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- Hollister, R. D., et al.
(författare)
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A review of open top chamber (OTC) performance across the ITEX Network
- 2023
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Ingår i: Arctic Science. - : Canadian Science Publishing. - 2368-7460. ; 9:2, s. 331-344
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Tidskriftsartikel (refereegranskat)abstract
- Open top chambers (OTCs) were adopted as the recommended warming mechanism by the International Tundra Experiment network in the early 1990s. Since then, OTCs have been deployed across the globe. Hundreds of papers have reported the im-pacts of OTCs on the abiotic environment and the biota. Here, we review the impacts of the OTC on the physical environment, with comments on the appropriateness of using OTCs to characterize the response of biota to warming. The purpose of this review is to guide readers to previously published work and to provide recommendations for continued use of OTCs to under -stand the implications of warming on low stature ecosystems. In short, the OTC is a useful tool to experimentally manipulate temperature; however, the characteristics and magnitude of warming varies greatly in different environments; therefore, it is important to document chamber performance to maximize the interpretation of biotic response. When coupled with long-term monitoring, warming experiments are a valuable means to understand the impacts of climate change on natural ecosystems.
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| 7. |
- Duncanson, Laura, et al.
(författare)
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Aboveground biomass density models for NASA's Global Ecosystem Dynamics Investigation (GEDI) lidar mission
- 2022
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257 .- 1879-0704. ; 270
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Tidskriftsartikel (refereegranskat)abstract
- NASA's Global Ecosystem Dynamics Investigation (GEDI) is collecting spaceborne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). This paper presents the development of the models used to create GEDI's footprint-level (~25 m) AGBD (GEDI04_A) product, including a description of the datasets used and the procedure for final model selection. The data used to fit our models are from a compilation of globally distributed spatially and temporally coincident field and airborne lidar datasets, whereby we simulated GEDI-like waveforms from airborne lidar to build a calibration database. We used this database to expand the geographic extent of past waveform lidar studies, and divided the globe into four broad strata by Plant Functional Type (PFT) and six geographic regions. GEDI's waveform-to-biomass models take the form of parametric Ordinary Least Squares (OLS) models with simulated Relative Height (RH) metrics as predictor variables. From an exhaustive set of candidate models, we selected the best input predictor variables, and data transformations for each geographic stratum in the GEDI domain to produce a set of comprehensive predictive footprint-level models. We found that model selection frequently favored combinations of RH metrics at the 98th, 90th, 50th, and 10th height above ground-level percentiles (RH98, RH90, RH50, and RH10, respectively), but that inclusion of lower RH metrics (e.g. RH10) did not markedly improve model performance. Second, forced inclusion of RH98 in all models was important and did not degrade model performance, and the best performing models were parsimonious, typically having only 1-3 predictors. Third, stratification by geographic domain (PFT, geographic region) improved model performance in comparison to global models without stratification. Fourth, for the vast majority of strata, the best performing models were fit using square root transformation of field AGBD and/or height metrics. There was considerable variability in model performance across geographic strata, and areas with sparse training data and/or high AGBD values had the poorest performance. These models are used to produce global predictions of AGBD, but will be improved in the future as more and better training data become available.
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| 8. |
- Yu, Lei, et al.
(författare)
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Ocean current patterns drive the worldwide colonization of eelgrass (Zostera marina)
- 2023
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Ingår i: Nature Plants. - 2055-026X .- 2055-0278. ; 9:8, s. 1207-1220
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Tidskriftsartikel (refereegranskat)abstract
- Currents are unique drivers of oceanic phylogeography and thus determine the distribution of marine coastal species, along with past glaciations and sea-level changes. Here we reconstruct the worldwide colonization history of eelgrass (Zostera marina L.), the most widely distributed marine flowering plant or seagrass from its origin in the Northwest Pacific, based on nuclear and chloroplast genomes. We identified two divergent Pacific clades with evidence for admixture along the East Pacific coast. Two west-to-east (trans-Pacific) colonization events support the key role of the North Pacific Current. Time-calibrated nuclear and chloroplast phylogenies yielded concordant estimates of the arrival of Z. marina in the Atlantic through the Canadian Arctic, suggesting that eelgrass-based ecosystems, hotspots of biodiversity and carbon sequestration, have only been present there for ~243ky (thousand years). Mediterranean populations were founded ~44kya, while extant distributions along western and eastern Atlantic shores were founded at the end of the Last Glacial Maximum (~19kya), with at least one major refuge being the North Carolina region. The recent colonization and five- to sevenfold lower genomic diversity of the Atlantic compared to the Pacific populations raises concern and opportunity about how Atlantic eelgrass might respond to rapidly warming coastal oceans.
