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

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

Vedolizumab for Treating Moderately to Severely Active Crohn’s Disease After Prior Therapy: An Evidence Review Group Perspective of a NICE Single Technology Appraisal

As part of its single technology appraisal process, the National Institute for Health and Care Excellence (NICE) invited the manufacturer of vedolizumab (Takeda UK) to submit evidence of the clinical effectiveness and cost effectiveness of vedolizumab for the treatment of patients with moderate-to-severe, active Crohn’s disease. The School of Health and Related Research (ScHARR) at the University of Sheffield was commissioned as the Evidence Review Group (ERG) and produced a critical review of the evidence of the clinical effectiveness and cost effectiveness of the technology, based upon the company’s submission to NICE. The GEMINI II and III trials formed the main supporting evidence for the intervention. Both studies were phase III, randomised, double-blind, placebo-controlled, multicentre trials designed to evaluate the efficacy and safety of vedolizumab. They included patients who were naïve to tumour necrosis factor alpha antagonist (anti-TNF-α) therapy and patients who had an inadequate response to, loss of response to or intolerance of immunomodulators or anti-TNF-α agents. GEMINI II was designed to evaluate the efficacy and safety of vedolizumab as an induction treatment (dosing at weeks 0 and 2, with assessment at week 6) and maintenance treatment (during weeks 6–52). In contrast, GEMINI III was designed to evaluate the efficacy and safety of vedolizumab as an induction treatment only, with doses at weeks 0, 2 and 6, and assessment at weeks 6 and 10. In the absence of any direct head-to-head, randomised, controlled trials comparing vedolizumab with other relevant biologic therapies (adalimumab and infliximab) for the treatment of moderate-to-severe Crohn’s disease, the company conducted a network meta-analysis, which compared vedolizumab, adalimumab, infliximab and placebo for the outcomes of clinical response, enhanced clinical response, clinical remission and discontinuation due to adverse events. The company model estimated the incremental cost-effectiveness ratio (ICER) for vedolizumab compared with the standard of care (consisting of 5-aminosalicylic acids, corticosteroids and immunosuppressants) to be £21,620 per quality-adjusted life-year (QALY) gained within the anti-TNF-α-failure population (which included a confidential patient access scheme for vedolizumab). The ICERs were above £30,000 per QALY gained for the mixed intention-to-treat population (including both anti-TNF-α-naïve and anti-TNF-α-failure populations) and in patients who were anti-TNF-α naïve only. The ERG identified a number of limitations that were believed to limit the robustness of the results presented by the company. These limitations could not be addressed by the ERG without major restructuring of the economic model. Therefore, the ERG concluded that the results from the company’s model needed to be interpreted with caution and that it was unclear whether the ICERs would increase or decrease following amendment of the identified structural issues

Profiling strugglers in a graduate-entry medicine course at Nottingham: a retrospective case study

Background 10-15% of students struggle at some point in their medicine course. Risk factors include weaker academic qualifications, male gender, mental illness, UK ethnic minority status, and poor study skills. Recent research on an undergraduate medicine course provided a toolkit to aid early identification of students likely to struggle, who can be targeted by established support and study interventions. The present study sought to extend this work by investigating the number and characteristics of strugglers on a graduate-entry medicine (GEM) programme. Methods A retrospective study of four GEM entry cohorts (2003–6) was carried out. All students who had demonstrated unsatisfactory progress or left prematurely were included. Any information about academic, administrative, personal, or social difficulties, were extracted from their course progress files into a customised database and examined. Results 362 students were admitted to the course, and 53 (14.6%) were identified for the study, of whom 15 (4.1%) did not complete the course. Students in the study group differed from the others in having a higher proportion of 2ii first degrees, and scoring less well on GAMSAT, an aptitude test used for admission. Within the study group, it proved possible to categorise students into the same groups previously reported (struggler throughout, pre-clinical struggler, clinical struggler, health-related struggler, borderline struggler) and to identify the majority using a number of flags for early difficulties. These flags included: missed attendance, unsatisfactory attitude or behaviour, health problems, social/family problems, failure to complete immunity status checks, and attendance at academic progress committee. Conclusions Problems encountered in a graduate-entry medicine course were comparable to those reported in a corresponding undergraduate programme. A toolkit of academic and non-academic flags of difficulty can be used for early identification of many who will struggle, and could be used to target appropriate support and interventions

The risk of oesophago-gastric cancer in symptomatic patients in primary care: A large case-control study using electronic records

BACKGROUND: Over 15 000 new oesophago-gastric cancers are diagnosed annually in the United Kingdom, with most being advanced disease. We identified and quantified features of this cancer in primary care. METHODS: Case-control study using electronic primary-care records of the UK patients aged ≥40 years was performed. Cases with primary oesophago-gastric cancer were matched to controls on age, sex and practice. Putative features of cancer were identified in the year before diagnosis. Odds ratios (ORs) were calculated for these features using conditional logistic regression, and positive predictive values (PPVs) were calculated. RESULTS: A total of 7471 cases and 32 877 controls were studied. Sixteen features were independently associated with oesophago-gastric cancer (all P5% in patients ≥55 years was for dysphagia. In patients <55 years, all PPVs were <1%. CONCLUSION: Symptoms of oesophago-gastric cancer reported in secondary care were also important in primary care. The results should inform guidance and commissioning policy for upper GI endoscopy

Effects of Interleukin-10 Polymorphisms, Helicobacter pylori Infection, and Smoking on the Risk of Noncardia Gastric Cancer

OBJECTIVE: Both variations in the interleukin-10 (IL10) gene and environmental factors are thought to influence inflammation and gastric carcinogenesis. Therefore, we investigated the associations between IL10 polymorphisms, Helicobacter pylori (H. pylori) infection, and smoking in noncardia gastric carcinogenesis in Koreans. METHODS: We genotyped three promoter polymorphisms (-1082A>G, -819T>C, and -592 A>C) of IL10 in a case-control study of 495 noncardia gastric cancer patients and 495 sex- and age-matched healthy controls. Multiple logistic regression models were used to detect the effects of IL10 polymorphisms, H. pylori infection, and smoking on the risk of gastric cancer, which was stratified by the histological type of gastric cancer. RESULTS: The IL10-819C and -592C alleles were found to have complete linkage disequilibrium, and all three IL10 polymorphisms were associated with an increased risk of intestinal-type noncardia gastric cancer. These associations were observed only in H. pylori-positive subjects and current smokers. A statistically significant interaction between the IL10-592 genotype and H. pylori infection on the risk of intestinal-type gastric cancer was observed (P for interaction  = 0.047). In addition, H. pylori-positive smokers who were carriers of either the IL10-1082G (OR [95% CI]  = 17.76 [6.17-51.06]) or the -592C (OR [95% CI]  = 8.37 [2.79-25.16]) allele had an increased risk of intestinal-type gastric cancer compared to H. pylori-negative nonsmokers homozygous for IL10-1082A and -592A, respectively. The interaction between the IL10-1082 polymorphism and the combined effects of H. pylori infection and smoking tended towards significance (P for interaction  = 0.080). CONCLUSIONS: Inflammation-related genetic variants may interact with H. pylori infection and smoking to increase the risk of noncardia gastric cancer, particularly the intestinal-type. These findings may be helpful in identifying individuals at an increased risk for developing noncardia gastric cancer