Uncertainty quantification in nuclear criticality modelling using a high dimensional model representation

An adaptive high dimensional model representation (HDMR) is used to decompose the response parameter into a superposition of lower dimensional subspaces which are in-turn projected on to a polynomial basis. These projections are evaluated using an adaptive quadrature scheme which is used to infer the polynomial orders of the basis. The combination of adaptive HDMR and adaptive quadrature techniques results in a sparse polynomial expansion which has been optimised to represent the variance of the response with the minimum number of polynomials. The combined application of these techniques is illustrated using UOX and MOX pin cell problems with evaluated nuclear covariance data. We show that this approach to calculating the variance in is an order of magnitude more efficient when compared to Latin Hypercube sampling with the same number of samples for problems involving up to 988 random dimensions

Constructing living buildings: a review of relevant technologies for a novel application of biohybrid robotics

Biohybrid robotics takes an engineering approach to the expansion and exploitation of biological behaviours for application to automated tasks. Here, we identify the construction of living buildings and infrastructure as a high-potential application domain for biohybrid robotics, and review technological advances relevant to its future development. Construction, civil infrastructure maintenance and building occupancy in the last decades have comprised a major portion of economic production, energy consumption and carbon emissions. Integrating biological organisms into automated construction tasks and permanent building components therefore has high potential for impact. Live materials can provide several advantages over standard synthetic construction materials, including self-repair of damage, increase rather than degradation of structural performance over time, resilience to corrosive environments, support of biodiversity, and mitigation of urban heat islands. Here, we review relevant technologies, which are currently disparate. They span robotics, self-organizing systems, artificial life, construction automation, structural engineering, architecture, bioengineering, biomaterials, and molecular and cellular biology. In these disciplines, developments relevant to biohybrid construction and living buildings are in the early stages, and typically are not exchanged between disciplines. We, therefore, consider this review useful to the future development of biohybrid engineering for this highly interdisciplinary application.publishe

The relationship between workers' self-reported changes in health and their attitudes towards a workplace intervention: lessons from smoke-free legislation across the UK hospitality industry

Background: The evaluation of smoke-free legislation (SFL) in the UK examined the impacts on exposure to second-hand smoke, workers’ attitudes and changes in respiratory health. Studies that investigate changes in the health of groups of people often use self-reported symptoms. Due to the subjective nature it is of interest to determine whether workers’ attitudes towards the change in their working conditions may be linked to the change in health they report. Methods: Bar workers were recruited before the introduction of the SFL in Scotland and England with the aim of investigating their changes to health, attitudes and exposure as a result of the SFL. They were asked about their attitudes towards SFL and the presence of respiratory and sensory symptoms both before SFL and one year later. Here we examine the possibility of a relationship between initial attitudes and changes in reported symptoms, through the use of regression analyses. Results: There was no difference in the initial attitudes towards SFL between those working in Scotland and England. Bar workers who were educated to a higher level tended to be more positive towards SFL. Attitude towards SFL was not found to be related to change in reported symptoms for bar workers in England (Respiratory, p = 0.755; Sensory, p = 0.910). In Scotland there was suggestion of a relationship with reporting of respiratory symptoms (p = 0.042), where those who were initially more negative to SFL experienced a greater improvement in self-reported health. Conclusions: There was no evidence that workers who were more positive towards SFL reported greater improvements in respiratory and sensory symptoms. This may not be the case in all interventions and we recommend examining subjects’ attitudes towards the proposed intervention when evaluating possible health benefits using self-reported methods. Keywords: ‘Self-Reported Health’, Attitudes, ‘Workplace Intervention’, ‘Public Health Intervention

The politics of regulatory enforcement and compliance: Theorizing and operationalizing political influences

There is broad consensus in the literature on regulatory enforcement and compliance that politics matters. However, there is little scholarly convergence on what politics is or rigorous theorization and empirical testing of how politics matters. Many enforcement and compliance studies omit political variables altogether. Among those that address political influences on regulatory outcomes, politics has been defined in myriad ways and, too often, left undefined. Even when political constructs are explicitly operationalized, the mechanisms by which they influence regulatory outcomes are thinly hypothesized or simply ignored. If politics is truly as important to enforcement and compliance outcomes as everyone in the field seems to agree, regulatory scholarship must make a more sustained and systematic effort to understand their relationship, because overlooking this connection risks missing what is actually driving regulatory outcomes. This article examines how the construct of “politics” has been conceptualized in regulatory theory and analyzes how it has been operationalized in empirical studies of regulatory enforcement and compliance outcomes. It brings together scholarship across disciplines that rarely speak but have much to say to one another on this subject in order to constitute a field around the politics of regulation. The goal is to sharpen theoretical and empirical understandings of when and how regulation works by better accounting for the role politics plays in its enforcement

Balancing Autonomy and Collaboration in Large-Scale and Disciplinary Diverse Teams for Successful Qualitative Research

