all available experimental data on γN→Δ\gamma N \to \Delta transitions, we analyze the charge and magnetic dipole distributions of the Δ\Delta baryon and discuss its shape. We conclude that the quadrupole moment of the Δ\Delta is a good indicator of the deformation and that the Δ+\Delta^+ charge distribution has an oblate shape. We also calculate transverse moments and find that they do not lead to unambiguous conclusions about the underlying shape.Comment: Extended introduction, references added, other small modifications. To appear in Phys. Rev. D. 14 pages, 8 figure

    Renormalization of HQET ΔB=2\Delta B=2 operators: O(aa) improvement and 1/m1/m matching with QCD

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    We determine a basis of dimension-7 operators which arise at O(aa) in the Symanzik expansion of the ΔB=2\Delta B=2 operators with static heavy quarks. We consider both Wilson-like and Ginsparg-Wilson light quarks. Exact chiral symmetry reduces the number of these O(aa) counterterms by a factor of two. Only a subset of these operators has previously appeared in the literature. We then extend the analysis to the O(1/m1/m) operators contributing beyond the static approximation.Comment: 7 pages, presented at the 31st International Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, German

    Virtual libraries of tissue and clinical samples: potential role of a 3-D microscope.

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    Our international innovative teaching group from different European Universities (De Montfort University, DMU, UK; and the Spanish University of Alcalá, University Miguel Hernández and University of San Pablo CEU), in conjunction with practicing biomedical scientists in the National Health Service (UK) and biomedical researchers, are developing two complete e-learning packages for teaching and learning medical parasitology, named DMU e-Parasitology (accessible at: http://parasitology.dmu.ac.uk), and biology and chemistry, named DMU e-Biology (accessible at: http://parasitology.dmu.ac.uk/ebiology/index.htm), respectively. Both packages will include a virtual microscope with a complete library of digitised tissue images, clinical slides and cell culture slides/mini-videos for enhancing the teaching and learning of a myriad of techniques applicable to health science undergraduate and postgraduate students. Thus, these packages include detecting human parasites, by becoming familiar with their infective structures and/or organs (e.g. eggs, cysts) and/or explore pathogenic tissues stained with traditional (e.g. haematoxylin & eosin) or more modern (e.g. immunohistochemistry) techniques. The Virtual Microscope (VM) module in the DMU e-Parasitology package is almost completed (accessible at: http://parasitology.dmu.ac.uk/learn/microscope.htm) and contains a section for the three major groups of human-pathogenic parasites (Peña-Fernández et al., 2018) [1]. Digitised slides are provided with the functionality of a microscope by using the gadget Zoomify®, and we consider that they can enhance learning, as previous studies reported in the literature have reported similar sensitivity and specificity rates for identification of parasites for both digitised and real slides. The DMU e-Biology’s VM, currently in development, will provide healthy and pathological tissue samples from a range of mammalian tissues and organs. This communication will provide a description of both virtual libraries and the process of developing them. In conjunction, we will use a three-dimensional (3D) super-resolution microscopy, 3D Cell Explorer (Nanolive, Lausanne, Switzerland), to incorporate potential 3D microscopic photographs/short videos of cells to provide students with information about the spatial arrangement and morphologies of cells that are essential for life

    Controlled generation of large volumes of atmospheric clouds in a ground-based environmental chamber

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    Atmospheric clouds were generated in a 23,000 cubic meter environmental chamber as the first step in a two part study on the effects of contaminants on cloud formation. The generation procedure was modeled on the terrestrial generation mechanism so that naturally occurring microphysics mechanisms were operative in the cloud generation process. Temperature, altitude, liquid water content, and convective updraft velocity could be selected independently over the range of terrestrially realizable clouds. To provide cloud stability, a cotton muslin cylinder 29.3 meters in diameter and 24.2 meters high was erected within the chamber and continuously wetted with water at precisely the same temperature as the cloud. The improved instrumentation which permitted fast, precise, and continual measurements of cloud temperature and liquid water content is described

    Non-perturbative scale evolution of four-fermion operators in two-flavour QCD

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    We apply finite-size recursion techniques based on the Schrodinger functional formalism to determine the renormalization group running of four-fermion operators which appear in the Delta S=2 effective weak Hamiltonian of the Standard Model. Our calculations are done using O(a) improved Wilson fermions with N_f=2 dynamical flavours. Preliminary results are presented for the four-fermion operator which determines the B_K parameter in tmQCD.Comment: 7 pages, 2 figures, talk presented at Lattice2006 (Renormalization

    Non-perturbative renormalisation and running of BSM four-quark operators in Nf=2 QCD

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    We perform a non-perturbative study of the scale-dependent renormalisation factors of a complete set of dimension-six four-fermion operators without power subtractions. The renormalisation-group (RG) running is determined in the continuum limit for a specific Schrödinger Functional (SF) renormalisation scheme in the framework of lattice QCD with two dynamical flavours (Nf= 2). The theory is regularised on a lattice with a plaquette Wilson action and O(a)-improved Wilson fermions. For one of these operators, the computation had been performed in Dimopoulos et al. (JHEP 0805, 065 (2008). arXiv:0712.2429); the present work completes the study for the rest of the operator basis, on the same simulations (configuration ensembles). The related weak matrix elements arise in several operator product expansions; in Δ F= 2 transitions they contain the QCD long-distance effects, including contributions from beyond-Standard Model (BSM) processes. Some of these operators mix under renormalisation and their RG-running is governed by anomalous dimension matrices. In Papinutto et al. (Eur Phys J C 77(6), 376 (2017). arXiv:1612.06461) the RG formalism for the operator basis has been worked out in full generality and the anomalous dimension matrix has been calculated in NLO perturbation theory. Here the discussion is extended to the matrix step-scaling functions, which are used in finite-size recursive techniques. We rely on these matrix-SSFs to obtain non-perturbative estimates of the operator anomalous dimensions for scales ranging from O(Λ QCD) to O(MW)

    Participação popular na elaboração de políticas públicas de desenvolvimento local: análise de práticas no município de Serrinha/RN.

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    Este artigo apresenta os resultados de uma pesquisa sobre as práticas participativas no município de Serrinha/RN entre os anos de 1997 e 2004, demonstrando qual foi o processo utilizado para realizar estas práticas em um momento e local considerados modelo. A análise foi desenvolvida através de um modelo de pesquisa com base na literatura relativa ao processo ideal para aplicação de uma política pública participativa. Verificou-se que houve um real interesse em implantar um processo de desenvolvimento local no município, mas ele não foi totalmente eficaz. Apesar disso, foi possível constatar um considerável avanço na consciência política da população, especialmente no meio rural, e a perenidade da organização social em torno de projetos de geração de emprego e renda. Apresentam-se propostas de como políticas de desenvolvimento podem ser conduzidas de forma participativa e com base em benefícios locais
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