149 research outputs found

    Macroscopic Traļ¬ƒc Model Validation of Large Networks and the Introduction of a Gradient Based Solver

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    Traļ¬ƒc models are important for the evaluation of various Intelligent Transport Systems and the development of new traļ¬ƒc infrastructure. In order for this to be done accurately and with conļ¬dence the correct parameter values of the model must be identiļ¬ed. The focus of this thesis is the identiļ¬cation and conļ¬rmation of these parameters, which is model validation. Validation is performed on two diļ¬€erent models; the ļ¬rst-order CTM and the second-order METANET model. The CTM is validated for two UK sites of 7.8 and 21.9 km and METANET for the same two sites using a variety of meta-heuristic algorithms. This is done using a newly developed method to allow for the optimisation method to determine the number of parameters to be used and the spatial extent of their application. This allows for the removal of expert engineering knowledge and ad-hoc decomposition of networks. This thesis also develops a methodology by use of Automatic Diļ¬€erentiation to allow gradient based optimisation to be used. This approach successfully validated the METANET model for the 21.9 km site and also a large network surrounding the city of Manchester of 186.9 km. This proves that gradient based optimisation can be used for the macroscopic traļ¬ƒc model validation problem. In fact the performance of the developed gradient method is superior to the meta-heuristics tested for the same sites. The methodology deļ¬ned also allows for more data to be obtained from the model such as its Jacobian and the sensitivity of the objective function being used relative to the individual parameters. Space-Time contour plots of this newly acquired data show structures and shock waves that are not visible in the mean speed contour diagrams

    Judicial Review, Irrationality, and the Legitimacy of Merits-Review

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    The definition of the irrationality ground of judicial review recognises the constitutional principle of the separation of powers, in allowing for judicial control of the executive only very rarely. The author in a previous article in this study found that the courts, on occasions, had intervened in circumstances where administrative decisions arguably were not irrational. To this end, the purpose of this article is to assess the constitutionality of these seemingly low standards of irrationality. The author does so by reference either to the manner of review employedā€”the use of the proportionality principle, for exampleā€”or the context of the administrative decision under scrutiny, such as the infringement of the applicantā€™s fundamental rights. The author finds that the cases from the previous article where low standards of irrationality were arguably adopted were, in fact, legitimate according to these chosen methods of evaluation. However, this is an interim conclusion because, for reasons of word length, the author is unable to complete a full assessment here. It is therefore proposed that a subsequent article will continue to examine the constitutionality of these cases. Furthermore, the author will also try and establish a zone of executive decision-making, for reasons of democracy, where the courts are excluded from irrationality review. If the author is unsuccessful in this regard, the final conclusion of this study will inevitably be that low standards of judicial intervention exist without limitā€”a clear assault on the constitutional principle stated above

    Pilot trial and process evaluation of a multilevel smoking prevention intervention in further education settings

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    Background: Preventing smoking uptake among young people is a public health priority. Further education (FE) settings provide access to the majority of 16- to 18-year-olds, but few evaluations of smoking prevention interventions have been reported in this context to date. Objectives: To evaluate the feasibility and acceptability of implementing and trialling a new multilevel smoking prevention intervention in FE settings. Design: Pilot cluster randomised controlled trial and process evaluation. Setting: Six UK FE institutions. Participants: FE students aged 16ā€“18 years. Intervention: ā€˜The Filter FEā€™ intervention. Staff working on Action on Smoking and Health Walesā€™ ā€˜The Filterā€™ youth project applied existing staff training, social media and youth work resources in three intervention settings, compared with three control sites with usual practice. The intervention aimed to prevent smoking uptake by restricting the sale of tobacco to under-18s in local shops, implementing tobacco-free campus policies, training FE staff to deliver smoke-free messages, publicising The Filter youth projectā€™s online advice and support services, and providing educational youth work activities. Main outcome measures: (1) The primary outcome assessed was the feasibility and acceptability of delivering and trialling the intervention. (2) Qualitative process data were analysed to explore student, staff and intervention team experiences of implementing and trialling the intervention. (3) Primary, secondary and intermediate (process) outcomes and economic evaluation methods were piloted. Data sources: New students at participating FE settings were surveyed in September 2014 and followed up in September 2015. Qualitative process data were collected via interviews with FE college managers (nā€‰=ā€‰5) and the intervention team (nā€‰=ā€‰6); focus groups with students (nā€‰=ā€‰11) and staff (nā€‰=ā€‰5); and observations of intervention settings. Other data sources were semistructured observations of intervention delivery, intervention team records, ā€˜mystery shopperā€™ audits of local shops and college policy documents. Results: The intervention was not delivered as planned at any of the three intervention settings, with no implementation of some community- and college-level components, and low fidelity of the social media component across sites. Staff training reached 28 staff and youth work activities were attended by 190 students across the three sites (<ā€‰10% of all eligible staff and students), with low levels of acceptability reported. Implementation was limited by various factors, such as uncertainty about the value of smoking prevention activities in FE colleges, intervention management weaknesses and high turnover of intervention staff. It was feasible to recruit, randomise and retain FE settings. Prevalence of weekly smoking at baseline was 20.6% and was 17.2% at follow-up, with low levels of missing data for all pilot outcomes. Limitations: Only 17% of eligible students participated in baseline and follow-up surveys; the representativeness of student and staff focus groups is uncertain. Conclusions: In this study, FE settings were not a supportive environment for smoking prevention activities because of their non-interventionist institutional cultures promoting personal responsibility. Weaknesses in intervention management and staff turnover also limited implementation. Managers accept randomisation but methodological work is required to improve student recruitment and retention rates if trials are to be conducted in FE settings. Trial registration: Current Controlled Trials ISRCTN19563136. Funding: This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 5, No. 8. See the NIHR Journals Library website for further project information. It was also funded by the Big Lottery Fund

