359 research outputs found
Large eddy simulation of an ethyleneâair turbulent premixed V-flame
AbstractLarge eddy simulation (LES) using a dynamic eddy viscosity subgrid scale stress model and a fast-chemistry combustion model without accounting for the finite-rate chemical kinetics is applied to study the ignition and propagation of a turbulent premixed V-flame. A progress variable c-equation is applied to describe the flame front propagation. The equations are solved two dimensionally by a projection-based fractional step method for low Mach number flows. The flow field with a stabilizing rod without reaction is first obtained as the initial field and ignition happens just upstream of the stabilizing rod. The shape of the flame is affected by the velocity field, and following the flame propagation, the vortices fade and move to locations along the flame front. The LES computed time-averaged velocity agrees well with data obtained from experiments
Effect modification of the association between meteorological variables and mortality by urban climatic conditions in the tropical city of Kaohsiung, Taiwan
A deeper understanding of extreme hot weather are needed in cities sensitive to heat effects, an investigation was done in the tropical town of Kaohsiung in Taiwan. Its 11 districts were divided into three climatic classes varying from high urban heat, low levels of green space and lack of proximity to water bodies to low urban heat, adequate green space and proximity to water bodies. Daily data on natural mortality, meteorological variables, and pollutants from May-October 1999-2008 were analysed using generalised additive models for the time-series data. Subgroup analyses were conducted, stratifying decedents according to the level of planning activity required in order to mitigate adverse heat effects in their residential areas, classifying districts as âlevel 1â for those requiring a high level of mitigation action; âlevel 2â for those requiring some action; and âlevel 3â for those that need only preserve existing conditions. Stratified analyses showed that mortality increases per 1 °C rise on average, either on the same day or in the previous 4 days (lags 0-4), were associated with 2.8%, 2.3% and -1.3% for level 1, 2 and 3 districts, respectively. The slope describing the association between temperature and mortality was higher above 29.0 °C resulting in corresponding increases of 4.2%, 5.0% and 0.3% per per 1 °C rise in temperature, respectively. Other meteorological variables were not significantly associated with mortality. It is concluded that hot season mortality in Kaohsiung is only sensitive to heat effects in districts classified as having unfavourably climatic conditions and requiring mitigation efforts in city planning. Urban planning measures designed to improve climatic conditions could reduce excess mortality resulting from extreme hot weathe
Determinants of antibiotic prescribing for upper respiratory tract infections in an emergency department with good primary care access: a qualitative analysis
Upper respiratory tract infections (URTIs) account for substantial attendances at emergency departments (EDs). There is a need to elucidate determinants of antibiotic prescribing in time-strapped EDs â popular choices for primary care despite highly accessible primary care clinics. Semi-structured in-depth interviews were conducted with purposively sampled physicians (n = 9) in an adult ED in Singapore. All interviews were analysed using thematic analysis and further interpreted using the Social Ecological Model to explain prescribing determinants. Themes included: (1) reliance on clinical knowledge and judgement, (2) patient-related factors, (3) patientâphysician relationship factors, (4) perceived practice norms, (5) policies and treatment guidelines and (6) patient education and awareness. The physicians relied strongly on their clinical knowledge and judgement in managing URTI cases and seldom interfered with their peersâ clinical decisions. Despite departmental norms of not prescribing antibiotics for URTIs, physicians would prescribe antibiotics when faced with uncertainty in patientsâ diagnoses, treating immunocompromised or older patients with comorbidities, and for patients demanding antibiotics, especially under time constraints. Participants had a preference for antibiotic prescribing guidelines based on local epidemiology, but viewed hospital policies on prescribing as a hindrance to clinical judgement. Participants highlighted the need for more public education and awareness on the appropriate use of antibiotics and management of URTIs. Organisational practice norms strongly influenced antibiotic prescribing decisions by physicians, who can be swayed by time pressures and patient demands. Clinical decision support tools, hospital guidelines and patient education targeting at individual, interpersonal and community levels could reduce unnecessary antibiotic use
Accredited qualifications for capacity development in disaster risk reduction and climate change adaptation
Increasingly practitioners and policy makers working
across the globe are recognising the importance of
bringing together disaster risk reduction and climate
change adaptation. From studies across 15 Pacific island
nations, a key barrier to improving national resilience
to disaster risks and climate change impacts has been
identified as a lack of capacity and expertise resulting
from the absence of sustainable accredited and quality
assured formal training programmes in the disaster risk
reduction and climate change adaptation sectors. In the
2016 UNISDR Science and Technology Conference
on the Implementation of the Sendai Framework for
Disaster Risk Reduction 2015â2030, it was raised that
most of the training material available are not reviewed
either through a peer-to-peer mechanism or by the
scientific community and are, thus, not following quality
assurance standards. In response to these identified
barriers, this paper focuses on a call for accredited formal
qualifications for capacity development identified in the
2015 United Nations landmark agreements in DRR and
