A coded-aperture technique allowing x-ray phase contrast imaging with conventional sources

Phase contrast imaging (PCI) solves the basic limitation of x-ray imaging, i.e., poor image contrast resulting from small absorption differences. Up to now, it has been mostly limited to synchrotron radiation facilities, due to the stringent requirements on the x-ray source and detectors, and only one technique was shown to provide PCI images with conventional sources but with limits in practical implementation. The authors propose a different approach, based on coded apertures, which provides high PCI signals with conventional sources and detectors and imposes practically no applicability limits. They expect this method to cast the basis of a widespread diffusion of PCI. (C) 2007 American Institute of Physics

A preliminary approach to intelligent x-ray imaging for baggage inspection at airports

Identifying explosives in baggage at airports relies on being able to characterize the materials that make up an X-ray image. If a suspicion is generated during the imaging process (step 1), the image data could be enhanced by adapting the scanning parameters (step 2). This paper addresses the first part of this problem and uses textural signatures to recognize and characterize materials and hence enabling system control. Directional Gabor-type filtering was applied to a series of different X-ray images. Images were processed in such a way as to simulate a line scanning geometry. Based on our experiments with images of industrial standards and our own samples it was found that different materials could be characterized in terms of the frequency range and orientation of the filters. It was also found that the signal strength generated by the filters could be used as an indicator of visibility and optimum imaging conditions predicted

The use and abuse of history by the military

This paper examines the use and abuse of history by the military. In particular it focuses on military history and its employment in support of officer education by professional armed forces. The paper will examine what is meant by the term ‘military history’, dividing the discipline into ‘popular’, ‘academic’, and ‘professional’ categories and analysing each in turn. The main focus of the paper is on the latter, which relates to the employment of military history by armed forces in the belief that it is ‘useful’. It is somewhat unusual for a subject in the arts and humanities to find its value discussed in such utilitarian terms and the paper seeks to establish just what ‘useful’ might mean in this context before offering suggestions as to what this implies about the way in which military history is taught

A Splutter of Musketry? The British military response to the Anglo-Iranian oil dispute, 1951.

This paper examines the British response to the crisis that resulted from the Iranian decision to nationalise the Anglo-Iranian Oil Company in 1951.The British government contemplated the use of military force from the outset of the crisis and a series of plans were developed. Unfortunately, in a manner similar to the Suez Crisis five years later, the military were unable to provide a suitable response until political considerations had made the use of force unattractive. Despite this, the Foreign Secretary, the Minister of Defence, and the Chiefs of Staff continued to press for an armed response. This paper uses newly released archival sources to examine the military plans and preparations and to analyse the way in which these interacted with political considerations to undermine the British position in Iran

Systematics of Low Threshold Modulation Searches in DMS II

AbstractThe Cryogenic Dark Matter Search experiment (CDMS II) used underground-based germanium and silicon detectors to search for the scattering of Weakly Interacting Massive Particles (WIMPs), which are among the leading candidates for the dark matter component of the universe. Using the ionization and athermal phonons measured in particle interactions, CDMS II was able to achieve excellent discrimination between the nuclear recoils expected for WIMP interactions and radioactively produced electron recoils. With the rise of interest in the low energy interactions of light mass WIMPs, the SuperCDMS collaboration has undertaken a search for an annually modulating signal at low thresholds in the CDMS II data. Previous results detailed the analysis of data from eight germanium detectors over the course of six runs, to thresholds of 5 keVnr (nuclear recoil equivalent energy). We will discuss the impact of systematics at these low thresholds and their implications for thresholds down to 2.27 keVnr

Maritime Strategy and policy for smaller navies

This paper focuses on small navies and seeks to examine the extent to which traditional approaches to maritime policy and strategy are relevant to them. It will examine alternative ways of defining what is meant by the term ‘small navy’ before addressing traditional interpretations about the roles and missions of navies, and of maritime strategy, in order to question the extent to which ‘small navies’ are different or distinct from their larger counterparts or, indeed, from each other. In terms of their size, capabilities and aspirations most navies are small. This is as true today as it has always been. Large navies dominate the headlines and receive ample coverage in both popular and academic publications but they are the exception not the rule. Their smaller counterparts have a lower profile except when they emerge as potential allies or enemies and there is a tendency to approach them in such terms, defining them by their relationship to larger navies regardless of whether this actually provides the most useful way in which to understand them. Equally, there is a tendency for historians and commentators to approach maritime strategy from a perspective built upon an examination of the activity of larger navies on the assumption that the resultant concepts and principles will apply to small navies as much as large ones. While this may be the case the relative paucity of literature devoted specifically to smaller navies makes it difficult to draw firm conclusion

A Study on Optimizing Infrared Heating Technology for Asphalt Pavement Maintenance and Rehabilitation

In Canada especially, cracking and potholes on asphalt concrete pavements is a continuous problem requiring constant repairs. With the increased expansion and use of asphalt pavement infrastructure, combined with more severe climactic conditions and freeze thaw cycles experienced by asphalt pavements, pavement maintenance and repair practices need to improve the quality and longevity of their repairs. When compared to current standard crack and pothole repair processes such as crack sealing, crack filling, and full milling and replacement, infrared heating repairs can consistently provide a longer lasting repair then crack sealing, crack filling, and mill and replace patch repairs. Infrared heating repairs provide a repair which is more cost effective than full roadway replacement, with significantly longer lifespans than most conventional repair methods, filling in an intermediary repair gap present in the current pavement maintenance roster. The City of Waterloo cooperated with University of Waterloo’s Centre for Pavement and Transportation Technology and infrared heating manufacturer Heat Design Equipment Inc. (HDE) to evaluate the use of infrared heating repairs on a local project. This project was located along Sugarbush Drive which requires major pavement rehabilitation. Upon visual inspection, and laboratory testing completed on the asphalt, granular base course, and subgrade materials, results indicated that Sugarbush Drive was a prime candidate for infrared heating repairs, mainly because the sampled asphalt cores contained high percentages of asphalt binder. It was recommended that the City of Waterloo proceed with the use of infrared heating technology to repair the entirety of Sugarbush Drive, and continue partnership with CPATT to observe and record the performance of the repair throughout the road’s lifespan. The development of a patching mixture utilizing infrared heating consisted of using reclaimed asphalt pavement (RAP) and rejuvenating agents. The properties of three different RAP sources were evaluated through laboratory testing in order to determine their respective performance gradings. Good performance was achieved from two of the standard RAP sources retrieved from previously used milled asphalt pavement materials from the region, however, extremely high stiffness was observed from a RAP source consisting of unused excess asphalt mixtures, and further testing was recommended to confirm the properties of the RAP source

Reporting suicide: what lessons has the media learnt?

Last December, the Press Complaints Commission teamed up with Polis to organise a seminar about how suicide is reported by the media. The idea of holding a discussion to bring together journalists, academics, regulatory bodies and those with specialist knowledge of mental health issues stemmed from the spate of suicides in and around Bridgend earlier that year, and the widespread public debate the media coverage of those deaths generated

Progress, pressures and politics: challenges at self-regulatory media councils in South East Europe

Catherine Speller is a consultant working on communications, media and policy matters who recently completed a report for UNESCO on the needs of media councils in South East Europe. She previously spent seven years at the UK Press Complaints Commission. Here, she highlights the main challenges faced by the self-regulatory media councils in this region