Research priorities in the secondary prevention of atrial fibrillation: a National Heart, Lung, and Blood Institute virtual workshop report

There has been sustained focus on the secondary prevention of coronary heart disease and heart failure; yet, apart from stroke prevention, the evidence base for the secondary prevention of atrial fibrillation (AF) recurrence, AF progression, and AF-related complications is modest. Although there are multiple observational studies, there are few large, robust, randomized trials providing definitive effective approaches for the secondary prevention of AF. Given the increasing incidence and prevalence of AF nationally and internationally, the AF field needs transformative research and a commitment to evidenced-based secondary prevention strategies. We report on a National Heart, Lung, and Blood Institute virtual workshop directed at identifying knowledge gaps and research opportunities in the secondary prevention of AF. Once AF has been detected, lifestyle changes and novel models of care delivery may contribute to the prevention of AF recurrence, AF progression, and AF-related complications. Although benefits seen in small subgroups, cohort studies, and selected randomized trials are impressive, the widespread effectiveness of AF secondary prevention strategies remains unknown, calling for development of scalable interventions suitable for diverse populations and for identification of subpopulations who may particularly benefit from intensive management. We identified critical research questions for 6 topics relevant to the secondary prevention of AF: (1) weight loss; (2) alcohol intake, smoking cessation, and diet; (3) cardiac rehabilitation; (4) approaches to sleep disorders; (5) integrated, team-based care; and (6) nonanticoagulant pharmacotherapy. Our goal is to stimulate innovative research that will accelerate the generation of the evidence to effectively pursue the secondary prevention of AF.Emelia J. Benjamin, Sana M. Al-Khatib, Patrice Desvigne-Nickens, Alvaro Alonso, Luc Djoussé, Daniel E. Forman, Anne M. Gillis, Jeroen M.L. Hendriks, Mellanie True Hills, Paulus Kirchhof, Mark S. Link, Gregory M. Marcus, Reena Mehra, Katherine T. Murray, Ratika Parkash, Ileana L. Piña, Susan Redline, Michiel Rienstra, Prashanthan Sanders, Virend K. Somers, David R. Van Wagoner, Paul J. Wang, Lawton S. Cooper, Alan S. G

Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy

During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the Swift data into on- and off-anomaly spectra to characterize the soft excess via spectral fitting. The cause of the spectral differences is likely due to a change in the intrinsic spectrum rather than to variable obscuration or partial covering. The Chandra spectra have lower signal-to-noise ratios, but are consistent with the Swift data. Our preferred model of the soft excess is emission from an optically thick, warm Comptonizing corona, the effective optical depth of which increases during the anomaly. This model simultaneously explains all three observations: the UV emission-line flux decrease, the soft-excess increase, and the emission-line anomaly

TRY plant trait database – enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Experimental investigation of reactivity controlled compression ignition with n-butanol/n-heptane in a heavy-duty diesel engine

Butanol is a potential alternative fuel to be applied in the internal combustion engine for its sustainability and low-sooting propensity. In this paper, n-butanol is port injected as low reactivity fuel and n-heptane is directly injected into cylinder as high reactivity fuel to achieve high thermal efficiency as well as low soot/NOx emissions. To understand the effects of charge preparation parameters and load range of this reactivity controlled compression ignition combustion, experiments are performed in a single cylinder heavy-duty diesel engine. The results show that single direct injection causes either too early combustion phasing or excessive HC/CO emissions. Increasing the inlet boosting pressure is beneficial to obtain high thermal efficiency but HC/CO emissions deteriorate remarkably. The double direct injection strategy can phase the combustion properly and obtain high gross indicated efficiency without sacrificing CO emissions too much. Additionally, a high exhaust gas recirculation rate is necessary to achieve proper control of combustion phasing as the reactivity of n-butanol is not low enough. It is found that the n-butanol/n-heptane reactivity controlled compression ignition can be operated from low to medium loads. And the sensitivity of combustion phasing to the direct injection timing decreases as the load increases. At medium–high load, combustion couldn't be phased after the top dead center, which leads to high pressure rise rates and high peak pressures. Extremely low particulate matter and NOx emissions are observed throughout this tested load range and a gross indicated efficiency over 50% can be observed from low to medium load

Modelling of methane-air combustion on ceramic foam surface burners in the radiation mode

The flame behaviour of a ceramic foam surface burner in the radiation mode has been studied. Two models are presented. The first numerical model is based on the skeletal mechanism for lean methane-air combustion consisting of 25 reactions among 16 species. Surface radiation of the burner is included. The second simple analytical model is based on the known behaviour of 1D flames on an externally cooled perfectly conducting burner. The radiative heat loss of the burner is balanced with the energy loss of the flame to the burner. Both models predict the same non-adiabatic flame temperature within a few degrees. There is a slight difference between the predicted surface temperatures, which is caused by errors in the average value for the heat capacity in the second model. Results of the surface and gas temperature measurements show the same trends as the numerical computations, although the absolute values show some discrepancies. The discrepancies of the surface temperature are caused by uncertainties of the effective emissivity of the surface, and the discrepancies of the gas temperature are caused by the rather large corrections of the thermocouple temperature

