1,219 research outputs found

    Resonant charging and stopping power of slow channelling atoms in a crystalline metal

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    Fast moving ions travel great distances along channels between low-index crystallographic planes, slowing through collisions with electrons, until finally they hit a host atom initiating a cascade of atomic displacements. Statistical penetration ranges of incident particles are reliably used in ion-implantation technologies, but a full, necessarily quantum-mechanical, description of the stopping of slow, heavy ions is challenging and the results of experimental investigations are not fully understood. Using a self-consistent model of the electronic structure of a metal, and explicit treatment of atomic structure, we find by direct simulation a resonant accumulation of charge on a channelling ion analogous to the Okorokov effect but originating in electronic excitation between delocalized and localized valence states on the channelling ion and its transient host neighbours, stimulated by the time-periodic potential experienced by the channelling ion. The charge resonance reduces the electronic stopping power on the channelling ion. These are surprising and interesting new chemical aspects of channelling, which cannot be predicted within the standard framework of ions travelling through homogeneous electron gases or by considering either ion or target in isolation. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft

    Shelter models for consequence and risk assessment of CO2 pipelines

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    Pipelines are acknowledged as one of the most efficient and cost-effective methods for transporting large volumes of various fluids over long distances and therefore the majority of proposed schemes for Carbon Capture and Storage (CCS) involve high pressure pipelines transporting carbon dioxide (CO2). In order to be able to design and route pipelines safely, it is a code requirement that a separation distance, or safety zone, is defined between the pipeline and any habitable dwellings along the route. Safety zones are generally defined on the basis of a Quantitative Risk Assessment (QRA). The purpose of a QRA is to assess the risks posed by a pipeline failure to people in the vicinity and to ensure that consistent levels of risk are applied along the pipeline route. The risk levels are normally calculated along a transect drawn perpendicular to the pipeline. These levels are then compared with defined acceptance criteria to determine the safety zone i.e. the distance from the pipeline within which the risk to the public from a pipeline failure is considered to be unacceptable. The calculation of the risk level requires the determination of both the probability of a failure occurring in the pipeline and the consequences of that failure to the population. For natural gas pipelines, existing and accepted QRA techniques can be implemented to define the consequences of failure based on the thermal hazards. However for CO2 pipelines, the consequences of failure need to be considered differently, as they relate to a toxic hazard rather than a thermal hazard. Therefore in order to conduct a consequence analysis, what is required is a determination of the concentration of CO2 to which an individual may be exposed during a release event. This type of data can be generated either using dispersion models. These models will produce a profile of the change in CO2 concentration with time at various distances from the release, see for example [1, 2], that can then be used in the QRA to determine the toxic dose and therefore the level of harm experienced by an individual. However, none of these approaches consider the effect of shelter on the dose experienced by an individual who is within a building at the time of the release or is outside and enters a building to seek shelter. The work described in this paper seeks to address this gap and describes the application of two models ̶ an analytical and a Computational Fluid Dynamics (CFD) model ̶ that can be used to determine the effects of shelter on the toxic dose received by an individual during a pipeline release event. The motivation behind this work was: i) to develop a validated and computationally efficient shelter model, which had been tested against experimental data and CFD models, ii) to use both CFD and analytical models to demonstrate how shelter should be considered as part of the QRA procedure for a CO2 pipeline. A description of the analytical model has been published previously [3]. Therefore, the current paper concentrates on an explanation of the development and application of the CFD model. Using a case study scenario for a single roomed building, engulfed by a transient cloud of CO2, comparisons are made between the output of the analytical models and the CFD models for the same scenario. A sensitivity analysis indicates the input parameters that most affect the resultant toxic effects within the building. The paper further demonstrates how both models can be extended to investigate the effects of partial coverage of the building with the cloud of CO2 and the impact of partitions within the building. Predictions of toxic dose are made for both models and it is demonstrated how these results can be used in a QRA analysis. This work has been funded by the UK Carbon Capture and Research Centre within the framework of the S-Cape project (Shelter and Escape in the Event of a Release of CO2 from CCS Transport Infrastructure UKCCSRC-C2-179). References [1] M. Molag, C. Dam, Modelling of accidental releases from a high pressure CO2 pipelines, in:  10th International Conference on Greenhouse Gas Control Technologies, Amsterdam, 2011, pp. 2301-2307. [2] J. Koornneef, M. Spruijt, M. Molag, A. Ramírez, W. Turkenburg, A. Faaij, Quantitative risk assessment of CO2 transport by pipelines - A review of uncertainties and their impacts, Journal of Hazardous Materials, 177 (2010) 12-27. [3] C.J.Lyons, J.M.Race, H.F.Hopkins, P Cleaver, Prediction of the consequences of a CO2 pipeline release on building occupants. in Hazards 25: Edinburgh International Conference Centre, Edinburgh; United Kingdom; 13 May 2015 through 15 May 2015. vol. 160, Institution of Chemical Engineers Symposium Series, Red Hook, Hazards 25, Edinburgh, 201

