3,194 research outputs found

    They Came To a City

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    The program was scanned from an original held in the University Archives.This play was produced and directed by Thelma Baulderstone. It was staged at the Hut from 21st to 23rd May 1945

    OH+^+ emission from cometary knots in planetary nebulae

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    We model the molecular emission from cometary knots in planetary nebulae (PNe) using a combination of photoionization and photodissociation region (PDR) codes, for a range of central star properties and gas densities. Without the inclusion of ionizing extreme ultraviolet (EUV) radiation, our models require central star temperatures TT_* to be near the upper limit of the range investigated in order to match observed H2_2 and OH+^+ surface brightnesses consistent with observations - with the addition of EUV flux, our models reproduce observed OH+^+ surface brightnesses for T100kKT_* \ge 100 \, {\rm kK}. For T<80kKT_* < 80 \, {\rm kK}, the predicted OH+^+ surface brightness is much lower, consistent with the non-detection of this molecule in PNe with such central star temperatures. Our predicted level of H2_2 emission is somewhat weaker than commonly observed in PNe, which may be resolved by the inclusion of shock heating or fluorescence due to UV photons. Some of our models also predict ArH+^+ and HeH+^+ rotational line emission above detection thresholds, despite neither molecule having been detected in PNe, although the inclusion of photodissociation by EUV photons, which is neglected by our models, would be expected to reduce their detectability.Comment: Accepted by MNRAS, 11 pages, 15 figures. Author accepted manuscript. Accepted on 24/04/18. Deposited on 27/04/1

    First-year assessment: aligning perceptions and practice with purpose

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    Modelling the ArH+^+ emission from the Crab Nebula

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    We have performed combined photoionization and photodissociation region (PDR) modelling of a Crab Nebula filament subjected to the synchrotron radiation from the central pulsar wind nebula, and to a high flux of charged particles; a greatly enhanced cosmic ray ionization rate over the standard interstellar value, ζ0\zeta_0, is required to account for the lack of detected [C I] emission in published Herschel SPIRE FTS observations of the Crab Nebula. The observed line surface brightness ratios of the OH+^+ and ArH+^+ transitions seen in the SPIRE FTS frequency range can only be explained with both a high cosmic ray ionization rate and a reduced ArH+^+ dissociative recombination rate compared to that used by previous authors, although consistent with experimental upper limits. We find that the ArH+^+/OH+^+ line strengths and the observed H2_2 vibration-rotation emission can be reproduced by model filaments with nH=2×104n_{\rm{H}} = 2 \times 10^4 cm3^{-3}, ζ=107ζ0\zeta = 10^7 \zeta_0 and visual extinctions within the range found for dusty globules in the Crab Nebula, although far-infrared emission from [O I] and [C II] is higher than the observational constraints. Models with nH=1900n_{\rm{H}} = 1900 cm3^{-3} underpredict the H2_2 surface brightness, but agree with the ArH+^+ and OH+^+ surface brightnesses and predict [O I] and [C II] line ratios consistent with observations. These models predict HeH+^+ rotational emission above detection thresholds, but consideration of the formation timescale suggests that the abundance of this molecule in the Crab Nebula should be lower than the equilibrium values obtained in our analysis.Comment: Accepted by MNRAS. Author accepted manuscript. Accepted on 05/09/2017. Deposited on 05/09/1

    A qualitative analysis of beliefs related to gender equality in the Church of Christ

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    In recent years, American Christian churches, including the Church of Christ, have grappled with the role of women in their congregations. As women have gained legal rights, expanded social roles, and access to leadership, certain churches, including the Church of Christ, have lagged in adapting to these changes. This study aims to understand the organizational change process within these churches, exploring why belief systems can be slow to change and how some congregations have successfully transitioned from a complementarian to an egalitarian stance related to women\u27s leadership roles. The research employs a contextual lens, considering how human psychology influences beliefs and behavior. Cognitive psychology reveals the challenge of changing rigid beliefs as humans are wired to hold onto preconceived notions. Organizational culture change is hindered by this resistance, leading to cognitive inflexibility and reduced adaptability. The study examines 12 congregations within the Church of Christ denomination that have successfully shifted towards egalitarian practices using the methodology of structured interviews. Qualitative analysis of interview results uncovered themes related to successful transitions and factors impeding change. In order of relative strength, the themes were a) Biblical interpretation; b) exposure to women in leadership; c) cognitive flexibility; d) dialogue; e) age demographics; and f) time. Identifying common themes promoting or hindering belief system changes, this research offers valuable insights for facilitating social change within these communities and useful directions for future research and practice, and the expansion of diversity, equity, and inclusion in their leadership roles

    Slow equivariant lump dynamics on the two sphere

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    The low-energy, rotationally equivariant dynamics of n CP^1 lumps on S^2 is studied within the approximation of geodesic motion in the moduli space of static solutions. The volume and curvature properties of this moduli space are computed. By lifting the geodesic flow to the completion of an n-fold cover of the moduli space, a good understanding of nearly singular lump dynamics within this approximation is obtained.Comment: 12 pages, 3 figure

    The Evolution of Data Science: A New Mode of Knowledge Production

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    Is data science a new field of study or simply an extension or specialization of a discipline that already exists, such as statistics, computer science, or mathematics? This article explores the evolution of data science as a potentially new academic discipline, which has evolved as a function of new problem sets that established disciplines have been ill-prepared to address. The authors find that this newly-evolved discipline can be viewed through the lens of a new mode of knowledge production and is characterized by transdisciplinarity collaboration with the private sector and increased accountability. Lessons from this evolution can inform knowledge production in other traditional academic disciplines as well as inform established knowledge management practices grappling with the emerging challenges of Big Data

    Analyzing X-ray variability by State Space Models

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    In recent years, autoregressive models have had a profound impact on the description of astronomical time series as the observation of a stochastic process. These methods have advantages compared with common Fourier techniques concerning their inherent stationarity and physical background. If autoregressive models are used, however, it has to be taken into account that real data always contain observational noise often obscuring the intrinsic time series of the object. We apply the technique of a Linear State Space Model which explicitly models the noise of astronomical data and allows to estimate the hidden autoregressive process. As an example, we have analysed a sample of Active Galactic Nuclei (AGN) observed with EXOSAT and found evidence for a relationship between the relaxation timescale and the spectral hardness.Comment: 4 pages, Latex, uses Kluwer Style file crckapb.cls To appear in Proc. of Astronomical Time Series, Tel Aviv, 199
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