Volcanic Ash Contamination of High Voltage Insulators

Awarded Best Paper (Student) - Joint Winner - EEA Conference 2011Recent work in the University of Canterbury high voltage laboratory uncovered an interesting phenomenon. While studying the effect of volcanic ash contamination on high voltage insulator flashover levels, ash was seen ‘blowing’ off the insulator surface before flashover occurred. The goal of this project was to investigate and explain the observed phenomenon to provide a basis for potential development of self-cleaning insulators. Four different types of insulator and three different ash grain sizes were tested. The insulator electric fields were modelled; corona discharge waveforms and visual observations were obtained. Areas of ash removal coincided with areas of corona discharge. It was initially proposed that the ash was removed by an alternating current corona wind however the results do not support this theory. Instead, the observed results suggest that the ash acquires a negative charge and is removed by an electrostatic force. The electrostatic force is strongest during the negative half cycle of the applied voltage due to space charge and hence the ash pulses off the insulator at 50Hz. The amount of ash removed increased with the applied voltage however this led to a trade off between ash removal and flashover. The maximum amount of ash removed during this project was approximately 90% from the top weather shed and 30% from the middle and bottom weather sheds. This study focused on the removal of dry ash. It is unlikely that wet ash can be removed in this fashion, without flashover, due to the conductive and adhesive nature of wet ash

An Economic Comparison between Grid Based and Isolated Rural Electrification in Nepal

This paper presents a methodology for financial analysis that compares costs and benefits of rural electrification by grid expansion with isolated micro hydro schemes. Financial analysis of three existing isolated micro hydro schemes in different parts of Nepal are compared against the alternative option of grid expansion. Case study results are tabulated and discussed

Surface modification of HVOF thermal sprayed WC–CoCr coatings by laser treatment

In this work the affects of laser characteristics on microstructure and microhardness of high velocity oxygen fuel sprayed (HVOF) WC–CoCr coatings were investigated. The coating was deposited with a Sulzer Metco WokaJet™-400 kerosene fuel and the laser surface treatments were applied using CO2 laser with 10.6 μm wavelength. Large variations in surface properties were produced from variation in the laser processing parameters. In total, four levels of peak power (100, 200, 300 and 350 W), four levels of spot diameter (0.2, 0.4, 0.6 and 1 mm) and three levels of pulse repetition frequency (PRF) were investigated. An initial set of tests were followed by a more detailed 33 factorial design of experiments. Pulse repetition frequency and duty cycle were set in order to maintain the same overlap in the x and y directions for the raster scanned sample spot impact dimensions. Overlaps of 30% were used in the initial tests and 10% in the more detailed trials. The results have shown that care must be taken to keep the irradiance at a relatively low level compared to uncoated surfaces. High irradiance can in this case result in rough and porous surfaces. Lower levels of irradiance are shown to provide more uniform microstructures, reduced porosity and increased microhardness

Graduate Entry Medicine: Selection Criteria and Student Performance

Background: Graduate entry medicine raises new questions about the suitability of students with different backgrounds. We examine this, and the broader issue of effectiveness of selection and assessment procedures. Methods: The data included background characteristics, academic record, interview score and performance in pre-clinical modular assessment for two years intake of graduate entry medical students. Exploratory factor analysis is a powerful method for reducing a large number of measures to a smaller group of underlying factors. It was used here to identify patterns within and between the selection and performance data. Principal Findings: Basic background characteristics were of little importance in predicting exam success. However, easily interpreted components were detected within variables comprising the ‘selection ’ and ‘assessment ’ criteria. Three selection components were identified (‘Academic’, ‘GAMSAT’, ‘Interview’) and four assessment components (‘General Exam’, ‘Oncology’, ‘OSCE’, ‘Family Case Study’). There was a striking lack of relationships between most selection and performance factors. Only ‘General Exam ’ and ‘Academic ’ showed a correlation (Pearson’s r = 0.55, p,0.001). Conclusions: This study raises questions about methods of student selection and their effectiveness in predicting performance and assessing suitability for a medical career. Admissions tests and most exams only confirmed previous academic achievement, while interview scores were not correlated with any consequent assessment

Symbiont-mediated RNA interference in insects

RNA interference (RNAi) methods for insects are often limited by problems with double-stranded (ds) RNA delivery, which restricts reverse genetics studies and the development of RNAi-based biocides. We therefore delegated to insect symbiotic bacteria the task of: (i) constitutive dsRNA synthesis and (ii) trauma-free delivery. RNaseIII-deficient, dsRNA-expressing bacterial strains were created from the symbionts of two very diverse pest species: a long-lived blood-sucking bug, Rhodnius prolixus, and a short-lived globally invasive polyphagous agricultural pest, western flower thrips (Frankliniella occidentalis). When ingested, the manipulated bacteria colonized the insects, successfully competed with the wild-type microflora, and sustainably mediated systemic knockdown phenotypes that were horizontally transmissible. This represents a significant advance in the ability to deliver RNAi, potentially to a large range of non-model insects

Comparative Dosimetric Analysis and Normal Tissue Complication Probability Modelling of Four-Dimensional Computed Tomography Planning Scans Within the UK NeoSCOPE Trial

