| 1. |
- Berglund, Kim, 1982-, et al.
(författare)
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A novel reciprocating tribometer for friction and wear measurements with high contact pressure and large area contact configurations
- 2021
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Ingår i: Lubricants. - : MDPI. - 2075-4442. ; 9:12
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Tidskriftsartikel (refereegranskat)abstract
- There are many moving machine assemblies with conformal tribological contacts at very high contact pressures, e.g., sliding bearings, propeller shaft bearings and machine guideways. Furthermore, applications such as trunnion and guide vane bearing in Kaplan turbines have very low sliding speeds and oscillatory types of motion. Although there is a vast selection of tribology test rigs available, there is still a lack of test equipment to perform friction and wear tests under high contact pressure, reciprocatory sliding and large area contact. The aim of this work is thus to develop a novel reciprocating tribometer and test method that enables friction and wear tests under low-speed reciprocatory sliding with contact pressures up to 90 MPa in a flat-on-flat contact configuration. First, a thorough description of the test rig design is given. Secondly, the influence of contact pressure and stroke length on the tribological properties of a stainless steel and polymer composite material combination is studied. The significance of considering creep, friction during the stroke and contact temperature is specifically highlighted. The novel tribometer can be used to screen different bearing and shaft material combinations and to evaluate the friction and wear performance of self-lubricating bearings for the specific operating conditions found in Kaplan turbines.
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| 2. |
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| 3. |
- Bucin, Dragan, et al.
(författare)
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Heart transplantation across the antibodies against HLA and ABO
- 2006
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Ingår i: Transplant International. - : Frontiers Media SA. - 1432-2277 .- 0934-0874. ; 19:3, s. 239-244
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Tidskriftsartikel (refereegranskat)abstract
- We have intentionally performed heart transplantation in a 5-year-old child, despite the most unfavourable risk factors for patient survival; the presence of high level of antibodies against donor's human leucocyte antigen (HLA) class I/II and blood group antigens. Pretransplant treatment by mycophenolate mofetil, prednisolone, tacrolimus, intravenous immunoglobulin, rituximab, protein-A immunoadsorption (IA) and plasma exchange reduced antibody titres against the donor's lymphocytes from 128 to 16 and against the donor's blood group antigen from 256 to 0. The patient was urgently transplanted with a heart from an ABO incompatible donor (A(1) to O). A standard triple-drug immunosuppressive protocol was used. No hyperacute rejection was seen. Antibodies against the donor's HLA antigens remained at a low level despite three acute rejections. Rising anti-A(1) blood group antibodies preceded the second rejection and were reduced by two blood group-specific IAs and remained at a low level. The patient is doing well despite the persistence of donor-reactive antibodies.
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| 4. |
- Fricke, Katrin, et al.
(författare)
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Impact of Left Ventricular Morphology on Adverse Outcomes Following Stage 1 Palliation for Hypoplastic Left Heart Syndrome: 20 Years of National Data From Sweden
- 2022
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Ingår i: Journal of the American Heart Association. - : John Wiley & Sons. - 2047-9980. ; 11:7
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hypoplastic left heart syndrome is associated with significant morbidity and mortality. We aimed to assess the influence of left ventricular morphology and choice of shunt on adverse outcome in patients with hypoplastic left heart syndrome and stage 1 palliation. METHODS AND RESULTS: This was a retrospective analysis of patients with hypoplastic left heart syndrome with stage 1 palliation between 1999 and 2018 in Sweden. Patients (n=167) were grouped based on the anatomic subtypes aortic-mitral atresia, aortic atresia-mitral stenosis (AA-MS), and aortic-mitral stenosis. The left ventricular phenotypes including globular left ventricle (Glob-LV), miniaturized and slit-like left ventricle (LV), and the incidence of major adverse events (MAEs) including mortality were assessed. The overall mortality and MAEs were 31% and 41%, respectively. AA-MS (35%) was associated with both mortality (all other subtypes versus AA-MS: interstage-I: hazard ratio [HR], 2.7; P=0.006; overall: HR, 2.2; P=0.005) and MAEs (HR, 2.4; P=0.0009). Glob-LV (57%), noticed in all patients with AA-MS, 61% of patients with aortic stenosis-mitral stenosis, and 19% of patients with aortic atresia-mitral atresia, was associated with both mortality (all other left ventricular phenotypes versus Glob-LV: interstage-I: HR, 4.5; P=0.004; overall: HR, 3.4; P=0.0007) and MAEs (HR, 2.7; P=0.0007). There was no difference in mortality and MAEs between patients with AA-MS and without AA-MS with Glob-LV (P>0.15). Patients with AA-MS (35%) or Glob-LV (38%) palliated with a Blalock-Taussig shunt had higher overall mortality compared with those palliated with Sano shunts, irrespective of the stage 1 palliation year (AA-MS: HR, 2.6; P=0.04; Glob-LV: HR, 2.1; P=0.03). CONCLUSIONS: Glob-LV and AA-MS are independent morphological risk factors for adverse short-and long-term outcome, especially if a Blalock-Taussig shunt is used as part of stage 1 palliation. These findings are important for the clinical management of patients with hypoplastic left heart syndrome.
