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- Rothen, Hans Ulrich, et al.
(författare)
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Influence of gas composition on recurrence of atelectasis after a reexpansion maneuver during general anaesthesia
- 1995
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Ingår i: Anesthesiology. - 0003-3022 .- 1528-1175. ; 82:4, s. 832-842
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Atelectasis, an important cause of impaired gas exchange during general anesthesia, may be eliminated by a vital capacity maneuver. However, it is not clear whether such a maneuver will have a sustained effect. The aim of this study was to determine the impact of gas composition on reappearance of atelectasis and impairment of gas exchange after a vital capacity maneuver.METHODS:A consecutive sample of 12 adults with healthy lungs who were scheduled for elective surgery were studied. Thirty minutes after induction of anesthesia with fentanyl and propofol, the lungs were hyperinflated manually up to an airway pressure of 40 cmH2O. FIO2 was either kept at 0.4 (group 1, n = 6) or changed to 1.0 (group 2, n = 6) during the recruitment maneuver. Atelectasis was assessed by computed tomography. The amount of dense areas was measured at end-expiration in a transverse plane at the base of the lungs. The ventilation-perfusion distributions (VA/Q) were estimated with the multiple inert gas elimination technique. The static compliance of the total respiratory system (Crs) was measured with the flow interruption technique.RESULTS:In group 1 (FIO2 = 0.4), the recruitment maneuver virtually eliminated atelectasis for at least 40 min, reduced shunt (VA/Q < 0.005), and increased at the same time the relative perfusion to poorly ventilated lung units (0.005 < VA/Q < 0.1; mean values are given). The arterial oxygen tension (PaO2) increased from 137 mmHg (18.3 kPa) to 163 mmHg (21.7 kPa; before and 40 min after recruitment, respectively; P = 0.028). In contrast to these findings, atelectasis recurred within 5 min after recruitment in group 2 (FIO2 = 1.0). Comparing the values before and 40 min after recruitment, all parameters of VA/Q were unchanged. In both groups, Crs increased from 57.1/55.0 ml.cmH2O-1 (group 1/group 2) before to 70.1/67.4 ml.cmH2O-1 after the recruitment maneuver. Crs showed a slow decrease thereafter (40 min after recruitment: 61.4/60.0 ml.cmH2O-1), with no difference between the two groups.CONCLUSIONS:The composition of inspiratory gas plays an important role in the recurrence of collapse of previously reexpanded atelectatic lung tissue during general anesthesia in patients with healthy lungs. The reason for the instability of these lung units remains to be established. The change in the amount of atelectasis and shunt appears to be independent of the change in the compliance of the respiratory system.
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| 2. |
- Al-Saadi, Munir, 1965-
(författare)
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Thermomechanical Processing of Nickel-Base Alloy 825
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Alloy 825 material was studied using a Gleeble-3800 thermosimulatorby performing single-hot compression experiments.Optical microscopy and electron backscatter diffraction wereutilized to characterize the microstructure. Dynamicrecrystallization is not considerable in the as-cast alloy anddislocation recovery is deemed to be dominant. Based on thisfinding, the effect of adding trace amounts of alloying additionson the mechanical properties of cast alloy 825 was studied, withemphasis on whether or not dynamic recrystallization occurred.The results show that dynamic recrystallization was moreprevalent under all test conditions in samples containing a traceamount of magnesium, but not for the conventional alloy.However, alloying with trace magnesium did not lead to animprovement of the mechanical properties. Instead, processingmaps for hot forging of conventional Alloy 825 were required toidentify optimal working parameters and to achieve dynamicrecrystallization. The hot deformation behavior of cast Alloy 825was characterized by using dynamic materials modelling of hotcompression data. The results show that the maximum powerdissipation efficiency is over 35%. The highest efficiency isachieved in the temperature range of 1100 ℃ - 1250 ℃ and instrain rates in the range of 0.01 ≤ strain rate / s ≤ 0.1. The optimumprocessing parameters for good strain hardening are obtained inthe temperature range between 950 ℃ and 1100 ℃ with strainrates of 0.3 ≤ strain rate/ s ≤ 10.0. In addition, the influence of thedeformation level on the recrystallization and microstructuralchanges in Alloy 825 during hot forging operations attemperatures between 950 °C and 1200 °C was studied. Themaximum yield strength and ultimate tensile strength wereobtained after forging to achieve a true strain of 0.9 were 413 MPa and 622 MPa , respectively, with a ductility of 40%.However, Alloy 825 is often supplied as annealed bars.Therefore, the effect of the forging strain magnitude andsubsequent annealing on the microstructure, strengtheningmechanisms and room temperature mechanical properties wereinvestigated to assess the suitability of current industrialpractice. The results showed that the majority of strengtheningwas attributed to grain refinement, the dislocation densities thatarise due to the large forging strain, and due to solid solutionstrengthening. The results of calculations are in excellentagreement with experimental data, with less than 1% difference.These results can be used by future researchers and industry topredict the strength of Alloy 825 and similar alloys, especially inmaterial after a completed hot forging operation.
