Deconvolution of ASCA X-ray data: I. Spectral-imaging method

In this paper we describe a self-contained method for performing the spectral-imaging deconvolution of X-ray data on clusters of galaxies observed by the ASCA satellite. Spatially-resolved spectral studies of data from this satellite require such a correction because its optics redistribute photons over regions which are of comparable size to the angular scales of interest in clusters. This scattering is a function not only of spatial position but also energy. To perform a correction for these effects we employ Maximum-Likelihood deconvolution of the image (within energy bands of 1 keV) to determine the spatial redistribution, followed by a Monte-Carlo energy reassignment of photon energies with position to determine the spectral redistribution. We present tests on simulated cluster data, convolved with the various instrumental characteristics and the X-ray background, which show that our methodology can successfully recover a variety of intrinsic temperature profiles in typical observational circumstances. In Paper-II we apply our spectral-imaging deconvolution procedure to a large sample of galaxy clusters to determine temperature profiles, some of which will be used in subsequent mass determinations, presented in Paper-III.Comment: MNRAS, accepted. Paper and single page postscript copies of each test's radial profile are available on: http://www-xray.ast.cam.ac.uk/~daw

Diagrammatic insights into next-to-soft corrections

We confirm recently proposed theorems for the structure of next-to-soft corrections in gauge and gravity theories using diagrammatic techniques, first developed for use in QCD phenomenology. Our aim is to provide a useful alternative insight into the next-to-soft theorems, including tools that may be useful for further study. We also shed light on a recently observed double copy relation between next-to-soft corrections in the gauge and gravity cases.Comment: 12 pages, 4 figure

The Cornell Potential from General Geometries in AdS / QCD

We consider the heavy quark-antiquark potential in the AdS / QCD correspondence, focusing in particular on a recently calculated AdS-like metric deformed by back-reaction effects. We find that tuning the long-distance behaviour of the potential leads to a discrepancy at small distances, and discuss how to better constrain AdS / QCD geometries. A systematic comparison of various geometries is presented, based on goodness of fit to lattice data in the quenched approximation. The back-reacted geometry is seen to be phenomenologically favoured over an alternative geometry with the same number of parameters, although it does not perform as well as some other geometries.Comment: 12 pages, 4 figures. Revised and expanded version to appear in Physics Letters

New insights into soft gluons and gravitons

The study of gluon radiation in QCD, in the limit of small ("soft") momentum, remains an active research area, with a variety of phenomenological and theoretical applications. Soft gluon emission leads to large logarithms in perturbation theory which have to be summed up to all orders in the coupling, and also governs the structure of infrared singularities. Recently, new techniques and mathematical structures have been discovered, which enhance our understanding of these all-order properties. This contribution will review a number of key topics, including the relationship between QCD and gravity.Comment: 6 pages, 3 figures; Proceedings of 36th International Conference on High Energy Physics, July 4-11, 2012, Melbourne, Australi

Precision bolometer bridge

Prototype precision bolometer calibration bridge is manually balanced device for indicating dc bias and balance with either dc or ac power. An external galvanometer is used with the bridge for null indication, and the circuitry monitors voltage and current simultaneously without adapters in testing 100 and 200 ohm thin film bolometers

The Apollo 15 deployable boom anomaly

During the Apollo 15 mission, a boom with an attached mass spectrometer was required to retract periodically so that the instrument would not be in the field of view of other experiments. The boom did not fully retract on five of 12 occasions. Data analysis indicated that the boom probably retracted to within approximately 2.54 centimeters (1 inch) of full retraction. The pertinent boom-design details, the events in the mission related to the anomaly, a discussion of the inflight and postflight investigation of the problem, a discussion of the design changes to the boom mechanism as a result of the investigation, and subsequent flight performance are presented

The troubling terrain of lifelong learning: a highway cruise or a cross-country trek?

Educational theory now takes for granted that lifelong learning is inherently good. It is assumed that in a globalised era people need to continue learning over their lifespan. Without a demonstrable general awareness of determinants, educational theory pictures lifelong learning as a cruise on the highway of life. By contrast, educational research shows that it is more in the nature of a lifelong cross-country trek. Determinants are situated in the terrain of each person's unique life experiences. Although policy supports universal lifelong learning theoretically, the reality of the policy agenda is quite different. What little research into propensity to lifelong learning exists indicates that up to a third of the population not only do not but will not participate. Theory evidently does not fully reflect reality. However, research is providing an emerging picture of participation and non-participation in formal lifelong learning. Indeed, it is the terrain of people's lives which holds the key to understanding that participation and non-participation. Motivators required for a trek differ from those required for a cruise. Lifelong learning research is an area of educational research's terrain which should trouble theory until theory better reflects reality