    The UK clinical aptitude test and clinical course performance at Nottingham: a prospective cohort study

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    Background The UK Clinical Aptitude Test (UKCAT) was introduced in 2006 as an additional tool for the selection of medical students. It tests mental ability in four distinct domains (Verbal Reasoning, Quantitative Reasoning, Abstract Reasoning, and Decision Analysis), and the results are available to students and admission panels in advance of the selection process. Our first study showed little evidence of any predictive validity for performance in the first two years of the Nottingham undergraduate course. The study objective was to determine whether the UKCAT scores had any predictive value for the later parts of the course, largely delivered via clinical placements. Methods Students entering the course in 2007 and who had taken the UKCAT were asked for permission to use their anonymised data in research. The UKCAT scores were incorporated into a database with routine pre-admission socio-demographics and subsequent course performance data. Correlation analysis was followed by hierarchical multivariate linear regression. Results The original study group comprised 204/254 (80%) of the full entry cohort. With attrition over the five years of the course this fell to 185 (73%) by Year 5. The Verbal Reasoning score and the UKCAT Total score both demonstrated some univariate correlations with clinical knowledge marks, and slightly less with clinical skills. No parts of the UKCAT proved to be an independent predictor of clinical course marks, whereas prior attainment was a highly significant predictor (p <0.001). Conclusions This study of one cohort of Nottingham medical students showed that UKCAT scores at admission did not independently predict subsequent performance on the course. Whilst the test adds another dimension to the selection process, its fairness and validity in selecting promising students remains unproven, and requires wider investigation and debate by other schools

    A 2 Ɨ 2 factorial, randomised, open-label trial to determine the clinical and cost-effectiveness of hypertonic saline (HTS 6%) and carbocisteine for airway clearance versus usual care over 52ā€‰weeks in adults with bronchiectasis:a protocol for the CLEAR clinical trial

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    Background: Current guidelines for the management of bronchiectasis (BE) highlight the lack of evidence to recommend mucoactive agents, such as hypertonic saline (HTS) and carbocisteine, to aid sputum removal as part of standard care. We hypothesise that mucoactive agents (HTS or carbocisteine, or a combination) are effective in reducing exacerbations over a 52-week period, compared to usual care. Methods: This is a 52-week, 2 Ɨ 2 factorial, randomized, open-label trial to determine the clinical effectiveness and cost effectiveness of HTS 6% and carbocisteine for airway clearance versus usual care-the Clinical and cost-effectiveness of hypertonic saline (HTS 6%) and carbocisteine for airway clearance versus usual care (CLEAR) trial. Patients will be randomised to (1) standard care and twice-daily nebulised HTS (6%), (2) standard care and carbocisteine (750 mg three times per day until visit 3, reducing to 750 mg twice per day), (3) standard care and combination of twice-daily nebulised HTS and carbocisteine, or (4) standard care. The primary outcome is the mean number of exacerbations over 52 weeks. Key inclusion criteria are as follows: Adults with a diagnosis of BE on computed tomography, BE as the primary respiratory diagnosis, and two or more pulmonary exacerbations in the last year requiring antibiotics and production of daily sputum. Discussion: This trial's pragmatic research design avoids the significant costs associated with double-blind trials whilst optimising rigour in other areas of trial delivery. The CLEAR trial will provide evidence as to whether HTS, carbocisteine or both are effective and cost effective for patients with BE. Trial registration: EudraCT number: 2017-000664-14 (first entered in the database on 20 October 2017). ISRCTN.com, ISRCTN89040295. Registered on 6 July/2018. Funder: National Institute for Health Research, Health Technology Assessment Programme (15/100/01). Sponsor: Belfast Health and Social Care Trust. Ethics Reference Number: 17/NE/0339. Protocol version: V3.0 Final_14052018

