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- Kilpeläinen, Tuomas O, et al.
(author)
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Genome-wide meta-analysis uncovers novel loci influencing circulating leptin levels
- 2016
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Journal article (peer-reviewed)abstract
- Leptin is an adipocyte-secreted hormone, the circulating levels of which correlate closely with overall adiposity. Although rare mutations in the leptin (LEP) gene are well known to cause leptin deficiency and severe obesity, no common loci regulating circulating leptin levels have been uncovered. Therefore, we performed a genome-wide association study (GWAS) of circulating leptin levels from 32,161 individuals and followed up loci reaching P<10(-6) in 19,979 additional individuals. We identify five loci robustly associated (P<5 × 10(-8)) with leptin levels in/near LEP, SLC32A1, GCKR, CCNL1 and FTO. Although the association of the FTO obesity locus with leptin levels is abolished by adjustment for BMI, associations of the four other loci are independent of adiposity. The GCKR locus was found associated with multiple metabolic traits in previous GWAS and the CCNL1 locus with birth weight. Knockdown experiments in mouse adipose tissue explants show convincing evidence for adipogenin, a regulator of adipocyte differentiation, as the novel causal gene in the SLC32A1 locus influencing leptin levels. Our findings provide novel insights into the regulation of leptin production by adipose tissue and open new avenues for examining the influence of variation in leptin levels on adiposity and metabolic health.
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- Shia-Hui, Peng, 1967, et al.
(author)
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CAA analysis of a wing section with flap side-edges based on hybrid RANS-LES computation
- 2015
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In: 21st AIAA/CEAS Aeroacoustics Conference, AIAA Aviation. - Reston, Virginia : American Institute of Aeronautics and Astronautics. - 9781624103674
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Conference paper (peer-reviewed)abstract
- Based on hybrid RANS-LES computation of the turbulent flow around a double-flapped wing section, CAA (Computational Aero-Acoustics) analysis was conducted using the Curle, the Kirchhoff and the FW-H acoustic analogy methods. The focus was placed on the flow-induced noise due to the flap side-edges (FSE). It was shown that the FSE has triggered extensive unsteady vortex motions and being the most potent noise-generating source with significant pressure fluctuations on the side-edge surface. In the CAA analysis, two integral surfaces, defined by the iso-surface of vorticity magnitude, were verified when using the Kirchhoff and the FW-H methods. The Kirchhoff method is more sensitive to the location of the integral surface. The analysis using the Curle method indicates that the pressure fluctuations on the surface of the main wing and the first flap have made similar contributions to the far-field noise level, while the second flap contributes slightly less. The Kirchhoff and FW-H methods have predicted overall higher noise levels comparing to the Curle method. In the comparison, the result obtained with a stochastic method based on a RANS solution was also involved. The result has clearly demonstrated that, to capture the most potential noise generation in the presence of flap side edges, turbulence-resolving simulations should be incorporated in hybrid CFD/CAA analysis.
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| 9. |
- Engström, Gunnar, et al.
(author)
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The Swedish CArdioPulmonary BioImage Study : objectives and design
- 2015
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In: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 278:6, s. 645-659
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Journal article (peer-reviewed)abstract
- Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.
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| 10. |
- Hockerdal, Erik, et al.
(author)
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Real-time performance of DAE and ODE based estimators evaluated on a diesel engine
- 2018
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In: Science China Information Sciences. - : SCIENCE PRESS. - 1674-733X .- 1869-1919. ; 61:7
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Journal article (peer-reviewed)abstract
- Computation and sampling time requirements for real-time implementation of observers is studied. A common procedure for state estimation and observer design is to have a system model in continuous time that is converted to sampled time with Euler forward method and then the observer is designed and implemented in sampled time in the real time system. When considering state estimation in real time control systems for production there are often limited computational resources. This becomes especially apparent when designing observers for stiff systems since the discretized implementation requires small step lengths to ensure stability. One way to reduce the computational burden, is to reduce the model stiffness by approximating the fast dynamics with instantaneous relations, transforming an ordinary differential equations (ODE) model into a differential algebraic equation (DAE) model. Performance and sampling frequency limitations for extended Kalman filter (EKF)s based on both the original ODE model and the reduced DAE model are here analyzed and compared for an industrial system. Furthermore, the effect of using backward Euler instead of forward Euler when discretizing the continuous time model is also analyzed. The ideas are evaluated using measurement data from a diesel engine. The engine is equipped with throttle, exhaust gas recirculation (EGR), and variable geometry turbines (VGT) and the stiff model dynamics arise as a consequence of the throttle between two control volumes in the air intake system. The process of simplifying and modifying the stiff ODE model to a DAE model is also discussed. The analysis of the computational effort shows that even though the ODE, for each time-update, is less computationally demanding than the resulting DAE, an EKF based on the DAE model achieves better estimation performance than one based on the ODE with less computational effort. The main gain with the DAE based EKF is that it allows increased step lengths without degrading the estimation performance compared to the ODE based EKF.
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