    The changing of the guard: groupwork with people who have intellectual disabilities

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    This paper considers the impact of service systems on group activities. It describes an inter-professional groupwork project facilitated by a social worker and a community nurse. The project provided an emancipatory experience for a group of adults who had intellectual disabilities. The group was charged with the task of reviewing and updating the recruitment and interview processes used by a 'Learning Disability Partnership Board', when employing new support workers. The paper begins with a brief history of intellectual disability and provides a context to the underpinning philosophical belief that people should be encouraged and supported to inhabit valued social roles no matter what disability they may have. It then identifies the ways in which the sponsoring health, education and social care services impacted on the creation and development of a groupwork project. It might have been expected that the nature of the intellectual disability would have been the major influence on group process. However the paper reveals that organisational constraints had a significant impact on group functioning. Issues including, staffing budgets and transport contracts impacted on group process and function. The results of the project show how, with adequate support, people with intellectual disability can make important decisions that have long-reaching impacts on the services

    Structural and Functional Analysis of Cell Wall-Anchored PolypeptideAdhesin BspA in <i>Streptococcus agalactiae</i>

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    Streptococcus agalactiae (group B Streptococcus, GBS) is the predominant cause of early-onset infectious disease in neonates and is responsible for life-threatening infections in elderly and immunocompromised individuals. Clinical manifestations of GBS infection include sepsis, pneumonia, and meningitis. Here, we describe BspA, a deviant antigen I/II family polypeptide that confers adhesive properties linked to pathogenesis in GBS. Heterologous expression of BspA on the surface of the non-adherent bacterium Lactococcus lactis confers adherence to scavenger receptor gp340, human vaginal epithelium, and to the fungus Candida albicans. Complementary crystallographic and biophysical characterization of BspA reveal a novel β-sandwich adhesion domain and unique asparagine-dependent super-helical stalk. Collectively, these findings establish a new bacterial adhesin structure that has in effect been hijacked by a pathogenic Streptococcus species to provide competitive advantage in human mucosal infections

    Prospects for progress on health inequalities in England in the post-primary care trust era : professional views on challenges, risks and opportunities

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    Background - Addressing health inequalities remains a prominent policy objective of the current UK government, but current NHS reforms involve a significant shift in roles and responsibilities. Clinicians are now placed at the heart of healthcare commissioning through which significant inequalities in access, uptake and impact of healthcare services must be addressed. Questions arise as to whether these new arrangements will help or hinder progress on health inequalities. This paper explores the perspectives of experienced healthcare professionals working within the commissioning arena; many of whom are likely to remain key actors in this unfolding scenario. Methods - Semi-structured interviews were conducted with 42 professionals involved with health and social care commissioning at national and local levels. These included representatives from the Department of Health, Primary Care Trusts, Strategic Health Authorities, Local Authorities, and third sector organisations. Results - In general, respondents lamented the lack of progress on health inequalities during the PCT commissioning era, where strong policy had not resulted in measurable improvements. However, there was concern that GP-led commissioning will fare little better, particularly in a time of reduced spending. Specific concerns centred on: reduced commitment to a health inequalities agenda; inadequate skills and loss of expertise; and weakened partnership working and engagement. There were more mixed opinions as to whether GP commissioners would be better able than their predecessors to challenge large provider trusts and shift spend towards prevention and early intervention, and whether GPs’ clinical experience would support commissioning action on inequalities. Though largely pessimistic, respondents highlighted some opportunities, including the potential for greater accountability of healthcare commissioners to the public and more influential needs assessments via emergent Health & Wellbeing Boards. Conclusions - There is doubt about the ability of GP commissioners to take clearer action on health inequalities than PCTs have historically achieved. Key actors expect the contribution from commissioning to address health inequalities to become even more piecemeal in the new arrangements, as it will be dependent upon the interest and agency of particular individuals within the new commissioning groups to engage and influence a wider range of stakeholders.</p

