1,787 research outputs found

    Non-minimally Coupled Gravitational and Electromagnetic Fields: pp-Wave Solutions

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    We give the Lagrangian formulation of a generic non-minimally extended Einstein-Maxwell theory with an action that is linear in the curvature and quadratic in the electromagnetic field. We derive the coupled field equations by a first order variational principle using the method of Lagrange multipliers. We look for solutions describing plane-fronted Einstein-Maxwell waves with parallel rays. We give a family of exact solutions associated with a partially massless spin-2 photon and a partially massive spin-2 graviton

    A qualitative study on CALL knowledge and materials design: Insights from pre-service EFL teachers

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    This is the final version of the article. Available from IGI Global via the DOI in this record.The present study investigates how academic coursework and formal learning of instructional technology and materials design help pre-service English language teachers' development of critical knowledge of CALL materials. The participants are 111 pre-service English language teachers enrolled in a TEFL programme at a Turkish University. Throughout a 14-week semester, these participants learn to design a variety of CALL materials including online teaching tools and a set of Web 2.0 tools. The article explores the skills and knowledge of pre-service teachers on the design and development of audio-visual web-based activities, through qualitative content analysis of their written reflections. The analyses of reflections on practice have revealed that these teachers demonstrate strong and critical understanding of CALL in enriching authenticity, enhancing motivation, facilitating language learning, and providing multimodal resources. They also display great awareness of instructional knowledge, in particular, in the design and interface of technology to facilitate learning

    The power of suggestion: examining the impact of presence or absence of shared first language in the antenatal clinic

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    © 2019 Foundation for the Sociology of Health & Illness Healthcare encounters involving participants from diverse linguistic backgrounds are becoming more common due to the globalisation of health care and increasing migration levels. Research suggests that this diversity has a significant impact on health outcomes; however less is known about how it is managed in the actual consultation process. This article presents an analysis of antenatal screening consultations video recorded in Hong Kong, using conversation analysis. We consider how the use of a second or subsequent language impacts on these consultations, and on discussions and decisions about further action. The presence or absence of shared first language did not appear to affect the extent to which particular courses of action were promoted or recommended. Recommendations were a common occurrence across consultations with and without shared first language. However, we argue that the routine use of recommendations can be consequential, as second language speakers may have more limited resources to interrogate or contest these. This finding has implications for the ability for professionals to maximise patient involvement in decision-making

    Enhanced He-alpha emission from "smoked" Ti targets irradiated with 400nm, 45 fs laser pulses

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    We present a study of He-like 1s(2)-1s2p line emission from solid and low-density Ti targets under similar or equal to 45 fs laser pulse irradiation with a frequency doubled Ti: Sapphire laser. By varying the beam spot, the intensity on target was varied from 10(15) W/cm(2) to 10(19) W/cm(2). At best focus, low density "smoked" Ti targets yield similar to 20 times more He-alpha than the foil targets when irradiated at an angle of 45 degrees with s-polarized pulses. The duration of He-alpha emission from smoked targets, measured with a fast streak camera, was similar to that from Ti foils

    FACET : a new long-lived particle detector in the very forward region of the CMS experiment

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    We describe a proposal to add a set of very forward detectors to the CMS experiment for the high-luminosity era of the Large Hadron Collider to search for beyond the standard model long-lived particles, such as dark photons, heavy neutral leptons, axion-like particles, and dark Higgs bosons. The proposed subsystem is called FACET for Forward-Aperture CMS ExTension, and will be sensitive to any particles that can penetrate at least 50 m of magnetized iron and decay in an 18 m long, 1 m diameter vacuum pipe. The decay products will be measured in detectors using identical technology to the planned CMS Phase-2 upgrade.Peer reviewe

    Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

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    The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum
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