2,676 research outputs found

    Taylor-Lagrange renormalization scheme. Application to light-front dynamics

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    The recently proposed renormalization scheme based on the definition of field operators as operator valued distributions acting on specific test functions is shown to be very convenient in explicit calculations of physical observables within the framework of light-front dynamics. We first recall the main properties of this procedure based on identities relating the test functions to their Taylor remainder of any order expressed in terms of Lagrange's formulae, hence the name given to this scheme. We thus show how it naturally applies to the calculation of state vectors of physical systems in the covariant formulation of light-front dynamics. As an example, we consider the case of the Yukawa model in the simple two-body Fock state truncation.Comment: 18 pages, 6 figures, introduction changed, corrected typos, to be published in Physical Review

    Multi-scale analysis of timber framed structures filled with earth and stones

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    This paper deals with the seismic analysis of timber framed houses filled by stones and earth mortar using a multi-scale approach going from the cell to the wall and then to the house. At the scale of the elementary cells, experimental results allow fitting the parameters of a new versatile hysteretic law presented herein through the definition of a macro-element. Then, at the scale of wall, the numerical simulations are able to predict its behavior under quasi-static cyclic loading and is compared to experimental results allowing validating the macro-element model

    Discharge suppression system for a double focusing, atmospheric pressure ionization mass spectrometer

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    An electrical discharge suppression system for a medium throughput (∌2 l/s) pumping line has been devised that works up to potentials of ±15 kV. This device permits atmospheric pressure ionization sources to be interfaced to high-resolution, magnetic sector mass spectrometers with source potentials of 6-10 k

    Chinese Whispers: A brief history of eponymous orthopaedic examinations

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    Eponymous orthopaedic examinations frequently appear in modern clinical examinations, yet their original description and cause for change are often omitted from medical education today. This is important to appreciate in order to understand their diagnostic relevance in modern medicine and subsequent interpretation of results by fellow clinicians. This article reviews the original description of these tests by their namesakes, how they have evolved over time and their relevance in orthopaedics today. An online literature review (PubMed) was conducted of the original descriptions and other published literature detailing their history, evolution, sensitivity and specificity. While elements of these tests have been lost naturally over time to the ‘Chinese Whispers’ effect, most have evolved positively secondary to a deepening anatomical and pathological understanding of their target conditions. They retain some usefulness in clinical medicine, however it is recognized that their diagnostic value is invariably supplanted by improvements in diagnostic imaging

    Cochlear implant simulator with independent representation of the full spiral ganglion

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    In cochlear implant simulation with vocoders, narrow-band carriers deliver the envelopes from each analysis band to the cochlear positions of the simulated electrodes. However, this approach does not faithfully represent the continuous nature of the spiral ganglion. The proposed “SPIRAL” vocoder simulates current spread by mixing all envelopes across many tonal carriers. SPIRAL demonstrated that the classic finding of reduced speech-intelligibility benefit with additional electrodes could be due to current spread. SPIRAL produced lower speech reception thresholds than an equivalent noise vocoder. These thresholds are stable for between 20 and 160 carriers
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