| 1. |
- Koenig, Alkuin M., et al.
(författare)
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Observed in-plume gaseous elemental mercury depletion suggests significant mercury scavenging by volcanic aerosols
- 2023
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Ingår i: Environmental Science: Atmospheres. - 2634-3606. ; 3:10, s. 1418-1438
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Tidskriftsartikel (refereegranskat)abstract
- Terrestrial volcanism is known to emit mercury (Hg) into the atmosphere. However, despite many years of investigation, its net impact on the atmospheric Hg budget remains insufficiently constrained, in part because the transformations of Hg in volcanic plumes as they age and mix with background air are poorly understood. Here we report the observation of complete gaseous elemental mercury (GEM) depletion events in dilute and moderately aged (& SIM;3-7 hours) volcanic plumes from Piton de la Fournaise on Reunion Island. While it has been suggested that co-emitted bromine could, once photochemically activated, deplete GEM in a volcanic plume, we measured low bromine concentrations in both the gas- and particle-phase and observed complete GEM depletion even before sunrise, ruling out a leading role of bromine chemistry here. Instead, we hypothesize that the GEM depletions were mainly caused by gas-particle interactions with sulfate-rich volcanic particles (mostly of submicron size), abundantly present in the dilute plume. We consider heterogeneous GEM oxidation and GEM uptake by particles as plausible manifestations of such a process and derive empirical rate constants. By extrapolation, we estimate that volcanic aerosols may scavenge 210 Mg y(-1) (67-480 Mg y(-1)) of Hg from the atmosphere globally, acting effectively as atmospheric mercury sink. While this estimate is subject to large uncertainties, it highlights that Hg transformations in aging volcanic plumes must be better understood to determine the net impact of volcanism on the atmospheric Hg budget and Hg deposition pathways.
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| 2. |
- Caniglia, Guido, et al.
(författare)
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A pluralistic and integrated approach to action-oriented knowledge for sustainability
- 2021
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Ingår i: Nature Sustainability. - : Springer Science and Business Media LLC. - 2398-9629. ; 4:2, s. 93-100
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Forskningsöversikt (refereegranskat)abstract
- Sustainability science needs to better mobilize a range of knowledge to support transformative change. This Perspective contends that such transformative, action-oriented knowledge emerges from integrating multiple kinds of knowledge and ways of knowing. Sustainability science needs more systematic approaches for mobilizing knowledge in support of interventions that may bring about transformative change. In this Perspective, we contend that action-oriented knowledge for sustainability emerges when working in integrated ways with the many kinds of knowledge involved in the shared design, enactment and realization of change. The pluralistic and integrated approach we present rejects technocratic solutions to complex sustainability challenges and foregrounds individual and social learning. We argue that research institutions devoted to sustainability should focus more on creating the conditions for experimenting with multiple kinds of knowledge and ways of knowing to foster sustainability-oriented learning.
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| 3. |
- Demol, P., et al.
(författare)
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Improved many-body expansions from eigenvector continuation
- 2020
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Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 101:4
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Tidskriftsartikel (refereegranskat)abstract
- Quantum many-body theory has witnessed tremendous progress in various fields, ranging from atomic and solid-state physics to quantum chemistry and nuclear structure. Due to the inherent computational burden linked to the ab initio treatment of microscopic fermionic systems, it is desirable to obtain accurate results through low-order perturbation theory. In atomic nuclei, however, effects such as strong short-range repulsion between nucleons can spoil the convergence of the expansion and make the reliability of perturbation theory unclear. Mathematicians have devised an extensive machinery to overcome the problem of divergent expansions by making use of so-called resummation methods. In large-scale many-body applications, such schemes are often of limited use since no a priori analytical knowledge of the expansion is available. We present here eigenvector continuation as an alternative resummation tool that is both efficient and reliable because it is based on robust and simple mathematical principles.
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| 4. |
- Koenig, S., et al.
(författare)
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Eigenvector continuation as an efficient and accurate emulator for uncertainty quantification
- 2020
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 810
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Tidskriftsartikel (refereegranskat)abstract
- First principles calculations of atomic nuclei based on microscopic nuclear forces derived from chiral effective field theory (EFT) have blossomed in the past years. A key element of such ab initio studies is the understanding and quantification of systematic and statistical errors arising from the omission of higher-order terms in the chiral expansion as well as the model calibration. While there has been significant progress in analyzing theoretical uncertainties for nucleon-nucleon scattering observables, the generalization to multi-nucleon systems has not been feasible yet due to the high computational cost of evaluating observables for a large set of low-energy couplings. In this Letter we show that a new method called eigenvector continuation (EC) can be used for constructing an efficient and accurate emulator for nuclear many-body observables, thereby enabling uncertainty quantification in multi-nucleon systems. We demonstrate the power of EC emulation with a proof-of-principle calculation that lays out all correlations between bulk ground-state observables in the few-nucleon sector. On the basis of ab initio calculations for the ground-state energy and radius in 4 He, we demonstrate that EC is more accurate and efficient compared to established methods like Gaussian processes.
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| 5. |
- Ortiz Catalan, Max Jair, 1982, et al.
(författare)
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Virtual Reality
- 2014
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Ingår i: Biosystems and Biorobotics. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 2195-3570 .- 2195-3562. - 9783642385551 ; 4, s. 249-265
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter provides an overview on the use of Virtual Reality (VR) in rehabilitation with respect to recent neuroscience and physical therapy reviews of individuals with motor impairments. A wide range of technologies have been employed to provide rehabilitation supported by VR. Several studies have found evidence of the benefits of VR rehabilitation technologies. However, support for their efficacy is still limited due the lack of generalizable results and the uncoordinated effort of many individual, heterogeneous studies that have been conducted. Although VR has clear potential as a rehabilitation tool to improve treatment outcomes, future trials need to take into account the individual perspective of each patient group and consolidate research methodologies across trials to allow for stronger conclusions across the heterogeneous field of neurorehabilitation. Interventions must be designed with a strong focus on the patient’s needs and clinical outcomes, rather than on the technology available to the clinician.
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