Characterization, design, and optimization of a two-pass twisted nematic liquid crystal spatial light modulator system for arbitrary complex modulation

Arbitrary two-dimensional complex modulation of an optical field is a powerful tool for coherent optical systems. No single spatial light modulator (SLM) offers true arbitrary complex modulation, but they can be combined in order to achieve this. In this work, two sides of a twisted nematic (TN) liquid crystal SLM are used sequentially to implement different arbitrary modulation schemes. In order to fully explore and exploit the rich modulation behavior offered by a TN device, a generalized Jones matrix approach is used. A method for $\textit{in situ}$ characterization of the SLM inside the two-pass system is demonstrated, where each side of the SLM is independently characterized. This characterization data is then used to design appropriate polarizer configurations to implement arbitrary complex modulation schemes (albeit without 100% efficiency). Finally, an $\textit{in situ}$ optimization technique that corrects states by applying a translation in the complex plane is demonstrated. This technique can correct both for variations across the SLM and bulk changes in the SLM behavior due to the changing temperature.Engineering and Physical Sciences Research Council (EPSRC) (EP/G037256/1)

Single-step fabrication of thin-film linear variable bandpass filters based on metal-insulator-metal geometry

A single-step fabrication method is presented for ultra-thin, linearly variable optical bandpass filters (LVBFs) based on a metal–insulator–metal arrangement using modified evaporation deposition techniques. This alternate process methodology offers reduced complexity and cost in comparison to conventional techniques for fabricating LVBFs. We are able to achieve linear variation of insulator thickness across a sample, by adjusting the geometrical parameters of a typical physical vapor deposition process. We demonstrate LVBFs with spectral selectivity from 400 to 850 nm based on Ag (25 nm) and MgF$_{2}$ (75–250 nm). Maximum spectral transmittance is measured at ∼70% with a $\textit{Q}$-factor of ∼20.Engineering and Physical Sciences Research Council (EPSRC) (EP/L015455/1); Cambridge Commonwealth, European and International Trust

Inequalities and outcomes : end stage kidney disease in ethnic minorities

The international evidence about outcomes of End Stage Kidney Disease (ESKD) for ethnic minorities was reviewed to identify gaps and make recommendations for researchers and policy makers. Nine databases were searched systematically with 112 studies from 14 different countries included and analysed to produce a thematic map of the literature. Reviews (n = 26) highlighted different mortality rates and specific causes between ethnic groups and by stage of kidney disease associated with individual, genetic, social and environmental factors. Primary studies focussing on uptake of treatment modalities (n = 19) found ethnic differences in access. Research evaluating intermediate outcomes and quality of care in different treatment phases (n = 35) e.g. dialysis adequacy, transplant evaluation and immunosuppression showed ethnic minorities were disadvantaged. This is despite a survival paradox for some ethnic minorities on dialysis seen in studies of longer term outcomes (n = 29) e.g. in survival time post-transplant and mortality. There were few studies which focussed on end of life care (n = 3) and ethnicity. Gaps identified were: limited evidence from all stages of the ESKD pathway, particularly end of life care; a lack of system oriented studies with a reliance on national routine datasets which are limited in scope; a dearth of qualitative studies; and a lack studies from many countries with limited cross country comparison and learning. Differences between ethnic groups occur at various points and in a variety of outcomes throughout the kidney care system. The combination of individual factors and system related variables affect ethnic groups differently indicating a need for culturally intelligent policy informed by research to prevent disadvantage

High-Angular Resolution Electron Backscatter Diffraction as a New Tool for Mapping Lattice Distortion in Geological Minerals

Analysis of distortions of the crystal lattice within individual mineral grains is central to the investigation of microscale processes that control and record tectonic events. These distortions are generally combinations of lattice rotations and elastic strains, but a lack of suitable observational techniques has prevented these components being mapped simultaneously and routinely in earth science laboratories. However, the technique of high-angular resolution electron backscatter diffraction (HR-EBSD) provides the opportunity to simultaneously map lattice rotation and elastic strain gradients with exceptional precision, on the order of 0.01° for rotations and 10−4 in strain, using a scanning electron microscope. Importantly, these rotations and lattice strains relate to densities of geometrically necessary dislocations and residual stresses. Recent works have begun to apply and adapt HR-EBSD to geological minerals, highlighting the potential of the technique to provide new insights into the microphysics of rock deformation. Therefore, the purpose of this review is to provide a summary of the technique, to identify caveats and targets for further development, and to suggest areas where it offers potential for major advances. In particular, HR-EBSD is well suited to characterizing the roles of different dislocation types during crystal plastic deformation and to mapping heterogeneous internal stress fields associated with specific deformation mechanisms/microstructures or changes in temperature, confining pressure, or macroscopic deviatoric stress. These capabilities make HR-EBSD a particularly powerful new technique for analyzing the microstructures of deformed geological materials.D. Wallis, L. N. Hansen, and A. J. Wilkinson acknowledge support from the Natural Environment Research Council grant NE/M0009661. T. B. Britton acknowledges support for his research fellowship from the Royal Academy of Engineering

