| 1. |
- Mazur, G. P., et al.
(författare)
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Towards modeling quasi-periodic oscillations of microquasars with oscillating slender tori
- 2013
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 554
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Tidskriftsartikel (refereegranskat)abstract
- Context. One of the often discussed models for high-frequency quasi-periodic oscillations of X-ray binaries is the oscillating torus model, which considers oscillation modes of slender accretion tori. Aims. Here, we aim at developing this model by considering the observable signature of an optically thick slender accretion torus subject to simple periodic deformations. Methods. We compute light curves and power spectra of a slender accretion torus subject to simple periodic deformations: vertical or radial translation, rotation, expansion, and shear. Results. We show that different types of deformations lead to very different Fourier power spectra and therefore could be observationally distinguished. Conclusions. This work is a first step in a longer term study of the observable characteristics of the oscillating torus model. It gives promising perspectives on the possibility of constraining this model by studying the observed power spectra of quasi-periodic oscillations.
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| 2. |
- Ander, Mats, 1964, et al.
(författare)
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Development, accomplishment and evaluation of a project course in applied mechanics---Lessons learnt
- 2009
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Ingår i: Svenska mekanikdagarna, Södertälje 2009, 15-17-juni, Session 7:4-Utbildning, sid 99 (1 page abstract). ; , s. 99-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Development, accomplishment and evaluation of a project course in applied mechanics---Lessons learnt M. Ander , T. Grönstedt, T. Abrahamsson and G. JohanssonThis presentation concerns teaching and learning from working in projects within the Chalmers Master programme in Solid and fluid mechanics. The academic tradition requires teaching solid and fluid mechanics as separated subjects of applied mechanics. The researchers/teachers and students belonging to either discipline do not meet on daily basis and thus two separate cultures develop; CFD for fluids and FEM for solids.However, in industry today fresh engineers will meet challenges in multidisciplinary problems and they are expected to be able to know how to treat them. As a remedy to better prepare for their engineering profession, a project course in applied mechanics has been developed. The outline of the course follows the CDIO[1] learning approach: Conceive, Design, Implement and Operate. Starting off from back of the envelope calculations, where all students are required to address all disciplines, the project proceeds towards distinct specializations. The students, divided into groups of six to seven members, focus on ‘student specialists’ roles in solid/structural mechanics-FEM, fluid dynamics, and experimental modal analysis EMA, simulating a true multidisciplinary working environment. The projects studied incorporate a fluid structure interaction core problem, but are required to pose challenges within each specialisation. The task is formulated as a competition to find better solutions or as an investigation of existing methods to solve a problem at hand. The examination is based on individual assignments, group work, presentation of a final report and opposition. As resources for analysing the problems, the students have access to wind tunnel testing, EMA-equipment, computer rooms with commercial software for CFD and FEM. This year we have introduced the ANSYS workbench as a common platform for fluid–structure interaction simulations, allowing the teams to work more closely together. The student perspective is dominated by the urge to approach real world problems with industrial tools. A better contact and understanding between students as well as between teachers/researchers in the different disciplines of applied mechanics are achieved by this approach. Some outstanding challenges are the limited time frame of the course, the time consuming communication required within the teachers team and the student frustration arising from having to address open end problems. [1]www.cdio.org
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| 4. |
- Holmberg, Mats, 1958, et al.
(författare)
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A Longitudinal Study of Medial Temporal Lobe Volumes in Graves Disease
- 2022
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 107:4, s. 1040-1052
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Tidskriftsartikel (refereegranskat)abstract
- Context: Neuropsychiatric symptoms are common features of Graves disease (GD) in hyperthyroidism and after treatment. The mechanism behind these symptoms is unknown, but reduced hippocampal volumes have been observed in association with increased thyroid hormone levels. Objective: This work aimed at investigating GD influence on regional medial temporal lobe (MTL) volumes. Methods: Sixty-two women with newly diagnosed GD underwent assessment including magnetic resonance (MR) imaging in hyperthyroidism and 48 of them were followed up after a mean of 16.4±4.2 SD months of treatment. Matched thyroid-healthy controls were also assessed twice at a 15-month interval. MR images were automatically segmented using multiatlas propagation with enhanced registration. Regional medial temporal lobe (MTL) volumes for amygdalae and hippocampi were compared with clinical data and data from symptom questionnaires and neuropsychological tests. Results: Patients had smaller MTL regions than controls at inclusion. At follow-up, all 4 MTL regions had increased volumes and only the volume of the left amygdala remained reduced compared to controls. There were significant correlations between the level of thyrotropin receptor antibodies (TRAb) and MTL volumes at inclusion and also between the longitudinal difference in the levels of free 3,5,3′-triiodothyronine and TRAb and the difference in MTL volumes. There were no significant correlations between symptoms or test scores and any of the 4 MTL volumes. Conclusion: Dynamic alterations in the amygdalae and hippocampi in GD reflect a previously unknown level of brain involvement both in the hyperthyroid state of the condition and after treatment. The clinical significance, as well as the mechanisms behind these novel findings, warrant further study of the neurological consequences of GD.
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| 6. |
- Holmberg, Mats, 1958, et al.
