Biochar amendment and greenhouse gas emissions from agricultural soils

The aim of this study was to investigate the effects of biochar amendment on soil greenhouse gas (GHG) emissions and to elucidate the mechanisms behind these effects. I investigated the suppression of soil carbon dioxide (CO2) and nitrous oxide (N2O) emissions in a bioenergy and arable crop soil, at a range of temperatures and with or without wetting/drying cycles. More detailed investigation on the underlying mechanisms focused on soil N2O emissions. I tested how biochar altered soil physico-chemical properties and the subsequent effects on soil N2O emissions. In addition, 15N pool dilution techniques were used to investigate the effect of biochar on soil N transformations. Biochar amendment significantly suppressed soil GHG emissions for two years within a bioenergy soil in the field and for several months in an arable soil. I hypothesised that soil CO2 emissions were suppressed under field conditions by a combination of mechanisms: biochar induced immobilisation of soil inorganic-N (BII), increased C-use efficiency, reduced C-mineralising enzyme activity and adsorption of CO2 to the biochar surface. Soil CO2 emissions were increased for two days following wetting soil due to the remobilisation of biochar-derived labile C within the soil. Soil N2O emissions were suppressed in laboratory incubations within several months of biochar addition due to increased soil aeration, BII or increased soil pH that reduced the soil N2O: N2 ratio; effects that varied depending on soil inorganic-N concentration and moisture content. These results are significant as they consistently demonstrate that fresh hardwood biochar has the potential to reduce soil GHG emissions over a period of up to two years in bioenergy crop soil, while simultaneously sequestering C within the soil. They also contribute greatly to understanding of the mechanisms underlying the effect of biochar addition on soil N transformations and N2O emissions within bioenergy and arable soils. This study supports the hypothesis that if scaled up, biochar amendment to soil may contribute to significant reductions in global GHG emissions, contributing to climate change mitigation. Further studies are needed to ensure that these conclusions can be extrapolated over the longer term to other field sites, using other types of biochar

Biochar amendment and greenhouse gas emissions from agricultural soils

The aim of this study was to investigate the effects of biochar amendment on soil greenhouse gas (GHG) emissions and to elucidate the mechanisms behind these effects. I investigated the suppression of soil carbon dioxide (CO2) and nitrous oxide (N2O) emissions in a bioenergy and arable crop soil, at a range of temperatures and with or without wetting/drying cycles. More detailed investigation on the underlying mechanisms focused on soil N2O emissions. I tested how biochar altered soil physico-chemical properties and the subsequent effects on soil N2O emissions. In addition, 15N pool dilution techniques were used to investigate the effect of biochar on soil N transformations. Biochar amendment significantly suppressed soil GHG emissions for two years within a bioenergy soil in the field and for several months in an arable soil. I hypothesised that soil CO2 emissions were suppressed under field conditions by a combination of mechanisms: biochar induced immobilisation of soil inorganic-N (BII), increased C-use efficiency, reduced C-mineralising enzyme activity and adsorption of CO2 to the biochar surface. Soil CO2 emissions were increased for two days following wetting soil due to the remobilisation of biochar-derived labile C within the soil. Soil N2O emissions were suppressed in laboratory incubations within several months of biochar addition due to increased soil aeration, BII or increased soil pH that reduced the soil N2O: N2 ratio; effects that varied depending on soil inorganic-N concentration and moisture content. These results are significant as they consistently demonstrate that fresh hardwood biochar has the potential to reduce soil GHG emissions over a period of up to two years in bioenergy crop soil, while simultaneously sequestering C within the soil. They also contribute greatly to understanding of the mechanisms underlying the effect of biochar addition on soil N transformations and N2O emissions within bioenergy and arable soils. This study supports the hypothesis that if scaled up, biochar amendment to soil may contribute to significant reductions in global GHG emissions, contributing to climate change mitigation. Further studies are needed to ensure that these conclusions can be extrapolated over the longer term to other field sites, using other types of biochar

On the Lichnerowicz conjecture for CR manifolds with mixed signature

We construct examples of nondegenerate CR manifolds with Levi form of signature $(p,q)$, $2\leq p\leq q$, which are compact, not locally CR flat, and admit essential CR vector fields. We also construct an example of a noncompact nondegenerate CR manifold with signature $(1,n-1)$ which is not locally CR flat and admits an essential CR vector fields. These provide counterexamples to the analogue of the Lichnerowicz conjecture for CR manifolds with mixed signature.Comment: 7 page

Determining the accuracy of crowdsourced tweet verification for auroral research

The Aurorasaurus citizen science project harnesses volunteer crowdsourcing to identify sightings of an aurora (or the "northern/southern lights") posted by citizen scientists on Twitter. Previous studies have demonstrated that aurora sightings can be mined from Twitter but with the caveat that there is a high level of accompanying non-sighting tweets, especially during periods of low auroral activity. Aurorasaurus attempts to mitigate this, and thus increase the quality of its Twitter sighting data, by utilizing volunteers to sift through a pre-filtered list of geo-located tweets to verify real-time aurora sightings. In this study, the current implementation of this crowdsourced verification system, including the process of geo-locating tweets, is described and its accuracy (which, overall, is found to be 68.4%) is determined. The findings suggest that citizen science volunteers are able to accurately filter out unrelated, spam-like, Twitter data but struggle when filtering out somewhat related, yet undesired, data. The citizen scientists particularly struggle with determining the real-time nature of the sightings and care must therefore be taken when relying on crowdsourced identification

