95 research outputs found
Diesel fuel and Diesel fuel with Water Emulsions Spray and Combustion Characterization
The legislative demand to simultaneously reduce nitrogen oxide(s) emissions and
particulate matter emissions from compression ignition engines is proving difficult
to achieve in the real world. One promising strategy is the use of Diesel fuel emulsified
with water. There is little work concerning the e↵ect of emulsification on
fuel injection sprays. This work details an experimental campaign to characterize
non-vaporizing sprays of Diesel fuel and Diesel emulsions, with 10% and 20% water
by mass. Characterization of the fuel sprays has been done using: high speed
photography, applying focused shadowgraphy and a di↵used back-lighting technique
and; hydraulically using a force transducer placed 0.5mm from the injector nozzle
to measure spray momentum flux. All measurements have been made in an optically
accessible high pressure chamber filled with nitrogen, resulting in an ambient
gas density of 22.6 kg/m3 and 34.5 kg/m3, with injection pressures of 500, 700 and
1000bar used.
The images collected have been used to determine the spray cone angle, the tip
penetration and the tip velocity. The signal from the force transducer has been used
to determine spray momentum flux, instantaneous mass flow rate, dimensionless
nozzle coefficients and injection velocity. The injection pressure had no discernible
influence on the spray cone angle for the Diesel fuel sprays but did for the emulsified
fuels. Increasing the ambient density resulted in an increase in the spray cone angle
for Diesel fuel, this was not always the case for the emulsified fuel sprays. The spray
tip emerged from the nozzle and accelerated for a very short period after the start
of injection until a maximum velocity was reached.
The momentum flux for each fuel was almost the same for corresponding conditions.
Increasing the chamber gas density reduced the measured spray momentum.
The total mass of fuel injected for Diesel fuel was larger than for the emulsions
for the equivalent conditions and duration, although emulsions had a larger density
and viscosity. The emulsions had a higher injection velocity. The nozzle discharge
coefficient for Diesel was higher than for the emulsions. The velocities measured
hydraulically are much higher than the maximum tip velocities measured optically.
The study has been completed by some preliminary combustion studies of the
fuels in an optically accessible combustion chamber. The emulsion tested exhibited
much lower natural flame luminosity, used to determine the spatially integrated
natural luminosity of the flame which may be useful as a soot indicator. There was
no evidence that the microexplosion phenomenon was present in these tests.Advanced Engine Research (A.E.R, Basildon, Essex, UK
Life expectancy in relation to cardiovascular risk factors: 38 year follow-up of 19 000 men in the Whitehall study
Objective To assess life expectancy in relation to cardiovascular risk factors recorded in middle age
2022 Joint ESC/EACTS review of the 2018 guideline recommendations on the revascularization of left main coronary artery disease in patients at low surgical risk and anatomy suitable for PCI or CABG
Task Force structure and summary of clinical evidence of 2022 ESC/EACTS review of the 2018 guideline recommendations on the revascularization of left main coronary artery disease. CABG, coronary artery bypass grafting; PCI, percutaneous coronary intervention; LM, left main; SYNTAX, Synergy Between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery. a'Event' refers to the composite of death, myocardial infarction (according to Universal Definition of Myocardial Infarction if available, otherwise protocol defined) or stroke. In October 2021, the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS) jointly agreed to establish a Task Force (TF) to review recommendations of the 2018 ESC/EACTS Guidelines on myocardial revascularization as they apply to patients with left main (LM) disease with low-to-intermediate SYNTAX score (0-32). This followed the withdrawal of support by the EACTS in 2019 for the recommendations about the management of LM disease of the previous guideline. The TF was asked to review all new relevant data since the 2018 guidelines including updated aggregated data from the four randomized trials comparing percutaneous coronary intervention (PCI) with drug-eluting stents vs. coronary artery bypass grafting (CABG) in patients with LM disease. This document represents a summary of the work of the TF; suggested updated recommendations for the choice of revascularization modality in patients undergoing myocardial revascularization for LM disease are included. In stable patients with an indication for revascularization for LM disease, with coronary anatomy suitable for both procedures and a low predicted surgical mortality, the TF concludes that both treatment options are clinically reasonable based on patient preference, available expertise, and local operator volumes. The suggested recommendations for revascularization with CABG are Class I, Level of Evidence A. The recommendations for PCI are Class IIa, Level of Evidence A. The TF recognized several important gaps in knowledge related to revascularization in patients with LM disease and recognizes that aggregated data from the four randomized trials were still only large enough to exclude large differences in mortality.</p
Earth observations into action: the systemic integration of earth observation applications into national risk reduction decision structures
Purpose - As stated in the United Nations Global Assessment Report 2022 Concept Note, decision-makers everywhere need data and statistics that are accurate, timely, sufficiently disaggregated, relevant, accessible and easy to use. The purpose of this paper is to demonstrate scalable and replicable methods to advance and integrate the use of earth observation (EO), specifically ongoing efforts within the Group on Earth Observations (GEO) Work Programme and the Committee on Earth Observation Satellites (CEOS) Work Plan, to support risk-informed decision-making, based on documented national and subnational needs and requirements.
