Selective Memory: Assessing Conventions of Memory in the Archival Literature

Scholarly applications of memory concepts in the archival literature broadly assume the role of memory as essential to the function of archival research and practice. While academicians in the archival field maintain the necessity of foregrounding memory as an essential concept underpinning both practical and theoretical research, it has nonetheless encountered some justified critique. Memory itself has become harder to define among the critical archival literature, applied liberally and, sometimes, even without merit. Critiques of these problems with memory concepts examined instances or groupings of instances where memory concepts were applied in the scholarship. A systemic overview of memory concepts in the archival literature for the past three decades, in concert with modern cooperative usages of memory in other fields, demonstrates the necessity for a revised taxonomic model for memory among the archival profession. The application of this survey of archival scholarship offers perspective on memory concepts for archival scholarship and engages with the developing memory studies field with an eye towards the increasing interdisciplinary concerns for memory professions in light of that developing field

Cross-correlation of the unresolved X-ray background with faint galaxies

At the faint end of the deepest X-ray surveys, a population of X-ray luminous galaxies is seen. In this paper, we present the results of a cross-correlation between the residual, unresolved X-ray photons in a very deep X-ray survey and the positions of faint galaxies, in order to examine the importance of these objects at even fainter flux levels. We measure a significant correlation on all angular scales up to ~1 arcmin. This signal could account for a significant fraction of the unresolved X-ray background, approximately 35 per cent if the clustering is similar to optically selected galaxies. However, the angular form of the correlation is seen to be qualitatively similar to that expected for clusters of galaxies and the X-ray emission could be associated with hot gas in clusters or with QSOs within galaxy clusters rather than emission from individual faint galaxies. The relative contribution from each of these possibilities cannot be determined with the current data.Comment: 7 pages LaTeX including 9 EPS figures. Uses mn.sty. Accepted for publication by MNRA

The discovery of very red counterparts to faint X-ray sources

We present deep K-band imaging at the positions of four very faint X-ray sources found in the UK ROSAT Deep Survey to have no optical counterpart brighter than R~23. Likely identifications are found within the ROSAT error circle in all four fields with R-K colours of between 3.2 +/- 0.4 and 6.4 +/- 0.6. From a consideration of the R-K colours and X-ray to optical luminosity ratios of the candidate identifications, we tentatively classify two of the X-ray sources as very distant (z ~ 1) clusters of galaxies, one as a narrow emission line galaxy and one as an obscured QSO.Comment: 7 pages, LaTeX, 7 figures (1 postscript file each). Uses mn.sty and epsf.sty. Accepted by MNRAS. For more information see http://www.astro.soton.ac.uk/~amn/UKdee

The effect of tidal flow directionality on tidal turbine performance characteristics

With many Tidal Energy Conversion (TEC) devices at full scale prototype stage there are two distinct design groups for Horizontal Axis Tidal Turbines (HATTs). Devices with a yaw mechanism allowing the turbine to always face into the flow, and devices with blades that can rotate through 180° to harness a strongly bi-directional flow. As marine turbine technology verges on the realm of economic viability this paper reveals the performance of Cardiff University's concept tidal turbine with its support structure either upstream or downstream and with various proximities between the rotating plane of the turbine and its support stanchion. Through the use of validated Computational Fluid Dynamics (CFD) modelling this work shows the optimal proximity between rotor plane and stanchion as well as establishing, in the given context, the use of a yaw mechanism to be superior to a bi-directional system from a performance perspective

Temporal Evolution of Financial Market Correlations

We investigate financial market correlations using random matrix theory and principal component analysis. We use random matrix theory to demonstrate that correlation matrices of asset price changes contain structure that is incompatible with uncorrelated random price changes. We then identify the principal components of these correlation matrices and demonstrate that a small number of components accounts for a large proportion of the variability of the markets that we consider. We then characterize the time-evolving relationships between the different assets by investigating the correlations between the asset price time series and principal components. Using this approach, we uncover notable changes that occurred in financial markets and identify the assets that were significantly affected by these changes. We show in particular that there was an increase in the strength of the relationships between several different markets following the 2007--2008 credit and liquidity crisis.Comment: 15 pages, 10 figures, 1 table. Accepted for publication in Phys. Rev. E. v2 includes additional section

Desire Paths in the Information Landscape

Libraries and archives serve so many different users who come to information institutions with various perspectives, needs, experiences, and desires around accessing physical or digital collections. While our users may find what they are looking for immediately, many have to beat their own paths through complex systems and metadata that doesn’t align with their needs. Their search strategies may leave digital “desire paths”–alternative routes through the information landscape that can show us how to better meet their needs. This article covers three scenarios where users’ desire paths can be seen or where gaps around user experience can be better addressed. Through an analysis of institutional accessibility statements, queer archival experiences, and the affordances of volunteer crowdsourcing, the authors investigate desire paths in the information landscape and what practitioners and scholars can learn from them. This article also takes a highly experimental approach to scholarly collaboration, by revealing rather than concealing our writing process through the use of different fonts to represent the different makers of this piece: we preserve our comments, feedback, corrections, discussions, and the evolving perspectives of the authors, reviewers, and editors. Artifacts of collaboration are often invisible and obscure the many kinds of work and thinking that goes into a piece of writing. By making this process visible, we make our shared desire path visible to you, dear reader, and invite you to walk it, too

The feasibility of using electromagnetic waves in determining the moisture content of building fabrics and the cause of the water ingress

In this paper, the feasibility of using electromagnetic (EM) waves is determining the moisture content of building fabrics and the case of water ingress in experimentally assessed. This paper will concentrate on investigating the propagation of EM waves through typical structures and their interaction with concealed pipework, wiring and timber. All current methods are overviewed and analysed. Novel microwave sensor described in this paper operates in 6 GHz to 12 GHz frequency range using Marconi 6200A microwave test set. Results of experimental test confirm that microwaves can be used as an alternative nondestructive method for identifying different object behind the walls

An XMM and Chandra view of massive clusters of galaxies to z=1

The X-ray properties of a sample of high redshift (z>0.6), massive clusters observed with XMM-Newton and Chandra are described, including two exceptional systems. One, at z=0.89, has an X-ray temperature of T=11.5 (+1.1, -0.9) keV (the highest temperature of any cluster known at z>0.6), an estimated mass of (1.4+/-0.2)x10^15 solar masses and appears relaxed. The other, at z=0.83, has at least three sub-clumps, probably in the process of merging, and may also show signs of faint filamentary structure at large radii,observed in X-rays. In general there is a mix of X-ray morphologies, from those clusters which appear relaxed and containing little substructure to some highly non-virialized and probably merging systems. The X-ray gas metallicities and gas mass fractions of the relaxed systems are similar to those of low redshift clusters of the same temperature, suggesting that the gas was in place, and containing its metals, by z=0.8. The evolution of the mass-temperature relation may be consistent with no evolution or with the ``late formation'' assumption. The effect of point source contamination in the ROSAT survey from which these clusters were selected is estimated, and the implications for the ROSAT X-ray luminosity function discussed.Comment: 9 pages, in Carnegie Observatories Astrophysics Series, Vol. 3: Clusters of Galaxies: Probes of Cosmological Structure and Galaxy Evolution, ed. J. S. Mulchaey, A. Dressler, and A. Oemler. See http://www.ociw.edu/ociw/symposia/series/symposium3/proceedings.html for a full-resolution versio