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| 9. |
- Benz, Alexander P., et al.
(författare)
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Stroke risk prediction in patients with atrial fibrillation with and without rheumatic heart disease
- 2021
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Ingår i: Cardiovascular Research. - : Oxford University Press. - 0008-6363 .- 1755-3245. ; 118:1, s. 295-304
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Tidskriftsartikel (refereegranskat)abstract
- Aims Patients with atrial fibrillation (AF) and rheumatic heart disease (RHD), especially mitral stenosis, are assumed to be at high risk of stroke, irrespective of other factors. We aimed to re-evaluate stroke risk factors in a contemporary cohort of AF patients. Methods and results We analysed data of 15 400 AF patients presenting to an emergency department and who were enrolled in the global RE-LY AF registry, representing 47 countries from all inhabited continents. Follow-up occurred at 1 year after enrolment. A total of 1788 (11.6%) patients had RHD. These patients were younger (51.4 +/- 15.7 vs. 67.8 +/- 13.6 years), more likely to be female (66.2% vs. 44.7%) and had a lower mean CHA(2)DS(2)-VASc score (2.1 +/- 1.7 vs. 3.7 +/- 2.2) as compared to patients without RHD (all P<0.001). Significant mitral stenosis (average mean transmitral gradient 11.5 +/- 6.5 mmHg) was the predominant valve lesion in those with RHD (59.6%). Patients with RHD had a higher baseline rate of anticoagulation use (60.4% vs. 45.2%, P<0.001). Unadjusted stroke rates at 1 year were 2.8% and 4.1% for patients with and without RHD, respectively. The performance of the CHA(2)DS(2)-VASc score was modest in both groups [stroke at 1 year, c-statistics 0.69, 95% confidence interval (CI) 0.60-0.78 and 0.63, 95% CI 0.61-0.66, respectively]. In the overall cohort, advanced age, female sex, prior stroke, tobacco use, and non-use of anticoagulation were predictors for stroke (all P<0.05). Mitral stenosis was not associated with stroke risk (adjusted odds ratio 1.07, 95% CI 0.67-1.72, P=0.764). Conclusion The performance of the CHA(2)DS(2)-VASc score was modest in AF patients both with and without RHD. In this cohort, moderate-to-severe mitral stenosis was not an independent risk factor for stroke.
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| 10. |
- Fabritz, Larissa, et al.
(författare)
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Dynamic risk assessment to improve quality of care in patients with atrial fibrillation : the 7th AFNET/EHRA Consensus Conference
- 2021
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Ingår i: Europace. - : Oxford University Press. - 1099-5129 .- 1532-2092. ; 23:3, s. 329-344
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Tidskriftsartikel (refereegranskat)abstract
- AimsThe risk of developing atrial fibrillation (AF) and its complications continues to increase, despite good progress in preventing AF-related strokes.Methods and resultsThis article summarizes the outcomes of the 7th Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA) held in Lisbon in March 2019. Sixty-five international AF specialists met to present new data and find consensus on pressing issues in AF prevention, management and future research to improve care for patients with AF and prevent AF-related complications. This article is the main outcome of an interactive, iterative discussion between breakout specialist groups and the meeting plenary. AF patients have dynamic risk profiles requiring repeated assessment and risk-based therapy stratification to optimize quality of care. Interrogation of deeply phenotyped datasets with outcomes will lead to a better understanding of the cardiac and systemic effects of AF, interacting with comorbidities and predisposing factors, enabling stratified therapy. New proposals include an algorithm for the acute management of patients with AF and heart failure, a call for a refined, data-driven assessment of stroke risk, suggestions for anticoagulation use in special populations, and a call for rhythm control therapy selection based on risk of AF recurrence.ConclusionThe remaining morbidity and mortality in patients with AF needs better characterization. Likely drivers of the remaining AF-related problems are AF burden, potentially treatable by rhythm control therapy, and concomitant conditions, potentially treatable by treating these conditions. Identifying the drivers of AF-related complications holds promise for stratified therapy.
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| 11. |
- Johnson, Linda S.B., et al.
