| 1. |
- Bécoulet, A., et al.
(författare)
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Science and technology research and development in support to ITER and the Broader Approach at CEA
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10
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Tidskriftsartikel (refereegranskat)abstract
- In parallel to the direct contribution to the procurement phase of ITER and Broader Approach, CEA has initiated research & development programmes, accompanied by experiments together with a significant modelling effort, aimed at ensuring robust operation, plasma performance, as well as mitigating the risks of the procurement phase. This overview reports the latest progress in both fusion science and technology including many areas, namely the mitigation of superconducting magnet quenches, disruption-generated runaway electrons, edge-localized modes (ELMs), the development of imaging surveillance, and heating and current drive systems for steady-state operation. The WEST (W Environment for Steady-state Tokamaks) project, turning Tore Supra into an actively cooled W-divertor platform open to the ITER partners and industries, is presented.
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| 2. |
- Davies, Stuart J., et al.
(författare)
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ForestGEO: Understanding forest diversity and dynamics through a global observatory network
- 2021
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207. ; 253
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Tidskriftsartikel (refereegranskat)abstract
- ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems ≥1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world's known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species' demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capacity across the world's forested nations, and increased collaboration and integration among research networks and disciplines addressing forest science.
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| 3. |
- Leite, Melina de Souza, et al.
(författare)
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Major axes of variation in tree demography across global forests
- 2024
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Ingår i: Ecography. - 0906-7590 .- 1600-0587.
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Tidskriftsartikel (refereegranskat)abstract
- The future trajectory of global forests is closely intertwined with tree demography, and a major fundamental goal in ecology is to understand the key mechanisms governing spatio-temporal patterns in tree population dynamics. While previous research has made substantial progress in identifying the mechanisms individually, their relative importance among forests remains unclear mainly due to practical limitations. One approach to overcome these limitations is to group mechanisms according to their shared effects on the variability of tree vital rates and quantify patterns therein. We developed a conceptual and statistical framework (variance partitioning of Bayesian multilevel models) that attributes the variability in tree growth, mortality, and recruitment to variation in species, space, and time, and their interactions – categories we refer to as organising principles (OPs). We applied the framework to data from 21 forest plots covering more than 2.9 million trees of approximately 6500 species. We found that differences among species, the species OP, proved a major source of variability in tree vital rates, explaining 28–33% of demographic variance alone, and 14–17% in interaction with space, totalling 40–43%. Our results support the hypothesis that the range of vital rates is similar across global forests. However, the average variability among species declined with species richness, indicating that diverse forests featured smaller interspecific differences in vital rates. Moreover, decomposing the variance in vital rates into the proposed OPs showed the importance of unexplained variability, which includes individual variation, in tree demography. A focus on how demographic variance is organized in forests can facilitate the construction of more targeted models with clearer expectations of which covariates might drive a vital rate. This study therefore highlights the most promising avenues for future research, both in terms of understanding the relative contributions of groups of mechanisms to forest demography and diversity, and for improving projections of forest ecosystems.
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| 4. |
- Altmaier, M., et al.