Design/methodology/approach - Promotion of open data sharing and geospatial technology solutions at national and subnational scales encourages the accelerated implementation of successful EO applications. These solutions may also be linked to specific Sendai Framework for Disaster Risk Reduction (DRR) 2015–2030 Global Targets that provide trusted answers to risk-oriented decision frameworks, as well as critical synergies between the Sendai Framework and the 2030 Agenda for Sustainable Development. This paper provides examples of these efforts in the form of platforms and knowledge hubs that leverage latest developments in analysis ready data and support evidence-based DRR measures.
Findings - The climate crisis is forcing countries to face unprecedented frequency and severity of disasters. At the same time, there are growing demands to respond to policy at the national and international level. EOs offer insights and intelligence for evidence-based policy development and decision-making to support key aspects of the Sendai Framework. The GEO DRR Working Group and CEOS Working Group Disasters are ideally placed to help national government agencies, particularly national Sendai focal points to learn more about EOs and understand their role in supporting DRR.
Originality/value - The unique perspective of EOs provide unrealized value to decision-makers addressing DRR. This paper highlights tangible methods and practices that leverage free and open source EO insights that can benefit all DRR practitioners
Review article: Natural hazard risk assessments at the global scale
Since 1990, natural hazards have led to over 1.6 million fatalities globally, and economic losses are estimated at an average of around $260–310 billion per year. The scientific and policy community recognise the need to reduce these risks. As a result, the last decade has seen a rapid development of global models for assessing risk from natural hazards at the global scale. In this paper, we review the scientific literature on natural hazard risk assessments at the global scale, and specifically examine whether and how they have examined future projections of hazard, exposure, and/or vulnerability. In doing so, we examine similarities and differences between the approaches taken across the different hazards, and identify potential ways in which different hazard communities can learn from each other. For example, we show that global risk studies focusing on hydrological, climatological, and meteorological hazards, have included future projections and disaster risk reduction measures (in the case of floods), whilst these are missing in global studies related to geological hazards. The methods used for projecting future exposure in the former could be applied to the geological studies. On the other hand, studies of earthquake and tsunami risk are now using stochastic modelling approaches to allow for a fully probabilistic assessment of risk, which could benefit the modelling of risk from other hazards. Finally, we discuss opportunities for learning from methods and approaches being developed and applied to assess natural hazard risks at more continental or regional scales. Through this paper, we hope to encourage dialogue on knowledge sharing between scientists and communities working on different hazards and at different spatial scales
Natural hazard risk assessments at the global scale
Since 1990, natural hazards have led to over 1.6 million fatalities globally, and economic losses are estimated at an average of around USD 260–310 billion per year. The scientific and policy communities recognise the need to reduce these risks. As a result, the last decade has seen a rapid development of global models for assessing risk from natural hazards at the global scale. In this paper, we review the scientific literature on natural hazard risk assessments at the global scale, and we specifically examine whether and how they have examined future projections of hazard, exposure, and/or vulnerability. In doing so, we examine similarities and differences between the approaches taken across the different hazards, and we identify potential ways in which different hazard communities can learn from each other. For example, there are a number of global risk studies focusing on hydrological, climatological, and meteorological hazards that have included future projections and disaster risk reduction measures (in the case of floods), whereas fewer exist in the peer-reviewed literature for global studies related to geological hazards. On the other hand, studies of earthquake and tsunami risk are now using stochastic modelling approaches to allow for a fully probabilistic assessment of risk, which could benefit the modelling of risk from other hazards. Finally, we discuss opportunities for learning from methods and approaches being developed and applied to assess natural hazard risks at more continental or regional scales. Through this paper, we hope to encourage further dialogue on knowledge sharing between disciplines and communities working on different hazards and risk and at different spatial scales
