PRImary care Streptococcal Management (PRISM) study:In vitro study, diagnostic cohorts and a pragmatic adaptive randomised controlled trial with nested qualitative study and cost-effectiveness study

Background: Antibiotics are still prescribed to most patients attending primary care with acute sore throat, despite evidence that there is modest benefit overall from antibiotics. Targeting antibiotics using either clinical scoring methods or rapid antigen detection tests (RADTs) could help. However, there is debate about which groups of streptococci are important (particularly Lancefield groups C and G), and uncertainty about the variables that most clearly predict the presence of streptococci. Objective: This study aimed to compare clinical scores or RADTs with delayed antibiotic prescribing. Design: The study comprised a RADT in vitro study; two diagnostic cohorts to develop streptococcal scores (score 1; score 2); and, finally, an open pragmatic randomised controlled trial with nested qualitative and cost-effectiveness studies. Setting: The setting was UK primary care general practices. Participants: Participants were patients aged ≥ 3 years with acute sore throat. Interventions: An internet program randomised patients to targeted antibiotic use according to (1) delayed antibiotics (control group), (2) clinical score or (3) RADT used according to clinical score. Main outcome measures: The main outcome measures were self-reported antibiotic use and symptom duration and severity on seven-point Likert scales (primary outcome: mean sore throat/difficulty swallowing score in the first 2-4 days). Results: The IMI TestPack Plus Strep A (Inverness Medical, Bedford, UK) was sensitive, specific and easy to use. Lancefield group A/C/G streptococci were found in 40% of cohort 2 and 34% of cohort 1. A five-point score predicting the presence of A/C/G streptococci [FeverPAIN: Fever; Purulence; Attend rapidly (≤ 3 days); severe Inflammation; and No cough or coryza] had moderate predictive value (bootstrapped estimates of area under receiver operating characteristic curve: 0.73 cohort 1, 0.71 cohort 2) and identified a substantial number of participants at low risk of streptococcal infection. In total, 38% of cohort 1 and 36% of cohort 2 scored ≤ 1 for FeverPAIN, associated with streptococcal percentages of 13% and 18%, respectively. In an adaptive trial design, the preliminary score (score 1; n = 1129) was replaced by FeverPAIN (n = 631). For score 1, there were no significant differences between groups. For FeverPAIN, symptom severity was documented in 80% of patients, and was lower in the clinical score group than in the delayed prescribing group (-0.33; 95% confidence interval -0.64 to -0.02; p = 0.039; equivalent to one in three rating sore throat a slight rather than moderately bad problem), and a similar reduction was observed for the RADT group (-0.30; -0.61 to 0.00; p = 0.053). Moderately bad or worse symptoms resolved significantly faster (30%) in the clinical score group (hazard ratio 1.30; 1.03 to 1.63) but not the RADT group (1.11; 0.88 to 1.40). In the delayed group, 75/164 (46%) used antibiotics, and 29% fewer used antibiotics in the clinical score group (risk ratio 0.71; 0.50 to 0.95; p = 0.018) and 27% fewer in the RADT group (0.73; 0.52 to 0.98; p = 0.033). No significant differences in complications or reconsultations were found. The clinical score group dominated both other groups for both the cost/quality-adjusted life-years and cost/change in symptom severity analyses, being both less costly and more effective, and cost-effectiveness acceptability curves indicated the clinical score to be the most likely to be cost-effective from an NHS perspective. Patients were positive about RADTs. Health professionals' concerns about test validity, the time the test took and medicalising self-limiting illness lessened after using the tests. For both RADTs and clinical scores, there were tensions with established clinical experience. Conclusions: Targeting antibiotics using a clinical score (FeverPAIN) efficiently improves symptoms and reduces antibiotic use. RADTs used in combination with FeverPAIN provide no clear advantages over FeverPAIN alone, and RADTs are unlikely to be incorporated into practice until health professionals' concerns are met and they have experience of using them. Clinical scores also face barriers related to clinicians' perceptions of their utility in the face of experience. This study has demonstrated the limitation of using one data set to develop a clinical score. FeverPAIN, derived from two data sets, appears to be valid and its use improves outcomes, but diagnostic studies to confirm the validity of FeverPAIN in other data sets and settings are needed. Experienced clinicians need to identify barriers to the use of clinical scoring methods. Implementation studies that address perceived barriers in the use of FeverPAIN are needed

Use of recycled products in UK construction industry: An empirical investigation into critical impediments and strategies for improvement