(författare)
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Structural brain changes in hyperthyroid Graves' disease: protocol for an ongoing longitudinal, case-controlled study in Göteborg, Sweden-the CogThy project.
- 2019
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 9:11
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Tidskriftsartikel (refereegranskat)abstract
- Cognitive impairment and reduced well-being are common manifestations of Graves' disease (GD). These symptoms are not only prevalent during the active phase of the disease but also often prevail for a long time after hyperthyroidism is considered cured. The pathogenic mechanisms involved in these brain-derived symptoms are currently unknown. The overall aim of the CogThy study is to identify the mechanism behind cognitive impairment to be able to recognise GD patients at risk.The study is a longitudinal, single-centre, case-controlled study conducted in Göteborg, Sweden on premenopausal women with newly diagnosed GD. The subjects are examined: at referral, at inclusion and then every 3.25 months until 15 months. Examinations include: laboratory measurements; eye evaluation; neuropsychiatric and neuropsychological testing; structural MRI of the whole brain, orbits and medial temporal lobe structures; functional near-infrared spectroscopy of the cerebral prefrontal cortex and self-assessed quality of life questionnaires. The primary outcome measure is the change in medial temporal lobe structure volume. Secondary outcome measures include neuropsychological, neuropsychiatric, hormonal and autoantibody variables. The study opened for inclusion in September 2012 and close for inclusion in October 2019. It will provide novel information on the effect of GD on medial temporal lobe structures and cerebral cortex functionality as well as whether these changes are associated with cognitive and affective impairment, hormonal levels and/or autoantibody levels. It should lead to a broader understanding of the underlying pathogenesis and future treatment perspectives.The study has been reviewed and approved by the Regional Ethical Review Board in Göteborg, Sweden. The results will be actively disseminated through peer-reviewed journals, national and international conference presentations and among patient organisations after an appropriate embargo time.44321 at the public project database for research and development in Västra Götaland County, Sweden (https://www.researchweb.org/is/vgr/project/44321).
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| 7. |
- Johansson, Birgitta, 1957, et al.
(författare)
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The relationship between mental fatigue, depression, and cognition in Graves' disease.
- 2023
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Ingår i: European thyroid journal. - 2235-0640 .- 2235-0802. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Mental fatigue, depression, anxiety, and cognitive complaints are common in Graves' disease (GD). Our aims were to assess the relationship between these variables in patients with GD during both hyperthyroidism and a long stable euthyroidism.A prospective longitudinal case-control study where 65 premenopausal women diagnosed with GD and 65 matched controls were assessed twice with 15 months in between. The first visit for patients was in overt hyperthyroidism and the second after treatment.During the hyperthyroid phase, mental fatigue, depression, and anxiety were significantly increased for GD patients compared to controls (all P < 0.001). Among GD patients, 89% reported mental fatigue and among controls 14%. No difference in cognitive tests was found. After 15 months, significant improvements for GD patients after treatment were found for the items of mental fatigue, depression, and anxiety (all P < 0.001), but these were unchanged in controls. GD patients reported residual mental fatigue (38%), 23% without depression, and 15% mental fatigue combined with depression. Self-reported cognitive complaints were pronounced while cognitive tests did not reveal any deficiencies.Mental fatigue and emotional distress are common in the hyperthyroid phase. These improve with treatment but are still more common in GD patients after 15 months of therapy than in controls. The residual mental fatigue is shown to be a phenomenon distinct from depression in this study. This indicates the importance of assessing mental fatigue in GD patients and underlines the need for rehabilitation and healthcare support as fatigue will have consequences for work ability.
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| 8. |
- Johansson, Hans-Erik, 1960-, et al.
(författare)
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Energy restriction in obese women suggest linear reduction of hepatic fat content and time-dependent metabolic improvements
- 2019
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Ingår i: Nutrition & Diabetes. - : Springer Science and Business Media LLC. - 2044-4052. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Energy restriction reduces liver fat, improves hepatic insulin resistance and lipid metabolism. However, temporal data in which these metabolic improvements occur and their interplay is incomplete. By performing repeated MRI scans and blood analysis at day 0, 3, 7, 14 and 28 the temporal changes in liver fat and related metabolic factors were assessed at five times during a low-calorie diet (LCD, 800-1100 kcal/day) in ten obese non-diabetic women (BMI 41.7 ± 2.6 kg/m2) whereof 6 had NAFLD. Mean weight loss was 7.4 ± 1.2 kg (0.7 kg/day) and liver fat decreased by 51 ± 16%, resulting in only three subjects having NAFLD at day 28. Marked alteration of insulin, NEFA, ALT and 3-hydroxybuturate was evident 3 days after commencing LCD, whereas liver fat showed a moderate but a linear reduction across the 28 days. Other circulating-liver fat markers (e.g. triglycerides, adiponectin, stearoyl-CoA desaturase-1 index, fibroblast growth factor 21) demonstrated modest and variable changes. Marked elevations of NEFA, 3-hydroxybuturate and ALT concentrations occurred until day 14, likely reflecting increased tissue lipolysis, fat oxidation and upregulated hepatic fatty acid oxidation. In summary, these results suggest linear reduction in liver fat, time-specific changes in metabolic markers and insulin resistance in response to energy restriction.
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