Trusting children to enhance youth justice policy: The importance and value of children’s voices

Purpose: To explore the integration of children’s voices within youth justice policy and practice development. Design/methodology/approach: The authors theorise the efficacy of participatory practices in youth justice by presenting original empirical data drawn from innovative child friendly methodological approaches, including activity-oriented focus groups, questionnaires and in-depth interviews. Findings: Children’s voices have been noticeably absent from youth justice policy development in England. Children continue to be the recipients of adult-led, deficit-facing practices underpinned by a longstanding preoccupation with identifying and managing ‘risk’. These practices have undermined children’s knowledge and potential by distrusting their perspectives. In contrast, the internationally-relevant cogent arguments set out in this paper allude to the importance and benefits of engaging with children and listening to their voices in the planning and delivery of ‘Child First’ youth justice. Practical implications: It is recommended that youth justice professionals treat children in the Youth Justice System as children (not ‘offenders’), fostering non-hierarchical, empathic, trusting relationships with children, strengthen the child’s involvement in policy and practice processes and centralise their educative, health and wellbeing needs. Originality/value: The paper explores empirical examples from the emerging (but still limited) evidence-base of youth justice research studies that have placed the child’s voice at the centre of understanding their experiences at different stages of the Youth Justice System

Interfacial Amino Acids Support Spa47 Oligomerization and Shigella Type Three Secretion System Activation

Like many Gram-negative pathogens, Shigella rely on a type three secretion system (T3SS) for injection of effector proteins directly into eukaryotic host cells to initiate and sustain infection. Protein secretion through the needle-like type three secretion apparatus (T3SA) requires ATP hydrolysis by the T3SS ATPase Spa47, making it a likely target for in vivo regulation of T3SS activity and an attractive target for small molecule therapeutics against shigellosis. Here, we developed a model of an activated Spa47 homo-hexamer, identifying two distinct regions at each protomer interface that we hypothesized to provide intermolecular interactions supportingSpa47 oligomerization and enzymatic activation. Mutational analysis and a series of high-resolution crystal structures confirm the importance of these residues, as many of the engineered mutants are unable to form oligomers and efficiently hydrolyze ATP in vitro. Furthermore, in vivo evaluation of Shigella virulence phenotype uncovered a strong correlation between T3SS effector protein secretion, host cell membrane disruption, and cellular invasion by the tested mutant strains, suggesting that perturbation of the identified interfacial residues/interactions influences Spa47 activity through preventing oligomer formation, which in turn regulates Shigella virulence. The most impactful mutations are observed within the conserved Site 2 interface where the native residues support oligomerization and likely contribute to a complex hydrogen bonding network that organizes the active site and supports catalysis. The critical reliance on these conserved residues suggests that aspects of T3SS regulation may also be conserved, providing promise for the development of a cross-species therapeutic that broadly targetsT3SS ATPase oligomerization and activation

Knowledge sharing between design and manufacture

The aim of this research is to develop a representation method that allows knowledge to be readily shared between collaborating systems (agents) in a design/manufacturing environment. Improved mechanisms for interpreting the terms used to describe knowledge across system boundaries are proposed and tested. The method is also capable of handling complex product designs and realistic manufacturing scenarios involving several parties. This is achieved using an agent-architecture to simulate the effects of individual manufacturing facilities (e.g. machine tools and foundries) on product features. It is hypothesised that knowledge sharing between such agents can be enhanced by integrating common product and manufacturing information models with a shared ontology, and that the shared ontology can be based largely on The Process Specification Language (PSL)

Knowledge sharing between design and manufacture

Object-oriented modelling has become an established technique for product and manufacturing knowledge representation. Various models offering generalised classes and class hierarchies have been proposed for this purpose. Additional bespoke classes are however typically required for specific domain representations. This causes problems when knowledge needs to be shared between domains using different models to describe common entities. These issues are especially complex when several systems are involved. For example, a designer accessing product, manufacturing, and third party systems may face multiple definitions of components, facilities and processes. This paper proposes a model that addresses some of these issues. The proposed model can describe manufacturing knowledge without additional bespoke classes. The detailed semantics of the model are based on recent work on ontologies, notably the Process Specification Language (PSL). Whilst PSL provides detailed semantics, it is not inherently object-oriented. The integration of PSL with object-oriented modelling methods is therefore the principle contribution of this work

Knowledge reuse in manufacturability analysis

This paper proposes a knowledge representation method that supports greater reuse of manufacturing knowledge in design. The method draws on recent research into object-oriented product and manufacturing models, and problem solving agents. A research platform is proposed, and the results of a test case (based on a simplified jet engine combustion chamber) are described. The paper concludes with three basic principles of reuse, i.e. product/process separation, procedural/declarative knowledge separation, and guidelines for the optimum location of rules and constraints within product/manufacturing models