1,738 research outputs found

    Examining Children\u27s Perceptions and Use of Their Neighbourhood Built Environments: A Novel Participatory Mapping Approach

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    This thesis uses a mixed methods approach to contribute towards a more complete understanding of the relationship between the built environment and children’s active school travel. It is argued that active travel –human powered transportation – to and from school provides regular physical activity that can help reverse rising rates of overweight or obese Canadian children. The built environment of a child’s school neighbourhood has been shown to influence travel decisions. To achieve higher rates of children’s active travel, a comprehensive understanding of the built environment is required. This study uses child-led perceptual mapping (CLPM) and GIS analysis in a case study with children from three elementary schools in London, Ontario to determine how perception and use of their school neighbourhood varies according to the built environment. The typology for the perceptual mapping activities was inspired by that of urban theorist Kevin Lynch, with children identifying destinations, zones, and routes. A high degree of participation is attained according to Roger Hart’s Ladder of Participation. It is observed that children perceive of their neighbourhood in unique and complex ways. Children did not perceive land uses by the designated function, nor did they define land uses in singular ways. Prominent features were also not confined to the proximity around their school. Layering the child directed methods as an effective tool in understanding issues facing children’s active travel. It is concluded that active travel must be a priority cemented in policy, and that stakeholders should engage in participatory research across disciplines if rates of active travel are to increase. CLPM is a novel approach that should be used by researchers who aim to understand children’s perception and use of the built environment. Children deserve a major stakeholder role in the school travel planning process, and further research on the impact of the built environment on children’s active travel is needed

    Metabolomics--a novel window into inflammatory disease

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    Inflammation is an important component of normal responses to infection and injury. However, chronic activation of the immune system, perhaps due to aberrant responses to normal stimuli, can lead to the establishment of a chronic inflammatory state. Such inflammatory conditions are often debilitating, and are associated with a number of important co-morbidities including cardiovascular disease. Resting non-proliferative tissues have distinctive metabolic activities and requirements, which differ considerably from those in infiltrating immune cells, which are undergoing proliferation and differentiation. Immune responses in tissues may therefore be modulated by the relative abundance of substrates in the inflamed site. In turn immune cell activity can feed back and affect metabolic behaviour of the tissues, as most clearly demonstrated in cachexia - the loss of cellular mass driven by tumour necrosis factor-alpha (TNF-α) a key mediator of the inflammatory response. Here we discuss the potential for metabolomic analysis to clarify the interactions between inflammation and metabolic changes underlying many diseases. We suggest that an increased understanding of the interaction between inflammation and cellular metabolism, energy substrate use, tissue breakdown markers, the microbiome and drug metabolites, may provide novel insight into the regulation of inflammatory diseases

    How does your state select its judges?

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    A full factorial numerical investigation and validation of precision end milling process for hardened tool steel

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    Tool steel materials have poor machinability, as the high hardness of the material will cause high cutting forces, premature failure of the cutting tools, and is also associated with machining induced tensile stresses within the work piece. Due to high experimental costs, there is no recent research on end milling tool steel, using full factorial experimental or numerical design. A 3D FE-model of a precision end milling process with a two flute ball nose cutter were established in this paper. The FE-Model used a subroutine to model hardening realised through the Johnson-Cook model, additionally were a material removal criteria developed and implemented. Through full factorial numerical simulations the influence of cutting parameters on cutting force of H13 tool steel was studied. Depth of cut was found to be the most influential machining parameter on cutting forces followed by feed rate and surface speed. Four milling experiments were carried out to validate the simulation results. It was found that the simulation and the experiments had a good agreement on the cutting forces. The validated FEA model can be used for further studies on residual stress or temperatures and to optimise the cutting process

    An investigation of novel extraction procedures used in the preconcentration of polycyclic aromatic hydrocarbons from environmental samples

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    The accurate determination of PAHs at trace levels in environmental matrices is a complex problem and as a result, methods for the preconcentration and determination of PAHs are continuously under investigation. Techniques are required which are sufficiently sensitive and selective to enable the quantitation of PAHs at lower levels than ever before. The importance of trace determination of PAHs in environmental samples is reviewed in chapter 1. Various sample matrices, extractive techniques and analytical methods were examined for the enrichment and determination of PAHs in the environment. The importance of accurate and complete extraction from various matrices is discussed. Particular mention was made to the universal problem of losses of low MW PAHs with the various techniques reviewed. The extraction of five low MW PAHs compounds from aqueous samples is reported on in chapter 2 and chapter 3. Two standard techniques liquid/liquid extraction and solid phase extraction operated in offline mode were reviewed and applied to the first five PAHs recommended as priority pollutants by the USEPA. A more novel extractive procedure was examined in chapter 3 for the same group of compounds. This was online solid phase extraction. In this case the compounds were extracted from the aqueous solution and transferred online to the analytical system by the actuation of a switching valve. This system was then compared and contrasted with extractive systems previously described. The concept of Multi Solid Phase Dispersion was reviewed in Chapter 4. It is a unique system which takes advantage of the physiochemical properties of Cig packing material. These properties allow the material interact with biological matrices in such away as to extract organic material preferentially. This extractive procedure was then applied to the extraction of PAHs from bovine milk samples. The application of ATR/FTIR to the enrichment and detection of compounds is reviewed in chapter 5. A system was developed which allowed the detection of fluoranthene from aqueous samples. The ability of the system to determine PAHs was assessed in chapter 6 . Determination was achieved through the application of various mathematical algorithms and the effectiveness of the algorithms was compared. The system was then used to quantify a number of PAHs simultaneously

    Guest Editorial : Can additive manufacturing breathe new life into aging assets?

