| 1. |
- Engel, B., et al.
(författare)
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The prediction of crack propagation in coarse grain RR1000 using a unified modelling approach
- 2020
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Ingår i: International Journal of Fatigue. - : ELSEVIER SCI LTD. - 0142-1123 .- 1879-3452. ; 137
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Tidskriftsartikel (refereegranskat)abstract
- The polycrystalline nickel-base superalloy RR1000 is used as turbine rotor material in Rolls-Royce aero engines and has to withstand a wide variety of load and temperature changes during operation. In order to maximize the potential of the material and to improve component design, it is of great interest to understand, and subsequently be able to accurately model the crack propagation caused by thermo-mechanical fatigue conditions. In this work, experimental data is analysed and used to inform unified modelling approaches in order to predict the crack propagation behaviour of RR1000 under a variety of stress-controlled thermo-mechanical fatigue conditions.
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| 2. |
- Gunduz, C., et al.
(författare)
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Long-term positive airway pressure therapy is associated with reduced total cholesterol levels in patients with obstructive sleep apnea: data from the European Sleep Apnea Database (ESADA)
- 2020
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Ingår i: Sleep Medicine. - : Elsevier BV. - 1389-9457. ; 75, s. 201-209
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Tidskriftsartikel (refereegranskat)abstract
- Background and aim: Obstructive sleep apnea (OSA) is an independent risk factor for dyslipidemia. The current study examined the effects of positive airway pressure (PAP) treatment on lipid status in the European Sleep Apnea Database (ESADA). Methods: The prospective cohort study enrolled 1564 OSA subjects (74% male, mean age 54 ± 11y, body mass index (BMI) 32.7 ± 6.6 kg/m2 and apnea-hypopnea index (AHI) 40.3 ± 24.4 n/h) undergoing PAP therapy for at least three months (mean 377.6 ± 419.5 days). Baseline and follow-up total cholesterol (TC) from nine centers were analyzed. Repeated measures and logistic regression tests (adjusted for age, sex, weight changes, lipid lowering medication, PAP compliance, and treatment duration) were used to compare changes in TC concentration. Incident risk for a coronary heart disease event (CHD) was used to compute a Framingham CHD risk score (estimated from age, BMI, blood pressure, and TC). Results: Adjusted means of TC decreased from 194.2 mg/dl to 189.3 mg/dl during follow-up (p = 0.019). A clinically significant (10%) reduction of TC at PAP follow-up was observed in 422 patients (27%). Duration of PAP therapy was identified as independent predictor for TC reduction, which implies an approximately 10% risk reduction for incident CHD events (from 26.7% to 24.1% in men and from 11.2% to 10.1% in women, p < 0.001 respectively). Conclusion: This observational study demonstrates a reduction of TC after long-term PAP treatment. The close association between TC concentration and cardiovascular (CV) mortality suggests that identification and treatment of OSA may have a beneficial effect on overall CV risk due to this mechanism. This possibility needs to be evaluated in prospective randomized studies. © 2020 Elsevier B.V.
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| 3. |
- Henriksson, Hanna, et al.
(författare)
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Cardiorespiratory fitness, muscular strength, and obesity in adolescence and later chronic disability due to cardiovascular disease: a cohort study of 1 million men
- 2020
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Ingår i: European Heart Journal. - : OXFORD UNIV PRESS. - 0195-668X .- 1522-9645. ; 41:15, s. 1503-
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Tidskriftsartikel (refereegranskat)abstract
- Aims Cardiorespiratory fitness, muscular strength, and obesity in adulthood are risk factors for cardiovascular disease (CVD). However, Little is known regarding the associations of these risk factors, already in adolescence, with later disability due to chronic CVD. Hence, we investigated associations of cardiorespiratory fitness, muscular strength, and body mass index (BMI) in adolescence with Later chronic disability due to specific causes of CVD disability (i.e. cerebrovascutar disease, ischaemic heart disease and heart failure). Methods and results This population-based cohort study included 1 078 685 male adolescents (16-19 years) from the Swedish military conscription register from 1972 to 1994. Cardiorespiratory fitness (bicycle ergometer test), muscular strength (knee extension strength), and BMI were measured during the conscription examination. Information about disability pension due to CVD was retrieved from the Social Insurance Agency during a mean follow-up of 28.4 years. Cardiorespiratory fitness was strongly and inversely associated with later risk of chronic CVD disability for all investigated causes. The association was particularly strong for ischaemic heart diseases (hazard ratio 0.11, 95% confidence interval 0.05-0.29 for highest vs. lowest fitness-quintiles). Furthermore, overweight/obesity were associated with CVD disability for all investigated causes. Conversely, associations of muscular strength with CVD disability were generally weak. Conclusions This study provides evidence for associations between low levels of cardiorespiratory fitness and obesity with later risk of chronic disability due to CVD. Preventive actions may begin at young ages and include promotion of cardiorespiratory fitness and healthy body weight.