CCA and uses the Pacific Islands Region of where this
is now being implemented with the launch of the Pacific
Regional Federation of Resilience Professionals, for
DRR and CCA. A key issue is providing an accreditation
and quality assurance mechanism that is shared across
boundaries. This paper argues that by using the United
Nations landmark agreements of 2015, support for a
regionally accredited capacity development that ensures
all countries can produce, access and effectively use
scientific information for disaster risk reduction and
climate change adaptation. The newly launched Pacific
Regional Federation of Resilience Professionals who
work in disaster risk reduction and climate change
adaptation may offer a model that can be used more
widely
Study protocol for "Moving bright, eating smart"- a phase 2 clinical trial on the acceptability and feasibility of a diet and physical activity intervention to prevent recurrence in colorectal cancer survivors
Background: Colorectal cancer is the second most common cancer and cancer-killer in Hong Kong with an alarming increasing incidence in recent years. The latest World Cancer Research Fund report concluded that foods low in fibre, and high in red and processed meat cause colorectal cancer whereas physical activity protects againstcolon cancer. Yet, the influence of these lifestyle factors on cancer outcome is largely unknown even though cancer survivors are eager for lifestyle modifications. Observational studies suggested that low intake of a Western-pattern diet and high physical activity level reduced colorectal cancer mortality. The Theory of PlannedBehaviour and the Health Action Process Approach have guided the design of intervention models targeting a wide range of health-related behaviours.Methods/design: We aim to demonstrate the feasibility of two behavioural interventions intended to improve colorectal cancer outcome and which are designed to increase physical activity level and reduce consumption of a Western-pattern diet. This three year study will be a multicentre, randomised controlled trial in a 2x2 factorialdesign comparing the “Moving Bright, Eating Smart” (physical activity and diet) programme against usual care. Subjects will be recruited over a 12-month period, undertake intervention for 12 months and followed up for a further 12 months. Baseline, interim and three post-intervention assessments will be conducted. Two hundred and twenty-two colorectal cancer patients who completed curative treatment without evidence of recurrence will be recruited into the study. Primary outcome measure will be whether physical activity and dietary targets are met at the end of the 12-month intervention. Secondary outcome measures include the magnitude andmechanism of behavioural change, the degree and determinants of compliance, and the additional health benefits and side effects of the intervention.Discussion: The results of this study will establish the feasibility of targeting the two behaviours (diet and physical activity) and demonstrate the magnitude of behaviour change. The information will facilitate the design of a further larger phase III randomised controlled trial with colorectal cancer outcome as the study endpoint to determine whether this intervention model would reduce colorectal cancer recurrence and mortality
Accredited qualifications for capacity development in disaster risk reduction and climate change adaptation
Increasingly practitioners and policy makers working
across the globe are recognising the importance of
bringing together disaster risk reduction and climate
change adaptation. From studies across 15 Pacific island
nations, a key barrier to improving national resilience
to disaster risks and climate change impacts has been
identified as a lack of capacity and expertise resulting
from the absence of sustainable accredited and quality
assured formal training programmes in the disaster risk
reduction and climate change adaptation sectors. In the
2016 UNISDR Science and Technology Conference
on the Implementation of the Sendai Framework for
Disaster Risk Reduction 2015â2030, it was raised that
most of the training material available are not reviewed
either through a peer-to-peer mechanism or by the
scientific community and are, thus, not following quality
assurance standards. In response to these identified
barriers, this paper focuses on a call for accredited formal
qualifications for capacity development identified in the
2015 United Nations landmark agreements in DRR and
CCA and uses the Pacific Islands Region of where this
is now being implemented with the launch of the Pacific
Regional Federation of Resilience Professionals, for
DRR and CCA. A key issue is providing an accreditation
and quality assurance mechanism that is shared across
boundaries. This paper argues that by using the United
Nations landmark agreements of 2015, support for a
regionally accredited capacity development that ensures
all countries can produce, access and effectively use
scientific information for disaster risk reduction and
climate change adaptation. The newly launched Pacific
Regional Federation of Resilience Professionals who
work in disaster risk reduction and climate change
adaptation may offer a model that can be used more
widely
Accredited qualifications for capacity development in disaster risk reduction and climate change adaptation
