Using action research to design and evaluate sustained and inclusive engagement to improve children’s knowledge and perception of STEM careers

Previous research suggests that early experience of and exposure to the world of work is an important predictor of a child’s future involvement in a STEM career. Many interventions have focused on those in secondary education age 11 years and above. Far fewer interventions have explored the impact of STEM outreach engagements among younger age groups. This study investigates the impact of a project that delivered career-driven STEM interventions on young children’s (7–10 years old) career knowledge and perceptions over time. Using an action research approach, this study outlines 10 distinct features for designing child-centred STEM interventions. These were delivered in 6 primary schools across North-East England over a 2-year period. A STEM Career Knowledge and Aspirations Tool was used to collect data to evaluate the impact of these interventions. Children sorted 30 job cards (mix of STEM and non-STEM) into jobs they knew, and also into jobs they would like to do. Baseline data and follow up data were collected in 2015 (n = 352) and 2017 (n = 356). Data analysis suggests the sustained interventions had a particularly positive effect on girls. In 2015 prior to the interventions, girls were significantly less likely than boys to know the following STEM jobs: surveyor, technician and game tester. In 2017, following the sustained intervention, there was no significant difference between boys and girls. Furthermore, one of the STEM jobs, Engineer, showed the greatest increase in the percentage of boys and girls that wanted to do it in 2017 compared to 2015

Neutronic Optimisations of Breeder Blankets for Fusion Reactors

Fusion is seen by many as the ultimate energy source, capable of providing safe, clean and sustainable energy. Research has been carried out into fusion since the 1920s and substantial progress has been made. While the ultimate goal of providing energy from fusion remains elusive there is a clear understanding of the tasks that must be achieved to make fusion energy a reality. Deuterium and tritium (DT) offer a high probability of fusion when compared to any other combination of isotopes. Consequently DT fusion is the focus of all large scale fusion research programmes. As there is no natural source of tritium, fusion reactors are being designed with tritium breeder blankets to ensure self-sufficiency. The research contained within this thesis contributes to the ongoing development of breeder blankets for fusion reactors in terms of reducing their cost and improving their performance. The thesis follows a general theme of varying material composition to better utilise the local neutron spectra within fusion breeder blankets. The novel contributions of this thesis are as follows: The first contribution of this thesis is a technique that improves the accuracy of simulations involving time varying tritium production [171]. The technique identifies a minimum spacial resolution that should be used when performing burn-up studies in solid-type breeder blankets. Previously the tritium production with respect to time has been overestimated due to lack of spatial segmentation within the breeder blanket. Following on from this a parameter study was carried out to ascertain a more optimal composition for breeder blankets. The results of this study allows blanket designers to minimise the cost of the blanket while increasing the heat generated or maximising the tritium produced. The composition of breeder blankets operating with a DD neutron source was also optimised. This allows breeder blankets to create tritium from DD plasmas more efficiently. The use of DD plasmas to generate tritium is a proposed method of negating the need for an external supply of tritium to start up reactors. The sustainability of fusion is investigated and a method of reducing the use of beryllium within breeder blankets is presented. Blankets utilising this method were also shown to generate more heat, produce more tritium and showed lower peak heating. Varying the isotopic composition of materials was considered as a method to reduce helium production and improve the material properties without additional activity [132]. For the first, time cost benefit analysis of isotopically tailored materials in fusion reactors has been carried out and various methods to offset the enrichment cost have been identified. Multilayer blankets are investigated as a method of increasing the tritium production and are shown to achieve tritium production levels that are unobtainable for blankets with a uniform composition. Higher tritium production from blankets is particularly necessary in reactor designs that involve a reduction in the blanket volume. The composition of structural materials used within breeder blankets was also investigated. New material compositions are considered that offer reduced helium production. Additionally, materials that potentially offer improved material properties (e.g. fracture toughness and yield stress) are shown to be achievable. This is achieved by the addition of enriched Ni or Mo; the enrichment of the natural element allows it to be reintroduced without significant increase in activity. The final chapter summarises the research carried out, makes recommendations with regards to the design of future breeder blankets and presents further research opportunities

