48,358 research outputs found
Review : Why study the media ?
Silverstone’s Why Study the Media? (hereafter WSM) is a dif� cult book to review, especially in such a short space. The content spans millennia of theoretical, analytical and historical perspectives on our media, but is none the less entirely contemporary and relevant in its focus. Silverstone’s perspective is at times elusive because the book sets out, successfully I think, to answer the question posed in the title. But it does so by raising major questions in media studies, important questions, in a way that does not imply quick and easy answers
Active engagement with assessment and feedback can improve group-work outcomes and boost student confidence
This study involves evaluation of a novel iterative group-based learning task developed to enable students to actively engage with assessment and feedback in order to improve the quality of their written work. The students were all in the final semester of their final year of study and enrolled on either BSc Zoology or BSc Marine and Freshwater Biology at a mainstream UK university, but the findings of this research can be generalised to a wider student body. The main findings are that in a group work context, individual students can use provided assessment criteria to accurately assess the work produced by their group and that their ability to produce and recognise work of a higher quality improves as a result of a social dialogue around self/peer assessment and self/tutor generated feedback. The study also reveals that producing poorer work over-assess and those achieving the highest marks under-assess. Over-assessing students focus to a greater extent upon the superficial deficiencies in their work, whereas under assessing students are more likely to focus on more significant issues. High-achieving under-assessing students lack confidence in their own abilities, but believe feedback provides a confidence boost
The Black Hole Mass - Spheroid Luminosity relation
The differing M_bh-Luminosity relations presented in McLure & Dunlop, Marconi
& Hunt and Erwin et al. have been investigated. A number of issues have been
identified and addressed in each of these studies, including but not limited
to: the removal of a dependency on the Hubble constant; a correction for dust
attenuation in the bulges of disc galaxies; the identification of lenticular
galaxies previously treated as elliptical galaxies; and application of the same
(Y|X) regression analysis. These adjustments result in relations which now
predict similar black hole masses. The optimal K-band relation is
log(M_bh/M_sun) = -0.37(+/-0.04)[M_K +24] + 8.29(+/-0.08), with a total (not
intrinsic) scatter in log M_bh equal to 0.33 dex. This level of scatter is
similar to the value of 0.34 dex from the M_bh-sigma relation of Tremaine et
al. and compares favourably with the value of 0.31 dex from the M_bh-n relation
of Graham & Driver. Using different photometric data, consistent relations in
the B- and R-band are also provided, although we do note that the small (N=13)
R-band sample used by Erwin et al. is found here to have a slope of
-0.30(+/-0.06) and a total scatter of 0.31 dex. Performing a symmetrical
regression on the larger K-band sample gives a slope of -0.40, implying M_bh ~
L^{1.00}. Implications for galaxy-black hole coevolution, in terms of dry
mergers, are briefly discussed, as are predictions for intermediate mass black
holes. Finally, as previously noted by Tundo et al., a potential bias in the
galaxy sample used to define the M_bh-L relations is shown and a corrective
formula provided.Comment: 12 pages, to appaer in MNRA
Comment on "A Non-Parametric Estimate of Mass 'Scoured' in Galaxy Cores" (arXiv:1006.0488)
This comment is in response to the article titled "A Non-Parametric Estimate
of Mass Scoured in Galaxy Cores" (arXiv:1006.0488) written by Hopkins and
Hernquist. This comment politely mentions two relevant papers in which the main
conclusion from Hopkins & Hernquist had already been published six years ago
using the core-Sersic model. It then explains why Hopkins & Hernquist's concern
about the core-Sersic model is not valid.Comment: 1 page of text, plus reference
Theoretical study of refraction effects on noise produced by turbulent jets
The transmission of acoustic disturbances from the interior of a jet into the ambient air is studied. The jet is assumed infinitely long with mean velocity profile independent of streamwise location. The noise generator is a sequence of transient sources drifting with the local fluid and confined to a short length of the jet. In Part 1, supersonic jets are considered. Numerical results for mean-square pressure versus angle in the far-field show unexpected peaks which are very sharp. Analysis of simplified models indicates that these are complex quasi-resonant effects which appear to the stationary observer in a high frequency range. The peaks are real for the idealized model, but would be smoothed by mathematical integration over source position, velocity, and frequency. Subsonic jets were considered in part 2, and a preliminary study of the near-field was attempted. Mean-square radial displacements (or mean radial energy flow or space-time correlations of radial pressure gradient) are first found for very simple cases. The most difficult case studied is a sequence of transient sources at the center of a uniform-velocity circular cylindrical jet. Here a numerical triple integration is required and seems feasible although only preliminary results for mean square radial displacement are now available. These preliminary results show disturbances decreasing with increasing radial distance, and with increasing distance upstream and downstream from the source. A trend towards greater downstream disturbances appears even in the near field
- …