(författare)
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LVS-HARMED Risk Score for Incident Heart Failure in Patients With Atrial Fibrillation Who Present to the Emergency Department : Data from a World-Wide Registry
- 2021
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Ingår i: Journal of the American Heart Association. - : Wolters Kluwer. - 2047-9980. ; 10:18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Heart failure (HF) is a common complication to atrial fibrillation (AF), leading to rehospitalization and death. Early identification of patients with AF at risk for HF might improve outcomes. We aimed to derive a score to predict 1-year risk of new-onset HF after an emergency department (ED) visit with AF.Methods and Results: The RE-LY AF (Randomized Evaluation of Long-Term Anticoagulant Therapy) registry enrolled patients with AF presenting to an ED in 47 countries, and followed them for a year. The end point was HF hospitalization and/or HF death. Among 15 400 ED patients, 9765 had no prior HF (mean age, 64.9 +/- 14.9 years). Within 1 year, new-onset HF developed in 6.8% of patients, of whom 21% died of HF. Independent predictors of HF included left ventricular hypertrophy (odds ratio [OR], 1.47; 95% CI, 1.19-1.82), valvular heart disease (OR, 1.55; 95% CI, 1.18-2.04), smoking (OR, 1.42; 95% CI, 1.12-1.78), height (OR, 0.93; 95% CI, 0.90-0.95 per 3 cm), age (OR, 1.11; 95% CI, 1.07-1.15 per 5 years), rheumatic heart disease (OR, 1.77, 95% CI, 1.24-2.51), prior myocardial infarction (OR, 1.85; 95% CI, 1.45-2.36), remaining in AF at ED discharge (OR, 1.86; 95% CI, 1.46-2.36), and diabetes (OR, 1.33; 95% CI, 1.09-1.64). A continuous risk prediction score (LVS-HARMED [left ventricular, valvular heart disease, smoking or other tobacco use, height, age, rheumatic heart disease, myocardial infarction, emergency department discharge rhythm, and diabetes]) had good discrimination (C statistic, 0.735; 95% CI, 0.716-0.755). Validation was conducted internally using bootstrapping (optimism-corrected C statistic, 0.705) and externally (C statistic, 0.699). The 1-year incidence of HF hospitalization and/or HF death across quartile groups of the score was 1.1%, 4.5%, 6.9%, and 14.4%, respectively. LVS-HARMED also predicted incident stroke (C statistic, 0.753; 95% CI, 0.728-0.778).Conclusions: The LVS-HARMED score predicts new-onset HF after an ED visit for AF. Preventative strategies should be considered in patients with high LVS-HARMED HF risk.
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| 12. |
- Joseph, Philip G, et al.
(författare)
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Global variations in the prevalence, treatment, and impact of atrial fibrillation in a multi-national cohort of 153,152 middle-aged individuals.
- 2021
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Ingår i: Cardiovascular research. - : Oxford University Press (OUP). - 1755-3245 .- 0008-6363. ; 117:6, s. 1523-1531
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Tidskriftsartikel (refereegranskat)abstract
- To compare the prevalence of electrocardiogram (ECG)-documented atrial fibrillation (or flutter) (AF) across eight regions of the world, and to examine anti-thrombotic use and clinical outcomes.Baseline ECGs were collected in 153,152 middle-aged participants (ages 35 to 70 years) to document AF in two community-based studies, spanning 20 countries. Medication use and clinical outcome data (mean follow up of 7.4 years) were available in one cohort. Cross sectional analyses were performed to document the prevalence of AF and medication use, and associations between AF and clinical events were examined prospectively. Mean age of participants was 52.1 years, and 57.7% were female. Age and sex-standardized prevalence of AF varied 12-fold between regions; with the highest in North America, Europe, China and Southeast Asia (270-360 cases per 100,000 persons); and lowest in the Middle East, Africa, and South Asia (30-60 cases per 100,000 persons)(p<0.001). Compared with low-income countries (LICs), AF prevalence was 7-fold higher in middle-income countries (MICs) and 11-fold higher in high-income countries (HICs)(p<0.001). Differences in AF prevalence remained significant after adjusting for traditional AF risk factors. In LICs/MICs, 24% of participants with AF and a CHADS2 score ≥1 received anti-thrombotic therapy, compared with 85% in HICs. AF was associated with an increased risk of stroke (hazard ratio [HR: 2.29; 95% confidence interval [CI] 1.49-3.52) and death (HR: 2.97; 95% CI 2.25-3.93); with similar rates in different country income levels.Large variations in AF prevalence occur in different regions and country income settings, but this is only partially explained by traditional AF risk factors. Anti-thrombotic therapy is infrequently used in poorer countries despite the high risk of stroke associated with AF.We examined atrial fibrillation (AF) prevalence in 153,152 middle-aged participants spanning 20 countries. Age and sex-standardized prevalence of AF varied by as much as 12-fold between regions; highest in North America, Europe, China and Southeast Asia (270-360 cases per 100,000 persons); and lowest in the Middle East, Africa, and South Asia (30-60 cases per 100,000 persons)(p<0.001); and by as much as 11-fold between groups of countries at different income levels (p<0.001). Global variations were poorly explained by traditional AF risk factors. Future studies are needed to understand the predominant determinants driving the variation in AF burden across different regions of the world.