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| 5. |
- Grabowski, Martin, et al.
(författare)
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Influence of an enriched environment and cortical grafting on functional outcome in brain infarcts of adult rats
- 1995
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 133:1, s. 96-102
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to study if enriched housing conditions and fetal neocortical transplantation could enhance the functional outcome after focal brain ischemia in adult rats. The right middle cerebral artery (MCA) was ligated in 34 inbred, spontaneously hypertensive male rats, which were then randomly divided into three groups. Groups A and B were transferred to an enriched environment, i.e., a large cage with opportunities for various activities but not forcing the rats to do any particular tasks; group C was kept in standard laboratory cages. Three weeks after the MCA occlusion blocks of fetal neocortical tissue (Embryonic Day 17) were transplanted to the infarct cavity in groups B and C. Rats in group A (n = 11) and group B (n = 11) performed equally well and significantly better than rats in group C (n = 10) when placed on an inclined plane and when traversing a rotating pole 6 and 9 weeks after the MCA occlusion and in a leg placement test at 9, but not 6 and 12 weeks. Skilled forelimb function did not differ between the groups. Infarct size and thalamic atrophy did not differ between the groups and graft size was similar in group B and C. There was no correlation between infarct size and motor function in any of the tests in rats housed in an enriched environment. Since the environment can significantly alter functional outcome without reducing infarct size we suggest that more attention should be given to the role of the laboratory environment and to long term behavioral outcome in experimental stroke.
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| 6. |
- Johansson, Jens
(författare)
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Impact of Water-Level Variations on Slope Stability
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Waterfront-soil slopes are exposed to water-level fluctuations originating from either natural sources, e.g. extreme weather and tides, or from human activities such as watercourse regulation for irrigation, freshwater provision, hydropower production etc. Slope failures and bank erosion is potentially getting trees and other vegetation released along with bank landslides. When floating debris is reaching hydropower stations, there will be immediate risks of adverse loading on constructions, and clogging of spillways; issues directly connected to as well energy production as dam safety.The stability of a soil slope is governed by slope geometries, stress conditions, and soil properties. External water loading, pore-pressure changes, and hydrodynamic impact from water flow are factors being either influencing, or completely governing the actual soil properties. As a part of this study, knowledge concerning water-level fluctuations has been reviewed; sources, geotechnical effects on slopes, and approaches used for modelling, have been focused. It has been found a predominance of research focused on coastal erosion, quantification of sediment production, bio-environmentallyissues connected to flooding, and effects on embankment dams subjected to rapid drawdown. Though, also water-level rise has been shown to significantly influence slope stability. There seems to be a need for further investigations concerning effects of rapidly increased water pressures, loss of negative pore pressures, retrogressive failure development, and long-term effects of recurring rise-drawdown cycling.Transient water flow within soil structures affects pore-pressure conditions, strength, and deformation behavior of the soil. This in turn does potentially lead to soil-materialmigration, i.e. erosion. This process is typically considered in the context of embankment dams. Despite the effects of transient water flow, the use of simple limitequilibrium methods for slope analysis is still widely spread. Though, improved accessibility of high computer capacity allows for more and more advanced analyses to be carried out. In addition, optimized designs and constructions are increasingly demanded, meaning less conservative design approaches being desired. This is not atleast linked to economic as environmental aspects. One non-conservative view ofslope-stability analysis regards consideration of negative pore pressures in unsaturated soils. In this study, three different approaches used for hydro-mechanical coupling in FEM-modelling of slope stability, were evaluated. A fictive slope consisting of a wellgraded postglacial till was exposed to a series of water-level fluctuation cycles. Modelling based on classical theories of dry/fully saturated soil conditions, was put against two more advanced approaches with unsaturated-soil behavior considered. In the classical modelling, computations of pore-pressures and deformations were run separately, whereas the advanced approaches did allow for computations of porepressures and deformation to be fully coupled. The evaluation was carried out by comparing results concerning stability, vertical displacements, pore pressures, flow, and model-parameter influence. It was found that the more advanced approaches used did capture variations of pore pressures and flow to a higher degree than did the classical, more simple approach. Classical modelling resulted in smaller vertical displacements and smoother porepressure and flow developments. Flow patterns, changes of soil density governed by suction fluctuations, and changes of hydraulic conductivity, are all factors governing as well water-transport (e.g. dissipation of excess pore pressures) as soil-material transport(e.g. susceptibility to internal erosion to be initiated and/or continued). Therefore, the results obtained underline the strengths of sophisticated modelling.
