Road traffic is one of the main sources of particulate matter in the atmosphere. Despite its importance, there are significant challenges in quantitative evaluation of its contribution to airborne ...concentrations. This article first reviews the nature of the particle emissions from road vehicles including both exhaust and non-exhaust (abrasion and re-suspension sources). It then briefly reviews the various methods available for quantification of the road traffic contribution. This includes tunnel/roadway measurements, twin site studies, use of vehicle-specific tracers and other methods. Finally, the application of receptor modelling methods is briefly described. Based on the review, it can be concluded that while traffic emissions continue to contribute substantially to primary PM emissions in urban areas, quantitative knowledge of the contribution, especially of non-exhaust emissions to PM concentrations remain inadequate.
•Road traffic contributes emissions from exhaust, abrasion and re-suspension sources.•Chemical and physical properties of the emitted particles are described.•Available methods for quantification of traffic-derived concentrations are reviewed.
L'utilisation de podomètres est de plus en plus rependue dans le cadre d'interventions visant à rehausser le niveau d'activité physique (AP). Cependant, le seuil minimal de nombre de pas à atteindre ...pour améliorer le contrôle des facteurs de risque demeure incertain. Objectif Vérifier si les personnes atteintes de cardiopathie ischémique qui réalisent en moyenne au moins 7500 pas par jour ou plus de 15 minutes quotidiennes d'activité physique d'intensité moyenne à vigoureuse (APMV) (≥ 3,6 METs) sur une période d'un an ont un meilleur contrôle des facteurs de risque de MCV que ceux qui n'atteignent pas ces objectifs. Méthode Étude descriptive comparative où l'AP a été mesurée avec un podomètre (Digiwalker NL-1000) porté à la taille du lever au coucher durant 7 jours. Cette mesure a été prise 5 fois à intervalle de 3 mois. L'échantillon était composé 20 hommes et 16 femmes (66 ± 6 ans). Après 12 mois, les moyennes de pas quotidiens et de minutes passées à faire une APMV étaient calculées pour chaque participant. Ceux ayant exécuté une moyenne de ≥ 7500 pas étaient classés dans le groupe STEP+ et ceux ayant une moyenne de > 15 minutes d'APMV étaient classés dans MIN+. Les indicateurs cliniques de facteur de risque ont été mesurés 3 fois à intervalle de 6 mois. Résultats Les groupes STEP+ (n = 12) et STEP– (n = 23) ont respectivement exécuté 5040 ± 1522 et 9128 ± 1695 pas en moyenne sur 12 mois. Une différence significative a été observée entre ces groupes pour le tour de taille (Δ11,2 ± 3,4 cm), l'IMC (Δ 4,7 ± 1,7 kg/m2), triglycérides (Δ0,41 ± 0,14 mmol/L), et le cholestérol non-HDL (Δ0,46 ± 0,2 mmol/L). La moyenne quotidienne de minutes d'APMV chez les groupes MIN– et MIN+ étaient respectivement 8,0 ± 3,9 min et 22,8 ± 5,3 min. Le tour de taille atteignait davantage les cibles chez le groupe MIN+. Conclusion Les personnes avec une cardiopathie ischémique qui ont effectué 7500 pas/jour ou 15 min/jour d'APMV semblent avoir un meilleur contrôle de certains facteurs de risque tels que l'obésité et la dyslipidémie. Ces résultats encouragent les patients avec cardiopathie ischémique de maintenir une activité physique quotidienne de 7500 pas/jour ou 15 min d'APMV afin de réduire leur risque cardiovasculaire.
Civil aviation is fast-growing (about +5% every year), mainly driven by the developing economies and globalisation. Its impact on the environment is heavily debated, particularly in relation to ...climate forcing attributed to emissions at cruising altitudes and the noise and the deterioration of air quality at ground-level due to airport operations. This latter environmental issue is of particular interest to the scientific community and policymakers, especially in relation to the breach of limit and target values for many air pollutants, mainly nitrogen oxides and particulate matter, near the busiest airports and the resulting consequences for public health. Despite the increased attention given to aircraft emissions at ground-level and air pollution in the vicinity of airports, many research gaps remain. Sources relevant to air quality include not only engine exhaust and non-exhaust emissions from aircraft, but also emissions from the units providing power to the aircraft on the ground, the traffic due to the airport ground service, maintenance work, heating facilities, fugitive vapours from refuelling operations, kitchens and restaurants for passengers and operators, intermodal transportation systems, and road traffic for transporting people and goods in and out to the airport. Many of these sources have received inadequate attention, despite their high potential for impact on air quality. This review aims to summarise the state-of-the-art research on aircraft and airport emissions and attempts to synthesise the results of studies that have addressed this issue. It also aims to describe the key characteristics of pollution, the impacts upon global and local air quality and to address the future potential of research by highlighting research needs.
•Aviation is globally growing (+5% y−1) mainly driven by developing countries.•Airport operations cause an increase in ground-level pollution.•Chemical and physical properties of the emitted gases and particles are reviewed.•An overview of other additional sources within airports is provided.•Future research needs on aircraft emissions are highlighted.
