Development and validation of 'AutoRIF': Software for the automated analysis of radiation-induced foci

Copyright @ 2012 McVean et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Background: The quantification of radiation-induced foci (RIF) to investigate the induction and subsequent repair of DNA double strands breaks is now commonplace. Over the last decade systems specific for the automatic quantification of RIF have been developed for this purpose, however to ask more mechanistic questions on the spatio-temporal aspects of RIF, an automated RIF analysis platform that also quantifies RIF size/volume and relative three-dimensional (3D) distribution of RIF within individual nuclei, is required. Results: A java-based image analysis system has been developed (AutoRIF) that quantifies the number, size/volume and relative nuclear locations of RIF within 3D nuclear volumes. Our approach identifies nuclei using the dynamic Otsu threshold and RIF by enhanced Laplacian filtering and maximum entropy thresholding steps and, has an application ‘batch optimisation’ process to ensure reproducible quantification of RIF. AutoRIF was validated by comparing output against manual quantification of the same 2D and 3D image stacks with results showing excellent concordance over a whole range of sample time points (and therefore range of total RIF/nucleus) after low-LET radiation exposure. Conclusions: This high-throughput automated RIF analysis system generates data with greater depth of information and reproducibility than that which can be achieved manually and may contribute toward the standardisation of RIF analysis. In particular, AutoRIF is a powerful tool for studying spatio-temporal relationships of RIF using a range of DNA damage response markers and can be run independently of other software, enabling most personal computers to perform image analysis. Future considerations for AutoRIF will likely include more complex algorithms that enable multiplex analysis for increasing combinations of cellular markers.This article is made available through the Brunel Open Access Publishing Fund

Millimeter wave radiometry as a means of determining cometary surface and subsurface temperature

Thermal emission spectra for a variety of cometary nucleus models were evaluated by a radiative transfer technique adapted from modeling of terrestrial ice and snow fields. It appears that millimeter wave sensing from an interplanetary spacecraft is the most effective available means for distinguishing between alternate models of the nucleus and for evaluating the thermal state of the layer which is below the instantaneous surface where modern theories of the nucleus indicate that sublimation of the cometary volatiles actually occurs

Li I and K I Scatter in Cool Pleiades Dwarfs

We utilize high-resolution (R~60,000), high S/N (~100) spectroscopy of 17 cool Pleiades dwarfs to examine the confounding star-to-star scatter in the 6707 Li I line strengths in this young cluster. Our Pleiads, selected for their small projected rotational velocity and modest chromospheric emission, evince substantial scatter in the linestrengths of 6707 Li I feature that is absent in the 7699 K I resonance line. The Li I scatter is not correlated with that in the high-excitation 7774 O I feature, and the magnitude of the former is greater than the latter despite the larger temperature sensitivity of the O I feature. These results suggest that systematic errors in linestrength measurements due to blending, color (or color-based T_eff) errors, or line formation effects related to an overlying chromosphere are not the principal source of Li I scatter in our stars. There do exist analytic spot models that can produce the observed Li scatter without introducing scatter in the K I line strengths or the color-magnitude diagram. However, these models predict factor of >3 differences in abundances derived from the subordinate 6104 and resonance 6707 Li I features; we find no difference in the abundances determined from these two features. These analytic spot models also predict CN line strengths significantly larger than we observe in our spectra. The simplest explanation of the Li, K, CN, and photometric data is that there must be a real abundance component to the Pleiades Li dispersion. We suggest that this real abundance component is the manifestation of relic differences in erstwhile pre-main-sequence Li burning caused by effects of surface activity on stellar structure. We discuss observational predictions of these effects.Comment: 35 pages, 7 figures; accepted by Ap

Measurement of thermal conductance of multilayer and other insulation materials Final report

Thermal conductance measurements of multilayer, aluminumized polymeric films for space suit insulation material

Cygnus A at 99 GHz: Observations of the three principal components and interpretation of the central source

The three principal emission components of Cygnus A were observed at 99 GHz, the highest frequency at which radio measurements of this source have been accomplished. The observations show no definite indication of a high-frequency cutoff in the spectrum of the compact central component, which perhaps may be attributed to an optically thin synchrotron source that peaks at a frequency of several hundred GHz

Anglo-American corporate governance and the employment relationship: a case to answer

The corporate governance environment in the UK and US is generally thought to be hostile to the emergence of cooperative employment relations of the kind exemplified by labour-management partnerships. We discuss case study evidence from the UK which suggests that, contrary to this widespread perception, enduring and proactive partnerships may develop, in conditions where management can convince shareholders of the long-term gains from this approach, and where other regulatory factors operate to extend the time-horizon for financial returns. We conclude that there is more scope than is commonly allowed for measures which could reconcile liquidity in capital markets with cooperation in labour relations

Optimizing Pulsar Timing Arrays to Maximize Gravitational Wave Single Source Detection: a First Cut

Pulsar Timing Arrays (PTAs) use high accuracy timing of a collection of low timing noise pulsars to search for gravitational waves in the microhertz to nanohertz frequency band. The sensitivity of such a PTA depends on (a) the direction of the gravitational wave source, (b) the timing accuracy of the pulsars in the array and (c) how the available observing time is allocated among those pulsars. Here, we present a simple way to calculate the sensitivity of the PTA as a function of direction of a single GW source, based only on the location and root-mean-square residual of the pulsars in the array. We use this calculation to suggest future strategies for the current North American Nanohertz Observatory for Gravitational Waves (NANOGrav) PTA in its goal of detecting single GW sources. We also investigate the affects of an additional pulsar on the array sensitivity, with the goal of suggesting where PTA pulsar searches might be best directed. We demonstrate that, in the case of single GW sources, if we are interested in maximizing the volume of space to which PTAs are sensitive, there exists a slight advantage to finding a new pulsar near where the array is already most sensitive. Further, the study suggests that more observing time should be dedicated to the already low noise pulsars in order to have the greatest positive effect on the PTA sensitivity. We have made a web-based sensitivity mapping tool available at http://gwastro.psu.edu/ptasm.Comment: 14 pages, 3 figures, accepted by Ap