Evaluation of an alphanumeric target as a means of determining the resolution of a photographic reconnaissance system

This experiment relates three forms of resolution as predictors of recognition and identification of objects that could be of interest in a military photo-reconaissance situation. Of the three forms of resolution, two are based on existing types of resolution target currently used for assesment purposes and the third, being evaluated under this experiment, is based on a Block Letter (alphanumeric) target. The results and conclusions of this experiment will show that at a confidence of 90%, the Block Letter target provides a significantly better resolution value for the prediction of recognition and identification of the type of objects used in this experiment

The bird communities of three disused quarries on the Magnesian limestone of Durham county

In order to assess the ornithological importance of three disused quarries on the Magnesian Limestone escarpment in Durham county the distribution and abundance of the breeding birds were examined using the CBC technique. Thirty-nine bird species were recorded on the sites, of which twenty-seven species were considered to be holding territories. The habitat was also sampled at 137 randomly located 0.02 ha sample units at each site. Variables recorded were those that were thought to be the most important in influencing the distribution and abundance of the birds on the sites. In addition to the census, the behaviour of all birds recorded on the sites during the same period was quantified. Correlations between the breeding bird communities at the three sites and the habitat variables were explored using numerical classification (two-way indicator species analysis), indirect gradient analysis (detrended correspondence analysis) and direct gradient analysis (canonical correspondence analysis).Ordination of the combined data from the three quarries illustrated a gradient of bird species composition from open grassland to enclosed canopy scrub. When the ordination was constrained by the environmental variables two enviromnental gradients became apparent. Both were associated with the increasing cover relating to the successional sequence at the quarries. The first gradient was that of uninterrupted succession from bare quarry to enclosed canopy ash woodland. The second gradient was from a well developed field layer to low scrub, which was interpreted as a form of sub-climax. The behavioural analysis indicated that although broad patterns in habitat selection could be determined from the coarse scale approach, the more subtle patterns in habitat utilisation were lost at this level of analysis. The importance of specific aspects of the habitat were elucidated using chi-square analysis. This analysis further indicated the importance of the hawthorn scrub to breeding and foraging birds. The grassland was also found to be important for foraging birds. The implications of these findings in view of the importance of die quarries as examples of limestone grassland is discussed. The potential benefits to the common farmland avifauna of sympathetic management of these sites is also discussed. The preliminary results of this study indicate that the appropriate management of the successional process at these sites could benefit both the avifauna and flora

The development of a SPME-GC/MS method for the analysis of VOC emissions from historic plastic and rubber materials

Analytical methods have been developed for the analysis of VOC emissions from historic plastic and rubber materials using SPME-GC/MS. Parameters such as analysis temperature, sampling time and choice of SPME fibre coating were investigated and sampling preparation strategies explored, including headspace sampling in vials and in gas sampling bags. The repeatability of the method was evaluated. It was found that a 7. d accumulation time at room temperature, followed by sampling using a DVB/CAR/PDMS fibre, with a sampling time of 60. min at room temperature was a suitable strategy for the detection of VOC emissions from a wide range of historic plastic and rubber artefacts. For 20. ml vials, a sample size of 50. mg was found to be appropriate and grinding the samples improved the repeatability of the analysis and yielded higher levels of emissions. A non-destructive adaptation of the method that could be used directly on historic objects in a museum environment is also presented. The detected emissions improve understanding of ongoing degradation processes within historic plastic and rubber materials, in addition to providing information on material composition

Classifying degraded modern polymeric museum artefacts by their smell

Volatile organic compound (VOC) analysis is a successful method for diagnosing medical conditions such as Alzheimer’s disease. However, despite its relevance to heritage, it has found little application in museums. We report the first use of VOC analysis to ‘diagnose’ degradation in modern polymeric museum artefacts. Modern polymers are increasingly found in museum collections but pose serious conservation difficulties due to unstable and widely varying formulations. Solid-phase microextraction gas chromatography/mass spectrometry and linear discriminant analysis were used to classify samples according to the length of time they had been artificially degraded. Classification accuracies of 50-83% were obtained after validation with separate test sets. The method was applied to three artefacts from collections at Tate to detect evidence of degradation. This novel approach could be used for any material in heritage collections and more widely in the field of polymer degradation

Parameterising User Uptake in Economic Evaluations: The role of discrete choice experiments.

Model-based economic evaluations of new interventions have shown that user behaviour (uptake) is a critical driver of overall impact achieved. However, early economic evaluations, prior to introduction, often rely on assumed levels of uptake based on expert opinion or uptake of similar interventions. In addition to the likely uncertainty surrounding these uptake assumptions, they also do not allow for uptake to be a function of product, intervention, or user characteristics. This letter proposes using uptake projections from discrete choice experiments (DCE) to better parameterize uptake and substitution in cost-effectiveness models. A simple impact model is developed and illustrated using an example from the HIV prevention field in South Africa. Comparison between the conventional approach and the DCE-based approach shows that, in our example, DCE-based impact predictions varied by up to 50% from conventional estimates and provided far more nuanced projections. In the absence of observed uptake data and to model the effect of variations in intervention characteristics, DCE-based uptake predictions are likely to greatly improve models parameterizing uptake solely based on expert opinion. This is particularly important for global and national level decision making around introducing new and probably more expensive interventions, particularly where resources are most constrained

Virtual Field Studies: Conducting Studies on Public Displays in Virtual Reality

Field studies on public displays can be difficult, expensive, and time-consuming. We investigate the feasibility of using virtual reality (VR) as a test-bed to evaluate deployments of public displays. Specifically, we investigate whether results from virtual field studies, conducted in a virtual public space, would match the results from a corresponding real-world setting. We report on two empirical user studies where we compared audience behavior around a virtual public display in the virtual world to audience behavior around a real public display. We found that virtual field studies can be a powerful research tool, as in both studies we observed largely similar behavior between the settings. We discuss the opportunities, challenges, and limitations of using virtual reality to conduct field studies, and provide lessons learned from our work that can help researchers decide whether to employ VR in their research and what factors to account for if doing so

Ambient base-free glycerol oxidation over bimetallic PdFe/SiO₂ by in situ generated active oxygen species

Low temperature oxidation of alcohols over heterogeneous catalysts is exceptionally challenging, particularly under neutral conditions. Herein, we report on an efficient, base-free method to oxidise glycerol over a 0.5%Pd-0.5þ/SiO2 catalyst at ambient temperature in the presence of gaseous H2 and O2. The exceptional catalytic performance was attributed to the in situ formation of highly reactive surface-bound oxygenated species, which promote the dehydrogenation on the alcohol. The PdFe bimetallic catalyst was determined to be significantly more active than corresponding monometallic analogues, highlighting the important role both metals have in this oxidative transformation. Fe leaching was confirmed to occur over the course of the reaction but sequestering experiments, involving the addition of bare carbon to the reactions, confirmed that the reaction was predominantly heterogeneous in nature. Investigations with electron paramagnetic resonance spectroscopy suggested that the reactivity in the early stages was mediated by surface-bound reactive oxygen species; no homogeneous radical species were observed in solution. This theory was further evidenced by a direct H2O2 synthesis study, which confirmed that the presence of Fe in the bimetallic catalyst neither improved the synthesis of H2O2 nor promoted its decomposition over the PdFe/SiO2 catalyst