(författare)
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TALISMAN - A European Commission FP7 project promoting transnational access to large infrastructures for a safe management of actinides
- 2014
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Ingår i: Plutonium Futures: The Science 2014; Las Vegas; United States; 7 September 2014 through 12 September 2014. - 9781510808089 ; , s. 165-166
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Konferensbidrag (refereegranskat)abstract
- TALISMAN is a large international project funded within the European Commission FP7 EURATOM framework. The aim of TALISMAN is to offer transnational access to large infrastructures for a safe management of actinides. Although clearly focusing on R&D activities from European Union member states, TALISMAN is also open to participation from non-EU countries. TALISMAN is coordinated by CEA (contact by stephane.bourg@cea.fr), supported by a Governing Board and the ExCom. Dedicated studies on Pu containing materials are integral part of TALISMAN. Safety issues are of fundamental importance for the acceptance and sustainable application of nuclear energy. Actinides play a central role in the nuclear fuel cycle from mining, fuel fabrication, energy production, up to reprocessing, partitioning and transmutation treatment of used fuel, and finally the management and disposal of radioactive waste. Fundamental understanding of actinide properties and behavior in fuel materials during the separation processes and in geological repositories is an imperative prerequisite to tackle the related safety issues. Unravelling the complexity of the actinide components of used nuclear fuel certainly represents one of the great challenges in nuclear science. To meet the needs of safe and sustainable management of nuclear energy it is essential to maintain a high level of expertise in actinide sciences both on a European and international level. Educating and training the next generation of scientists and engineers who will contribute to developing safe actinide management strategies is a key mission. Because actinides are radioactive elements and handling requires specific safety measures, their study requires advanced tools and facilities that are only available to a limited extent. Only a few academic and research organisations have the capabilities and licenses to work on actinide elements. From a European perspective it is therefore strategic to coordinate the existing actinide infrastructures in Europe and strengthen the community of scientists working on actinides. Within TALISMAN we offer (for positively evaluated scientific research proposals submitted in reply to a specific TALISMAN call) access to the previous ACTINET Pooled Facilities (CEA Atalante and CEA DPC, France; ITU Laboratories & hot-cells, European Commission; KIT-INE laboratories and KIT-INE beamline, Germany; HZDR-IRE & ROBL, Germany; PSI microXAS Beamline, Switzerland) to which two new facilities have been added: NNL Central Lab in the UK and CHALMERS in Sweden. TALISMAN is also open to scientists and research organizations from outside the European Union. TALISMAN leads and coordinates a network of actinide facilities across Europe, but also manages a network between facilities and users to increase the knowledge for a safer management of actinides. TALISMAN also enhances the efforts made to support education and training issues by continuing the former ACTINET Summer School series and travel grant attributions for attending international conferences like the Plutonium Futures series. The TALISMAN project website is regularly updated and offers detailed information on all TALISMAN activities at http://www.talisman-project.eu. This is including contact addresses, TALISMAN newsletters, announcements and description of open and forthcoming calls for transnational user access and indicates several other options to perform actinide research within the TALISMAN context.
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| 5. |
- Bourg, S., et al.
(författare)
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ACSEPT-Partitioning technologies and actinide science: Towards pilot facilities in Europe
- 2011
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Ingår i: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493. ; 241:9, s. 3427-3435
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Tidskriftsartikel (refereegranskat)abstract
- Actinide recycling by separation and transmutation is considered worldwide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste and to optimise the use of natural resources. With its multidisciplinary consortium of 34 partners from 12 European countries plus Australia and Japan, the European Research Project ACSEPT (Actinide recycling by SEParation and Transmutation) aims at contributing to the development of this strategy by studying both hydrometallurgical and pyrochemical partitioning routes. ACSEPT is organised into three technical domains: (i) Considering technically mature aqueous separation processes, ACSEPT works to optimise and select the most promising ones dedicated either to actinide partitioning (for the heterogeneous recycling of actinides in ADS target or specific actinide bearing blanket fuels in fast reactor) or to grouped actinide separation (for the homogeneous recycling of the actinides in fast reactor fuels). In addition, dissolution and conversion studies are underway taking into account the specific requirements of these specific fuels. (ii) Concerning pyrochemical separation processes. ACSEPT focuses on the enhancement of the two reference cores processes selected within FP6-EUROPART. R&D efforts are also devoted to key scientific and technical issues compulsory to set up a complete separation process (head-end steps, salt treatment for recycling and waste management). (iii) By integrating all the experimental results in engineering and system studies, both in hydro and pyro domains, ACSEPT will deliver relevant flowsheets and recommendations to prepare for future demonstrations at a pilot level. After more than two years of work, significant progress was achieved in process development with the demonstration of the SANEX and innovative SANEX flowsheets. Chemical systems were selected for GANEX and are under study. In addition, efforts were made to increase collaborations, mutualise and homogenise procedures and share good practices. Based on these assessments, it is now time to look at the future challenges to overcome. A training and education program is implemented to share the knowledge among the partitioning community, present and future generations of researchers. Specific attention is paid to the funding of post-doctorate fellowships, two having been appointed respectively at the end of 2008 and at the end of 2009. Through this training and education programme, the first ACSEPT International Workshop was organised last March in Lisbon, Portugal. It gave an emphasis to young researchers' contributions (two thirds of the contributions) and allowed young scientists to meet and exchange with international recognised experts.
