1,493 research outputs found

    Investigating the source of Planck-detected AME: high resolution observations at 15 GHz

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    The Planck 28.5 GHz maps were searched for potential Anomalous Microwave Emission (AME) regions on the scale of 3\sim3^{\circ} or smaller, and several new regions of interest were selected. Ancillary data at both lower and higher frequencies were used to construct spectral energy distributions (SEDs), which seem to confirm an excess consistent with spinning dust models. Here we present higher resolution observations of two of these new regions with the Arcminute Microkelvin Imager Small Array (AMI SA) between 14 and 18 GHz to test for the presence of a compact (\sim10 arcmin or smaller) component. For AME-G107.1+5.2, dominated by the {\sc Hii} region S140, we find evidence for the characteristic rising spectrum associated with the either the spinning dust mechanism for AME or an ultra/hyper-compact \textsc{Hii} region across the AMI frequency band, however for AME-G173.6+2.8 we find no evidence for AME on scales of 210\sim 2-10 arcmin.Comment: 13 pages, 8 figures, 4 tables. Submitted to Advances in Astronomy AME Special Issu

    TIME's past in the present: nostalgia and the black and white image

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    In 1995, the Hubble Space Telescope sent back to astronomers at the University of Arizona a series of vivid colour images of the Eagle Nebula, a dense formation of interstellar gas and dust the likes of which cradle newborn stars. As evidence that our perceptual universe, in every sense of the word, is defined by the representational powers of colour technology, the Hubble's “cosmic close-ups” are a clear case in point. Colour has become a standard representational form and hence the visual form. If so, what can be said of the recent popularity and proliferation of the black-and-white image? No self-respecting café-bar or discriminating home, it seems, can now do without a black and white print on the wall. Commercial photography and certain forms of advertising have found a new niche in black and white, and even sepia is staging a come-back. The popularity of the black-and-white image cannot be divorced from the commercial culture in which it circulates; it is a “look” and a marker of taste. Monochrome is a stylistic trend but a revealing one, especially if one considers the growing preoccupation in America with heritage and memory. Both Susan Sontag and Roland Barthes give black and white a status of authenticity judged in relation to past time “properly” captured. For Sontag, monochrome gives an image a sense of age, historical distance, and aura. She writes, “the cold intimacy of color seems to seal off the photograph from patina.” Likewise, Barthes comments on the artifice of colour, how it is a “coating applied later on to the original truth of black and white.” For both critics, monochrome is an aesthetic of the authentic figured around a basic quality of pastness

    Ancillary academia: video shorts and the production of university paratexts

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    This article considers the production of media paratexts beyond the bounds of the entertainment industry. Specifically, it examines the development of video content strategy by universities, and the paratextual function that video shorts serve in the construction of institutional identity. Taking a production studies approach, the article expands the scope of paratextual analysis by exploring the development of video content by university marketers, and the role of promotional intermediaries in selling video expertise to the education market

    TIME's past in the present: nostalgia and the black and white image

    Get PDF
    In 1995, the Hubble Space Telescope sent back to astronomers at the University of Arizona a series of vivid colour images of the Eagle Nebula, a dense formation of interstellar gas and dust the likes of which cradle newborn stars. As evidence that our perceptual universe, in every sense of the word, is defined by the representational powers of colour technology, the Hubble's “cosmic close-ups” are a clear case in point. Colour has become a standard representational form and hence the visual form. If so, what can be said of the recent popularity and proliferation of the black-and-white image? No self-respecting café-bar or discriminating home, it seems, can now do without a black and white print on the wall. Commercial photography and certain forms of advertising have found a new niche in black and white, and even sepia is staging a come-back. The popularity of the black-and-white image cannot be divorced from the commercial culture in which it circulates; it is a “look” and a marker of taste. Monochrome is a stylistic trend but a revealing one, especially if one considers the growing preoccupation in America with heritage and memory. Both Susan Sontag and Roland Barthes give black and white a status of authenticity judged in relation to past time “properly” captured. For Sontag, monochrome gives an image a sense of age, historical distance, and aura. She writes, “the cold intimacy of color seems to seal off the photograph from patina.” Likewise, Barthes comments on the artifice of colour, how it is a “coating applied later on to the original truth of black and white.” For both critics, monochrome is an aesthetic of the authentic figured around a basic quality of pastness