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| 4. |
- Berggård, Cecilia, 1975-
(författare)
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Transcription Factor AP-2 in Relation to Personality and Antidepressant Drugs
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The CNS monoaminergic systems are considered as the head engine regulating neuropsychiatric functions and personality. Transcription factor AP-2 is known to be essential for the development of the brainstem including the monoaminergic nuclei, and has the ability to regulate many genes in the monoaminergic systems. The ability of transcription factors to regulate specific gene expression, has lately made them hot candidates as drug targets. In this thesis, results indicating a role of AP-2 in the molecular effects of the antidepressant drugs citalopram and phenelzine, are presented. A polymorphism in the second intron of the gene encoding AP-2ß has previously been associated with anxiety-related personality traits as estimated by the Karolinska Scales of Personality (KSP). In this thesis, results confirming this association, gained by using a larger material and several different personality scales, are presented. Furthermore, data is presented showing an association between the activity of platelet monoamine oxidase, a trait-dependent marker for personality, and the genotype of the AP-2ß intron 2 polymorphism. The functional importance of the AP-2ß intron 2 polymorphism has not yet been elucidated. Included in this thesis are results showing that the AP-2ß intron 2 polymorphism is not in linkage disequilibrium with the only other described polymorphism in the AP-2ß gene, i.e. in the AP-2ß promoter (-67 G/A). Introns have in several studies been shown to include binding sites for regulatory proteins, and thus, to be important in transcriptional regulation. Results are presented demonstrating that one human brain nuclear protein binds only to the long variant of the AP-2ß intron 2 polymorphism. If this protein is involved in the regulation of the AP-2ß gene, it would affect the expression levels of the AP-2ß protein. In general, this thesis further establishes the role of transcription factor AP-2 as a regulatory factor of importance for personality and monoaminergic functions.
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| 8. |
- Calmunger, Mattias
(författare)
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High-Temperature Behaviour of Austenitic Alloys : Influence of Temperature and Strain Rate on Mechanical Properties and Microstructural Development
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The global increase in energy consumption and the global warming from greenhouse gas emission creates the need for more environmental friendly energy production processes. Biomass power plants with higher efficiency could generate more energy but also reduce the emission of greenhouse gases, e.g. CO2. Biomass is the largest global contributor to renewable energy and offers no net contribution of CO2 to the atmosphere. One way to increase the efficiency of the power plants is to increase temperature and pressure in the boiler parts of the power plant.The materials used for the future biomass power plants, with higher temperature and pressure, require improved properties, such as higher yield strength, creep strength and high-temperature corrosion resistance. Austenitic stainless steels and nickel-base alloys have shown good mechanical and chemical properties at the operation temperatures of today’s biomass power plants. However, the performance of austenitic stainless steels at the future elevated temperatures is not fully understood.The aim of this licentiate thesis is to increase our knowledge about the mechanical performance of austenitic stainless steels at the demanding conditions of the new generation power plants. This is done by using slow strain rate tensile deformation at elevated temperature and long term hightemperature ageing together with impact toughness testing. Microscopy is used to investigate deformation, damage and fracture behaviours during slow deformation and the long term influence of temperature on toughness in the microstructure of these austenitic alloys. Results show that the main deformation mechanisms are planar dislocation deformations, such as planar slip and slip bands. Intergranular fracture may occur due to precipitation in grain boundaries both in tensile deformed and impact toughness tested alloys. The shape and amount of σ-phase precipitates have been found to strongly influence the fracture behaviour of some of the austenitic stainless steels. In addition, ductility is affected differently by temperature depending on alloy tested and dynamic strain ageing may not always lead to a lower ductility.
