| 1. |
- Ablikim, M., et al.
(författare)
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Probing CP symmetry and weak phases with entangled double-strange baryons
- 2022
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 606:7912, s. 64-69
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Tidskriftsartikel (refereegranskat)abstract
- Though immensely successful, the standard model of particle physics does not offer any explanation as to why our Universe contains so much more matter than antimatter. A key to a dynamically generated matter-antimatter asymmetry is the existence of processes that violate the combined charge conjugation and parity (CP) symmetry(1). As such, precision tests of CP symmetry may be used to search for physics beyond the standard model. However, hadrons decay through an interplay of strong and weak processes, quantified in terms of relative phases between the amplitudes. Although previous experiments constructed CP observables that depend on both strong and weak phases, we present an approach where sequential two-body decays of entangled multi-strange baryon-antibaryon pairs provide a separation between these phases. Our method, exploiting spin entanglement between the double-strange baryon and its antiparticle(2) (+), has enabled a direct determination of the weak-phase difference, (xi(P) - xi(S)) = (1.2 +/- 3.4 +/- 0.8) x 10(-2) rad. Furthermore, three independent CP observables can be constructed from our measured parameters. The precision in the estimated parameters for a given data sample size is several orders of magnitude greater than achieved with previous methods(3). Finally, we provide an independent measurement of the recently debated Lambda decay parameter alpha(Lambda) (refs. (4,5)). The Lambda(Lambda) over bar asymmetry is in agreement with and compatible in precision to the most precise previous measurement(4).
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| 2. |
- Al-Najjar, Basim, 1954-, et al.
(författare)
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Benchmarking of Maintenance Performance : a Case Study in Two Manufacturers of Furniture
- 2004
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Ingår i: IMA Journal of Management Mathematics. - : Oxford University Press (OUP). - 1471-678X .- 1471-6798. ; 15:3, s. 253-270
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Tidskriftsartikel (refereegranskat)abstract
- When profit margins of a plant are decreasing then, the need for reliable and efficient maintenance policy becomes more important. Measuring maintenance performance is important for companies to recognise whether their planned goals are achieved or not. Also, such measurements can be utilised for benchmarking, which is one of the tools for never-ending improvement. But, these objectives cannot be achieved without well-documented data of the relevant variables. Better data coverage and quality is necessary for following maintenance performance development and it would, in many cases, clarify the ambiguity concerning the main problem in the context, namely that neither the production nor maintenance department can show what effect maintenance has on profitability.A more effective maintenance policy indirectly implies improvements in product quality and manufacturing process effectiveness. Elongation of the production time, i.e. reducing the down time due to failures, planned replacements and repair, in addition to the improvement in the total maintenance activities, are also some of the results that can be expected when an efficient maintenance policy is used. Measuring and monitoring maintenance performance measures is required partly for detecting, and eventually treating as soon as possible, undesirable changes and partly to make benchmarking with the best in the branch, which saves appreciable economic losses for companies.In this paper, a model for how to identify the measurable variables, which are needed to develop measures for monitoring maintenance performance behaviour systematically, is developed. Five maintenance performance measures are proposed and applied. An additional model for systematically analysing the trend of maintenance performance measures, for an overall assessment of the company’s situation, is presented. Two case studies in manufacturers of furniture are conducted to verify these models.
