| 1. |
- Poyatos, R., et al.
(author)
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Global transpiration data from sap flow measurements: the SAPFLUXNET database
- 2021
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In: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 13:6, s. 2607-2649
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Journal article (peer-reviewed)abstract
- Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.
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| 2. |
- Wingate, L., et al.
(author)
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Interpreting canopy development and physiology using a European phenology camera network at flux sites
- 2015
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In: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 12:20, s. 5995-6015
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Journal article (peer-reviewed)abstract
- Plant phenological development is orchestrated through subtle changes in photoperiod, temperature, soil moisture and nutrient availability. Presently, the exact timing of plant development stages and their response to climate and management practices are crudely represented in land surface models. As visual observations of phenology are laborious, there is a need to supplement long-term observations with automated techniques such as those provided by digital repeat photography at high temporal and spatial resolution. We present the first synthesis from a growing observational network of digital cameras installed on towers across Europe above deciduous and evergreen forests, grasslands and croplands, where vegetation and atmosphere CO2 fluxes are measured continuously. Using colour indices from digital images and using piecewise regression analysis of time series, we explored whether key changes in canopy phenology could be detected automatically across different land use types in the network. The piecewise regression approach could capture the start and end of the growing season, in addition to identifying striking changes in colour signals caused by flowering and management practices such as mowing. Exploring the dates of green-up and senescence of deciduous forests extracted by the piecewise regression approach against dates estimated from visual observations, we found that these phenological events could be detected adequately (RMSE < 8 and 11 days for leaf out and leaf fall, respectively). We also investigated whether the seasonal patterns of red, green and blue colour fractions derived from digital images could be modelled mechanistically using the PROSAIL model parameterised with information of seasonal changes in canopy leaf area and leaf chlorophyll and carotenoid concentrations. From a model sensitivity analysis we found that variations in colour fractions, and in particular the late spring 'green hump' observed repeatedly in deciduous broadleaf canopies across the network, are essentially dominated by changes in the respective pigment concentrations. Using the model we were able to explain why this spring maximum in green signal is often observed out of phase with the maximum period of canopy photosynthesis in ecosystems across Europe. Coupling such quasi-continuous digital records of canopy colours with co-located CO2 flux measurements will improve our understanding of how changes in growing season length are likely to shape the capacity of European ecosystems to sequester CO2 in the future.
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| 3. |
- Manzano-Nunez, Ramiro, et al.
(author)
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A meta-analysis of the incidence of complications associated with groin access after the use of resuscitative endovascular balloon occlusion of the aorta in trauma patients.
- 2018
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In: Journal of Trauma and Acute Care Surgery. - : Lippincott Williams & Wilkins. - 2163-0755 .- 2163-0763. ; 85:3, s. 626-634
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Research review (peer-reviewed)abstract
- BACKGROUND: Serious complications related to groin access have been reported with the use of resuscitative endovascular balloon occlusion of the aorta (REBOA). We performed a systematic review and meta-analysis to estimate the incidence of complications related to groin access from the use of REBOA in adult trauma patients.METHODS: We identified articles in MEDLINE and EMBASE. We reviewed all studies that involved adult trauma patients that underwent the placement of a REBOA and included only those that reported the incidence of complications related to groin access. A meta-analysis of proportions was performed RESULTS: We 13 studies with a total of 424 patients. REBOA was inserted most commonly by trauma surgeons or emergency room physicians. Information regarding puncture technique was reported in 12 studies and was available for a total of 414 patients. Percutaneous access and surgical cutdown were performed in 304 (73.4%) and 110 (26.5%) patients respectively. Overall, complications related to groin access occurred in 5.6% of patients (n=24/424). Lower limb amputation was required in 2.1% of patients (9/424), of which three cases (3/424 [0.7%]) were directly related to the vascular puncture from the REBOA insertion. A meta-analysis which used the logit transformation showed a 5% (95% CI 3%-9%) incidence of complications without significant heterogeneity (LR test: χ2 = 0.73, p=0.2, Tau-square=0.2). In a second meta-analysis, we used the Freeman-Turkey double arcsine transformation and found an incidence of complications of 4% (95% CI 2%-7%) with low heterogeneity (I2 = 16.3%).CONCLUSION: We found that the incidence of complications related to groin access was of four to five percent based on a meta-analysis of 13 studies published worldwide. Currently, there are no benchmarks or quality measures as a reference to compare, and thus, further work is required to identify these benchmarks and improve the practice of REBOA in trauma surgery.LEVEL OF EVIDENCE: Systematic Review and Meta-analysis, Level III.
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| 4. |
- Manzano-Nunez, Ramiro, et al.
(author)
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Could resuscitative endovascular balloon occlusion of the aorta improve survival among severely injured patients with post-intubation hypotension?
- 2018
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In: European Journal of Trauma and Emergency Surgery. - : Springer Berlin/Heidelberg. - 1863-9933 .- 1863-9941. ; 44:4, s. 527-533
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Research review (peer-reviewed)abstract
- Current literature shows the association of post-intubation hypotension and increased odds of mortality in critically ill non-trauma and trauma populations. However, there is a lack of research on potential interventions that can prevent or ameliorate the consequences of endotracheal intubation and thus improve the prognosis of trauma patients with post-intubation hypotension. This review paper hypothesizes that the deployment of REBOA among trauma patients with PIH, by its physiologic effects, will reduce the odds of mortality in this population. The objective of this paper is to review the current literature on REBOA and post-intubation hypotension, and, furthermore, to provide a rational hypothesis on the potential role of REBOA in severely injured patients with post-intubation hypotension.
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| 5. |
- Zhang, Weijie, et al.
(author)
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The effect of relative humidity on eddy covariance latent heat flux measurements and its implication for partitioning into transpiration and evaporation
- 2023
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In: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923. ; 330
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Journal article (peer-reviewed)abstract
- While the eddy covariance (EC) technique is a well-established method for measuring water fluxes (i.e., evaporation or 'evapotranspiration’, ET), the measurement is susceptible to many uncertainties. One such issue is the potential underestimation of ET when relative humidity (RH) is high (>70%), due to low-pass filtering with some EC systems. Yet, this underestimation for different types of EC systems (e.g. open-path or closed-path sensors) has not been characterized for synthesis datasets such as the widely used FLUXNET2015 dataset. Here, we assess the RH-associated underestimation of latent heat fluxes (LE, or ET) from different EC systems for 163 sites in the FLUXNET2015 dataset. We found that the LE underestimation is most apparent during hours when RH is higher than 70%, predominantly observed at sites using closed-path EC systems, but the extent of the LE underestimation is highly site-specific. We then propose a machine learning based method to correct for this underestimation, and compare it to two energy balance closure based LE correction approaches (Bowen ratio correction, BRC, and attributing all errors to LE). Our correction increases LE by 189% for closed-path sites at high RH (>90%), while BRC increases LE by around 30% for all RH conditions. Additionally, we assess the influence of these corrections on ET-based transpiration (T) estimates using two different ET partitioning methods. Results show opposite responses (increasing vs. slightly decreasing T-to-ET ratios, T/ET) between the two methods when comparing T based on corrected and uncorrected LE. Overall, our results demonstrate the existence of a high RH bias in water fluxes in the FLUXNET2015 dataset and suggest that this bias is a pronounced source of uncertainty in ET measurements to be considered when estimating ecosystem T/ET and WUE.
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