Fast Regression of the Tritium Breeding Ratio in Fusion Reactors

The tritium breeding ratio (TBR) is an essential quantity for the design of modern and next-generation D-T fueled nuclear fusion reactors. Representing the ratio between tritium fuel generated in breeding blankets and fuel consumed during reactor runtime, the TBR depends on reactor geometry and material properties in a complex manner. In this work, we explored the training of surrogate models to produce a cheap but high-quality approximation for a Monte Carlo TBR model in use at the UK Atomic Energy Authority. We investigated possibilities for dimensional reduction of its feature space, reviewed 9 families of surrogate models for potential applicability, and performed hyperparameter optimisation. Here we present the performance and scaling properties of these models, the fastest of which, an artificial neural network, demonstrated $R^2=0.985$ and a mean prediction time of $0.898\ \mu\mathrm{s}$, representing a relative speedup of $8\cdot 10^6$ with respect to the expensive MC model. We further present a novel adaptive sampling algorithm, Quality-Adaptive Surrogate Sampling, capable of interfacing with any of the individually studied surrogates. Our preliminary testing on a toy TBR theory has demonstrated the efficacy of this algorithm for accelerating the surrogate modelling process.Comment: 12 pages, 8 figure

Scientist of the week: evaluating effects of a teacher-led STEM intervention to reduce stereotypical views of scientists in young children

Background: Previous research into children’s perceptions of science shows that children like science but often hold stereotypical views of scientists and commonly do not see themselves with a career as a scientist.Purpose: The aim of this study is to examine if a carefully designed medium-term, teacher-led STEM intervention, ‘Scientist of the Week’ which showcased a diverse range of working scientists and the skills they need, can lead to a positive change in the perception of scientists among young people.Sample Design and Methods: Using a case-control approach, this research used a tracked sample of 118 young people from aged 7 to 11 in a primary school in the North East of England. Words associated with scientists were collected before and after (directly, one month, one year) the intervention from the tracked sample and analysed to assess changes in stereotypical perceptions and any difference in responses between male and female participants.Results: Before the intervention, young children held many of the common stereotypes associated with scientists. Shortly afterwards, and one year following the intervention, the use of common stereotypes had fallen significantly across all children, with particular improvements in counter-stereotypical word usage for males. It also found that stereotypical images of scientists as highly intelligent were more difficult to counteract and that many of the positive changes in this view seen in the short term (weeks and months) diminished in the long term (one year later).Conclusions: This research has shown that with minimal expense and effort from teachers, negative stereotypes of scientists can be reduced through an intervention that does not require bringing scientists into the classroom. Some of the observed changes persisted in the longer-term, suggesting a lasting alteration in children’s perceptions of scientists following the interventio

A Theory of Change for Improving Children’s Perceptions, Aspirations and Uptake of STEM Careers

There is concern about the low numbers and diversity of young people choosing careers and study subjects in science, technology, engineering and maths (STEM) at university and beyond. Many interventions aimed at addressing this issue have focused on young people aged 14+ years old. However, these interventions have resulted in little improvement in the numbers and diversity of young people progressing into STEM careers. The aim of this study is to ask “What are the affordances of a Theory of Change (ToC) for increasing the diversity and number of young people choosing a career in STEM post-18?” An innovative ToC is introduced which provides the theoretical underpinnings and context for the complex mix of interventions necessary to lead to a significant change in the number and diversity of those choosing STEM careers. Case studies of interventions developed using the ToC are presented. This approach, and associated ToC, is widely applicable across STEM, education and public engagement fields

High resolution AMI Large Array imaging of spinning dust sources: spatially correlated 8 micron emission and evidence of a stellar wind in L675

We present 25 arcsecond resolution radio images of five Lynds Dark Nebulae (L675, L944, L1103, L1111 & L1246) at 16 GHz made with the Arcminute Microkelvin Imager (AMI) Large Array. These objects were previously observed with the AMI Small Array to have an excess of emission at microwave frequencies relative to lower frequency radio data. In L675 we find a flat spectrum compact radio counterpart to the 850 micron emission seen with SCUBA and suggest that it is cm-wave emission from a previously unknown deeply embedded young protostar. In the case of L1246 the cm-wave emission is spatially correlated with 8 micron emission seen with Spitzer. Since the MIR emission is present only in Spitzer band 4 we suggest that it arises from a population of PAH molecules, which also give rise to the cm-wave emission through spinning dust emission.Comment: accepted MNRA