Increasingly practitioners and policy makers working across the globe are recognising the importance of bringing together disaster risk reduction and climate change adaptation. From studies across 15 Pacific island nations, a key barrier to improving national resilience to disaster risks and climate change impacts has been identified as a lack of capacity and expertise resulting from the absence of sustainable accredited and quality assured formal training programmes in the disaster risk reduction and climate change adaptation sectors. In the 2016 UNISDR Science and Technology Conference on the Implementation of the Sendai Framework for Disaster Risk Reduction 2015-2030, it was raised that most of the training material available are not reviewed either through a peer-to-peer mechanism or by the scientific community and are, thus, not following quality assurance standards. In response to these identified barriers, this paper focuses on a call for accredited formal qualifications for capacity development identified in the 2015 United Nations landmark agreements in DRR and CCA and uses the Pacific Islands Region of where this is now being implemented with the launch of the Pacific Regional Federation of Resilience Professionals, for DRR and CCA. A key issue is providing an accreditation and quality assurance mechanism that is shared across boundaries. This paper argues that by using the United Nations landmark agreements of 2015, support for a regionally accredited capacity development that ensures all countries can produce, access and effectively use scientific information for disaster risk reduction and climate change adaptation. The newly launched Pacific Regional Federation of Resilience Professionals who work in disaster risk reduction and climate change adaptation may offer a model that can be used more widely
Population differences in associations of serotonin transporter promoter polymorphism (5HTTLPR) di- and triallelic genotypes with blood pressure and hypertension prevalence
Based on prior research finding the 5HTTLPR L allele associated with increased cardiovascular reactivity to laboratory stressors and increased risk of myocardial infarction, we hypothesized that the 5HTTLPR L allele will be associated with increased blood pressure (BP) and increased hypertension prevalence in 2 large nationally representative samples in the United States and Singapore. Methods Logistic regression and linear models tested associations between triallelic (Lâ˛Sâ˛, based on rs25531) 5HTTLPR genotypes and hypertension severity and mean systolic and diastolic blood pressure (SBP and DBP) collected during the Wave IV survey of the National Longitudinal Study of Adolescent to Adult Health (Add Health, N = 11,815) in 2008â09 and during 2004â07 in 4196 Singaporeans. Results In US Whites, LⲠallele carriers had higher SBP (0.9 mm Hg, 95% CI = 0.26-1.56) and greater odds (OR = 1.23, 95% CI = 1.10-1.38) of more severe hypertension than those with Sâ˛SⲠgenotypes. In African Americans, LⲠcarriers had lower mean SBP (â1.27 mm Hg, 95% CI = â2.53 to â0.01) and lower odds (OR = 0.78, 95% CI = 0.65-0.94) of more severe hypertension than those with the Sâ˛SⲠgenotype. In African Americans, those with Lâ˛LⲠgenotypes had lower DBP (â1.13 mm Hg, 95% CI = â2.09 to â0.16) than SⲠcarriers. In Native Americans, LⲠcarriers had lower SBP (â6.05 mm Hg, 95% CI = â9.59 to â2.51) and lower odds of hypertension (OR = 0.34, 95% CI = 0.13-0.89) than those with the Sâ˛SⲠgenotype. In Asian/Pacific Islanders those carrying the LⲠallele had lower DBP (â1.77 mm Hg, 95% CI = â3.16 to â0.38) and lower odds of hypertension (OR = 0.68, 95% CI = 0.48-0.96) than those with Sâ˛Sâ˛. In the Singapore sample SⲠcarriers had higher SBP (3.02 mm Hg, 95% CI = 0.54-5.51) and DBP (1.90 mm Hg, 95% CI = 0.49-3.31) than those with the Lâ˛LⲠgenotype. Conclusions These findings suggest that Whites carrying the LⲠallele, African Americans and Native Americans with the Sâ˛SⲠgenotype, and Asians carrying the SⲠallele will be found to be at higher risk of developing cardiovascular disease and may benefit from preventive measures
Does surrounding greenness moderate the relationship between apparent temperature and physical activity? Findings from the PHENOTYPE project
Background: Physical activity can be affected by both meteorological conditions and surrounding greenness, but few studies have evaluated the effects of these environmental factors on physical activity simultaneously. This multi-city comparative study aimed to assess the synergetic effects of apparent temperature and surrounding greenness on physical activity in four European cities. Specifically, we aimed to identify an interaction between surrounding greenness and apparent temperature in the effects on physical activity. Methods: Data were collected from 352 adult residents of Barcelona (Spain), Stoke-on-Trent (United Kingdom), Doetinchem (The Netherlands), and Kaunas (Lithuania) as part of the PHENOTYPE study. Participants wore a smartphone for seven consecutive days between May-December 2013 and provided additional sociodemographic survey data. Hourly average physical activity (Metabolic Equivalent of Task (MET)) and surrounding greenness (NDVI) were derived from the Calfit mobile application collecting accelerometer and location data. Hourly apparent temperature was calculated from temperature and relative humidity, which were obtained from local meteorological stations along with other meteorological covariates (rainfall, windspeed, and sky darkness). We assessed the interaction effects of apparent temperature and surrounding greenness on hourly physical activity for each city using linear mixed models, while adjusting for meteorological, demographic, and time-related variables. Results: We found significant interactions between apparent temperature and surrounding greenness on hourly physical activity in all four cities. Significant quadratic effects of apparent temperature were found in the highest level of surrounding greenness for Stoke-on-Trent and Doetinchem, with 4% decrease in median MET observed for a 10°C departure from optimal temperature (15.2°C and 14.6°C, respectively). On the other hand, significant linear effects were found for higher levels of surrounding greenness in Barcelona and Kaunas, whereby an increase of 10°C was associated with âź4% increase in median MET. Conclusion: Apparent temperature and surrounding greenness interacted in the effect on hourly physical activity across the four European cities, with varying effect between cities. While quadratic effects of temperature suggest diminishing levels of physical activity in the highest greenness levels in cities of temperate climates, the variation in surrounding greenness between cities could be further explored, particularly by looking at indoor-outdoor locations. The study findings support the need for evidence-based physical activity promotion and urban design
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