| 1. |
- Eklund, Gustav, et al.
(författare)
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Cryogenic merged-ion-beam experiments in DESIREE : Final-state-resolved mutual neutralization of Li+ and D-
- 2020
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 102:1
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Tidskriftsartikel (refereegranskat)abstract
- We have developed an experimental technique to study charge-and energy-flow processes in sub-eV collisions between oppositely charged, internally cold, ions of atoms, molecules, and clusters. Two ion beams are stored in separate rings of the cryogenic ion-beam storage facility DESIREE, and merged in a common straight section where a set of biased drift tubes is used to control the center-of-mass collision energy locally in fine steps. Here, we present measurements on mutual neutralization between Li+ and D- where a time-sensitive imaging-detector system is used to measure the three-dimensional distance between the neutral Li and D atoms as they reach the detector. This scheme allows for direct measurements of kinetic-energy releases, and here it reveals separate populations of the 3s state and the (3p + 3d) states in neutral Li while the D atom is left in its ground state 1s. The branching fraction of the 3s final state is measured to be 57.8 +/- 0.7% at a center-of-mass collision energy of 78 +/- 13 meV. The technique paves the way for studies of charge-, energy-, and mass-transfer reactions in single collisions involving molecular and cluster ions in well-defined quantum states.
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| 2. |
- Kristiansson, Moa K., 1989-, et al.
(författare)
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High-precision electron affinity of oxygen
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Negative ions are important in many areas of science and technology, e.g., in interstellar chemistry, for accelerator-based radionuclide dating, and in anti-matter research. They are unique quantum systems where electron-correlation effects govern their properties. Atomic anions are loosely bound systems, which with very few exceptions lack optically allowed transitions. This limits prospects for high-resolution spectroscopy, and related negative-ion detection methods. Here, we present a method to measure negative ion binding energies with an order of magnitude higher precision than what has been possible before. By laser-manipulation of quantum-state populations, we are able to strongly reduce the background from photodetachment of excited states using a cryogenic electrostatic ion-beam storage ring where keV ion beams can circulate for up to hours. The method is applicable to negative ions in general and here we report an electron affinity of 1.461 112 972(87) eV for O-16. High-precision measurements are useful to find isotopic shifts and electron correlation. Here the authors measure electron affinity and hyperfine splitting of atomic oxygen with higher precision than previous studies.
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| 3. |
- Schmidt-May, Alice F., 1988-, et al.
(författare)
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State-resolved mutual neutralization of 16O+ with 1H− and 2H− at collision energies below 100 meV
- 2024
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 109:5
-
Tidskriftsartikel (refereegranskat)abstract
- We measured the product-state distribution and its dependence on the hydrogen isotope for the mutual neutralization between 16O+ and 1,2H− at the double electrostatic ion-beam storage ring DESIREE for center-of-mass collision energies below 100 meV. We find at least six product channels into ground-state hydrogen and oxygen in different excited states. The majority of oxygen products populate terms corresponding to 2?22?3(4?∘)4? with 5S∘ as the main reaction product. We also observe product channels into terms corresponding to 2?22?3(4?)3?. Collisions with the heavier hydrogen isotope yield a branching into these lower excited states smaller than collisions with 1H−. The observed reaction products agree with the theoretical predictions. The detailed branching fractions, however, differ between the theoretical results, and none of them fully agree with the experiment.
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| 4. |
- Begovic, Ermina, et al.
(författare)
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Experimental modelling of local structure responses for high-speed planing craft in waves
- 2020
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Ingår i: Ocean Engineering. - : Elsevier Ltd. - 0029-8018 .- 1873-5258. ; 216
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Tidskriftsartikel (refereegranskat)abstract
- The modelling of planing craft dynamics in waves and related fluid-structure interaction is a hard challenge due to the highly nonlinear, transient and stochastic nature of the whole process. This paper explores the prospectives of detailed experimental modelling of the local structure responses for high-speed planing craft in waves. A novel experimental setup is presented where a well-defined model structure is integrated into the hull bottom of a typical planing craft model. The model is instrumented for measuring strains in the model structure, related slamming pressures, craft rigid body motions and accelerations. The experimental setup is thoroughly described and motivated and crucial aspects of the setup are verified through testing in idealized static loading conditions and by modal analysis. The capabilities of the experimental setup are demonstrated through systematic experiments in regular waves. The most indicative results are presented and discussed in relation to corresponding results from time-domain simulations The presented experimental modelling approach is concluded to enable uniquely detailed studies of the complete slamming related fluid-structure interaction process and provides a good tool for further research and development towards establishment of first principles-based methods for hydrodynamic and structure design of high-speed planing craft.