    Search for Sub-TeV Gamma Rays Coincident with BATSE Gamma Ray Bursts

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    Project GRAND is a 100m x 100m air shower array of proportional wire chambers (PWCs). There are 64 stations each with eight 1.29 m^2 PWC planes arranged in four orthogonal pairs placed vertically above one another to geometrically measure the angles of charged secondaries. A steel plate above the bottom pair of PWCs differentiates muons (which pass undeflected through the steel) from non-penetrating particles. FLUKA Monte Carlo studies show that a TeV gamma ray striking the atmosphere at normal incidence produces 0.23 muons which reach ground level where their angles and identities are measured. Thus, paradoxically, secondary muons are used as a signature for gamma ray primaries. The data are examined for possible angular and time coincidences with eight gamma ray bursts (GRBs) detected by BATSE. Seven of the GRBs were selected because of their good acceptance by GRAND and high BATSE Fluence. The eighth GRB was added due to its possible coincident detection by Milagrito. For each of the eight candidate GRBs, the number of excess counts during the BATSE T90 time interval and within plus or minus five degrees of BATSE's direction was obtained. The highest statistical significance reported in this paper (2.7 sigma) is for the event that was predicted to be the most likely to be observed (GRB 971110).Comment: To be presented at the XXVIII International Cosmic Ray Conference, Tsukuba, Japa

    Mass spectrometry imaging identifies palmitoylcarnitine as an immunological mediator during Salmonella Typhimurium infection

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    Salmonella Typhimurium causes a self-limiting gastroenteritis that may lead to systemic disease. Bacteria invade the small intestine, crossing the intestinal epithelium from where they are transported to the mesenteric lymph nodes (MLNs) within migrating immune cells. MLNs are an important site at which the innate and adaptive immune responses converge but their architecture and function is severely disrupted during S. Typhimurium infection. To further understand host-pathogen interactions at this site, we used mass spectrometry imaging (MSI) to analyse MLN tissue from a murine model of S. Typhimurium infection. A molecule, identified as palmitoylcarnitine (PalC), was of particular interest due to its high abundance at loci of S. Typhimurium infection and MLN disruption. High levels of PalC localised to sites within the MLNs where B and T cells were absent and where the perimeter of CD169+ sub capsular sinus macrophages was disrupted. MLN cells cultured ex vivo and treated with PalC had reduced CD4+CD25+ T cells and an increased number of B220+CD19+ B cells. The reduction in CD4+CD25+ T cells was likely due to apoptosis driven by increased caspase-3/7 activity. These data indicate that PalC significantly alters the host response in the MLNs, acting as a decisive factor in infection outcome

    Researching the use of force: The background to the international project

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    This article provides the background to an international project on use of force by the police that was carried out in eight countries. Force is often considered to be the defining characteristic of policing and much research has been conducted on the determinants, prevalence and control of the use of force, particularly in the United States. However, little work has looked at police officers’ own views on the use of force, in particular the way in which they justify it. Using a hypothetical encounter developed for this project, researchers in each country conducted focus groups with police officers in which they were encouraged to talk about the use of force. The results show interesting similarities and differences across countries and demonstrate the value of using this kind of research focus and methodology

    The challenge of enterprise/innovation: a case study of a modern university

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    In the prevailing economic and political climate for Higher Education a greater emphasis has been placed on diversifying the funding base. The present study was undertaken between 2012 and 2014 and addressed the implementation of an approach to the transformation of one academic school in a medium-sized modern university in Wales to a more engaged enterprise culture. A multimethod investigation included a bi-lingual (English and Welsh) online survey of academic staff and yielded a 71% response rate (n = 45). The findings informed a series of in-depth interviews (n = 24) with a representative sample of those involved in enterprise work (support staff, managers, senior managers), and those who were not. The results provided the platform for the ‘S4E model’ for effective engagement with enterprise: (1) Strategic significance for Enterprise, (2) Support for Enterprise, (3) Synergy for Enterprise, and (4) Success for Enterprise. The outcomes of the research and the recommendations from it have potential to inform practice in other academic schools within the university and, in a wider context, within other Schools of Education regionally, nationally and internationally. Its original empirical exploration of enterprise within education studies is a significant contribution to that body of knowledge

    Meta-analysis of genome-wide association studies of asthma in ethnically diverse North American populations.

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    Asthma is a common disease with a complex risk architecture including both genetic and environmental factors. We performed a meta-analysis of North American genome-wide association studies of asthma in 5,416 individuals with asthma (cases) including individuals of European American, African American or African Caribbean, and Latino ancestry, with replication in an additional 12,649 individuals from the same ethnic groups. We identified five susceptibility loci. Four were at previously reported loci on 17q21, near IL1RL1, TSLP and IL33, but we report for the first time, to our knowledge, that these loci are associated with asthma risk in three ethnic groups. In addition, we identified a new asthma susceptibility locus at PYHIN1, with the association being specific to individuals of African descent (P = 3.9 × 10(-9)). These results suggest that some asthma susceptibility loci are robust to differences in ancestry when sufficiently large samples sizes are investigated, and that ancestry-specific associations also contribute to the complex genetic architecture of asthma
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