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| 7. |
- Johansson, Maria, et al.
(författare)
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Factors Governing Human Fear of Brown Bear and Wolf
- 2012
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Ingår i: Human Dimensions of Wildlife. - London : Taylor & Francis. - 1087-1209 .- 1533-158X. ; 17:1, s. 58-74
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Tidskriftsartikel (refereegranskat)abstract
- This article analyzes people's subjectively experienced fear in areas with presence of brown bear or wolf. Departing from the Human-Environment Interaction Model (Küller, 1991), a hypothetical model of environmental and individual antecedents of fear was tested using structural equation modeling of survey data (n = 391). In the model of fear of brown bear, the main predictor was the appraisal of the species as dangerous/uncontrollable and unpredictable. In the model of fear of wolf, the greater experience with the species and a stronger appraisal of wolf as dangerous, uncontrollable, and unpredictable led to low social trust and this, together with the appraisal of wolf as dangerous/uncontrollable and unpredictable, increased the likelihood of fear. Efforts to reduce human fear of wolves should focus on building trust between the public and authorities, whereas efforts to reduce fear of brown bear should focus on the individual's appraisal of the species. © 2012 Copyright Taylor and Francis Group, LLC.
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| 8. |
- Johansson, Maria, et al.
(författare)
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Is Human Fear Affecting Public Willingness to Pay for the Management and Conservation of Large Carnivores?
- 2012
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Ingår i: Society & Natural Resources. - : Informa UK Limited. - 0894-1920 .- 1521-0723. ; 25:6, s. 610-620
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Tidskriftsartikel (refereegranskat)abstract
- From an interdisciplinary approach, this study aims at analyzing self-reported animal fear, specifically large carnivore fear, in relation to public willingness to pay to fulfill a governmental policy on large carnivore-induced costs. In a survey in Sweden involving more than 2,000 respondents, it was found that people whose animal fear was directed particularly toward large carnivores were less likely to be willing to pay these costs, or were likely to be willing to pay a lower amount of money. In the prediction of willingness to pay (WTP), the contribution of the fear variable was as equally important as previously addressed socioeconomic factors.
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| 9. |
- Johansson, Maria, et al.
(författare)
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Subjective experience of fear and the cognitive interpretation of large carnivores
- 2011
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Ingår i: Human Dimensions of Wildlife. - : Informa UK Limited. - 1087-1209 .- 1533-158X. ; 16:1, s. 15-29
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Tidskriftsartikel (refereegranskat)abstract
- This study describes the psychological characteristics of fear of brown bear (Ursus arctos) and wolf (Canis lupus) using the Cognitive Vulnerability Model. Data were obtained from a survey of 154 stakeholders. Subjective experience of fear was primarily linked to the perceived danger or harm that the animal represents and the perceived uncontrollability of the person's own response when encountering an animal. Feelings of disgust and perceived unpredictability of the animals' movements were of less importance. To reduce fear of brown bear and wolf it might therefore be more effective to enable people to learn more about their own reactions rather than learning more about wolf or bear behavior. Stakeholders varied in terms of which perceptions were more strongly linked to the fear. In efficient management of large carnivores, the consequences for the cognitive vulnerability in different stakeholder groups should be considered.
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| 10. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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