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| 5. |
- Hamawandi, Bejan, PhD, et al.
(författare)
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Composition Tuning of Nanostructured Binary Copper Selenides through Rapid Chemical Synthesis and their Thermoelectric Property Evaluation
- 2020
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Reduced energy consumption and environmentally friendly, abundant constituents are gaining more attention for the synthesis of energy materials. A rapid, highly scalable, and process-temperature-sensitive solution synthesis route is demonstrated for the fabrication of thermoelectric Cu2−xSe. The process relies on readily available precursors and microwave-assisted thermolysis, which is sensitive to reaction conditions; yielding Cu1.8Se at 200 °C and Cu2Se at 250 °C within 6–8 min reaction time. Transmission electron microscopy (TEM) revealed crystalline nature of as-made particles with irregular truncated morphology, which exhibit a high phase purity as identified by X-ray powder diffraction (XRPD) analysis. Temperature-dependent transport properties were characterized via electrical conductivity, Seebeck coefficient, and thermal diffusivity measurements. Subsequent to spark plasma sintering, pure Cu1.8Se exhibited highly compacted and oriented grains that were similar in size in comparison to Cu2Se, which led to its high electrical and low thermal conductivity, reaching a very high power-factor (24 µW/K−2cm−1). Density-of-states (DOS) calculations confirm the observed trends in electronic properties of the material, where Cu-deficient phase exhibits metallic character. The TE figure of merit (ZT) was estimated for the materials, demonstrating an unprecedentedly high ZT at 875 K of 2.1 for Cu1.8Se sample, followed by 1.9 for Cu2Se. Synthetic and processing methods presented in this work enable large-scale production of TE materials and components for niche applications.
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| 6. |
- Khodabandeh, E., et al.
(författare)
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CFD study of non-premixed swirling burners : Effect of turbulence models
- 2020
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Ingår i: Chinese Journal of Chemical Engineering. - : Elsevier BV. - 1004-9541 .- 2210-321X. ; 28:4, s. 1029-1038
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Tidskriftsartikel (refereegranskat)abstract
- This research investigates a numerical simulation of swirling turbulent non-premixed combustion. The effects on the combustion characteristics are examined with three turbulence models: namely as the Reynolds stress model, spectral turbulence analysis and Re-Normalization Group. In addition, the P-1 and discrete ordinate (DO) models are used to simulate the radiative heat transfer in this model. The governing equations associated with the required boundary conditions are solved using the numerical model. The accuracy of this model is validated with the published experimental data and the comparison elucidates that there is a reasonable agreement between the obtained values from this model and the corresponding experimental quantities. Among different models proposed in this research, the Reynolds stress model with the Probability Density Function (PDF) approach is more accurate (nearly up to 50%) than other turbulent models for a swirling flow field. Regarding the effect of radiative heat transfer model, it is observed that the discrete ordinate model is more precise than the P-1 model in anticipating the experimental behavior. This model is able to simulate the subcritical nature of the isothermal flow as well as the size and shape of the internal recirculation induced by the swirl due to combustion.
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| 7. |
- Lundstam, Karolina, et al.
(författare)
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Positive Effect of Parathyroidectomy Compared to Observation on BMD in a Randomized Controlled Trial of Mild Primary Hyperparathyroidism
- 2023
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Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 38:3, s. 372-380
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Tidskriftsartikel (refereegranskat)abstract
- Mild or asymptomatic disease is now the dominating presentation of primary hyperparathyroidism (PHPT). However, bone involvement with decreased bone mineral density (BMD) and an increased risk of fractures has been demonstrated. Indications for parathyroidectomy (PTX) in mild PHPT have been debated for years. There is a need of long-term randomized studies comparing PTX with observation without intervention (OBS). Here, we present bone health data from the Scandinavian Investigation of Primary Hyperparathyroidism (SIPH), a randomized controlled trial, comparing PTX to OBS. This study included 191 patients (96 OBS/95 PTX), and 129 patients (64 OBS/65 PTX) were followed for 10 years to the end of study (EOS). BMD was measured with dual-energy X-ray absorptiometry (DXA), peripheral fractures were noted, and spine radiographs were obtained for vertebral fracture assessment. There was a significant treatment effect of PTX on BMD compared with OBS for all analyzed compartments, most explicit for the lumbar spine (LS) and femoral neck (FN) (p < 0.001). The mean changes in T-score from baseline to 10 years were from 0.41 for radius 33% (Rad33) to 0.58 for LS greater in the PTX group than in the OBS group. There was a significant decrease in BMD for all compartments in the OBS group, most pronounced for FN, Rad33, and ultradistal radius (UDR) (p < 0.001). Even though there was a significant treatment effect of PTX compared with OBS, there was only a significant increase in BMD over time for LS (p < 0.001). We found no difference between groups in fracture frequency in the 10-year cohort, neither with modified intention-to-treat (mITT) analysis nor per protocol analysis. Because BMD is only a surrogate endpoint of bone health and PTX did not reduce fracture risk, observation could be considered a safe option for many patients with mild PHPT regarding bone health in a 10-year perspective.(c) 2023 The Authors.
