Sources of growth in the South African economy, 1945—1975.

Paper presented at the Wits History Workshop: Structure and Experience in the Making of Apartheid, 6-10 February, 1990

Impact of NHS Direct on other services: the characteristics and origins of its nurses

OBJECTIVE:: To characterise the NHS Direct nurse workforce and estimate the impact of NHS Direct on the staffing of other NHS nursing specialties. METHOD: A postal survey of NHS Direct nurses in all 17 NHS Direct call centres operating in June 2000. RESULTS: The response rate was 74% (682 of 920). In the three months immediately before joining NHS Direct, 20% (134 of 682, 95% confidence intervals 17% to 23%) of respondents had not been working in the NHS. Of the 540 who came from NHS nursing posts, one fifth had come from an accident and emergency department or minor injury unit (110 of 540), and one in seven from practice nursing (75 of 540). One in ten (65 of 681) nurses said that previous illness, injury, or disability had been an important reason for deciding to join NHS Direct. Sixty two per cent (404 of 649) of nurses felt their job satisfaction and work environment had improved since joining NHS Direct. CONCLUSION: The NHS Direct nurse workforce currently constitutes a small proportion (about 0.5%) of all qualified nurses in the NHS, although it recruits relatively experienced and well qualified nurses more heavily from some specialties, such as accident and emergency nursing, than others. However, its overall impact on staffing in any one specialty is likely to be small. NHS Direct has succeeded in providing employment for some nurses who might otherwise be unable to continue in nursing because of disability

Framework for software architecture visualization assessment.

In order to assess software architecture visualisation strategies, we qualitatively characterize then construct an assessment framework with 7 key areas and 31 features. The framework is used for evaluation and comparison of various strategies from multiple stakeholder perspectives. Six existing software architecture visualisation tools and a seventh research tool were evaluated. All tools exhibited shortcomings when evaluated in the framework

Phase Contrast Imaging with Coded Apertures Using Laboratory-Based X-ray Sources

X‐ray phase contrast imaging is a powerful technique that allows detection of changes in the phase of x‐ray wavefronts as they pass through a sample. As a result, details not visible in conventional x‐ray absorption imaging can be detected. Until recently the majority of applications of phase contrast imaging were at synchrotron facilities due to the availability of their high flux and coherence; however, a number of techniques have appeared recently that allow phase contrast imaging to be performed using laboratory sources. Here we describe a phase contrast imaging technique, developed at University College London, that uses two coded apertures. The x‐ray beam is shaped by the pre‐sample aperture, and small deviations in the x‐ray propagation direction are detected with the help of the detector aperture. In contrast with other methods, it has a much more relaxed requirement for the source size (it works with source sizes up to 100 μm). A working prototype coded‐aperture system has been built. An x‐ray detector with directly deposited columnar CsI has been used to minimize signal spill‐over into neighboring pixels. Phase contrast images obtained with the system have demonstrated its effectiveness for imaging low‐absorption materials

Effects of signal diffusion on x-ray phase contrast images

We discuss the problem of signal diffusion among neighbouring pixels in x-ray phase contrast imaging (XPCi) specifically for coded-aperture (CA) XPCi, but many of the discussed observations are directly transferable to other XPCi modalities. CA XPCi exploits the principle of pixel edge illumination by means of two CA masks. The first mask, placed in contact with the detector, creates insensitive regions between adjacent pixels; the second one, placed immediately before the sample, creates individual beams impinging on the boundaries between sensitive and insensitive regions on the detector, as created by the detector mask. In this way, edge illumination is achieved for all pixels of an area detector illuminated by a divergent and polychromatic beam generated by a conventional source. As the detector mask redefines the resolution properties of the detector, sample dithering can be used to effectively increase the system spatial resolution, without having to apply any post-processing procedure (e. g., deconvolution). This however creates artifacts in the form of secondary fringes (which have nothing to do with phase-related secondary fringes) if there is signal diffusion between adjacent pixels. In non-dithered images, signal diffusion between adjacent pixels causes a reduction in image contrast. This effect is investigated both theoretically and experimentally, and its direct implications on image quality are discussed. The interplay with the sample positioning with respect to the detector pixel matrix, which also has an effect on the obtained image contrast, is also discussed. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3606442

Quantum teleportation using non-orthogonal entangled channels

We study quantum teleportation with the resource of non-orthogonal qubit states. We first extend the standard teleportation protocol to the case of such states. We investigate how the loss of teleportation fidelity resulting for the use of non-orthogonal states compares to a similar loss of fidelity when noisy or non-maximally entangled states as used as teleportation resource. Our analysis leads to certain interesting results on the teleportation efficiency of both pure and mixed non-orthgonal states compared to that of non-maximally entangled and mixed states.Comment: 7 pages, latex, 5 eps fig

easySTORM: a robust, lower-cost approach to localisation and TIRF microscopy

TIRF and STORM microscopy are super-resolving fluorescence imaging modalities for which current implementations on standard microscopes can present significant complexity and cost. We present a straightforward and low-cost approach to implement STORM and TIRF taking advantage of multimode optical fibres and multimode diode lasers to provide the required excitation light. Combined with open source software and relatively simple protocols to prepare samples for STORM, including the use of Vectashield for non-TIRF imaging, this approach enables TIRF and STORM imaging of cells labelled with appropriate dyes or expressing suitable fluorescent proteins to become widely accessible at low cost