The suppression of fluorescence peaks in energy-dispersive X-ray diffraction

A novel method to separate diffraction and fluorescence peaks in energy- dispersive X-ray diffraction (EDXRD) is described. By tuning the excitation energy of an X-ray tube source to just below an elemental absorption edge, the corresponding fluorescence peaks of that element are completely suppressed in the resulting spectrum. Since Bremsstrahlung photons are present in the source spectrum up to the excitation energy, any diffraction peaks that lie at similar energies to the suppressed fluorescence peaks are uncovered. This technique is an alternative to the more usual method in EDXRD of altering the scattering angle in order to shift the energies of the diffraction peaks. However, in the back-reflection EDXRD technique [Hansford (2011). J. Appl. Cryst. 44, 514–525] changing the scattering angle would lose the unique property of insensitivity to sample morphology and is therefore an unattractive option. The use of fluorescence suppression to reveal diffraction peaks is demonstrated experimentally by suppressing the Ca K fluorescence peaks in the back-reflection EDXRD spectra of several limestones and dolomites. Three substantial benefits are derived: uncovering of diffraction peak(s) that are otherwise obscured by fluorescence; suppression of the Ca K escape peaks; and an increase in the signal-to-background ratio. The improvement in the quality of the EDXRD spectrum allows the identification of a secondary mineral in the samples, where present. The results for a pressed-powder pellet of the geological standard JDo-1 (dolomite) show the presence of crystallite preferred orientation in this prepared sample. Preferred orientation is absent in several unprepared limestone and dolomite rock specimens, illustrating an advantage of the observation of rocks in their natural state enabled by back-reflection EDXRD

A prototype ASIC for APD array readout of scintillating plastic fibers

We report on the development of custom front-end electronics for use with avalanche photodiode (APD) arrays as part of a NASA technology study for the readout of scintillating plastic fibers. APD arrays featuring 64 1 mm square pixels are used. We demonstrate that a pixel of these APD arrays coupled to relatively thin (0.25 mm) and short (15 cm) scintillating plastic fibers can be used to detect and measure the tracks of even minimum ionizing particles (MIPs). An applicationspecific integrated circuit (ASIC) implementation of the electronics is required to produce a detector sufficiently compact for practical use in a flight experiment featuring many thousands of channels. This paper briefly describes the detector concept and performance and presents the design and performance of a four-channel prototype ASIC fabricated using the 0.35 micron TSMC process

High-resolution X-ray diffraction with no sample preparation

It is shown that energy-dispersive X-ray diffraction (EDXRD) implemented in a back-reflection geometry is extremely insensitive to sample morphology and positioning even in a high-resolution configuration. This technique allows high quality X-ray diffraction analysis of samples that have not been prepared and is therefore completely non-destructive. The experimental technique was implemented on beamline B18 at the Diamond Light Source synchrotron in Oxfordshire, UK. The majority of the experiments in this study were performed with pre-characterized geological materials in order to elucidate the characteristics of this novel technique and to develop the analysis methods. Results are presented that demonstrate phase identification, the derivation of precise unit-cell parameters and extraction of microstructural information on unprepared rock samples and other sample types. A particular highlight was the identification of a specific polytype of a muscovite in an unprepared mica schist sample, avoiding the time-consuming and difficult preparation steps normally required to make this type of identification. The technique was also demonstrated in application to a small number of fossil and archaeological samples. Back-reflection EDXRD implemented in a high-resolution configuration shows great potential in the crystallographic analysis of cultural heritage artefacts for the purposes of scientific research such as provenancing, as well as contributing to the formulation of conservation strategies. Possibilities for moving the technique from the synchrotron into museums are discussed. The avoidance of the need to extract samples from high-value and rare objects is a highly significant advantage, applicable also in other potential research areas such as palaeontology, and the study of meteorites and planetary materials brought to Earth by sample-return missions

Teaching classroom management – A potential public health intervention?