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    Additive layer manufacturing technology has gained prominence in the aerospace sector and is being used for the rapid production of prototype parts. Its credibility has quite literally “taken off” and is now used to build in-flight production components for aircraft. Its applications are being adopted in other sectors such as medical and automotive as a potentially faster and more economical alternative to traditional manufacturing methods for certain applications. Though it offers huge potential to the oil and gas arena, its uptake so far has been limited. The industry’s risk-averse culture, lack of infrastructure, and stringent standards have been cited by leaders as barriers to adoption

    Numerical investigation of mechanical induced stress during precision end milling hardened tool steel

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    Hardened tool steels are widely used materials for forming dies, due to their increased strength and hardness. However, their machinability is very poor, due to the high hardness of the material, which leads to high cutting forces and premature failure of the cutting tools. This is also associated with machining induced tensile stresses within the work piece. No full factorial design has been performed when end milling tool steel, due to the high associated costs. Instead of physical experiments, numerical models are commonly used to save cost and time. However, most of the recent research focus was only on 2D FE-Models. 2D model can be used for simulation of some simplified process, however, the results are not sufficient for accurate prediction. Therefore, a 3D FE-model of a precision end milling process with a two-flute ball nose cutter were established in this paper, in order to build a multi cutting edge model. In the FE-Model, a subroutine was implemented to model work piece hardening during the cutting process. The subroutine realised an accurate prediction of the residual stress and cutting forces. In addition, a material removal criterion was developed and implemented. The influence of cutting parameters on cutting force for end milling H13 tool steel was studied, through full factorial numerical simulations, to evaluate the effectiveness of this FEA model. Subsequently, after validation of the FEM model through machining trials, empirical models were developed for predicting cutting forces and residual stress. The cutting parameters evaluated were cutting speed, feed rate and depth of cut. In summary, it was found that the simulation and the experiments had a good agreement on the value and trend of the residual stress. The FEM model can be effectively used to predict residual stress in the machined surface

    Wear behaviour of laser cladded Ni-based WC composite coating for Inconel hot extrusion : practical challenges and effectiveness

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    In forging, tooling costs make up a significant percentage of the total manufacturing cost. To combat tool failure, forging dies can be manufactured using or including layers of high wear-resistant alloys. The present work compares the manufacturing process challenges and wear response of traditional Nitriding to laser cladding using Ni-based WC on an H13 substrate for IN718 extrusion. The results have shown that machining of NiCrSiB + WC matrix material is problematic, both with regards to cutting tool wear and achievable surface finish. Assessment of pre- and post-extrusion Nitrided H13 and NiCrSiB + 30%WC laser clad dies shows more significant wear features in the case of the additively coated die. Crack formation and surface discontinuities attributed to the effects of material porosity and die heating are also discussed

    Prehospital critical care is associated with increased survival in adult trauma patients in Scotland

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    Background Scotland has three prehospital critical care teams (PHCCTs) providing enhanced care support to a usually paramedic-delivered ambulance service. The effect of the PHCCTs on patient survival following trauma in Scotland is not currently known nationally. Methods National registry-based retrospective cohort study using 2011-2016 data from the Scottish Trauma Audit Group. 30-day mortality was compared between groups after multivariate analysis to account for confounding variables. Results Our data set comprised 17 157 patients, with a mean age of 54.7 years and 8206 (57.5%) of male gender. 2877 patients in the registry were excluded due to incomplete data on their level of prehospital care, leaving an eligible group of 14 280. 13 504 injured adults who received care from ambulance clinicians (paramedics or technicians) were compared with 776 whose care included input from a PHCCT. The median Injury Severity Score (ISS) across all eligible patients was 9; 3076 patients (21.5%) met the ISS>15 criterion for major trauma. Patients in the PHCCT cohort were statistically significantly (all p < 0.01) more likely to be male; be transported to a prospective Major Trauma Centre; have suffered major trauma; have suffered a severe head injury; be transported by air and be intubated prior to arrival in hospital. Following multivariate analysis, the OR for 30-day mortality for patients seen by a PHCCT was 0.56 (95% CI 0.36 to 0.86, p=0.01). Conclusion Prehospital care provided by a physician-led critical care team was associated with an increased chance of survival at 30 days when compared with care provided by ambulance clinicians

    Testing the psychometric properties of Kidscreen-27 with Irish children of low socio-economic status

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    BACKGROUND: Kidscreen-27 was developed as part of a cross-cultural European Union-funded project to standardise the measurement of children’s health-related quality of life. Yet, research has reported mixed evidence for the hypothesised 5-factor model, and no confirmatory factor analysis (CFA) has been conducted on the instrument with children of low socio-economic status (SES) across Ireland (Northern and Republic). METHOD: The data for this study were collected as part of a clustered randomised controlled trial. A total of 663 (347 male, 315 female) 8–9-year-old children (M = 8.74, SD = .50) of low SES took part. A 5- and modified 7-factor CFA models were specified using the maximum likelihood estimation. A nested Chi-square difference test was conducted to compare the fit of the models. Internal consistency and floor and ceiling effects were also examined. RESULTS: CFA found that the hypothesised 5-factor model was an unacceptable fit. However, the modified 7-factor model was supported. A nested Chi-square difference test confirmed that the fit of the 7-factor model was significantly better than that of the 5-factor model. Internal consistency was unacceptable for just one scale. Ceiling effects were present in all but one of the factors. CONCLUSIONS: Future research should apply the 7-factor model with children of low socio-economic status. Such efforts would help monitor the health status of the population
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