538 research outputs found

    Strategies for Assessing Grassland Degradation with Biogeochemical Models

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    Marginal grasslands provide the basis for livestock rearing and rural livelihoods globally, but are subject to permanent degradation from mismanagement and climate change. Global biogeochemical models are so far not able to represent degradation tipping points in marginal grasslands because plant growth is dependent only on bio-climatic conditions and nutrient availability. Due to their central role for sustaining livelihoods, this lack of representation in such models needs to be addressed. We present an idea on processes and interactions to be considered and on the actual implementation of necessary changes. The model for which we exemplarily develop implementation strategies, LPJmL, accounts already for grassland dynamics globally in a fully coupled framework including soil dynamics and the hydrological cycle. Recent developments include the implementation of grassland harvesting schemes, the nitrogen cycle, fire management practices and representation of a variety of grass and legume species. Existing knowledge on the role of annual and perennial grass species for drought resistance will have to be utilized in order to advance model development. Different strategies for forming below-ground plant organs (roots and storage) have to be better understood from experimental studies before this can be implemented in models. Here, assumptions on functional relationships can be implemented and the resulting grass productivity can be analysed in comparison to field observations. Additionally, the formation of closed swards or tussocks plays a big role for the vulnerability to degradation by avoiding bare soil patches. This spatial phenomenon is usually neglected in models and can only be included by assumptions or in the form of aggregated effects. The long-term development of seed banks of key species determine the capability of regrowth after major drought periods so that seed bank formation and persistence is another component of necessary model development. All these components together with current developments of species competition and niche separation would build a framework that allows scenario assessments on tipping points depending on climatic conditions and management

    Migraine and vascular disease biomarkers: A population-based case-control study.

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    Background The underpinnings of the migraine-stroke association remain uncertain, but endothelial activation is a potential mechanism. We evaluated the association of migraine and vascular disease biomarkers in a community-based population. Methods Participants (300 women, 117 men) were recruited as a part of the Dutch CAMERA 1 (Cerebral Abnormalities in Migraine, an Epidemiologic Risk Analysis) study. Participants were aged 30-60 (mean 48) years, 155 migraine had with aura (MA), 128 migraine without aura (MO), and 134 were controls with no severe headaches. Plasma concentrations of fibrinogen, Factor II, D-dimer, high sensitivity C-reactive protein (hs-CRP), and von Willebrand factor antigen were compared between groups, also stratifying by sex. Results Fibrinogen and hs-CRP were elevated in migraineurs compared to controls. In logistic regression analyses, MO and MA had increased likelihood of elevated fibrinogen, and MA had increased likelihood of elevated Factor II and hs-CRP. Fibrinogen and Factor II were associated with MA in women but not men. In the migraine subgroup, the total number of years of aura, but not headache, predicted elevated hs-CRP, and the average number of aura, but not headache, attacks predicted all biomarkers but Factor II. Conclusions Elevated vascular biomarkers were associated with migraine, particularly MA, as well as with years of aura and number of aura attacks

    Benthic enrichment in the Georgia Bight related to Gulf Stream intrusions and estuarine outwelling

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    The distribution patterns of benthic biomass (microbiota, meiofauna, and macrofauna) over the expansive continental shelf of the Georgia Bight suggest nutrient inputs from intrusions of deep Gulf Stream waters at the shelf break…

    Application of a Near Infrared Imaging System for Thermographic Imaging of the Space Shuttle during Hypersonic Re-Entry

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    High resolution calibrated near infrared (NIR) imagery was obtained of the Space Shuttle s reentry during STS-119, STS-125, and STS-128 missions. The infrared imagery was collected using a US Navy NP-3D Orion aircraft using a long-range infrared optical package referred to as Cast Glance. The slant ranges between the Space Shuttle and Cast Glance were approximately 26-41 nautical miles at point of closest approach. The Hypersonic Thermodynamic Infrared Measurements (HYTHIRM) project was a NASA Langley led endeavor sponsored by the NASA Engineering Safety Center, the Space Shuttle Program Office and the NASA Aeronautics Research Mission Directorate to demonstrate a quantitative thermal imaging capability. HYTHIRM required several mission tools to acquire the imagery. These tools include pre-mission acquisition simulations of the Shuttle trajectory in relationship to the Cast Glance aircraft flight path, radiance modeling to predict the infrared response of the Shuttle, and post mission analysis tools to process the infrared imagery to quantitative temperature maps. The spatially resolved global thermal measurements made during the Shuttle s hypersonic reentry provides valuable flight data for reducing the uncertainty associated with present day ground-to-flight extrapolation techniques and current state-of-the-art empirical boundary-layer transition or turbulent heating prediction methods. Laminar and turbulent flight data is considered critical for the development of turbulence models supporting NASA s next-generation spacecraft. This paper will provide the motivation and details behind the use of an upgraded NIR imaging system used onboard a Navy Cast Glance aircraft and describe the characterizations and procedures performed to obtain quantitative temperature maps. A brief description and assessment will be provided of the previously used analog NIR camera along with image examples from Shuttle missions STS-121, STS-115, and solar tower test. These thermal observations confirmed the challenge of a long-range acquisition during re-entry. These challenges are due to unknown atmospheric conditions, image saturation, vibration etc. This provides the motivation for the use of a digital NIR sensor. The characterizations performed on the digital NIR sensor included radiometric, spatial, and spectral measurements using blackbody radiation sources and known targets. An assessment of the collected data for three Space Shuttle atmospheric re-entries, STS-119, STS-125, and STS-128, are provided along with a description of various events of interest captured using the digital NIR imaging system such as RCS firings and boundary layer transitions. Lastly the process used to convert the raw image counts to quantitative temperatures is presented along with comparisons to the Space Shuttle's onboard thermocouples