Author's manuscript version. The final published version is available from the publisher via: http://dx.doi.org/10.1108/HE-03-2014-0030© Emerald Group Publishing LimitedPurpose – The purpose of this paper is to explore the feasibility of a classroom management course as a public health intervention. Improved socio-emotional skills may boost children’s developmental and academic trajectory, while the costs of behaviour problems are enormous for schools with considerable impact on others’ well-being. Design/methodology/approach – In total, 40 teachers attended the Incredible Years (IY) Teacher Classroom Management (TCM) intervention in groups of ten. Afterwards teachers attended focus groups and semi-structured interviews were completed with headteachers to explore whether TCM was feasible, relevant and useful, research processes were acceptable and if it influenced teachers’ practice and pupils. Teachers completed standardised questionnaires about their professional self-efficacy, burnout and well-being before and after attendance. Findings – In all, 37/40 teachers completed the course. Teachers valued sharing experiences, the support of colleagues in the group and time out to reflect on practice and rehearse new techniques. Most teachers reported that they applied the strategies with good effect in their classrooms. Teachers’ questionnaires suggested an improvement in their self-efficacy in relation to classroom management (p=0.03); other scales changed in the predicted direction but did not reach statistical significance. Research limitations/implications – Although preliminary and small, these feasibility study findings suggest that it was worthwhile proceeding to a definitive randomised controlled trial (RCT). Practical implications – Should the RCT demonstrate effectiveness, then the intervention is an obvious candidate for implementation as a whole school approach. Originality/value – Successful intervention with one teacher potentially benefits every child that they subsequently teach and may increase the inclusion of socio-economically deprived children living in challenging circumstances in mainstream education. © Emerald Group Publishing Limited.National Institute for Health Research (NIHR

Weather conditions and voter turnout in Dutch national parliament elections, 1971–2010

While conventional wisdom assumes that inclement weather on election day reduces voter turnout, there is remarkably little evidence available to support truth to such belief. This paper examines the effects of temperature, sunshine duration and rainfall on voter turnout in 13 Dutch national parliament elections held from 1971 to 2010. It merges the election results from over 400 municipalities with election-day weather data drawn from the nearest weather station. We find that the weather parameters indeed affect voter turnout. Election-day rainfall of roughly 25 mm (1 inch) reduces turnout by a rate of one percent, whereas a 10-degree-Celsius increase in temperature correlates with an increase of almost one percent in overall turnout. One hundred percent sunshine corresponds to a one and a half percent greater voter turnout compared to zero sunshine

An engaged approach to exploring issues around poverty and mental health: A reflective evaluation of the research process from researchers and community partners involved in the DeStress study

Background Involving patients, service users, carers and members of the public in research has been part of health policy and practice in the UK for the last 15 years. However, low‐income communities tend to remain marginalized from the co‐design and delivery of mental health research, perpetuating the potential for health inequalities. Greater understanding is therefore needed on how to meaningfully engage low‐income communities in mental health research. Objectives To explore and articulate whether and how an engaged research approach facilitated knowledge coproduction relating to poverty and mental distress. Setting A reflective evaluation of community and researcher engagement in the DeStress study that took place in two low‐income areas of South‐west England. Design Reflective evaluation by the authors through on‐going feedback, a focus group and first‐person writing and discussion on experiences of working with the DeStress project, and how knowledge coproduction was influenced by an engaged research approach. Results An engaged research approach influenced the process and delivery of the DeStress project, creating a space where community partners felt empowered to coproduce knowledge relating to poverty‐related mental distress, treatment and the training of health professionals that would otherwise have been missed. We examine motivations for involvement, factors sustaining engagement, how coproduction influenced research analysis, findings and dissemination of outputs, and what involvement meant for different stakeholders. Conclusion Engaged research supported the coproduction of knowledge in mental health research with low‐income communities which led to multiple impacts

The ferric leaching kinetics of arsenopyrite

Abstract In this investigation batch, ferric leaching experiments were carried out in a 100 m l l jacketed vessel maintained at 258C. The parameters varied during the course of the experimental program included the initial redox potential, the total iron concentration, the solids concentration and the pH of the leaching solution. The initial redox potential used ranged from 625 to 470 mV, the overall iron concentration ranged from 8 to 32 g. l l y1 , the mineral concentration ranged from 5 to 20 g. l l y1 and the initial pH used ranged from 1.10 to 1.45. The redox potential of the leach solution was monitored continuously using a redox probe connected to a computer. The leach rates were calculated from the measured change in the redox potential of the leaching solution. The variation in the ferric leaching rate of the arsenopyrite as a function of the solution redox potential displayed similar trends, irrespective of the conditions employed. The ferric leaching rate of the arsenopyrite decreased with decreasing redox potential of the leaching solution and could be accurately described using a modified Butler-Volmer equation; yr s r e y . High concentrations of ferric iron and protons, and a reduction in the solids Ž concentration were found to impede the leach rate. The 'rest potential' i.e., the redox potential at . which the dissolution of arsenopyrite stops of the arsenopyrite was found to be higher under these conditions. However, no occluding sulphur layer could be detected on the surface of mineral particles, hence the results suggest that the reactivity of the mineral decreases with an increase in the effective concentration of the ferric iron species. Therefore, although the results suggest the Ž . PII: S 0 3 0 4 -3 8 6 X 9 9 0 0 0 0 7 -9 ( ) R. Ruitenberg et al.r Hydrometallurgy 52 1999 37-53 38 likelihood of an electrochemical mechanism being operative, it is necessary to modify the Butler-Volmer-based model to account for the above observations in order to obtain a model capable of predicting the ferric leaching rate of arsenopyrite across a broad range of operating conditions.

