517 research outputs found

    Unified mechanism of local drivers in a percolation model of atrial fibrillation

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    The mechanisms of atrial fibrillation (AF) are poorly understood, resulting in disappointing success rates of ablative treatment. Different mechanisms defined largely by different atrial activation patterns have been proposed and, arguably, this dispute has slowed the progress of AF research. Recent clinical evidence suggests a unifying mechanism of local drivers based on sustained re-entrant circuits in the complex atrial architecture. Here, we present a percolation inspired computational model showing spontaneous emergence of AF that strongly supports, and gives a theoretical explanation for, the clinically observed diversity of activation. We show that the difference in surface activation patterns is a direct consequence of the thickness of the discrete network of heart muscle cells through which electrical signals percolate to reach the imaged surface. The model naturally follows the clinical spectrum of AF spanning sinus rhythm, paroxysmal and persistent AF as the decoupling of myocardial cells results in the lattice approaching the percolation threshold. This allows the model to make the novel prediction that for paroxysmal AF, re-entrant circuits emerge near the endocardium, but in persistent AF they emerge deeper in the bulk of the atrial wall. If experimentally verified, this may go towards explaining the lowering ablation success rate as AF becomes more persistent

    Mitigation and screening for environmental assessment

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    This article considers how, as a matter of law and policy, mitigation measures should be taken into account in determining whether a project will have significant environmental effects and therefore be subject to assessment under the EU Environmental Impact Assessment (EIA) Directive. This is not straightforward: it is problematic to distinguish clearly between an activity and the measures proposed to minimise or mitigate for the adverse consequences of the activity. The issue is a salient one in impact assessment law, but under-explored in the literature and handled with some difficulty by the courts. I argue that there is an unnecessarily and undesirably narrow approach currently taken under the EIA Directive, which could be improved upon by taking a more adaptive approach; alternatively a heightened standard of review of ‘significance’, and within this of the scope for mitigation measures to bring projects beneath the significance threshold, may also be desirable

    Integrating Technical Standards into ET Curricula to Meet ABET Standards and Industry Needs

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    With technical standards affecting nearly every aspect of our daily lives, from computers to the components and materials used in car engines, it is critical that undergraduate students are educated on the importance of standards and provided with opportunities to locate and apply relevant technical standards to real world situations. In addition, with ABET accreditation requiring students to have a “basic understanding and familiarity with,” and experience “using” codes and standards, faculty need to consider how such material can be naturally integrated into the curriculum. At Purdue University, education about codes and standards has been integrated into the mechanical engineering technology (MET) curriculum for decades with significant success. This paper discusses how standards are incorporated into mechanical design and quality control courses, as well as strategies for integrating standards into more courses in an MET curriculum. In addition, a discussion of standards resources that are freely available is included. Finally, a call to action for industry is presented, explaining the need and potential areas where industry can increase involvement in teaching students about technical standards

    From Fan Parks to Live Sites: Mega events and the territorialisation of urban space

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    This article draws on the work of Gilles Deleuze and Felix Guattari to consider the phenomenon of Live Sites and Fan Parks which are now enshrined within the viewing experience of mega sports events. Empirically, the article draws upon primary research on Live Sites generated during the London 2012 Olympic Games. Live Sites are represented as new spaces within which to critically locate and conceptually explore the shifting dynamics of urban space, subjectivity and its performative politic. The authors argue that the first, or primary, spaces of mega sporting events (the official venues) and their secondary counterparts (Live Sites) simply extend brandscaping tendencies but that corporate striation is always incomplete, opening up possibilities for disruption and dislocation

    Photonic Doppler velocimetry probe used to measure grain boundaries of dynamic shocked materials

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    Author Institution: Mission Support and Test Services, LLC; Los Alamos National LaboratorySlides presented at the 2018 Photonic Doppler Velocimetry (PDV) Users Workshop, Drury Plaza Hotel, Santa Fe, New Mexico, May 16-18, 2018

    Access to finance: an empirical analysis

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    YesFinancial access is gradually being recognised as an important input to economic development. Using World Bank (2007) database, this study measures the extent of financial access in developed and developing countries. Further, it develops a new Socio-Economic Development Index, which incorporates financial access. It then compares socio-economic development of various countries as shown by Human Development Index (HDI) alone and by the new index incorporating financial access. The results of the study show that Spain ranks highest in terms of financial access followed by Belgium, Malta and South Korea. In addition, the ranking of countries in terms of HDI changes if financial access is taken into accoun
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