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| 4. |
- Hoeijmakers, H. J., et al.
(författare)
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Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) : IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 641
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Tidskriftsartikel (refereegranskat)abstract
- Context. WASP-121 b is a hot Jupiter that was recently found to possess rich emission (day side) and transmission (limb) spectra, suggestive of the presence of a multitude of chemical species in the atmosphere. Aims. We survey the transmission spectrum of WASP-121 b for line-absorption by metals and molecules at high spectral resolution and elaborate on existing interpretations of the optical transmission spectrum observed with the Hubble Space Telescope (HST). Methods. We applied the cross-correlation technique and direct differential spectroscopy to search for sodium and other neutral and ionised atoms, TiO, VO, and SH in high-resolution transit spectra obtained with the HARPS spectrograph. We injected models assuming chemical and hydrostatic equilibrium with a varying temperature and composition to enable model comparison, and employed two bootstrap methods to test the robustness of our detections. Results. We detect neutral Mg, Na, Ca, Cr, Fe, Ni, and V, which we predict exists in equilibrium with a significant quantity of VO, supporting earlier observations by HST/WFC3. Non-detections of Ti and TiO support the hypothesis that Ti is depleted via a cold-trap mechanism, as has been proposed in the literature. Atomic line depths are under-predicted by hydrostatic models by a factor of 1.5 to 8, confirming recent findings that the atmosphere is extended. We predict the existence of significant concentrations of gas-phase TiO2, VO2, and TiS, which could be important absorbers at optical and near-IR wavelengths in hot Jupiter atmospheres. However, accurate line-list data are not currently available for them. We find no evidence for absorption by SH and find that inflated atomic lines can plausibly explain the slope of the transmission spectrum observed in the near-ultraviolet with HST. The Na I D lines are significantly broadened (FWHM ∼50 to 70 km s-1) and show a difference in their respective depths of ~15 scale heights, which is not expected from isothermal hydrostatic theory. If this asymmetry is of astrophysical origin, it may indicate that Na I forms an optically thin envelope, reminiscent of the Na I cloud surrounding Jupiter, or that it is hydrodynamically outflowing.
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| 5. |
- Seidel, J. V., et al.
(författare)
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Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) : V. Detection of sodium on the bloated super-Neptune WASP-166b
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 641
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Tidskriftsartikel (refereegranskat)abstract
- Planet formation processes or evolution mechanisms are surmised to be at the origin of the hot Neptune desert. Studying exoplanets currently living within or at the edge of this desert could allow disentangling the respective roles of formation and evolution. We present the High Accuracy Radial velocity Planet Searcher (HARPS) transmission spectrum of the bloated super-Neptune WASP-166b, located at the outer rim of the Neptune desert. Neutral sodium is detected at the 3.4σ level (0.455†±â€ 0.135%), with a tentative indication of line broadening, which could be caused by winds blowing sodium farther into space, a possible manifestation of the bloated character of these highly irradiated worlds. We put this detection into context with previous work claiming a non-detection of sodium in the same observations and show that the high noise in the trace of the discarded stellar sodium lines was responsible for the non-detection. We highlight the impact of this low signal-to-noise ratio remnant on detections for exoplanets similar to WASP-166b.
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