    2011 Report of NSF Workshop Series on Scientific Software Security Innovation Institute

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    Over the period of 2010-2011, a series of two workshops were held in response to NSF Dear Colleague Letter NSF 10-050 calling for exploratory workshops to consider requirements for Scientific Software Innovation Institutes (S2I2s). The specific topic of the workshop series was the potential benefits of a security-focused software institute that would serve the entire NSF research and development community. The first workshop was held on August 6th, 2010 in Arlington, VA and represented an initial exploration of the topic. The second workshop was held on October 26th, 2011 in Chicago, IL and its goals were to 1) Extend our understanding of relevant needs of MREFC and large NSF Projects, 2) refine outcome from first workshop with broader community input, and 3) vet concepts for a trusted cyberinfrastructure institute. Towards those goals, the participants other 2011workshop included greater representation from MREFC and large NSF projects, and, for the most part, did not overlap with the participants from the 2010 workshop. A highlight of the second workshop was, at the invitation of the organizers, a presentation by Scott Koranda of the LIGO project on the history of LIGOā€™s identity management activities and how those could have benefited from a security institute. A key analysis he presented is that, by his estimation, LIGO could have saved 2 senior FTE-years of effort by following suitable expert guidance had it existed. The overarching finding from the workshops is that security is a critical crosscutting issue for the NSF software infrastructure and recommended a security focused activity to address this issue broadly, for example a security software institute (S2I2) under the SI2 program. Additionally, the 2010 workshop participants agreed to 15 key additional findings, which the 2011 workshop confirmed, with some refinement as discussed in this report.NSF Grant # 1043843Ope

    Very Early Optical Afterglows of Gamma-Ray Bursts: Evidence for Relative Paucity of Detection

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    Very early observations with the Swift satellite of gamma-ray burst (GRB) afterglows reveal that the optical component is not detected in a large number of cases. This is in contrast to the bright optical flashes previously discovered in some GRBs (e.g. GRB 990123 and GRB 021211). Comparisons of the X-ray afterglow flux to the optical afterglow flux and prompt gamma-ray fluence is used to quantify the seemingly deficient optical, and in some cases X-ray, light at these early epochs. This comparison reveals that some of these bursts appear to have higher than normal gamma-ray efficiencies. We discuss possible mechanisms and their feasibility for explaining the apparent lack of early optical emission. The mechanisms considered include: foreground extinction, circumburst absorption, Ly-alpha blanketing and absorption due to high redshift, low density environments, rapid temporal decay, and intrinsic weakness of the reverse shock. Of these, foreground extinction, circumburst absorption, and high redshift provide the best explanations for most of the non-detections in our sample. There is tentative evidence of suppression of the strong reverse shock emission. This could be because of a Poynting-flux-dominated flow or a pure non-relativistic hydrodynamical reverse shock.Comment: 22 pages, 5 figures. Accepted for publication in Ap

    A Prospective Randomized Controlled Trial of the Effects of Vitamin D Supplementation on Cardiovascular Disease Risk