Quantitative evidence synthesis methods for the assessment of the effectiveness of treatment sequences for clinical and economic decision-making: a review and taxonomy of simplifying assumptions

Sequential use of alternative treatments for chronic conditions represents a complex intervention pathway; previous treatment and patient characteristics affect both the choice and effectiveness of subsequent treatments. This paper critically explores the methods for quantitative evidence synthesis of the effectiveness of sequential treatment options within a health technology assessment (HTA) or similar process. It covers methods for developing summary estimates of clinical effectiveness or the clinical inputs for the cost-effectiveness assessment and can encompass any disease condition. A comprehensive review of current approaches is presented, which considers meta-analytic methods for assessing the clinical effectiveness of treatment sequences and decision-analytic modelling approaches used to evaluate the effectiveness of treatment sequences. Estimating the effectiveness of a sequence of treatments is not straightforward or trivial and is severely hampered by the limitations of the evidence base. Randomised controlled trials (RCTs) of sequences were often absent or very limited. In the absence of sufficient RCTs of whole sequences, there is no single best way to evaluate treatment sequences; however, some approaches could be re-used or adapted, sharing ideas across different disease conditions. Each has advantages and disadvantages, and is influenced by the evidence available, extent of treatment sequences (number of treatment lines or permutations), and complexity of the decision problem. Due to the scarcity of data, modelling studies applied simplifying assumptions to data on discrete treatments. A taxonomy for all possible assumptions was developed, providing a unique resource to aid the critique of existing decision-analytic models

Rapid acceptability and adherence testing of a lipid-based nutrient supplement and a micronutrient powder among refugee children and pregnant and lactating women in Algeria

OBJECTIVE: To assess the acceptability and adherence to daily doses of lipid-based nutrient supplement (LNS) among children and micronutrient powder (MNP) among children and pregnant and lactating women. DESIGN: Household interviews and sachet counting were conducted to measure acceptability and adherence, 15 and 30 d after product distribution. Qualitative information on product acceptability was collected using focus group discussions. SETTING: Saharawi refugee camps, Algeria, August-October 2009. SUBJECTS: LNS was distributed to 123 children aged 6-35 months (LNS-C), and MNP to 112 children aged 36-59 months (MNP-C) and 119 pregnant or lactating women (MNP-W). RESULTS: At the end of the test 98·4 % of LNS-C, 90·4 % of MNP-C and 75·5 % of MNP-W participants reported that they liked the product (P<0·05). Other measures of acceptability did not differ. Median consumption of sachets was highest in the LNS-C group (P<0·001). 'Good' adherence to the daily regimen (consumption of 75-125 % of recommended dose) was 89·1 % in the LNS-C, compared with 57·0 % in the MNP-C and 65·8 % in the MNP-W groups (P<0·001). Qualitative findings supported the quantitative measures and guided selection of local product names, packaging designs, distribution mechanisms, and the design of the information campaign in the subsequent programme scale-up. CONCLUSIONS: Acceptability, consumption and adherence were higher in participants receiving LNS compared with MNP. However, both products were found to be suitable when compared with predefined acceptability criteria. Acceptability studies are feasible and important in emergency nutrition programmes when the use of novel special nutritional products is considered

Peptidomimetic inhibitors of N-myristoyltransferase from human malaria and leishmaniasis parasites

N-Myristoyltransferase (NMT) has been shown to be essential in Leishmania and subsequently validated as a drug target in Plasmodium. Herein, we discuss the use of antifungal NMT inhibitors as a basis for inhibitor development resulting in the first sub-micromolar peptidomimetic inhibitors of Plasmodium and Leishmania NMTs. High-resolution structures of these inhibitors with Plasmodium and Leishmania NMTs permit a comparative analysis of binding modes, and provide the first crystal structure evidence for a ternary NMT-Coenzyme A/myristoylated peptide product complex