46,695 research outputs found

    High Redshift Standard Candles: Predicted Cosmological Constraints

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    We investigate whether future measurements of high redshift standard candles (HzSCs) will be a powerful probe of dark energy, when compared to other types of planned dark energy measurements. Active galactic nuclei and gamma ray bursts have both been proposed as potential HzSC candidates. Due to their high luminosity, they can be used to probe unexplored regions in the expansion history of the universe. Information from these regions can help constrain the properties of dark energy, and in particular, whether it varies over time. We consider both linear and piecewise parameterizations of the dark energy equation of state, w(z)w(z), and assess the optimal redshift distribution a high-redshift standard-candle survey could take to constrain these models. The more general the form of the dark energy equation of state w(z)w(z) being tested, the more useful high-redshift standard candles become. For a linear parameterization of w(z)w(z), HzSCs give only small improvements over planned supernova and baryon acoustic oscillation measurements; a wide redshift range with many low redshift points is optimal to constrain this linear model. However to constrain a general, and thus potentially more informative, form of w(z)w(z), having many HzSCs can significantly improve limits on the nature of dark energy.Comment: Accepted MNRAS, 27 Pages, 15 figures, matches published versio

    String-Inspired Triplet See-Saw from Diagonal Embedding of SU(2)_L in SU(2)_A x SU(2)_B

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    Motivated by string constructions, we consider a variant on the Type II see-saw mechanism involving the exchange of triplet representations of SU(2)_L in which this group arises from a diagonal embedding into SU(2)_A x SU(2)_B. A natural assignment of Standard Model lepton doublets to the two underlying gauge groups results in a bimaximal pattern of neutrino mixings and an inverted hierarchy in masses. Simple perturbations around this leading-order structure can accommodate the observed pattern of neutrino masses and mixings.Comment: 8 pages; uses RevTe

    Doing it differently: Engaging interview participants with imaginative variation

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    Imaginative variation was identified by Husserl (1936/1970) as a phenomenological technique for the purpose of elucidating the manner in which phenomena appear to consciousness. Briefly, by engaging in the phenomenological reduction and using imaginative variation, phenomenologists are able to describe the experience of consciousness, having stepped outside of the natural attitude through the epochē. Imaginative variation is a stage aimed at explicating the structures of experience, and is best described as a mental experiment. Features of the experience are imaginatively altered in order to view the phenomenon under investigation from varying perspectives. Husserl argued that this process will reveal the essences of an experience, as only those aspects that are invariant to the experience of the phenomenon will not be able to change through the variation. Often in qualitative research interviews, participants struggle to articulate or verbalise their experiences. The purpose of this article is to detail a radical and novel way of using imaginative variation with interview participants, by asking the participants to engage with imaginative variation, in order to produce a rich and insightful experiential account of a phenomenon. We will discuss how the first author successfully used imaginative variation in this way in her study of the erotic experience of bondage, discipline, dominance & submission, and sadism & masochism (BDSM), before considering the usefulness of this technique when applied to areas of study beyond sexuality

    Revealing the Archetype: The Journey of a Trecento Madonna and Child at the National Museum of Scotland

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    The National Museums Scotland Madonna and Child project sought to uncover and document the history of a fine polychrome wood carving attributed to The Master of the Gualino St Catherine and to prepare it for display. A new body of knowledge has been assembled by the interdisciplinary team. The conservation treatment was informed by this work and led to further discoveries: the removal of overpaint exposing a previously hidden underdrawing. The ethics of the treatment decisions, including the removal of the Christ Child’s 1960s’ fingers required team dialogue and was opened up for the public to respond to in a series of blogs. The discovery of a rich polychromy including gold and glazed tin has led to further plans to produce a 3-D colour reconstruction. The collaborations developed during this project will facilitate future joint ventures for polychrome sculpture in Scottish collections

    Ortho-para transition rate in Ό\mu-molecular hydrogen and the proton's induced pseudoscalar coupling gpg_p

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    We report a measurement of the ortho-para transition rate in the pÎŒ\mup molecule. The experiment was conducted at TRIUMF via the measurement of the time dependence of the 5.2 MeV neutrons from muon capture in liquid hydrogen. The measurement yielded an ortho-para rate Λop=(11.1±1.7±0.60.9)×104\Lambda_{op} = (11.1 \pm 1.7 \pm^{0.9}_{0.6}) \times 10^4 s−1^{-1} that is substantially larger than the earlier result of Bardin {\it et al.} We discuss the striking implications for the proton's induced pseudoscalar coupling gpg_p.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
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