5,644 research outputs found
Heat and risk of myocardial infarction: hourly level case-crossover analysis of MINAP database.
OBJECTIVE: To quantify the association between exposure to higher temperatures and the risk of myocardial infarction at an hourly temporal resolution. DESIGN: Case-crossover study. SETTING: England and Wales Myocardial Ischaemia National Audit Project (MINAP) database. PARTICIPANTS: 24,861 hospital admissions for myocardial infarction occurring in 11 conurbations during the warmest months (June to August) of the years 2003-09. MAIN OUTCOME MEASURE: Odds ratio of myocardial infarction for a 1 °C increase in temperature. RESULTS: Strong evidence was found for an effect of heat acting 1-6 hours after exposure to temperatures above an estimated threshold of 20 °C (95% confidence interval 16 °C to 25 °C). For each 1 °C increase in temperature above this threshold, the risk of myocardial infarction increased by 1.9% (0.5% to 3.3%, P=0.009). Later reductions in risk seemed to offset early increases in risk: the cumulative effect of a 1 °C rise in temperature above the threshold was 0.2% (-2.1% to 2.5%) by the end of the third day after exposure. CONCLUSIONS: Higher ambient temperatures above a threshold of 20 °C seem to be associated with a transiently increased risk of myocardial infarction 1-6 hours after exposure. Reductions in risk at longer lags are consistent with heat triggering myocardial infarctions early in highly vulnerable people who would otherwise have had a myocardial infarction some time later ("short term displacement"). Policies aimed at reducing the health effects of hot weather should include consideration of effects operating at sub-daily timescales
Aggregation-fragmentation-diffusion model for trail dynamics
We investigate statistical properties of trails formed by a random process incorporating aggregation, fragmentation, and diffusion. In this stochastic process, which takes place in one spatial dimension, two neighboring trails may combine to form a larger one, and also one trail may split into two. In addition, trails move diffusively. The model is defined by two parameters which quantify the fragmentation rate and the fragment size. In the long-time limit, the system reaches a steady state, and our focus is the limiting distribution of trail weights. We find that the density of trail weight has power-law tail P(w)~w-Îł for small weight w. We obtain the exponent Îł analytically and find that it varies continuously with the two model parameters. The exponent Îł can be positive or negative, so that in one range of parameters small-weight trails are abundant and in the complementary range they are rare
Mental health impacts of flooding: a controlled interrupted time series analysis of prescribing data in England.
BACKGROUND: There is emerging evidence that people affected by flooding suffer adverse impacts on their mental well-being, mostly based on self-reports. METHODS: We examined prescription records for drugs used in the management of common mental disorder among primary care practices located in the vicinity of recent large flood events in England, 2011-2014. A controlled interrupted time series analysis was conducted of the number of prescribing items for antidepressant drugs in the year before and after the flood onset. Pre-post changes were compared by distance of the practice from the inundated boundaries among 930 practices located within 10 km of a flood. RESULTS: After control for deprivation and population density, there was an increase of 0.59% (95% CI 0.24 to 0.94) prescriptions in the postflood year among practices located within 1 km of a flood over and above the change observed in the furthest distance band. The increase was greater in more deprived areas. CONCLUSIONS: This study suggests an increase in prescribed antidepressant drugs in the year after flooding in primary care practices close to recent major floods in England. The degree to which the increase is actually concentrated in those flooded can only be determined by more detailed linkage studies
The effects of hourly differences in air pollution on the risk of myocardial infarction: case crossover analysis of the MINAP database.