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| 3. |
- Baard, Patrik, 1981-
(författare)
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Cautiously utopian goals : Philosophical analyses of climate change objectives and sustainability targets
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, the framework within which long-term goals are set and subsequently achieved or approached is analyzed. Sustainable development and climate change are areas in which goals have tobe set despite uncertainties. The analysis is divided into the normative motivations for setting such goals, what forms of goals could be set given the empirical and normative uncertainties, and how tomanage doubts regarding achievability or values after a goal has been set.Paper I discusses a set of questions that moral theories intended to guide goal-setting should respond to. It is often claimed that existent normative theories provide only modest guidance regarding climate change, and consequently have to be revised or supplemented. Two such suggested revisions or supplements are analyzed in order to determine whether they provide such guidance.Paper II applies the deep ecological framework to survey the extent to which it can be utilized to discuss issues concerning the management of climate change. It is suggested that the deep ecological framework can provide guidance by establishing a normative framework and an analysis of how the overarching values and principles can be specified to be relevant for actions.Paper III is focused on normative political theory, and explicates the two dimensions of empirical and normative uncertainty. By applying recent discussions in normative political theory on ideal/non-ideal theory, political realism, and the relation between normative demands and empirical constraints,strategies for managing the proposed goals are suggested.Paper IV suggests a form of goal that incorporates uncertainties. Cautious utopias allow greater uncertainty than realistic goals (goals that are known to be achievable or approachable, and desirable),but not to the same extent as utopian goals (goals wherein it is highly uncertain whether the goal can actually be achieved). Such goals have a performance-enhancing function. A definition and quality criteria for such goals are proposed.Paper V considers whether a goal that is becoming all the more unlikely to be achievable should be reconsidered. The paper focuses on the two degrees Celsius target, and asks whether it could still be a sensible goal to aspire to. By applying the principle that ‘ought’ implies ‘can’, the role of such obligations is investigated.Paper VI surveys how to treat circumstances in which an already set goal should be reconsidered and possibly revised, and what would evoke doubt in the belief upon which those goals have been set.Two situations are analyzed: (i) a problematic or surprising event occurs, upsetting confidence in one’s relevant beliefs, or (ii) respectable but dissenting views are voiced concerning one’s means and/or values. It is suggested that the validity of doubt has to be considered, in addition to the level in a goal-means hierarchy towards which doubt is raised.
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| 4. |
- Baard, Patrik, 1981-
(författare)
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Sustainable Goals : Feasible Paths to Desirable Long-Term Futures
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The general aim of this licentiate thesis is to analyze the framework in which long-term goals are set and subsequently achieved. It is often claimed that goals should be realistic, meaning that they should be adjusted to known abilities. This thesis will argue that this might be very difficult in areas related to sustainable development and climate change adaptation, and that goals that are, to an acceptable degree, unrealistic, can have important functions.Essay I discusses long-term goal setting. When there is a great temporal discrepancy between the point in time of setting and achieving a goal, many uncertainties have to be considered. The surrounding world and the agent’s abilities and values might change. This is an ontological uncertainty. We often form beliefs regarding how abilities and values might change, but this belief is always uncertain. This is an epistemological uncertainty. A form of goal called cautiously utopian goals is proposed, which incorporate such uncertainties, but enables goal setting with long time-frames.Essay II discusses the issue of goals intended to reduce great risks. We cannot expect an agent to do something that lies beyond this agent’s abilities, as exemplified in the principle ‘ought implies can’. Adjusting goals to what we currently, with a high degree of certainty know could be done is difficult. If not including an estimation of how abilities can change, important performance-enhancing functions of goals might be lost. It is argued that very ambitious goals should be set. This is partly due to the great magnitude and likelihood of unwanted consequences and partly due to the difficulty of delineating what lies in agents’ capacity to manage complex risks.Essay III discusses a decision-facilitating tool Sustainability Analysis to be used by Swedish municipal planners. One sub-part of the tool, Goal Conflict Analysis, can be used to identify how the consequences of a planned adaptation measure will affect other long-term municipal goals. Identified goal conflicts can then be used in order to determine whether the conflicts are acceptable, or whether a different adaptation measure should be worked out. The paper discusses a workshop in a Swedish municipality in which the tool has been tested.
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| 5. |
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| 6. |
- Bauhn, Lovisa, 1981, et al.