Psychological distress among primary school teachers: a comparison with clinical and population samples

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Objectives: This analysis explored the level of psychological distress among primary school teachers in the South West of England as compared to clinical and general population samples. Study design: Secondary analysis of data from the Supporting Teachers And childRen in Schools (STARS) trial completed by up to 90 teachers at baseline, 9, 18 and 30 months of follow up. Methods: We used the Everyday Feelings Questionnaire (EFQ) as a measure of psychological distress. Baseline data on teachers were compared with a population sample of professionals and a clinical sample of patients attending a depression clinic. Results: Our teacher cohort experienced higher levels of psychological distress than comparable professionals from the general population, which were sustained over 30 months follow-up. Levels of psychological distress were lower than those found in the clinical sample. Using a cut-point indicative of moderate depression, our data suggest between 19% and 29% of teachers experienced clinically significant distress at each time-point. Conclusions: We detected high and sustained levels of psychological distress among primary school teachers, which suggests an urgent need for intervention. Effective support for teachers’ mental health is particularly important given the potential impact of poor teacher mental health on pupil wellbeing, pupil attainment and teacher-pupil relationships.The STARS trial was funded by the National Institute for Health Research Public Health Research Programme (project number 10/3006/07) and the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care South West Peninsula

The impact of model grid zooming on tracer transport in the 1999/2000 Arctic polar vortex

International audienceWe have used a 3D chemistry transport model to evaluate the transport of HF and CH4 in the stratosphere during the Arctic winter of 1999/2000. Several model experiments were carried out with the use of a zoom algorithm to investigate the effect of different horizontal resolutions. Balloon-borne and satellite-borne observations of HF and CH4 were used to test the model. In addition, air mass descent rates within the polar vortex were calculated and compared to observations. Outside the vortex the model results agree well with the observations, but inside the vortex the model underestimates the observed vertical gradient in HF and CH4, even when the highest available resolution (1°×1°) is applied. The calculated diabatic descent rates agree with observations above potential temperature levels of 450 K. These model results suggest that too strong mixing through the vortex edge could be a plausible cause for the model discrepancies, associated with the calculated mass fluxes, although other reasons are also discussed. Based on our model experiments we conclude that a global 6°×9° resolution is too coarse to represent the polar vortex, whereas the higher resolutions, 3°×2° and 1°×1°, yield similar results, even with a 6°×9° resolution in the tropical region

Matrix-free calcium in isolated chromaffin vesicles

Isolated secretory vesicles from bovine adrenal medulla contain 80 nmol of Ca2+ and 25 nmol of Mg2+ per milligram of protein. As determined with a Ca2+-selective electrode, a further accumulation of about 160 nmol of Ca2+/mg of protein can be attained upon addition of the Ca2+ ionophore A23187. During this process protons are released from the vesicles, in exchange for Ca2+ ions, as indicated by the decrease of the pH in the incubation medium or the release of 9-aminoacridine previously taken up by the vesicles. Intravesicular Mg2+ is not released from the vesicles by A23 187, as determined by atomic emission spectroscopy. In the presence of N H Q , which causes the collapse of the secretory vesicle transmembrane proton gradient (ApH), Ca2+ uptake decreases. Under these conditions A23 187-mediated influx of Ca2+ and efflux of H+ cease at Ca2+ concentrations of about 4 pM. Below this concentration Ca2+ is even released from the vesicles. At the Ca2+ concentration at which no net flux of ions occurs the intravesicular matrix free Ca2+ equals the extravesicular free Ca2+. In the absence of NH4C1 we determined an intravesicular pH of 6.2. Under these conditions the Ca2+ influx ceases around 0.15 pM. From this value and the known pH across the vesicular membrane an intravesicular matrix free Ca2+ concentration of about 24 pM was calculated. This is within the same order of magnitude as the concentration of free Ca2+ in the vesicles determined in the presence of NH4C1. Calculation of the total Ca2+ present in the secretory vesicles gives an apparent intravesicular Ca2+ concentration of 40 mM, which is a factor of lo4 higher than the free intravesicular concentration of Ca2+. It can be concluded, therefore, that the concentration gradient of free Ca2+ across the secretory vesicle membrane in the intact chromaffin cells is probably small, which implies that less energy is required to accumulate and maintain Ca2+ within the vesicles than was previously anticipated