A human-driven decline in global burned area Andela, N.; Morton, D. C.; Giglio, L. ...
Science (American Association for the Advancement of Science),
06/2017, Letnik:
356, Številka:
6345
Journal Article
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Fire is an essential Earth system process that alters ecosystem and atmospheric composition. Here we assessed long-term fire trends using multiple satellite data sets. We found that global burned ...area declined by 24.3 ± 8.8% over the past 18 years. The estimated decrease in burned area remained robust after adjusting for precipitation variability and was largest in savannas. Agricultural expansion and intensification were primary drivers of declining fire activity. Fewer and smaller fires reduced aerosol concentrations, modified vegetation structure, and increased the magnitude of the terrestrial carbon sink. Fire models were unable to reproduce the pattern and magnitude of observed declines, suggesting that they may overestimate fire emissions in future projections. Using economic and demographic variables, we developed a conceptual model for predicting fire in human-dominated landscapes.
Dynamic global vegetation model (DGVM) projections are often put forth to aid resource managers in climate change-related decision making. However, interpreting model results and understanding their ...uncertainty can be difficult. Sources of uncertainty include embedded assumptions about atmospheric CO2 levels, uncertain climate projections driving DGVMs, and DGVM algorithm selection. For western Oregon and Washington, we implemented an Environmental Evaluation Modeling System (EEMS) decision support model using MC2 DGVM results to characterize biomass loss risk. MC2 results were driven by climate projections from 20 General Circulation Models (GCMs) and Earth System Models (ESMs), under Representative Concentration Pathways (RCPs) 4.5 and 8.5, with and without assumed fire suppression, for three different time periods. We produced maps of mean, minimum, and maximum biomass loss risk and uncertainty for each RCP / +/- fire suppression / time period. We characterized the uncertainty due to RCP, fire suppression, and climate projection choice. Finally, we evaluated whether fire or climate maladaptation mortality was the dominant driver of risk for each model run. The risk of biomass loss generally increases in current high biomass areas within the study region through time. The pattern of increased risk is generally south to north and upslope into the Coast and Cascade mountain ranges and along the coast. Uncertainty from climate future choice is greater than that attributable to RCP or +/- fire suppression. Fire dominates as the driving factor for biomass loss risk in more model runs than mortality. This method of interpreting DGVM results and the associated uncertainty provides managers with data in a form directly applicable to their concerns and should prove helpful in adaptive management planning.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Climate change has already affected southern California where regional increases in temperature and vegetation shifts have been observed. While all the CMIP5 temperature projections agree on a ...substantial level of warming throughout the year, there is fair bit of divergence in the magnitude and seasonality of projected changes in rainfall. While desert plants and animals are generally adapted to extreme conditions, some species may be approaching their physiological threshold. We calculated the climate velocity of both temperature and aridity (PPT/PET) in SE California to illustrate the spatial variability of climate projections and reported on the probable expansion of barren lands reducing current species survivorship. We used a vegetation model to illustrate both temporal and spatial shifts in land cover in response to changes in environmental conditions. Such information is useful to plan land use for renewable energy siting in the region.
•We present CMIP5 projections for the Desert Renewable Energy Conservation Plan in S. California.•Temperatures increase overall but precipitation magnitude and seasonality diverge.•Wetter future projections allow woody lifeforms to expand in the Mohave.•With wetter futures, herbaceous expand in Sonoran, reducing extent of desert and barren land.•With wetter futures, fuel loads and fire risk are increasing.
Carotid atherosclerosis represents 8 to 15% of ischemic strokes in relation to the concept of “vulnerable” plaque. Contrast enhanced ultrasound (CEUS) can detect moving microbubbles within the plaque ...corresponding to neovessels that constitute “precursors” of vulnerable plaque and intraplaque hemorrhage. CEUS was not studied specifically in acute ischemic strokes. The aim of this study is to analyse the prevalence of CEUS carotid plaque ipsilateral at the ischemic stroke as well as the main characteristics of contrast-plaques.
A single-centre prospective pilot study involving 33 consecutive patients with a stroke ≤10 days, diagnosed by an MRI with positive diffusion sequence and having a carotid plaque thickness ≥2.5mm with low or heterogeneous echogenicity, located in the ipsilateral carotid territory at the stroke. Plaque echogenicity was done by visual analysis and by measurement of the gray scale median (GSM). A transcranial Doppler monitoring was carried out in search of HITS. The contrast ultrasound was performed after 2.5 cc IV injection of SonoVue®. A video clip was recorded after injection which was used for interpretation by visual analysis in 3 grades, provided by two independent expert readers.