Large scale, multi-organisational collaborations between researchers from diverse disciplinary backgrounds are increasingly recognised as important to investigate and tackle complex real-world problems. However differing expectations, epistemologies, and preferences across these teams pose challenges to following best practice for ensuring high-quality and rigorous qualitative research, while maintaining goodwill and team cohesion across team members. This article presents critical reflections from the real-world experiences of a team navigating the challenges of collaborating on a large-scale, cross-disciplinary interview study. Based on these experiences, we extend the literature on large team qualitative collaboration by highlighting the importance of balancing autonomy and collaboration, and propose eight recommendations to support high quality research and team cohesion. We identify how this balance can be achieved at different times: when centralised decision-making should be prioritised, and autonomy can be allowed. We argue that prioritising time to develop shared understandings, build trust, and creating positive environments that accept and support differing researcher perspectives on qualitative methods is paramount. By exploring and reflecting on these differences, teams can identify how and when to support autonomy in decision-making, when to move forward collaboratively, and how to ensure that shared processes reflect the needs of the whole team. The reflexive findings, emanating from practical experience, can inform large research teams undertaking qualitative studies to explore complex issues. We make an original contribution to qualitative methods research by arguing that balancing autonomy and collaboration is the key to promoting high quality research and cohesion in large teams

Balancing Autonomy and Collaboration in Large-Scale and Disciplinary Diverse Teams for Successful Qualitative Research

Large scale, multi-organisational collaborations between researchers from diverse disciplinary backgrounds are increasingly recognised as important to investigate and tackle complex real-world problems. However differing expectations, epistemologies, and preferences across these teams pose challenges to following best practice for ensuring high-quality and rigorous qualitative research, while maintaining goodwill and team cohesion across team members. This article presents critical reflections from the real-world experiences of a team navigating the challenges of collaborating on a large-scale, cross-disciplinary interview study. Based on these experiences, we extend the literature on large team qualitative collaboration by highlighting the importance of balancing autonomy and collaboration, and propose eight recommendations to support high quality research and team cohesion. We identify how this balance can be achieved at different times: when centralised decision-making should be prioritised, and autonomy can be allowed. We argue that prioritising time to develop shared understandings, build trust, and creating positive environments that accept and support differing researcher perspectives on qualitative methods is paramount. By exploring and reflecting on these differences, teams can identify how and when to support autonomy in decision-making, when to move forward collaboratively, and how to ensure that shared processes reflect the needs of the whole team. The reflexive findings, emanating from practical experience, can inform large research teams undertaking qualitative studies to explore complex issues. We make an original contribution to qualitative methods research by arguing that balancing autonomy and collaboration is the key to promoting high quality research and cohesion in large teams

Search for sterile neutrino mixing in the MINOS long-baseline experiment

A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18×1020 protons on target in which neutrinos of energies between ~500¿¿MeV and 120 GeV are produced predominantly as ¿µ, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ¿µ flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles ¿24 and ¿34 are constrained to be less than 11° and 56° at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime t3/m3>2.1×10-12¿¿s/eV at 90% C.L

Physical Stress, Not Biotic Interactions, Preclude an Invasive Grass from Establishing in Forb-Dominated Salt Marshes

Biological invasions have become the focus of considerable concern and ecological research, yet the relative importance of abiotic and biotic factors in controlling the invasibility of habitats to exotic species is not well understood. Spartina species are highly invasive plants in coastal wetlands; however, studies on the factors that control the success or failure of Spartina invasions across multiple habitat types are rare and inconclusive.We examined the roles of physical stress and plant interactions in mediating the establishment of the smooth cordgrass, Spartina alterniflora, in a variety of coastal habitats in northern China. Field transplant experiments showed that cordgrass can invade mudflats and low estuarine marshes with low salinity and frequent flooding, but cannot survive in salt marshes and high estuarine marshes with hypersaline soils and infrequent flooding. The dominant native plant Suaeda salsa had neither competitive nor facilitative effects on cordgrass. A common garden experiment revealed that cordgrass performed significantly better when flooded every other day than when flooded weekly. These results suggest that physical stress rather than plant interactions limits cordgrass invasions in northern China.We conclude that Spartina invasions are likely to be constrained to tidal flats and low estuarine marshes in the Yellow River Delta. Due to harsh physical conditions, salt marshes and high estuarine marshes are unlikely to be invaded. These findings have implications for understanding Spartina invasions in northern China and on other coasts with similar biotic and abiotic environments

Leaf litter decomposition in temperate deciduous forest stands with a decreasing fraction of beech (Fagus sylvatica)

We hypothesised that the decomposition rates of leaf litter will increase along a gradient of decreasing fraction of the European beech (Fagus sylvatica) and increasing tree species diversity in the generally beech-dominated Central European temperate deciduous forests due to an increase in litter quality. We studied the decomposition of leaf litter including its lignin fraction in monospecific (pure beech) stands and in stands with up to five tree genera (Acer spp., Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia spp.) using a litterbag approach. Litter and lignin decomposition was more rapid in stand-representative litter from multispecific stands than in litter from pure beech stands. Except for beech litter, the decomposition rates of species-specific tree litter did not differ significantly among the stand types, but were most rapid in Fraxinus excelsior and slowest in beech in an interspecific comparison. Pairwise comparisons of the decomposition of beech litter with litter of the other tree species (except for Acerplatanoides) revealed a “home field advantage” of up to 20% (more rapid litter decomposition in stands with a high fraction of its own species than in stands with a different tree species composition). Decomposition of stand-representative litter mixtures displayed additive characteristics, not significantly more rapid than predicted by the decomposition of litter from the individual tree species. Leaf litter decomposition rates were positively correlated with the initial N and Ca concentrations of the litter, and negatively with the initial C:N, C:P and lignin:N ratios. The results support our hypothesis that the overall decomposition rates are mainly influenced by the chemical composition of the individual litter species. Thus, the fraction of individual tree species in the species composition seems to be more important for the litter decomposition rates than tree species diversity itself