Characterisation of the Temperature-dependent Dark Rate of Hamamatsu R7081-100 10" Photomultiplier Tubes

Dark noise is a dominant background in photomultiplier tubes (PMTs), which are commonly used in liquid-filled particle detectors for single-photon detection to see the results of particle interactions. A major contribution to dark noise is thermionic emission from the photocathode. The dark noise of Hamamatsu R7081-100 PMTs is characterised in a temperature and purity controlled water tank, with the thermionic emission contribution isolated. The results suggest that the intrinsic dark rate of PMTs does not depend on the medium, but does follow Richardson's law of thermionic emission. There are external contributions to the overall observed PMT count rate identified, but the intrinsic PMT dark rate in water matches that measured in air.Comment: 11 pages, 7 figures, 2 tables, prepared for submission to J. Instru

Exploring the Efficacy of Nile Red in Microplastic Quantification: A Costaining Approach

The presence of microplastic particles ([less than]5 mm) in the environment has generated considerable concern across public, political, and scientific platforms. However, the diversity of microplastics that persist in the environment poses complex analytical challenges for our understanding of their prevalence. The use of the dye Nile red to quantify microplastics is increasingly common. However, its use in microplastic analysis rarely accounts for its affinity with the breadth of particles that occur in environmental samples. Here, we examine Nile red’s ability to stain a variety of microplastic particles and common natural and anthropogenic particles found in environmental samples. To better constrain microplastic estimates using Nile red, we test the coapplication of a second stain that binds to biological material, 4′,6-diamidino-2-phenylindole (DAPI). We test the potential inflation of microplastic estimates using Nile red alone by applying this costaining approach to samples of drinking water and freshwater. The use of Nile red dye alone resulted in a maximum 100% overestimation of microplastic particles. These findings are of particular significance for the public dissemination of findings from an emotive field of study

Parameterised Geant4 simulation for total body PET research

Total-body positron emission tomography (PET) imaging has the potential to transform medical care of a number of diseases and augment our knowledge of systems biology. Various detector designs and geometries are currently under development for total-body PET imaging of humans. This variety, in particular the variation in axial field-of-view (aFOV), motivates a need to compare the performance of these devices in a consistent simulated environment. We present an open-source Geant4 simulation package that allows variation of relevant parameters such as the detector aFOV and the tracer radioisotope from the command line. Two simplified detector geometries based on the Siemens Biograph Vision Quadra and United Imaging uEXPLORER models are supported with variable granularity. The intrinsic radioactivity of the detector crystals is fully simulated. The simulation can be viewed with the built-in GUI, and the results are saved in a plain text format for easy analysis. Example Python analysis code is provided with the simulation, demonstrating calculation of the noise equivalent count rate (NECR) figure of merit using an approximation to the NEMA NU 2-2012 standard method. A good agreement between the simulated count rate performance and experimental data is observed for both geometries. The differences in results are attributed to simplifications in the simulation code, namely not accounting for the light-collection efficiency or readout dead-time. We demonstrate the importance of assessing the scanner performance using appropriate phantom length which significantly affects the obtained results. A dependence between the detector aFOV and the length of the source, with peak NECR plateauing as the detector extends beyond the region of interest is also presented.Comment: 13 pages in total, 6 figure

Changes in Energy Demand of Dance Activity and Cardiorespiratory Fitness During One Year of Vocational Contemporary Dance Training

Previous literature has demonstrated that the intensity of dance class, as well as its discontinuous nature, is not sufficient to elicit an aerobic training response and that the aerobic capacity of dancers is relatively low. These findings have raised questions of the suitability of training, through class and rehearsal, as adequate preparation for the physical demands of performance and a sustained, successful career in dance. The aim of this study was to describe changes in aerobic fitness and energy cost of dance movement occurring throughout one year of training. Subjects were thirteen female dance students; seven first year undergraduate students (UG), and six postgraduate students (PG). At three time-points (TP1, TP2, TP3) during one academic year each subject completed a treadmill test, to determine VO2peak (ml.kg-1.min-1) and lactate threshold (LT) (ml.kg-1.min-1 and %VO2peak), and a standardised four-minute dance sequence, where mean demand was expressed as VO2 (ml.kg-1.min-1), heart rate (b.min-1), %VO2peak, and %LT. Both groups displayed an overall decrease in mean VO2peak throughout the year, despite a peak in fitness at TP2 in the PG students. No significant changes in LT were noted over time for either group. A significant reduction in the relative intensity of the dance sequence, particularly in relation to mean VO2 (ml.kg-1.min-1) and %LT data, was observed over time in both groups although the degree of change was less in the UG group than the PG group. Apparent adaptations during a rehearsal period in the PG group are presented in contrast to previous research findings. Recommendations for future research include further investigation into the energy demand of rehearsal and cardiorespiratory adaptation during rehearsal periods as well as further reporting of measures related to LT and movement economy

Practising the Space Between: Embodying Belief as an Evangelical Anglican Student

This article explores the formation of British evangelical university students as believers. Drawing on ethnographic fieldwork conducted with a conservative evangelical Anglican congregation in London, I describe how students in this church come to embody a highly cognitive, word-based mode of belief through particular material practices. As they learn to identify themselves as believers, practices of reflexivity and accountability enable them to develop a sense of narrative coherence in their lives that allows them to negotiate tensions that arise from their participation in church and broader social structures. I demonstrate that propositional belief – in contexts where it becomes an identity marker – is bound up with relational practices of belief, such that distinctions between “belief in” and “belief that” are necessarily blurred in the lives of young evangelicals