The population consisted of 10 women and 23 men aged 73 on average. The topography of strokes in the carotid territory was located on the right in 11 (33%) cases and on the left in 22 (67%) cases. Seventeen patients had carotid stenosis between 0 and 49% according to the Nascet method and 16 patients had stenosis of 50 to 99%. The visual characterisation of the plaques had echolucent dominance (Type 1–2) in 18 cases and echogenic dominance (Type 3–4a) in 15 cases. Cardiovascular risk factors were common with no difference by sex. The inter-observer agreement of plaque enhancement was moderate in first reading (k=0.48) and excellent at consensus (k=0.91). Only one disagreement was found. Contrast agent enhancement of carotid plaque was observed in 11/32 patients, representing a prevalence of 34.4% – CI95% 17.9–50.9. Variables associated with contrast plaque included the absence of antiplatelet drug (63.6% vs. 23.8%, P=0.05) and the presence of a regular edge on the plaque (91% vs. 48%, P=0.04). There was no difference in contrast enhancement for stenosis>or<50% in diameter and neither for the type of plaque.
In a consecutive cohort of 33 patients, the prevalence of CEUS from an ipsilateral carotid plaque to a recent acute ischemic stroke was 34.4%. There was a statistically significant association between the contrast enhancement of the plaque and the absence of antiplatelet drug (P=0.05) and also the presence of a regular edge on the plaque (P=0.04). There was no correlation between plaque contrast and clinical and biological characteristics of patients or the presence of HITS.
Abstract
Background
The rationale behind the use of ethambutol in the standard tuberculosis treatment is to prevent the emergence of resistance to rifampicin in case of primary resistance to ...isoniazid. We evaluated whether early detection of isoniazid resistance using molecular testing allows the use an ethambutol-free regimen.
Methods
FAST-TB, a phase 4, French, multicenter, open-label, non-inferiority trial, compared 2 strategies: (1) polymerase chain reaction (PCR)-based detection of isoniazid and rifampicin resistance at baseline using Genotype MTBDRplus version 2.0 followed by ethambutol discontinuation if no resistance was detected (PCR arm) and (2) a standard 4-drug combination, pending phenotypic drug-susceptibility results (C arm). Adult patients with smear-positive pulmonary tuberculosis were enrolled. The primary endpoint was the proportion of patients with treatment success defined as bacteriological or clinical cure at the end of treatment. A non-inferiority margin of 10% was used.
Results
Two hundred three patients were randomized, 104 in the PCR arm and 99 in the C arm: 26.6% were female, median age was 37 (interquartile range, 28–51) years, 72.4% were born in Africa, and 5.4% were infected with human immunodeficiency virus. Chest x-ray showed cavities in 64.5% of the cases. Overall, 169 patients met criteria of treatment success: 87 of 104 (83.7%) in the PCR arm and 82 of 99 (82.8%) in the C arm with a difference of +0.8% (90% confidence interval, −7.9 to 9.6), meeting the noninferiority criteria in the intention-to-treat population (P = .02).
Conclusions
In a setting with low prevalence of primary isoniazid resistance, a 3-drug combination with isoniazid, rifampicin, and pyrazinamide, based on rapid detection of isoniazid resistance using molecular testing, was noninferior to starting the recommended 4-drug regimen.
The FAST-TB trial showed that after ruling out isoniazid resistance using a nucleic acid amplification test, a 3-drug combination of isoniazid, rifampicin, and pyrazinamide was noninferior to the standard 4-drug regimen with ethambutol with regards to tuberculosis treatment success.
Les granulocytes basophiles amplifient la production de complexes immuns au cours lupus érythémateux systémique et sont impliqués dans la physiopathologie de la néphropathie lupique (LN). Les LN de ...classe III/IV actives sont les plus sévères. Elles sont une source importante de morbidité surtout en cas de non-rémission après traitement. Il n’existe pas de biomarqueur permettant de prédire la réponse au traitement des LN.