OBJECTIVES: To investigate associations between air pollution levels and myocardial infarction (MI) on short timescales, with data at an hourly temporal resolution. DESIGN: Time stratified case crossover study linking clinical data from the Myocardial Ischaemia National Audit Project (MINAP) with PM(10), ozone, CO, NO(2), and SO(2) data from the UK National Air Quality Archive. Pollution effects were investigated with delays (lags) of 1-6, 7-12, 13-18, 19-24, and 25-72 hours in both single and multi-pollutant models, adjusted for ambient temperature, relative humidity, circulating levels of influenza and respiratory syncytial virus, day of week, holidays, and residual seasonality within calendar month strata. SETTING: Population based study in 15 conurbations in England and Wales. SUBJECTS: 79,288 diagnoses of myocardial infarction recorded over the period 2003-6. MAIN OUTCOME MEASURES: Excess risk of myocardial infarction per 10 µg/m(3) increase in pollutant level. RESULTS: In single pollutant models, PM(10) and NO(2) levels were associated with a very short term increase in risk of myocardial infarction 1-6 hours later (excess risks 1.2% (95% confidence interval 0.3 to 2.1) and 1.1% (0.3 to 1.8) respectively per 10 μg/m(3) increase); the effects persisted in multi-pollutant models, though with only weak evidence of an independent PM(10) effect (P = 0.05). The immediate risk increases were followed by reductions in risk at longer lags: we found no evidence of any net excess risk associated with the five pollutants studied over a 72 hour period after exposure. CONCLUSIONS: Higher levels of PM(10) and NO(2), which are typically markers of traffic related pollution, seem to be associated with transiently increased risk of myocardial infarction 1-6 hours after exposure, but later reductions in risk suggest that air pollution may be associated with bringing events forward in time ("short-term displacement") rather than increasing overall risk. The well established effect of air pollution on cardiorespiratory mortality may not be mediated through increasing the acute risk of myocardial infarction, but through another mechanism
Adiabatic theorem for non-hermitian time-dependent open systems
In the conventional quantum mechanics (i.e., hermitian QM) the adia- batic
theorem for systems subjected to time periodic fields holds only for bound
systems and not for open ones (where ionization and dissociation take place)
[D. W. Hone, R. Ketzmerik, and W. Kohn, Phys. Rev. A 56, 4045 (1997)]. Here
with the help of the (t,t') formalism combined with the complex scaling method
we derive an adiabatic theorem for open systems and provide an analytical
criteria for the validity of the adiabatic limit. The use of the complex
scaling transformation plays a key role in our derivation. As a numerical
example we apply the adiabatic theorem we derived to a 1D model Hamiltonian of
Xe atom which interacts with strong, monochromatic sine-square laser pulses. We
show that the gener- ation of odd-order harmonics and the absence of
hyper-Raman lines, even when the pulses are extremely short, can be explained
with the help of the adiabatic theorem we derived
Withholding and withdrawing life-sustaining treatment in a patient's best interests: Australian judicial deliberations
•Intractable disputes about withholding and withdrawing life-sustaining treatment from adults who lack capacity are rare but challenging. Judicial resolution may be needed in some of these cases. •A central concept for judicial (and clinical) decision making in this area is a patient's “best interests”. Yet what this term means is contested. •There is an emerging Supreme Court jurisprudence that sheds light on when life-sustaining treatment will, or will not, be judged to be in a patient's best interests. •Treatment that is either futile or overly burdensome is not in a patient's best interests. Although courts will consider patient and family wishes, they have generally deferred to the views of medical practitioners about treatment decisions
The prevalence and significance of renal perfusion defects in early kidney transplants quantified using 3D contrast enhanced ultrasound (CEUS)
Objectives - Vascular complications are one of the most common causes of early kidney transplant dysfunction. Contrast enhanced ultrasound increases sensitivity to tiny vascular changes.. The aim was to assess the prevalence and size of vascular abnormalities in renal transplantation patients following surgery using 3D CEUS to determine the significance of perfusion defects on renal function.
Methods - Ninety nine renal transplant patients underwent 3D CEUS after surgery to quantify perfusion defects as percentage total renal volume (TRV). Serum creatinine and estimated glomerular filtration rate (eGFR) were recorded up to three months post-surgery.
Results - In the 99 patients, 20 had perfusion defects (0.2 – 43% TRV). There was a meaningful difference in patients with perfusion defects in eGFR at 1 month (90% CI 2.7 to 19.2 ml/min/1.73m2) and 3 months (90% CI 1.9 to 19.6 ml/min/1.73m2) and in Creatinine at 3 months (90% CI -56 to -8 μmol/L) using a predetermined clinical threshold.
Perfusion defect size correlated well with both serum creatinine and eGFR at 3 months (R= 0.80 (p ≤ 0.000) and 0.58 (p= 0.038)). No correlation seen prior to 3 months.
Conclusions - Perfusion defects in kidney transplants were more common than expected and were highly likely to reduce renal function at 1-3 months and the size of the defect affected the degree of functional change at 3 months
The avifauna of the Barito Ulu region. Central Kalimantan
As part of the more general studies of the Barito Ulu Project, a detailed study was made of the avifauna in July-September 1989. The survey area, which lies at the geographical centre of the island of Borneo, consists mainly of primary forest in hilly terrain, and this Is the first detailed study that has been made In the hills of Kalimantan for many decades. A week was also spent in montane forest at 800-1000 m. An appendix lists 226 species that were recorded. The avifauna includes 15 Bornean endemics, and extensions to known range are made for Spizaetus alboniger, Arborophila hyperythra and Megalaima eximia. Data are provided also on 20 species for which there are no recent Kalimantan records. While species described as 'slope specialists' predominated, the presence of some 26 'extreme lowland specialists' may have significance for conservation, for example Lophura erythrophthalma, Melanoperdix nigra. Pitta baudi, Malacopteron albogulare and Pityriasis gymnocephala
Effect of 20 mph traffic speed zones on road injuries in London, 1986-2006: controlled interrupted time series analysis
Objective To quantify the effect of the introduction of 20 mph (32 km an hour) traffic speed zones on road collisions, injuries, and fatalities in London
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