    Aperture Array Configurations for SKA1 Core

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    This memo considers some aspects of the configuration of the SKA1 Low Frequency Aperture Array, both at the element and station level. At the element level I propose a possible scenario for forming station beams where elements are shared between stations and apodisation is implemented, with the aim of improving filling factor, overall sensitivity and sidelobe performance; the disadvantages of such a scheme with regards to beam former requirements and shortest available baseline are also discussed. At the station level, a randomised configuration within a filled central region together with spiral arms is explored

    Characterization of Optical Frequency Transfer Over 154 km of Aerial Fiber

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    We present measurements of the frequency transfer stability and analysis of the noise characteristics of an optical signal propagating over aerial suspended fiber links up to 153.6 km in length. The measured frequency transfer stability over these links is on the order of 10^-11 at an integration time of one second dropping to 10^-12 for integration times longer than 100 s. We show that wind-loading of the cable spans is the dominant source of short-timescale noise on the fiber links. We also report an attempt to stabilize the optical frequency transfer over these aerial links.Comment: 4 pages, submitted to Optics Letter

    Bayesian modelling of clusters of galaxies from multi-frequency pointed Sunyaev--Zel'dovich observations

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    We present a Bayesian approach to modelling galaxy clusters using multi-frequency pointed observations from telescopes that exploit the Sunyaev--Zel'dovich effect. We use the recently developed MultiNest technique (Feroz, Hobson & Bridges, 2008) to explore the high-dimensional parameter spaces and also to calculate the Bayesian evidence. This permits robust parameter estimation as well as model comparison. Tests on simulated Arcminute Microkelvin Imager observations of a cluster, in the presence of primary CMB signal, radio point sources (detected as well as an unresolved background) and receiver noise, show that our algorithm is able to analyse jointly the data from six frequency channels, sample the posterior space of the model and calculate the Bayesian evidence very efficiently on a single processor. We also illustrate the robustness of our detection process by applying it to a field with radio sources and primordial CMB but no cluster, and show that indeed no cluster is identified. The extension of our methodology to the detection and modelling of multiple clusters in multi-frequency SZ survey data will be described in a future work.Comment: 12 pages, 7 figures, submitted to MNRA

    Survey of methods used in the supervision of student teaching

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    Detection of a CMB decrement towards a cluster of mJy radiosources

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    We present the results of radio, optical and near-infrared observations of the field of TOC J0233.3+3021, a cluster of milliJansky radiosources from the TexOx Cluster survey. In an observation of this field with the Ryle Telescope (RT) at 15 GHz, we measure a decrement in the cosmic microwave background (CMB) of 675±95μ-675 \pm 95 \muJy on the RT's \approx 0.65 kλ\lambda baseline. Using optical and infrared imaging with the McDonald 2.7-m Smith Reflector, Calar Alto 3.5-m telescope and UKIRT, we identify the host galaxies of five of the radiosources and measure magnitudes of R24R \approx 24, J20J \approx 20, K18K \approx 18. The CMB decrement is consistent with the Sunyaev-Zel'dovich (SZ) effect of a massive cluster of galaxies, which if modelled as a spherical King profile of core radius θC=20\theta_C = 20^{\prime\prime} has a central temperature decrement of 900μ900 \muK. The magnitudes and colours of the galaxies are consistent with those of old ellipticals at z1z \sim 1. We therefore conclude that TOC J0233.3+3021 is a massive, high redshift cluster. These observations add to the growing evidence for a significant population of massive clusters at high redshift, and demonstrate the effectiveness of combining searches for AGN `signposts' to clusters with the redshift-independence of the SZ effect.Comment: Six pages; accepted for publication in MNRAS. Version with full-resolution UV plot available from http://www.mrao.cam.ac.uk/~garret/MB185.p
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