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- Kloosterman, Marielle, et al.
(författare)
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Characteristics and outcomes of atrial fibrillation in patients without traditional risk factors : an RE-LY AF registry analysis
- 2020
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Ingår i: Europace. - : Oxford University Press (OUP). - 1099-5129 .- 1532-2092. ; 22:6, s. 870-877
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Data on patient characteristics, prevalence, and outcomes of atrial fibrillation (AF) patients without traditional risk factors, often labelled 'lone AF', are sparse. Methods and results: The RE-LY AF registry included 15 400 individuals who presented to emergency departments with AF in 47 countries. This analysis focused on patients without traditional risk factors, including age >= 60years, hypertension, coronary artery disease, heart failure, left ventricular hypertrophy, congenital heart disease, pulmonary disease, valve heart disease, hyperthyroidism, and prior cardiac surgery. Patients without traditional risk factors were compared with age- and region-matched controls with traditional risk factors (1:3 fashion). In 796 (5%) patients, no traditional risk factors were present. However, 98% (779/796) had less-established or borderline risk factors, including borderline hypertension (130-140/80-90mmHg; 47%), chronic kidney disease (eGFR<60mL/min; 57%), obesity (body mass index>30; 19%), diabetes (5%), excessive alcohol intake (>14 units/week; 4%), and smoking (25%). Compared with patients with traditional risk factors (n=2388), patients without traditional risk factors were more often men (74% vs. 59%, P<0.001) had paroxysmal AF (55% vs. 37%, P<0.001) and less AF persistence after 1 year (21% vs. 49%, P<0.001). Furthermore, 1-year stroke occurrence rate (0.6% vs. 2.0%, P=0.013) and heart failure hospitalizations (0.9% vs. 12.5%, P<0.001) were lower. However, risk of AF-related re-hospitalization was similar (18% vs. 21%, P=0.09). Conclusion: Almost all patients without traditionally defined AF risk factors have less-established or borderline risk factors. These patients have a favourable 1-year prognosis, but risk of AF-related re-hospitalization remains high. Greater emphasis should be placed on recognition and management of less-established or borderline risk factors.
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| 14. |
- Krisai, Philipp, et al.
(författare)
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Incidence and Predictors of Heart Failure in Patients With Atrial Fibrillation
- 2021
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Ingår i: CJC Open. - : Elsevier BV. - 2589-790X. ; 3:12, s. 1482-1489
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Tidskriftsartikel (refereegranskat)abstract
- Background: Heart failure (HF) is a frequent cause of hospitalization and death in patients with atrial fibrillation (AF). Identifying AF patients at risk of HF hospitalization could help select individuals for intensive follow-up and treatment. Methods: We pooled data from 3 randomized trials (ACTIVE-A, RE-LY, AVERROES) of AF patients, for derivation and internal validation of a risk score for first HF hospitalization. Secondary endpoints were cardiovascular death and a composite of HF hospitalizations and cardiovascular death. Results: In 23,503 patients, the mean age was 71.3 years, and 62% were male. Over a mean follow-up of 2.0 years, 875 patients (3.7%) experienced their first HF hospitalization, and 1037 patients (4.4%) died from cardiovascular causes. Incidence rates per 100 patient-years were 1.85 for HF hospitalizations, 2.15 for cardiovascular death, and 3.71 for the composite. Independent predictors for HF hospitalizations included the following: increased age, weight, heart rate and serum creatinine level, lower height and systolic blood pressure, diabetes, vascular disease, valvular disease, heart rhythm, left ventricular hypertrophy, and intraventricular conduction delay. The C-statistic (95% confidence intervals by bootstrap simulations) was 0.717 (0.705-0.732). At 2 years of follow-up, the incidence rate of the primary outcome increased across risk-score quintiles: 0.49, 0.87, 1.29, 2.44, and 4.51 per 100 patient-years, respectively. Patients in the highest quintile had an absolute risk of 6.8% for the primary endpoint at 2 years. Conclusions: In a large AF population, new-onset HF was common. A combination of characteristics can identify high-risk patients for whom strategies to prevent HF should be considered.
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