Microwave observations of spinning dust emission in NGC6946

We report new cm-wave measurements at five frequencies between 15 and 18GHz of the continuum emission from the reportedly anomalous "region 4" of the nearby galaxy NGC6946. We find that the emission in this frequency range is significantly in excess of that measured at 8.5GHz, but has a spectrum from 15-18GHz consistent with optically thin free-free emission from a compact HII region. In combination with previously published data we fit four emission models containing different continuum components using the Bayesian spectrum analysis package radiospec. These fits show that, in combination with data at other frequencies, a model with a spinning dust component is slightly preferred to those that possess better-established emission mechanisms.Comment: submitted MNRA

Sunyaev-Zel'dovich observations of galaxy clusters out to the virial radius with the Arcminute Microkelvin Imager

We present observations using the Small Array of the Arcminute Microkelvin Imager (AMI; 14-18 GHz) of four Abell and three MACS clusters spanning 0.171-0.686 in redshift. We detect Sunyaev-Zel'dovich (SZ) signals in five of these without any attempt at source subtraction, although strong source contamination is present. With radio-source measurements from high-resolution observations, and under the assumptions of spherical $\beta$-model, isothermality and hydrostatic equilibrium, a Bayesian analysis of the data in the visibility plane detects extended SZ decrements in all seven clusters over and above receiver noise, radio sources and primary CMB imprints. Bayesian evidence ratios range from 10^{11}:1 to 10^{43}:1 for six of the clusters and 3000:1 for one with substantially less data than the others. We present posterior probability distributions for, e.g., total mass and gas fraction averaged over radii internal to which the mean overdensity is 1000, 500 and 200, r_200 being the virial radius. Reaching r_200 involves some extrapolation for the nearer clusters but not for the more-distant ones. We find that our estimates of gas fraction are low (compared with most in the literature) and decrease with increasing radius. These results appear to be consistent with the notion that gas temperature in fact falls with distance (away from near the cluster centre) out to the virial radius.Comment: 18 pages, 10 figures, submitted to MNRAS (updated authors and fixed Figure 1

AMI observations of Lynds Dark Nebulae: further evidence for anomalous cm-wave emission

Observations at 14.2 to 17.9 GHz made with the AMI Small Array towards fourteen Lynds Dark Nebulae with a resolution of 2' are reported. These sources are selected from the SCUBA observations of Visser et al. (2001) as small angular diameter clouds well matched to the synthesized beam of the AMI Small Array. Comparison of the AMI observations with radio observations at lower frequencies with matched uv-plane coverage is made, in order to search for any anomalous excess emission which can be attributed to spinning dust. Possible emission from spinning dust is identified as a source within a 2' radius of the Scuba position of the Lynds dark nebula, exhibiting an excess with respect to lower frequency radio emission. We find five sources which show a possible spinning dust component in their spectra. These sources have rising spectral indices in the frequency range 14.2--17.9 GHz. Of these five one has already been reported, L1111, we report one new definite detection, L675, and three new probable detections (L944, L1103 and L1246). The relative certainty of these detections is assessed on the basis of three criteria: the extent of the emission, the coincidence of the emission with the Scuba position and the likelihood of alternative explanations for the excess. Extended microwave emission makes the likelihood of the anomalous emission arising as a consequence of a radio counterpart to a protostar or a proto-planetary disk unlikely. We use a 2' radius in order to be consistent with the IRAS identifications of dark nebulae (Parker 1988), and our third criterion is used in the case of L1103 where a high flux density at 850 microns relative to the FIR data suggests a more complicated emission spectrum.Comment: submitted MNRA

Bayesian analysis of weak gravitational lensing and Sunyaev-Zel'dovich data for six galaxy clusters

We present an analysis of observations made with the Arcminute Microkelvin Imager (AMI) and the Canada-France-Hawaii Telescope (CFHT) of six galaxy clusters in a redshift range of 0.16--0.41. The cluster gas is modelled using the Sunyaev--Zel'dovich (SZ) data provided by AMI, while the total mass is modelled using the lensing data from the CFHT. In this paper, we: i) find very good agreement between SZ measurements (assuming large-scale virialisation and a gas-fraction prior) and lensing measurements of the total cluster masses out to r_200; ii) perform the first multiple-component weak-lensing analysis of A115; iii) confirm the unusual separation between the gas and mass components in A1914; iv) jointly analyse the SZ and lensing data for the relaxed cluster A611, confirming our use of a simulation-derived mass-temperature relation for parameterizing measurements of the SZ effect.Comment: 22 pages, 12 figures, 12 tables, published by MNRA