    HYTHIRM Radiance Modeling and Image Analyses in Support of STS-119, STS-125 and STS-128 Space Shuttle Hypersonic Re-entries

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    We provide the first geometrically accurate (i.e., 3-D) temperature maps of the entire windward surface of the Space Shuttle during hypersonic reentry. To accomplish this task we began with estimated surface temperatures derived from CFD models at integral high Mach numbers and used them, the Shuttle's surface properties and reasonable estimates of the sensor-to-target geometry to predict the emitted spectral radiance from the surface (in units of W sr-1 m-2 nm-1). These data were converted to sensor counts using properties of the sensor (e.g. aperture, spectral band, and various efficiencies), the expected background, and the atmosphere transmission to inform the optimal settings for the near-infrared and midwave IR cameras on the Cast Glance aircraft. Once these data were collected, calibrated, edited, registered and co-added we formed both 2-D maps of the scene in the above units and 3-D maps of the bottom surface in temperature that could be compared with not only the initial inputs but also thermocouple data from the Shuttle itself. The 3-D temperature mapping process was based on the initial radiance modeling process. Here temperatures were guessed for each node in a well-resolved 3-D framework, a radiance model was produced and compared to the processed imagery, and corrections to the temperature were estimated until the iterative process converged. This process did very well in characterizing the temperature structure of the large asymmetric boundary layer transition the covered much of the starboard bottom surface of STS-119 Discovery. Both internally estimated accuracies and differences with CFD models and thermocouple measurements are at most a few percent. The technique did less well characterizing the temperature structure of the turbulent wedge behind the trip due to limitations in understanding the true sensor resolution. (Note: Those less inclined to read the entire paper are encouraged to read an Executive Summary provided at the end.

    Reviewing the Market Stability Reserve in light of more ambitious EU ETS emission targets

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    The stringency of the EU's Emission Trading System (ETS) is bound to be ratcheted-up to deliver on more ambitious goals as formulated in the EU's Green Deal. Tightening the cap needs to consider the interactions with the Market Stability Reserve (MSR), which will be reviewed in 2021. We analyse these issues using the model LIMES-EU. First, we examine how revising MSR parameters impacts allowance cancellations. We find that varying key design parameters leads to cancellations in the range of 2.6–7.9 Gt – compared to 5.1 Gt under current regulation. Overall, the bank thresholds, which define when there is intake to/outtake from the MSR, have the highest impact. Intake rates above 12% only have a limited effect, and cause oscillatory intake behaviour. Second, we analyse how more ambitious climate 2030 targets can be achieved by adjusting the linear reduction factor (LRF). We find that the LRF increases MSR cancellations substantially up to 10.0 Gt. This implies that increasing its value from currently 2.2% to only 2.6% could be consistent with an EU-wide target of −55% by 2030. However, MSR cancellations are subject to large uncertainty, which increases the complexity of the market and induces high price uncertainty

    Global and regional burden of hospital admissions for pneumonia in older adults::A systematic review and meta-analysis

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    Pneumonia constitutes a substantial disease burden among adults overall and those who are elderly. We aimed to identify all studies investigating the disease burden among older adults (age, ≥65 years) admitted to the hospital with pneumonia. We estimated the hospital admission rate and in-hospital case-fatality ratio (CFR) of pneumonia in older adults, stratified by age and economic status (industrialized vs developing), with data from a systematic review of studies published from 1996 through 2017 and from 8 unpublished population-based studies. We applied these rate estimates to population estimates for 2015 to calculate the global and regional burden in older adults who would have been admitted to the hospital with pneumonia that year. We estimated the number of in-hospital pneumonia deaths by combining in-hospital CFRs with hospital admission estimates from hospital-based studies. We identified 109 eligible studies; 73 used clinical pneumonia as the case definition, and 36 used radiologically confirmed pneumonia as the case definition. We estimated that, in 2015, 6.8 million episodes (uncertainty range [UR], 5.8-8.0 episodes) of clinical pneumonia resulted in hospital admissions of older adults worldwide. The hospital admission rate increased with advancing age and was higher in men. The total disease burden was likely underestimated when using the definition of radiologically confirmed pneumonia. Based on data from 52 hospital studies reporting data on pneumonia mortality, we estimated that about 1.1 million in-hospital deaths (UR, 0.9-1.4 in-hospital deaths) occurred among older adults. The burden of pneumonia requiring hospitalization among older adults is substantial. Appropriate prevention and management strategies should be developed to reduce its impact

    Climate change reduces extent of temperate drylands and intensifies drought in deep soils

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    Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. While drylands as a whole are expected to increase in extent and aridity in coming decades, temperature and precipitation forecasts vary by latitude and geographic region suggesting different trajectories for tropical, subtropical, and temperate drylands. Uncertainty in the future of tropical and subtropical drylands is well constrained, whereas soil moisture and ecological droughts, which drive vegetation productivity and composition, remain poorly understood in temperate drylands. Here we show that, over the twenty first century, temperate drylands may contract by a third, primarily converting to subtropical drylands, and that deep soil layers could be increasingly dry during the growing season. These changes imply major shifts in vegetation and ecosystem service delivery. Our results illustrate the importance of appropriate drought measures and, as a global study that focuses on temperate drylands, highlight a distinct fate for these highly populated areas

    Joint Metabonomic and Instrumental Analysis for the Classification of Migraine Patients with 677-MTHFR Mutations

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    Migraine is a neurological disorder that correlates with an increased risk of cerebrovascular lesions. Genetic mutations of the MTHFR gene are correlated to migraine and to the increased risk of artery pathologies. Also, migraine patients show altered hematochemical parameters, linked to an impaired platelet aggregation mechanism. Hence, the vascular assessment of migraineurs is of primary importance
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