Aims: NeoSCOPE is a trial of two different neoadjuvant chemoradiotherapy regimens for resectable oesophageal cancer and was the first multicentre trial in the UK to incorporate four-dimensional computed tomography (4D-CT) into radiotherapy planning. Despite 4D-CT being increasingly accepted as a standard of care for lower third and junctional oesophageal tumours, there is limited evidence of its benefit over standard three-dimensional computed tomography (3D-CT). // Materials: Using NeoSCOPE 4D-CT cases, we undertook a dosimetric comparison study of 3D-CT versus 4D-CT plans comparing target volume coverage and dose to organs at risk. We used established normal tissue complication probability models to evaluate the potential toxicity reduction of using 4D-CT plans in oesophageal cancer. // Results: 4D-CT resulted in a smaller median absolute PTV volume and lower dose levels for all reported constraints with comparable target volume coverage. NTCP modelling suggests a significant relative risk reduction of cardiac and pulmonary toxicity endpoints with 4D-CT. // Conclusion: Our work shows that incorporating 4D-CT into treatment planning may significantly reduce the toxicity burden from this treatment

Ovine leukocyte microparticles generated by the CentriMag ventricular assist device in vitro

Ventricular assist devices (VADs) are a life-saving form of mechanical circulatory support in heart failure patients. However, VADs have not yet reached their full potential due to the associated side effects (thrombosis, bleeding, infection) related to the activation and damage of blood cells and proteins caused by mechanical stress and foreign materials. Studies of the effects of VADs on leukocytes are limited, yet leukocyte activation and damage including microparticle generation can influence both thrombosis and infection rates. Therefore, the aim was to develop a multicolour flow cytometry assessment of leukocyte microparticles (LMPs) using ovine blood and the CentriMag VAD as a model for shear stress. Ovine blood was pumped for 6 hours in the CentriMag and regular samples analysed for haemolysis, complete blood counts and leukocyte microparticles by flow cytometry during three different pump operating conditions (low flow, standard, high speed). The high speed condition caused significant increases in plasma-free haemoglobin; decreases in total leukocytes, granulocytes, monocytes and platelets; increases in CD45+ LMPs as well as two novel LMP populations: CD11bbright/HLA-DR- and CD11bdull/HLA-DR+, both of which were CD14-/CD21-. CD11bbright/HLA-DR- LMPs appeared to respond to an increase in shear magnitude whereas the CD11bdull/HLA-DR+ LMPs significantly increased in all pumping conditions. We propose that these two populations are released from granulocytes and T cells, respectively, but further research is needed to better characterise these two populations

Utilisation of the STEAP protein family in a diagnostic setting may provide a more comprehensive prognosis of prostate cancer

Prostate cancer is the second most common cancer diagnosed in men worldwide; however, few patients are affected by clinically significant disease within their lifetime. Unfortunately, the means to discriminate between patients with indolent disease and those who progress to aggressive prostate cancer is currently unavailable, resulting in over-treatment of patients. We therefore aimed to determine biomarkers of prostate cancer that can be used in the clinic to aid the diagnosis and prognosis. Immunohistochemistry analysis was carried out on prostate cancer specimens with a range of Gleason scores. Samples were stained and analysed for intensity of the Seven Transmembrane Epithelial Antigen of the Prostate (STEAP)-1, -2, -3, -4 and the Divalent Metal Transporter 1 (DMT1) proteins to determine suitable biomarkers for classification of patients likely to develop aggressive prostate cancer. Additionally, these proteins were also analysed to determine whether any would be able to predict future relapse using Kaplan Meier analysis. Data generated demonstrated that the protein expression levels of STEAP2 correlated significantly with Gleason score; furthermore, STEAP4 was a significant predictor of relapse. This data indicates that STEAP2 could be potential prognostic candidate for use in combination with the current prostate cancer detection methods and the presence of STEAP4 could be an indicator of possible relapse

Establishing Key Performance Indicators for Inflammatory Bowel Disease in the United Kingdom

Background and aimsHealthcare quality improvement (QI) is the systematic process to continuously improve the quality of care and outcomes for patients. The landmark Inflammatory Bowel Disease (IBD) UK National Audits provided a means to measure the variation in care, highlighting the need to define the standards of excellence in IBD care. Through a consensus approach, we aimed to establish key performance indicators (KPIs), providing reliable benchmarks for IBD care delivery in UK.MethodsKPIs that measure critical aspects of a patient journey within an IBD service were identified though stakeholder meetings. A two-stage Delphi consensus was then conducted. The first involved a multidisciplinary team of IBD clinicians and patients to refine definitions and methodology. The second stage assessed feasibility and utility of the proposed QI process by surveying gastroenterology services across UK.ResultsFirst, the four proposed KPIs were refined and included time from primary care referral to diagnosis in secondary care, time to treatment recommendation following a diagnosis, appropriate use of steroids and advanced therapies prescreening and assessment. Second, the Delphi consensus reported >85% agreement on the feasibility of local adoption of the QI process and >75% agreement on the utility of benchmarking of the KPIs.ConclusionsThrough a structured approach, we propose quantifiable KPIs for benchmarking to improve and reduce the individual variation in IBD care across the UK