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- Jahnke, T., et al.
(författare)
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Inner-Shell-Ionization-Induced Femtosecond Structural Dynamics of Water Molecules Imaged at an X-Ray Free-Electron Laser
- 2021
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Ingår i: Physical Review X. - : American Physical Society. - 2160-3308. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- The ultrafast structural dynamics of water following inner-shell ionization is a crucial issue in high-energy radiation chemistry. We have exposed isolated water molecules to a short x-ray pulse from a free-electron laser and detected momenta of all produced ions in coincidence. By combining experimental results and theoretical modeling, we can image dissociation dynamics of individual molecules in unprecedented detail. We reveal significant molecular structural dynamics in H2O2+, such as asymmetric deformation and bond-angle opening, leading to two-body or three-body fragmentation on a timescale of a few femtoseconds. We thus reconstruct several snapshots of structural dynamics at different time intervals, which highlight dynamical patterns that are relevant as initiating steps of subsequent radiation-damage processes.
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- Bagriy, I.D., et al.
(författare)
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H2 - Ecological source of decarbonization - The path to energy independence of Ukraine
- 2023
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- The research studied the pressing problem of the fuel and energy strategy of the XXI century. For the first time, there was shown the diversity of the authors' approach to theoretical and applied problems of hydrogen energy. General issues of fundamental and applied aspects of hydrogen origin were covered. The study provides the results of scientific developments on hydrogen mapping performed within the framework of scientific and practical exploratory and geo-ecological research on more than 200 hydrocarbon objects both on land (including mining fields) and in marine water areas. Prognostic and search system criteria were substantiated, with hydrogen being used for the first time as a component of the complex of methodical solutions in the search practice. The research showed the importance of solving the problem of geo-ecological processes and accidents in mine workings and wells, connected to numerous disasters. According to numerous studies of mine massives, a set of preventive measures and criteria that prevent explosive processes was provided.The presence of a unique complex of natural components of hydrogen technology, solar and wind energy resources and fresh waters of the Danube lakes and the Danube was stated.The study emphasises the decisive role of Ukraine in the competition for primacy in scientific developments. For the first time in world practice, the implementation of global projects for the extraction and production of green and white hydrogen was substantiated.The technology was tested on numerous hydrocarbon deposits, water resources and mine workings and therefore has all the prospects for the effective application in the search and extraction of hydrogen. This monograph can be useful and informative for specialists in the fields of oil and gas geology, general and regional geology, hydrology, environmental protection, as well as for the students and postgraduate students of fuel and energy, oil and gas geological and hydrological areas, as well as for domestic and foreign investors.
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4. |
- Bagriy, I.D., et al.
(författare)
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H2 - ENVIRONMENTAL AND ENERGY CHALLENGESOF THE XXI CENTURY. GLOBAL PROJECTSWAYS OF IMPLEMENTATION
- 2023
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Bok (refereegranskat)abstract
- The research studied the pressing problem of the fuel and energy strategy of the XXI century. For the first time, there was shown the diversity of the authors' approach to theoretical and applied problems of hydrogen energy. General issues of fundamental and applied aspects of hydrogen origin were covered. The study provides the results of scientific developments on hydrogen mapping performed within the framework of scientific and practical exploratory and geo-ecological research on more than 200 hydrocarbon objects both on land (including mining fields) and in marine water areas. Prognostic and search system criteria were substantiated, with hydrogen being used for the first time as a component of the complex of methodical solutions in the search practice. The research showed the importance of solving the problem of geo-ecological processes and accidents in mine workings and wells, connected to numerous disasters. According to numerous studies of mine massives, a set of preventive measures and criteria that prevent explosive processes was provided. The presence of a unique complex of natural components of hydrogen technology, solar and wind energy resources and fresh waters of the Danube lakes and the Danube was stated. The study emphasises the decisive role of Ukraine in the competition for primacy in scientific developments. For the first time in world practice, the implementation of global projects for the extraction and production of green and white hydrogen was substantiated. The technology was tested on numerous hydrocarbon deposits, water resources and mine workings and therefore has all the prospects for the effective application in the search and extraction of hydrogen. This monograph can be useful and informative for specialists in the fields of oil and gas geology, general and regional geology, hydrology, environmental protection, as well as for the students and postgraduate students of fuel and energy, oil and gas geological and hydrological areas, as well as for domestic and foreign investors.
