1,977 research outputs found

    The primordial deuterium abundance at z = 2.504 from a high signal-to-noise spectrum of Q1009+2956

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    The spectrum of the zem=2.63z_{\rm em} = 2.63 quasar Q1009+2956 has been observed extensively on the Keck telescope. The Lyman limit absorption system zabs=2.504z_{\rm abs} = 2.504 was previously used to measure D/H by Burles & Tytler using a spectrum with signal to noise approximately 60 per pixel in the continuum near Ly {\alpha} at zabs=2.504z_{\rm abs} = 2.504. The larger dataset now available combines to form an exceptionally high signal to noise spectrum, around 147 per pixel. Several heavy element absorption lines are detected in this LLS, providing strong constraints on the kinematic structure. We explore a suite of absorption system models and find that the deuterium feature is likely to be contaminated by weak interloping Ly {\alpha} absorption from a low column density H I cloud, reducing the expected D/H precision. We find D/H = 2.480.35+0.41×1052.48^{+0.41}_{-0.35}\times10^{-5} for this system. Combining this new measurement with others from the literature and applying the method of Least Trimmed Squares to a statistical sample of 15 D/H measurements results in a "reliable" sample of 13 values. This sample yields a primordial deuterium abundance of (D/H)p=(2.545±0.025)×105_{\rm p} = (2.545 \pm 0.025)\times10^{-5}. The corresponding mean baryonic density of the Universe is Ωbh2=0.02174±0.00025\Omega_{\rm b}h^2 = 0.02174\pm0.00025. The quasar absorption data is of the same precision as, and marginally inconsistent with, the 2015 CMB Planck (TT+lowP+lensing) measurement, Ωbh2=0.02226±0.00023\Omega_{\rm b}h^2 = 0.02226\pm0.00023. Further quasar and more precise nuclear data are required to establish whether this is a random fluctuation.Comment: accepted by MNRAS, 18 pages, 12 figures, 6 table

    Practice-based Qualitative Research: Participant Experiences of Walk-in Counselling and Traditional Counselling

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    Walk-in single session counselling is becoming a more widely used model for delivering mental health services across Ontario. This paper reports findings from the qualitative phase of a mixed method study, exploring the experiences of those attending walk-in counselling (WIC) model compared to the traditional service delivery model employing a wait list. We used a comparative case study design for the qualitative phase. Findings reveal that participant outcomes of the walk-in counselling model is influenced by accessibility, how a participant makes sense of the service, and the degree to which a participant is motivated and able to engage in counselling. WIC supports the mental health system by reducing wait lists associated with traditional service delivery models, and meeting the needs many people identify for immediate consultation. Other participants still perceive themselves as requiring ongoing counselling over time and involving in-depth exploration. This research supports health systems providing access to both models

    FDG-PET/CT(A) imaging in large vessel vasculitis and polymyalgia rheumatica:joint procedural recommendation of the EANM, SNMMI, and the PET Interest Group (PIG), and endorsed by the ASNC

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    Large vessel vasculitis (LVV) is defined as a disease mainly affecting the large arteries, with two major variants. Takayasu arteritis (TA) and giant cell arteritis (GCA). GCA often coexists with polymyalgia rheumatica (PMR) in the same patient, since both belong to the same disease spectrum. FDG-PET/CT is a functional imaging technique which is an established tool in oncology, and has also demonstrated a role in the field of inflammatory diseases. Functional FDG-PET combined with anatomical CT angiography, FDG-PET/CT(A), may be of synergistic value for optimal diagnosis, monitoring of disease activity, and evaluating damage progression in LVV There are currently no guidelines regarding PET imaging acquisition for LVV and PMR, even though standardization is of the utmost importance in order to facilitate clinical studies and for daily clinical practice. This work constitutes a joint procedural recommendation on FDG-PET/CT(A) imaging in large vessel vasculitis (LVV) and PMR from the Cardiovascular and Inflammation &amp; Infection Committees of the European Association of Nuclear Medicine (EANM), the Cardiovascular Council of the Society of Nuclear Medicine and Molecular Imaging (SNMMI), and the PET Interest Group (PIG), and endorsed by the American Society of Nuclear Cardiology (ASNC). The aim of this joint paper is to provide recommendations and statements, based on the available evidence in the literature and consensus of experts in the field, for patient preparation, and FDG-PET/CT(A) acquisition and interpretation for the diagnosis and follow-up of patients with suspected or diagnosed LVV and/or PMR. This position paper aims to set an internationally accepted standard for FDG-PET/CT(A) imaging and reporting of LVV and PMR.</p

    Adapting Game Mechanics with Micro-Machinations

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    In early game development phases game designers adjust game rules in a rapid, iterative and flexible way. In later phases, when software prototypes are available, play testing provides more detailed feedback about player experience. More often than not, the realized and the intended gameplay emerging from game software differ. Unfortunately, adjusting it is hard because designers lack a means for efficiently defining, fine-tuning and balancing game mechanics. The language Machinations provides a graphical notation for expressing the rules of game economies that fits with a designer’s understanding and vocabulary, but is limited to design itself. Micro-Mach

    Defining the Agenda for Serious Tort Reform

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    In this Article, the authors support Prof. Sugarman\u27s tort reform proposals, but argue that these proposals need more development before they will produce actual change

    Phyllostictine A : total synthesis, structural verification and determination of substructure responsible for plant growth inhibition

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    The first total synthesis of phyllostictine A (PA) is reported, which confirms the structure of this fungal metabolite and its (6S,7R,8S)-stereochemistry. Both synthetic PA and an analogue containing the 5-methylene-1,5-dihydro-2H-pyrrol-2-one nucleus exhibit μM inhibitory activity in root growth assays against Arabidopsis thaliana, indicating that this heterocyclic subunit is key to the herbicidal activity of the natural product

    Is having a sweetheart enough to survive?

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    Almost three decades after the description of improved left ventricular function caused by chronic impaired coronary perfusion, and the rise of the term “Hibernation,” finding that hibernating myocardium is still a challenge for cardiologists
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