L’objectif de l’étude était de mesurer si des marqueurs d’activation des basophiles (MAB) mesurés dans le sang périphérique au moment de la ponction biopsie rénale (PBR) (J0) chez des patients avec LN sévère prédisent la rémission rénale à 1 an. Etude observationnelle prospective recueillant les données cliniques et les MAB à J0 de patients atteints de LN Classe IIIA/IVA±V ou V ayant reçu un traitement d’induction. Ont été exclus les patients avec un débit de filtration glomérulaire au diagnostic<30ml/min/m2 et une sclérose glomérulaire >50 % à la PBR. La rémission a été définie comme une protéinurie <1g/j ou réduite de 50 % et <3g/j et une fonction rénale stable durant le suivi. Analyses univariées puis multivariées (modèle de COX) recherchant l’association entre les données cliniques, les MAB à J0 et la non-rémission de la LN à 12 mois.
La cohorte a compris 83 patients, 41 % avec une LN classe III/IV, 42 % avec une classe III/IV+V et 17 % une classe V ; 77 % sont entrés en rémission pendant les 12 mois suivants. En analyse univariée, seule la créatinine et le MAB1 à J0 étaient corrélés significativement à la non-rémission. En analyse multivariée, seul MAB1 prédisait la non-rémission (p=0,04) avec une valeur prédictive négative de 87 % pour une valeur<105 de moyenne géométrique d’intensité de fluorescence.
Le marqueur d’activation des basophiles MAB1 mesuré dans le sang périphérique au diagnostic des néphropathies lupiques sévères pourrait prédire la réponse ultérieure au traitement d’induction. C’est le premier biomarqueur pronostique identifié au diagnostic pour envisager la personnalisation du traitement.
Global change involves the simultaneous and rapid alteration of several key environmental parameters that control the dynamics of forests. Aber et al review the effects of several rapidly changing ...environmental drivers on ecosystem function, discuss interactions among them, and summarize predicted changes in productivity, carbon storage, and water balance.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The MC1 DGVM has been used in two international model comparison projects, VEMAP (Vegetation Ecosystem Modeling and Analysis Project) and VINCERA (Vulnerability and Impacts of North American forests ...to Climate Change: Ecosystem Responses and Adaptation). The latest version of MC1 was run on both VINCERA and VEMAP climate and soil input data to document how a change in the inputs can affect model outcome. We compared simulation results under the two sets of future climate scenarios and reported on how the different inputs can affect vegetation distribution and carbon budget projections. Under all future scenarios, the interior West becomes woodier as warmer temperatures and available moisture allow trees to get established in grasslands areas. Concurrently, warmer and drier weather causes the eastern deciduous and mixed forests to shift to a more open canopy woodland or savanna type while boreal forests disappear almost entirely from the Great Lakes area by the end of the 21st century. While under VEMAP scenarios the model simulated large increases in carbon storage in a future woodier West, the drier VINCERA scenarios accounted for large carbon losses in the east and only moderate gains in the West. But under all future climate scenarios, the total area burned by wildfires increased especially in C4 grasslands under all scenarios and in dry woodlands under VINCERA scenarios. The model simulated non-agricultural lands in the conterminous United States as a source of carbon in the 21st century under the VINCERA future climate scenarios but not VEMAP. However, the magnitude of this carbon source to the atmosphere could be greatly reduced if the CO
2 growth enhancement factor built in the model was enhanced but evidence that all mature forests across the entire country will respond positively to increased atmospheric CO2 is still lacking.
Greenhouse gas emissions have significantly altered global climate, and will continue to do so in the future. Increases in the frequency, duration, and/or severity of drought and heat stress ...associated with climate change could fundamentally alter the composition, structure, and biogeography of forests in many regions. Of particular concern are potential increases in tree mortality associated with climate-induced physiological stress and interactions with other climate-mediated processes such as insect outbreaks and wildfire. Despite this risk, existing projections of tree mortality are based on models that lack functionally realistic mortality mechanisms, and there has been no attempt to track observations of climate-driven tree mortality globally. Here we present the first global assessment of recent tree mortality attributed to drought and heat stress. Although episodic mortality occurs in the absence of climate change, studies compiled here suggest that at least some of the world's forested ecosystems already may be responding to climate change and raise concern that forests may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, even in environments that are not normally considered water-limited. This further suggests risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric feedbacks. Our review also identifies key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system. Overall, our review reveals the potential for amplified tree mortality due to drought and heat in forests worldwide.
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