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| 9. |
- ENGBERG, ARON, et al.
(författare)
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'A Fool for Christ' : Sense-Making and Negotiation of Identity in the Life Story of a Christian Soldier
- 2014
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Ingår i: Comprehending Christian Zionism : Perspectives in Comparison - Perspectives in Comparison. - Minneapolis : Fortress Press. - 9781451472264 - 9781451489644 ; , s. 33-59
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Bokkapitel (refereegranskat)abstract
- This chapter presents a narrative analysis of the life story of a Swedish Pentecostal who decided to join the Israeli Defense Forces out of his conviction that God wanted him to protect the chosen people. His story is treated as an example of lived Christian Zionism; as one of many manifestations that contemporary Christian affection for Israel can take. The analysis focuses on the central narrative pattern of calling-test of faith-confirmation, 'Jacob's' sense-making of his life choices, and the negotiation of his identity in relation to larger religious and cultural narratives.
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| 10. |
- Engberg, Elisabeth, 1961-
(författare)
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I fattiga omständigheter : Fattigvårdens former och understödstagare i Skellefteå socken under 1800-talet
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to shed light upon the Swedish nineteenth century poor relief system, how it operated in a local rural context, how it changed over time, and not least, who was supported and why. It raises questions about how the poor laws were interpreted on the parish level, how the welfare systems interacted with local society and about who was considered to be poor and entitled to support. The geographical setting of the thesis is Skellefteå, a rural parish in northern Sweden, and it concentrates upon the period 1830–1875.Swedish poor relief was governed by the fundamental principle that each parish had a duty to support their own poor and each parish was allowed a large amount of freedom to adjust their welfare arrangements according to local conditions. In Skellefteå, the main incentive for modification of the poor relief system was not new regulations from the national level, but social and economic transformations on the local level. This implies that local requirements were put before national legislation and suggests the existence of several regional, and perhaps also local, poor relief systems in nineteenth-century Sweden.On the local level, the results indicate the existence of a parochial social citizenship based upon a common understanding of social rights and duties in the community, and grounded in a strong sense of affiliation with the local society. Generally there was a larger distance between the poor and their providers in the wealthier and more socially stratified villages, hence a more egalitarian context seem to have facilitated identification and empathy with the poor. The local provision for the poor created and maintained bonds within a community, as well as it helped to build and reinforce boundaries towards those who did not belong. A sometimes suspicious and negative attitude towards outsiders was to some extent caused by a fear of increased poor relief expenses, but it also bears witness to a rural culture with a strong sense of belonging to one’s own village or hamlet.The majority of men and women supported by poor relief in Skellefteå belonged to the lower strata of society long before they became welfare recipients. They were landless rural people with weak kinship networks, that in most cases were unable to mobilize any significant support in times of need. Childhood, early middle age, and old age were identified as phases in the life cycle that seem to have entailed an increased risk of poverty and dependence. A substantial proportion of the poor were breadwinners, middle aged men with large households to support, while the widowed and unmarried paupers usually were women. For many of these households the life cycles’ vulnerable periods were further reinforced by other factors: a breadwinner’s illness or disability, the death of a spouse, a major subsistence crisis, or a larger marginalization caused by a deviation from society’s moral standards. In most cases there seems to have been a delicate interplay between several social risks that determined if and when a person or a household was to end up being supported by poor relief.
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