For the 2009 influenza A H1N1 pandemic, in most infected people these epidemiological quantities were short with a day or so to infectiousness and a few days of peak infectiousness to others.3 By ...contrast, for COVID-19, the serial interval is estimated at 4·4–7·5 days, which is more similar to SARS.4 First among the important unknowns about COVID-19 is the case fatality rate (CFR), which requires information on the denominator that defines the number infected. ...the effect of seasons on transmission of COVID-19 is unknown;11 however, with an R0 of 2–3, the warm months of summer in the northern hemisphere might not necessarily reduce transmission below the value of unity as they do for influenza A, which typically has an R0 of around 1·1–1·5.12 Closely linked to these factors and their epidemiological determinants is the impact of different mitigation policies on the course of the COVID-19 epidemic. A key issue for epidemiologists is helping policy makers decide the main objectives of mitigation—eg, minimising morbidity and associated mortality, avoiding an epidemic peak that overwhelms health-care services, keeping the effects on the economy within manageable levels, and flattening the epidemic curve to wait for vaccine development and manufacture on scale and antiviral drug therapies. Avoiding large gatherings of people will reduce the number of super-spreading events; however, if prolonged contact is required for transmission, this measure might only reduce a small proportion of transmissions. ...broader-scale social distancing is likely to be needed, as was put in place in China.
Although sinus node dysfunction (SND) and atrial arrhythmias frequently coexist and interact, the putative mechanism linking the 2 remain unclear. Although SND is accompanied by atrial myocardial ...structural changes in the right atrium, atrial fibrillation (AF) is a disease of variable interactions between left atrial triggers and substrate most commonly of left atrial origin. Significant advances have been made in our understanding of the genetic and pathophysiologic mechanism underlying the development and progression of SND and AF. Although some patients manifest SND as a result of electric remodeling induced by periods of AF, others develop progressive atrial structural remodeling that gives rise to both conditions together. The treatment strategy will thus vary according to the predominant disease phenotype. Although catheter ablation will benefit patients with predominantly AF and secondary SND, cardiac pacing may be the mainstay of therapy for patients with predominant fibrotic atrial cardiomyopathy. This contemporary review summarizes current knowledge on sinus node pathophysiology with the broader goal of yielding insights into the complex relationship between sinus node disease and atrial arrhythmias.
Severe Covid-19 Berlin, David A; Gulick, Roy M; Martinez, Fernando J
New England journal of medicine/The New England journal of medicine,
12/2020, Letnik:
383, Številka:
25
Journal Article
A 5-year Clean Air Action Plan was implemented in 2013 to reduce air
pollutant emissions and improve ambient air quality in Beijing. Assessment
of this action plan is an essential part of the ...decision-making process to
review its efficacy and to develop new policies. Both
statistical and chemical transport modelling have been previously applied to
assess the efficacy of this action plan. However, inherent uncertainties in
these methods mean that new and independent methods are required to support
the assessment process. Here, we applied a machine-learning-based random
forest technique to quantify the effectiveness of Beijing's action plan by
decoupling the impact of meteorology on ambient air quality. Our results
demonstrate that meteorological conditions have an important impact on the
year-to-year variations in ambient air quality. Further analyses show that
the PM2.5 mass concentration would have broken the target of the plan
(2017 annual PM2.5<60 µg m−3) were it not for the
meteorological conditions in winter 2017 favouring the dispersion of air
pollutants. However, over the whole period (2013–2017), the primary
emission controls required by the action plan have led to significant
reductions in PM2.5, PM10, NO2, SO2, and CO from 2013 to 2017 of approximately 34 %, 24 %, 17 %, 68 %, and 33 %, respectively, after meteorological correction. The marked decrease in PM2.5 and SO2 is largely attributable to a reduction in coal
combustion. Our results indicate that the action plan has been highly
effective in reducing the primary pollution emissions and improving air
quality in Beijing. The action plan offers a successful example for
developing air quality policies in other regions of China and other
developing countries.
Antiretroviral drugs have revolutionized the treatment and prevention of HIV infection; however, adherence is critical for sustained efficacy. Current HIV treatment consists of three-drug regimens, ...and current HIV pre-exposure prophylaxis (PrEP) consists of a two-drug regimen; both generally require adherence to once-daily dosing. Long-acting formulations are useful in the treatment and prevention of other conditions (e.g., contraceptives, antipsychotics) and help promote adherence. Newer long-acting formulations of approved and investigational antiretroviral drugs in existing and newer mechanistic classes are under study for HIV treatment and prevention, including some phase III trials. Although long-acting antiretroviral drugs hold promise, some clinical challenges exist, including managing side effects, drug-drug interactions, pregnancy, and long-lasting drug concentrations that could lead to the development of drug resistance. This review aims to summarize currently available information on long-acting antiretroviral drugs for HIV treatment and prevention.
Extreme drought events have negative effects on forest diversity and functioning. At the species level, however, these effects are still unclear, as species vary in their response to drought through ...specific functional trait combinations. We used long‐term demographic records of 21,821 trees and extensive databases of traits to understand the responses of 338 tropical dry forests tree species to ENSO2015, the driest event in decades in Northern South America. Functional differences between species were related to the hydraulic safety‐efficiency trade‐off, but unexpectedly, dominant species were characterised by high investment in leaf and wood tissues regardless of their leaf phenological habit. Despite broad functional trait combinations, tree mortality was more widespread in the functional space than tree growth, where less adapted species showed more negative net biomass balances. Our results suggest that if dry conditions increase in this ecosystem, ecological functionality and biomass gain would be reduced.
Extreme drought events have negative effects on forest diversity and functioning. We used long‐term demographic records of 21,821 trees and extensive databases of traits to understand the responses of 338 tropical dry forests tree species to an extreme. Our results indicate that irrespective of the drought adaptations, most trees will be negatively affected under drier scenarios predicted for tropical dry forests.
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