© 2014 Elsevier B.V. All rights reserved.Construction industry consumes about half of all material resources taken from nature, and generates a large portion of waste to landfill. A way of tackling negative environmental impacts impending from continuous material extraction and waste generation is the use of recycled materials for construction projects. However, the use of recycled materials is yet to become a commonplace in construction industry. This study evaluates the factors hampering the use of recycled products in UK construction industry as well as strategies that could be adopted to enhance its use in the industry. In order to identify the impediments and critical strategies, a two-fold methodical approach was used. An unstructured interview preceded a quantitative questionnaire survey which was used to elicit broader industry practitioners' opinion. The study shows that designers rarely specify recycled products. This is due to lack of adequate information about quality and market availability of the products, negative perception from clients, and unexpectedly high cost of the products, despite its perceived low quality. The study suggests that a number of strategies could be adopted to promote the use of the products. These include allocation of points to the use of recycled products in sustainable design appraisal tools, governments legislative measures, improved collaboration between designers, contractors and materials suppliers, contractors involvement at earlier stage of design, improved education of the professionals about the products, and the use of tax break to influence the cost of the products. The findings of this study would therefore help policy makers, manufacturers and construction professionals to identify the factors hampering the use of recycled products for construction projects as well as the strategies that could be adopted in order to create market for the products

PRESTATIEVERSCHILLEN IN KLEINE EN MIDDELGROTE DETAILHANDELSVESTIGINGEN MET GELIJKE BEDRIJFSSTRUC­ TUUR: TWEEËRLEI ANALYSE DER ACHTERGRONDEN

PRESTATIEVERSCHILLEN IN KLEINE EN MIDDELGROTE DETAILHANDELSVESTIGINGEN MET GELIJKE BEDRIJFSSTRUC­ TUUR: TWEEËRLEI ANALYSE DER ACHTERGRONDE

On the Conceptual Engine Design and Sizing Tool

In aeroengine design, predicting the effects of design parameters on total engine performance is extremely difficult, as all engine components are interrelated. Therefore, engine design tools are needed which provide the designer with more insight on the design process. This thesis focusses on the design of the fan and booster stages of a high-bypass-ratio twin-spool turbofan engine in the conceptual design phase, and consists of three modules: an aerothermodynamics, weight estimation and noise prediction module. After validation using existing engine data, the effects of increasing fan tip diameter, spool speed and bypass ratio on the engine weight, aerodynamic performance and noise production are tested.Aerospace EngineeringAerodynamics, Wind Energy & PropulsionFlight Performance and Propulsio

Design of a Semi-Empirical Tool for the Evaluation of Turbine Cooling Requirements in a Preliminary Design Stage

There is an everlasting demand for higher cycle efficiencies in gas turbine engines. One way to obtain a higher efficiency is to increase the overall pressure ratio (OPR) of the engine. In order to benefit from the efficiency increase whilst maintaining the same specific gas power, the turbine inlet temperature (TIT) has to increase with it. However, with the extremely high TIT used in modern day gas turbine engines, the melting point of the materials used in nozzle guide vanes (NGV) and high pressure turbine (HPT) blades is already exceeded. Therefore, the vanes and blades rely on active cooling on the in- and outside to prevent it from melting. However, the application of cooling air in the turbine is detrimental to the engine performance and hence is desired to be kept at a minimum. Next to application of a turbine cooling system with high heat transfer coefficients, a lower cooling air massflow can be obtained by using coolant of a lower temperature. The use of cryogenic fuels in hybrid engines currently investigated in for example the AHEAD project, can prove to be useful in that aspect; a heat exchanger can be applied to exchange heat between the coolant and the fuel to reduce the temperature of the cooling air. In this study, a semi-empirical turbine cooling program is developed which is able to calculate the thermal performance of a cooling system configuration and assess the effects of the cooling air on engine performance. For the determination of the heat transfer coefficient and pressure drop in the turbine cooling program, semi-empirical correlations from various journal articles are used rather than relying on computational intensive CFD calculations. Also, the tool is able to predict the cooling air requirement for any turbine cooling configuration to a reasonable level of accuracy, enough to be useful during the engine preliminary design phase. This turbine cooling program is used to study the effects of the cooling air on engine performance and research the feasibility of using pre-cooled coolant in a hybrid engine configuration. This main conclusions of this study are that, as expected, cooling air is detrimental to the engine performance. However, the magnitude of the turbine cooling requirements and hence the detrimental effect on the engine performance is commonly underestimated. Therefore, the proper prediction of turbine cooling requirements is important in early design stages, especially for engines operating at higher OPR and TIT. Furthermore, the cooling air requirements decrease if cooling air of a lower temperature is used. Re-using spent cooling air to cool the next row of vanes/blades turns out to have a negative effect on the engine performance. The findings in this report can prove to be important for future engine design where OPR and TIT values are expected to keep rising. Also, the assessment of the effect of coolant pre-cooling and re-use of coolant come in handy for the intended application in the AHEAD hybrid engine.Flight Performance & PropulsionAerospace Engineerin