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| 8. |
- Poikolainen Rosén, Anton, 1992-
(författare)
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Noticing nature : exploring more-than-human-centred design in urban farming
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis articulates, theorises and furthers the concept of “more-than-human-centred design” by studying the use and design of technology for noticing nature and caring for nature. The emerging field of more-than-human-centred design focuses on the mutual interdependence between humans and non-humans (e.g. organisms such as animals, plants and microbes, as well as autonomous technologies). It is a step away from seeing other organisms as inferior to humans or valuable only as resources. This implies that design research frameworks and methods need to be remade. How can we design for and with other organisms? What needs to be accommodated in a paradigm that allows for more-than-human-centred design? What are concrete design examples and implications of this kind of thinking? In short, there is a need to investigate what it means to design for more-than-human worlds.This is investigated in the thesis through a series of studies and design experiments, including ethnography (participant observation, interviews, surveys and workshops), design projects (design ideation, development and analysis of prototypes) and design critique of existing artefacts. Most of these studies are conducted within a four-year ethnography of a regenerative urban farming community in Stockholm, Sweden.The thesis draws on posthuman theory. This theory examines the implications of expanding concern and subjectivities beyond the human, and aims to understand the human subject and its relationship to the world in a non-anthropocentric light. Phenomenological analysis is further applied to articulate and understand the human-technology-nature relationship as it is experienced first-person.The thesis contributes an articulation of a more-than-human-centred design programme. Here, two design implications are suggested, “expanding the sensible” and “design for sensory-rich experiences”. Methods for noticing the more-than-human world are suggested, along with principles for designing for and with other organisms, such as finding leverage points in systems and providing a scaffold for naturally occurring processes. The meaning of “design”, “the designer” and “the user” is discussed. Lastly, a manifesto for more-than-human-centred design is proposed.
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| 9. |
- Poikolainen Rosén, Anton, et al.
(författare)
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Noticing the Environment : A Design Ethnography of Urban Farming
- 2022
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Ingår i: NordiCHI ’22. - New York, NY, USA : Association for Computing Machinery (ACM).
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Konferensbidrag (refereegranskat)abstract
- Sustainable HCI attempts to shift focus beyond humans, to care for both ourselves and our environment. In this paper, we build on this growing interest and contribute with a design ethnography of urban farming. We focus on practices of observing and gathering data about the environment which we frame as ‘noticing’. In our analysis, three approaches to noticing the environment were iden- tified, and design suggestions were developed for each approach: Green Thumbs (control-oriented), Dirty Nails (sensibility-oriented) and BeeNoculars (appreciation-oriented). The design suggestions, presented as posters, focus on ways to improve the alignment of the acquisition and display of data with the identified approaches. We discuss two themes: the noticing and balancing of systemic rela- tions and needs, and sensory-rich experiences of the environment. The paper contributes to a broader discussion in HCI of how tech- nologies could create a different understanding of and relationship to the environment.
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| 10. |
- Poikolainen Rosén, Anton, 1992-, et al.
(författare)
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Relating to the Environment through Photography : the Smartphone Camera as a Tool in Urban Farming
- 2020
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Ingår i: OzCHI '20. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450389754 ; , s. 506-519
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Konferensbidrag (refereegranskat)abstract
- Research on environmental sustainability in HCI is investigating the opportunities and hindrances technologies pose on living sustainably, beyond direct material impact of production, use and disposal. With this background, we focus on the smartphone camera as a tool that allows users to quickly and relatively effortlessly depict, save, share, access, augment or amplify information about the environment. Based on two years of participant observation studies, we present examples of how urban farmers use the smartphone camera as a tool in their practice. We discuss how the smartphone camera mediates human experiences of the environment and how certain uses of the camera may contribute to environmental sustainability. We highlight how the smartphone camera used as a tool in gardening was experienced to support (a) feelings of closeness or bonds towards the local environment and (b) the creation and sharing of knowledge.
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