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| 6. |
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| 7. |
- Manzano-Nunez, Ramiro, et al.
(författare)
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Outcomes and management approaches of resuscitative endovascular balloon occlusion of the aorta based on the income of countries
- 2020
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Ingår i: World Journal of Emergency Surgery. - : Springer Science and Business Media LLC. - 1749-7922. ; 15:57
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 The Author(s). Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) could provide a survival benefit to severely injured patients as it may improve their initial ability to survive the hemorrhagic shock. Although the evidence supporting the use of REBOA is not conclusive, its use has expanded worldwide. We aim to compare the management approaches and clinical outcomes of trauma patients treated with REBOA according to the countries' income based on the World Bank Country and Lending Groups. Methods: We used data from the AORTA (USA) and the ABOTrauma (multinational) registries. Patients were stratified into two groups: (1) high-income countries (HICs) and (2) low-to-middle income countries (LMICs). Propensity score matching extracted 1:1 matched pairs of subjects who were from an LMIC or a HIC based on age, gender, the presence of pupillary response on admission, impeding hypotension (SBP ≤ 80), trauma mechanism, ISS, the necessity of CPR on arrival, the location of REBOA insertion (emergency room or operating room) and the amount of PRBCs transfused in the first 24 h. Logistic regression (LR) was used to examine the association of LMICs and mortality. Results: A total of 817 trauma patients from 14 countries were included. Blind percutaneous approach and surgical cutdown were the preferred means of femoral cannulation in HICs and LIMCs, respectively. Patients from LMICs had a significantly higher occurrence of MODS and respiratory failure. LR showed no differences in mortality for LMICs when compared to HICs; neither in the non-matched cohort (OR = 0.63; 95% CI: 0.36-1.09; p = 0.1) nor in the matched cohort (OR = 1.45; 95% CI: 0.63-3,33; p = 0.3). Conclusion: There is considerable variation in the management practices of REBOA and the outcomes associated with this intervention between HICs and LMICs. Although we found significant differences in multiorgan and respiratory failure rates, there were no differences in the risk-adjusted odds of mortality between the groups analyzed. Trauma surgeons practicing REBOA around the world should joint efforts to standardize the practice of this endovascular technology worldwide.
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| 8. |
- Needham, Jessica F., et al.
(författare)
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Demographic composition, not demographic diversity, predicts biomass and turnover across temperate and tropical forests
- 2022
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 28, s. 2895-2909
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Tidskriftsartikel (refereegranskat)abstract
- The growth and survival of individual trees determine the physical structure of a forest with important consequences for forest function. However, given the diversity of tree species and forest biomes, quantifying the multitude of demographic strategies within and across forests and the way that they translate into forest structure and function remains a significant challenge. Here, we quantify the demographic rates of 1961 tree species from temperate and tropical forests and evaluate how demographic diversity (DD) and demographic composition (DC) differ across forests, and how these differences in demography relate to species richness, aboveground biomass (AGB), and carbon residence time. We find wide variation in DD and DC across forest plots, patterns that are not explained by species richness or climate variables alone. There is no evidence that DD has an effect on either AGB or carbon residence time. Rather, the DC of forests, specifically the relative abundance of large statured species, predicted both biomass and carbon residence time. Our results demonstrate the distinct DCs of globally distributed forests, reflecting biogeography, recent history, and current plot conditions. Linking the DC of forests to resilience or vulnerability to climate change, will improve the precision and accuracy of predictions of future forest composition, structure, and function.
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| 9. |
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