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5. |
- Hox, V, et al.
(författare)
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Benefits and harm of systemic steroids for short- and long-term use in rhinitis and rhinosinusitis: an EAACI position paper
- 2020
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Ingår i: Clinical and translational allergy. - : Wiley. - 2045-7022. ; 10:1, s. 1-
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Tidskriftsartikel (refereegranskat)abstract
- Because of the inflammatory mechanisms of most chronic upper airway diseases such as rhinitis and chronic rhinosinusitis, systemic steroids have been used for their treatment for decades. However, it has been very well documented that—potentially severe—side-effects can occur with the accumulation of systemic steroid courses over the years. A consensus document summarizing the benefits of systemic steroids for each upper airway disease type, as well as highlighting the potential harms of this treatment is currently lacking. Therefore, a panel of international experts in the field of Rhinology reviewed the available literature with the aim of providing recommendations for the use of systemic steroids in treating upper airway disease.
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- Almeida, Tiago Rodrigues de, 1996-, et al.
(författare)
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Trajectory Prediction for Heterogeneous Agents : A Performance Analysis on Small and Imbalanced Datasets
- 2024
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Ingår i: IEEE Robotics and Automation Letters. - : IEEE. - 2377-3766. ; 9:7, s. 6576-6583
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Tidskriftsartikel (refereegranskat)abstract
- Robots and other intelligent systems navigating in complex dynamic environments should predict future actions and intentions of surrounding agents to reach their goals efficiently and avoid collisions. The dynamics of those agents strongly depends on their tasks, roles, or observable labels. Class-conditioned motion prediction is thus an appealing way to reduce forecast uncertainty and get more accurate predictions for heterogeneous agents. However, this is hardly explored in the prior art, especially for mobile robots and in limited data applications. In this paper, we analyse different class-conditioned trajectory prediction methods on two datasets. We propose a set of conditional pattern-based and efficient deep learning-based baselines, and evaluate their performance on robotics and outdoors datasets (TH & Ouml;R-MAGNI and Stanford Drone Dataset). Our experiments show that all methods improve accuracy in most of the settings when considering class labels. More importantly, we observe that there are significant differences when learning from imbalanced datasets, or in new environments where sufficient data is not available. In particular, we find that deep learning methods perform better on balanced datasets, but in applications with limited data, e.g., cold start of a robot in a new environment, or imbalanced classes, pattern-based methods may be preferable.
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7. |
- Almeida, Tiago, 1996-, et al.
(författare)
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THÖR-Magni : Comparative Analysis of Deep Learning Models for Role-Conditioned Human Motion Prediction
- 2023
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Ingår i: 2023 IEEE/CVF International Conference on Computer Vision Workshops (ICCVW). - : IEEE. - 9798350307450 - 9798350307443 ; , s. 2192-2201
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Konferensbidrag (refereegranskat)abstract
- Autonomous systems, that need to operate in human environments and interact with the users, rely on understanding and anticipating human activity and motion. Among the many factors which influence human motion, semantic attributes, such as the roles and ongoing activities of the detected people, provide a powerful cue on their future motion, actions, and intentions. In this work we adapt several popular deep learning models for trajectory prediction with labels corresponding to the roles of the people. To this end we use the novel THOR-Magni dataset, which captures human activity in industrial settings and includes the relevant semantic labels for people who navigate complex environments, interact with objects and robots, work alone and in groups. In qualitative and quantitative experiments we show that the role-conditioned LSTM, Transformer, GAN and VAE methods can effectively incorporate the semantic categories, better capture the underlying input distribution and therefore produce more accurate motion predictions in terms of Top-K ADE/FDE and log-likelihood metrics.