Effects of exhaust gas recirculation at various loads on diesel engine performance and exhaust particle size distribution using four blends with a research octane number of 70 and diesel

Partially premixed combustion using gasoline-like fuels on compression ignition engines shows great potentials to break the soot-nitrogen oxides trade off and reduce both emissions simultaneously. By simply adjusting the dilution strategies and injection events, the control of partially premixed combustion is relatively easier compared to other low-temperature combustion concepts. However despite these advantages, recent research shows this concept tends to emit ultra-fine particles. Most previous work on partially premixed combustion only focuses on the soot emissions while the particulate matter in terms of number concentration and size distribution are not well investigated. Ultra-fine particles are dangerous to human health and are getting increasing attentions. Thus the detailed particulate matter emission from partially premixed combustion needs to be further investigated. In this work four gasoline-like ternary fuel blends are designed and experimentally tested under partially premixed combustion. The test blends all share the same two base fuels and blended with different additives. The fuel composition is varied to have the same research octane number. Tests are conducted under different engine loads and dilution strategies since the temperature and oxygen concentration are the key factors in the formation and oxidation of soot. Standard diesel is also tested under the same conditions as a comparison. It is found that these blends are capable of running under partially premixed combustion at low and medium loads and they produce near zero soot emissions when using high exhaust gas recirculation rate. However, these blends do emit smaller particles than diesel under all test loads. Besides, blends with oxygen content yield less soot emissions and smaller particles compared to non-oxygen blends

Experimental investigation of ethanol/diesel dual-fuel combustion in a heavy-duty diesel engine

Ethanol is a promising alternative fuel applicable in the internal combustion engine by virtue of its sustainability and soot-reducing potential. In this study, ethanol is injected into the intake port while diesel is directly injected into the cylinder of a heavy-duty diesel engine enabling dual-fuel operation. The main goals of the study are to probe the ethanol substitution ratio and load range and assess the resulting engine performance and emissions. Tests were performed with the original calibration at several loads using the European Stationary Cycle. The results show that ethanol mass ratios of up to 80% may be reached at low to medium loads without misfire. Addition of ethanol can reduce soot emissions, with no consistent effects on NOx emissions. As the ethanol mass ratio increases, dual-fuel operation suffers from incomplete combustion progressively. Increased HC and CO emissions are, however, believed to be manageable by a diesel oxidation catalyst at high loads. Both combustion and thermal efficiency decrease at low load when ethanol is introduced. However, thermal efficiency at medium load increases from 49.1% to 50%. For medium to high loads, thermal efficiency first increases to 50.7% and 49.7%, respectively, then decreases due to sub-optimal combustion phasing at high ethanol mass ratios. It is noteworthy that the pressure rise rate, ringing intensity, and peak pressure may appear to limit the ethanol ratio to below 40% for medium to high loads. However, this can be mitigated by delaying diesel injection timing, phasing the combustion later, without a large efficiency compromise

Biodiesel soot incandescence and NO emission studied in an optical engine

\u3cp\u3eHigh-speed imaging and thermodynamical characterization are applied to an optically accessible, heavy-duty diesel engine in order to compare soot incandescence and NO emission behaviour of four bioderived fuels: rapeseed-methylester, Jatropha oil (pure), Jatropha-methylester and a 50/50 blend of cyclohexanone with a Fischer-Tropsch synthetic fuel. Regular diesel fuel is used as a reference. Soot incandescence is observed at 0.3° crank angle resolution (200 images/cycle). The heat release rate and exhaust NO concentrations are used as indicators of average and peak temperatures, respectively, which are combined with soot incandescence signal to get a relative measure for a fuel's sooting propensity.\u3c/p\u3

Biodiesel soot incandescence and NO emission studied in an optical engine

High-speed imaging and thermodynamical characterization are applied to an optically accessible, heavy-duty diesel engine in order to compare soot incandescence and NO emission behaviour of four bioderived fuels: rapeseed-methylester, Jatropha oil (pure), Jatropha-methylester and a 50/50 blend of cyclohexanone with a Fischer-Tropsch synthetic fuel. Regular diesel fuel is used as a reference. Soot incandescence is observed at 0.3° crank angle resolution (200 images/cycle). The heat release rate and exhaust NO concentrations are used as indicators of average and peak temperatures, respectively, which are combined with soot incandescence signal to get a relative measure for a fuel's sooting propensity