Experiences of the Data Monitoring Committee for the RECOVERY trial, a large-scale adaptive platform randomised trial of treatments for patients hospitalised with COVID-19
Abstract: Aim: To inform the oversight of future clinical trials during a pandemic, we summarise the experiences of the Data Monitoring Committee (DMC) for the Randomised Evaluation of COVID therapy trial (RECOVERY), a large-scale randomised adaptive platform clinical trial of treatments for hospitalised patients with COVID-19. Methods and findings: During the first 24 months of the trial (March 2020 to February 2022), the DMC oversaw accumulating data for 14 treatments in adults (plus 10 in children) involving > 45,000 randomised patients. Five trial aspects key for the DMC in performing its role were: a large committee of members, including some with extensive DMC experience and others who had broad clinical expertise; clear strategic planning, communication, and responsiveness by the trial principal investigators; data collection and analysis systems able to cope with phases of very rapid recruitment and link to electronic health records; an ability to work constructively with regulators (and other DMCs) to address emerging concerns without the need to release unblinded mortality results; and the use of videoconferencing systems that enabled national and international members to meet at short notice and from home during the pandemic when physical meetings were impossible. Challenges included that the first four treatments introduced were effectively ‘competing’ for patients (increasing pressure to make rapid decisions on each one); balancing the global health imperative to report on findings with the need to maintain confidentiality until the results were sufficiently certain to appropriately inform treatment decisions; and reliably assessing safety, especially for newer agents introduced after the initial wave and in the small numbers of pregnant women and children included. We present a series of case vignettes to illustrate some of the issues and the DMC decision-making related to hydroxychloroquine, dexamethasone, casirivimab + imdevimab, and tocilizumab. Conclusions: RECOVERY’s streamlined adaptive platform design, linked to hospital-level and population-level health data, enabled the rapid and reliable assessment of multiple treatments for hospitalised patients with COVID-19. The later introduction of factorial assessments increased the trial’s efficiency, without compromising the DMC’s ability to assess safety and efficacy. Requests for the release of unblinded primary outcome data to regulators at points when data were not mature required significant efforts in communication with the regulators by the DMC to avoid inappropriate early trial termination
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
Social inequalities in self-rated health by age: Cross-sectional study of 22 457 middle-aged men and women
<p>Abstract</p> <p>Background</p> <p>We investigate the association between occupational social class and self-rated health (SRH) at different ages in men and women.</p> <p>Methods</p> <p>Cross sectional population study of 22 457 men and women aged 39–79 years living in the general community in Norfolk, United Kingdom, recruited using general practice age-sex registers in 1993–1997. The relationship between self-rated health and social class was examined using logistic regression, with a poor or moderate rating as the outcome.</p> <p>Results</p> <p>The prevalence of poor or moderate (lower) self-rated health increased with increasing age in both men and women. There was a strong social class gradient: in manual classes, men and women under 50 years of age had a prevalence of lower self-rated health similar to that seen in men and women in non-manual social classes over 70 years old. Even after adjustment for age, educational status, and lifestyle factors (body mass index (BMI), smoking, physical activity and alcohol consumption) there was still strong evidence of a social gradient in self-rated health, with unskilled men and women approximately twice as likely to report lower self-rated health as professionals (OR<sub>men </sub>= 2.44 (95%CI 1.69, 3.50); OR<sub>women </sub>= 1.97 (95%CI 1.45, 2.68).</p> <p>Conclusion</p> <p>There was a strong gradient of decreased SRH with age in both men and women. We found a strong cross-sectional association between SRH and social class, which was independent of education and major health related behaviors. The social class differential in SRH was similar with age. Prospective studies to confirm this association should explore social and emotional as well as physical pathways to inequalities in self reported health.</p
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