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8. |
- Borne, Kurtis D., et al.
(författare)
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Ultrafast electronic relaxation pathways of the molecular photoswitch quadricyclane
- 2024
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Ingår i: NATURE CHEMISTRY. - 1755-4330 .- 1755-4349. ; 16, s. 499-505
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Tidskriftsartikel (refereegranskat)abstract
- The light-induced ultrafast switching between molecular isomers norbornadiene and quadricyclane can reversibly store and release a substantial amount of chemical energy. Prior work observed signatures of ultrafast molecular dynamics in both isomers upon ultraviolet excitation but could not follow the electronic relaxation all the way back to the ground state experimentally. Here we study the electronic relaxation of quadricyclane after exciting in the ultraviolet (201 nanometres) using time-resolved gas-phase extreme ultraviolet photoelectron spectroscopy combined with non-adiabatic molecular dynamics simulations. We identify two competing pathways by which electronically excited quadricyclane molecules relax to the electronic ground state. The fast pathway (<100 femtoseconds) is distinguished by effective coupling to valence electronic states, while the slow pathway involves initial motions across Rydberg states and takes several hundred femtoseconds. Both pathways facilitate interconversion between the two isomers, albeit on different timescales, and we predict that the branching ratio of norbornadiene/quadricyclane products immediately after returning to the electronic ground state is approximately 3:2.
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9. |
- Cheng, Yu Chen, et al.
(författare)
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Imaging multiphoton ionization dynamics of CH3I at a high repetition rate XUV free-electron laser
- 2021
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Ingår i: Journal of Physics B-Atomic Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 54:1
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Tidskriftsartikel (refereegranskat)abstract
- XUV multiphoton ionization of molecules is commonly used in free-electron laser experiments to study charge transfer dynamics. However, molecular dissociation and electron dynamics, such as multiple photon absorption, Auger decay, and charge transfer, often happen on competing time scales, and the contributions of individual processes can be difficult to unravel. We experimentally investigate the Coulomb explosion dynamics of methyl iodide upon core-hole ionization of the shallow inner-shell of iodine (4d) and classically simulate the fragmentation by phenomenologically introducing ionization dynamics and charge transfer. Under our experimental conditions with medium fluence and relatively long XUV pulses (similar to 75 fs), we find that fast Auger decay prior to charge transfer significantly contributes to the charging mechanism, leading to a yield enhancement of higher carbon charge states upon molecular dissociation. Furthermore, we argue for the existence of another charging mechanism for the weak fragmentation channels leading to triply charged carbon atoms. This study shows that classical simulations can be a useful tool to guide the quantum mechanical description of the femtosecond dynamics upon multiphoton absorption in molecular systems.
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10. |
- Kockert, Hansjochen, et al.
(författare)
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UV-induced dissociation of CH2BrI probed by intense femtosecond XUV pulses
- 2022
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Ingår i: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 55:1
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Tidskriftsartikel (refereegranskat)abstract
- The ultraviolet (UV)-induced dissociation and photofragmentation of gas-phase CH2BrI molecules induced by intense femtosecond extreme ultraviolet (XUV) pulses at three different photon energies are studied by multi-mass ion imaging. Using a UV-pump-XUV-probe scheme, charge transfer between highly charged iodine ions and neutral CH2Br radicals produced by C-I bond cleavage is investigated. In earlier charge-transfer studies, the center of mass of the molecules was located along the axis of the bond cleaved by the pump pulse. In the present case of CH2BrI, this is not the case, thus inducing a rotation of the fragment. We discuss the influence of the rotation on the charge transfer process using a classical over-the-barrier model. Our modeling suggests that, despite the fact that the dissociation is slower due to the rotational excitation, the critical interatomic distance for charge transfer is reached faster. Furthermore, we suggest that charge transfer during molecular fragmentation may be modulated in a complex way.
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