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    Vitamin D (VitD) supplementation has been advocated for cardiovascular risk reduction; however, supporting data are sparse. The objective of this study was to determine whether VitD supplementation reduces cardiovascular risk. Subjects in this prospective, randomized, double-blind, placebo-controlled trial of post-menopausal women with serum 25-hydroxyvitamin D concentrations >10 and <60 ng/mL were randomized to Vitamin D3 2500 IU or placebo, daily for 4 months. Primary endpoints were changes in brachial artery flow-mediated vasodilation (FMD), carotid-femoral pulse wave velocity (PWV), and aortic augmentation index (AIx). The 114 subjects were mean (standard deviation) 63.9 (3.0) years old with a 25-hydroxyvitamin D level of 31.3 (10.6) ng/mL. Low VitD (<30 ng/mL) was present in 47% and was associated with higher body-mass index, systolic blood pressure, glucose, CRP, and lower FMD (all p<0.05). After 4 months, 25-hydroxyvitamin D levels increased by 15.7 (9.3) ng/mL on vitamin D3 vs. āˆ’0.2 (6.1) ng/mL on placebo (p<0.001). There were no significant differences between groups in changes in FMD (0.3 [3.4] vs. 0.3 [2.6] %, pā€Š=ā€Š0.77), PWV (0.00 [1.06] vs. 0.05 [0.92] m/s, pā€Š=ā€Š0.65), AIx (2.7 [6.3] vs. 0.9 [5.6] %, pā€Š=ā€Š0.10), or CRP (0.3 [1.9] vs. 0.3 [4.2] mg/L, pā€Š=ā€Š0.97). Multivariable models showed no significant interactions between treatment group and low VitD status (<30 ng/mL) for changes in FMD (pā€Š=ā€Š0.65), PWV (pā€Š=ā€Š0.93), AIx (pā€Š=ā€Š0.97), or CRP (pā€Š=ā€Š0.26).In conclusion, VitD supplementation did not improve endothelial function, arterial stiffness, or inflammation. These observations do not support use of VitD supplementation to reduce cardiovascular disease risk

    Case Reports1.ā€ƒA Late Presentation of Loeys-Dietz Syndrome: Beware of TGFĪ² Receptor Mutations in Benign Joint Hypermobility

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    Background: Thoracic aortic aneurysms (TAA) and dissections are not uncommon causes of sudden death in young adults. Loeys-Dietz syndrome (LDS) is a rare, recently described, autosomal dominant, connective tissue disease characterized by aggressive arterial aneurysms, resulting from mutations in the transforming growth factor beta (TGFĪ²) receptor genes TGFBR1 and TGFBR2. Mean age at death is 26.1 years, most often due to aortic dissection. We report an unusually late presentation of LDS, diagnosed following elective surgery in a female with a long history of joint hypermobility. Methods: A 51-year-old Caucasian lady complained of chest pain and headache following a dural leak from spinal anaesthesia for an elective ankle arthroscopy. CT scan and echocardiography demonstrated a dilated aortic root and significant aortic regurgitation. MRA demonstrated aortic tortuosity, an infrarenal aortic aneurysm and aneurysms in the left renal and right internal mammary arteries. She underwent aortic root repair and aortic valve replacement. She had a background of long-standing joint pains secondary to hypermobility, easy bruising, unusual fracture susceptibility and mild bronchiectasis. She had one healthy child age 32, after which she suffered a uterine prolapse. Examination revealed mild Marfanoid features. Uvula, skin and ophthalmological examination was normal. Results: Fibrillin-1 testing for Marfan syndrome (MFS) was negative. Detection of a c.1270G > C (p.Gly424Arg) TGFBR2 mutation confirmed the diagnosis of LDS. Losartan was started for vascular protection. Conclusions: LDS is a severe inherited vasculopathy that usually presents in childhood. It is characterized by aortic root dilatation and ascending aneurysms. There is a higher risk of aortic dissection compared with MFS. Clinical features overlap with MFS and Ehlers Danlos syndrome Type IV, but differentiating dysmorphogenic features include ocular hypertelorism, bifid uvula and cleft palate. Echocardiography and MRA or CT scanning from head to pelvis is recommended to establish the extent of vascular involvement. Management involves early surgical intervention, including early valve-sparing aortic root replacement, genetic counselling and close monitoring in pregnancy. Despite being caused by loss of function mutations in either TGFĪ² receptor, paradoxical activation of TGFĪ² signalling is seen, suggesting that TGFĪ² antagonism may confer disease modifying effects similar to those observed in MFS. TGFĪ² antagonism can be achieved with angiotensin antagonists, such as Losartan, which is able to delay aortic aneurysm development in preclinical models and in patients with MFS. Our case emphasizes the importance of timely recognition of vasculopathy syndromes in patients with hypermobility and the need for early surgical intervention. It also highlights their heterogeneity and the potential for late presentation. Disclosures: The authors have declared no conflicts of interes
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