(författare)
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The fate of hydroxyl radicals produced during H2O2 decomposition on a SIMFUEL surface in the presence of dissolved hydrogen
- 2018
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 507, s. 38-43
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Tidskriftsartikel (refereegranskat)abstract
- Over geologic timescales hydrogen peroxide will be one of the most important radiolytic oxidants challenging the spent fuel integrity in a deep repository. Consequently, the reaction between hydrogen peroxide and different kinds of UO 2 based materials has been the subject of several studies over recent decades. Parts of these studies have investigated the effect of dissolved hydrogen on this reaction, as large amounts of hydrogen are expected to be produced by anoxic corrosion of iron in the deep repositories. In some of the studies hydrogen has been shown to offset the radiolysis-driven oxidative dissolution of the fuel despite the expected inertia of hydrogen at repository temperatures. However, the underlying mechanism is primarily based on the effect of the metallic particles contained in the spent fuel. One clue to the mechanistic understanding is whether or not a reaction takes place between dissolved hydrogen and hydroxyl radicals adsorbed to a fuel surface resulting from the decomposition of H 2 O 2 . In the study presented here this reaction could be confirmed in an autoclave system with SIMFUEL, a hydrogen peroxide spiked solution, and deuterium gas. The results show that the studied reaction does not only occur, but accounts for a substantial part of the hydrogen peroxide consumption in the system. Only a very minor part, 0.02%, of the total consumed hydrogen peroxide caused oxidative dissolution of the SIMFUEL. The conclusion is supported by quantitative measurements of HDO, dissolved U in solution and O 2 in the gas phase.
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| 7. |
- Bauhn, Lovisa, 1981, et al.
(författare)
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The interaction of molecular hydrogen with α-radiolytic oxidants on a (U,Pu)O2 surface
- 2018
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 505, s. 54-61
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the impact of α-radiolysis of water on the oxidative dissolution of spent fuel, an un-irradiated, annealed MOX fuel pellet with high content of Pu (∼24 wt%), and a specific α-activity of 4.96 GBq/g MOX , was leached in carbonate-containing solutions of low ionic strength. The high Pu content in the pellet stabilizes the (U,Pu)O 2 (s) matrix towards oxidative dissolution, whereas the α-decays emitted from the surface are expected to produce ∼3.6 × 10 −7 mol H 2 O 2 /day, contributing to the oxidative dissolution of the pellet. Two sets of leaching tests were conducted under different redox conditions: Ar gas atmosphere and deuterium gas atmosphere. A relatively slow increase of the U and Pu concentrations was observed in the Ar case, with U concentrations increasing from 1·10-6 M after 1 h to ∼7 × 10-5 M after 58 days. Leaching under an atmosphere starting at 1 MPa deuterium gas was undertaken in order to evaluate any effect of dissolved hydrogen on the radiolytic dissolution of the pellet, as well as to investigate any potential recombination of the α-radiolytic products with dissolved deuterium. For the latter purpose, isotopic analysis of the D/H content was carried out on solution samples taken during the leaching. Despite the continuous production of radiolytic oxidants, the concentrations of U and Pu remained quite constant at the level of ∼3 × 10-8 M during the first 30 days, i.e. as long as the deuterium pressure remained higher than 0.8 MPa. These data rule out any oxidative dissolution of the pellet during the first month. The un-irradiated MOX fuel does not contain metallic ε-particles, hence it is mainly the interaction of ra diolytic oxidants and dissolved deuterium with the surface of the mixed actinide oxide that causes the neutralization of the oxidants. This conclusion is supported by the steadily increasing levels of HDO measured in the leachate samples.
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| 8. |
- Bhalla, Nayanika, et al.
(författare)
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Spatial transcriptomics of human placentas reveal distinct RNA patterns associated with morphology and preeclampsia
- 2023
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Ingår i: Placenta. - : Elsevier BV. - 0143-4004 .- 1532-3102. ; 139, s. 213-216
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Tidskriftsartikel (refereegranskat)abstract
- Spatial transcriptomics (ST) maps RNA level patterns within a tissue. This technology has not been previously applied to human placental tissue. We demonstrate analysis of human placental samples with ST. Unsupervised clustering revealed that distinct RNA patterns were found corresponding to different morphological structures. Additionally, when focusing upon terminal villi and hemoglobin associated structures, RNA levels differed between placentas from full term healthy pregnancies and those complicated by preeclampsia. The results from this study can provide a benchmark for future ST studies in placenta.
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| 10. |
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