| 1. |
- Andersson, Henric, 1963-, et al.
(författare)
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Experience from introducing Unified Modeling Language/Systems Modeling Language at Saab Aerosystems
- 2010
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Ingår i: Systems Engineering. - : Wiley. - 1098-1241 .- 1520-6858. ; 13:4, s. 369-380
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Tidskriftsartikel (refereegranskat)abstract
- A Unified Modeling Language/Systems Modeling Language (UML/SysML) subset was the modeling notation selected for an aerospace systems engineering project at Saab Aerosystems. In this paper, the rationale for selecting UML/SysML is given, along with a description of the situation at the project planning stage regarding business conditions, method and tools support. The usage of use case, sequence, and activity diagrams are described as well as definition of functional chains with SysML. Furthermore, the connections to system implementation activities including code generation and simulation are discussed. The advantages and disadvantages of using UML/SysML from experience in an industrial context are reported. It is also described how UML/SysML is related to industrial research projects in the Model Based Systems Engineering (MBSE) methods and tools area. Introducing UML/SysML with a methodology and a supporting toolset in an operative organization require a clear strategy, including planning, just-in-time training, and mentor support. Finally, industrial needs for further development of SysML are discussed.
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| 2. |
- Johansson, Anja, et al.
(författare)
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Ergonomic Evaluation of Two Different Locations of the Scales in a Supermarket Checkout System
- 1993
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Ingår i: Advances in Industrial Ergonomics and Safety V. ; , s. 667-674
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Konferensbidrag (refereegranskat)abstract
- The aim of this pilot study was to ergonomically evaluate the effect of the location of the scales in a supermarket checkout system. A location of the scales to the left of the cashier was compared with a location under the conveyor belt. Two cashiers were videotaped while working with the two scale locations, in both sitting and standing working postures. Analysis of the video tapes was performed using the WOPALAS method, the VIRA method, and by noting certain positions of the left arm. The left wrist movements were registered by a two-dimensional goniometer. The results indicate that the location under the conveyor belt is somewhat more ergonomically favourable. The improvement is more pronounced for the cashier with a greater reach.
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| 3. |
- Afshin, Ashkan, et al.
(författare)
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Health effects of dietary risks in 195 countries, 1990-2017 : a systematic analysis for the Global Burden of Disease Study 2017
- 2019
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Ingår i: The Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 393:10184, s. 1958-1972
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Tidskriftsartikel (refereegranskat)abstract
- Background: Suboptimal diet is an important preventable risk factor for non-communicable diseases (NCDs); however, its impact on the burden of NCDs has not been systematically evaluated. This study aimed to evaluate the consumption of major foods and nutrients across 195 countries and to quantify the impact of their suboptimal intake on NCD mortality and morbidity.Methods: By use of a comparative risk assessment approach, we estimated the proportion of disease-specific burden attributable to each dietary risk factor (also referred to as population attributable fraction) among adults aged 25 years or older. The main inputs to this analysis included the intake of each dietary factor, the effect size of the dietary factor on disease endpoint, and the level of intake associated with the lowest risk of mortality. Then, by use of diseasespecific population attributable fractions, mortality, and disability-adjusted life-years (DALYs), we calculated the number of deaths and DALYs attributable to diet for each disease outcome.Findings: In 2017, 11 million (95% uncertainty interval [UI] 10-12) deaths and 255 million (234-274) DALYs were attributable to dietary risk factors. High intake of sodium (3 million [1-5] deaths and 70 million [34-118] DALYs), low intake of whole grains (3 million [2-4] deaths and 82 million [59-109] DALYs), and low intake of fruits (2 million [1-4] deaths and 65 million [41-92] DALYs) were the leading dietary risk factors for deaths and DALYs globally and in many countries. Dietary data were from mixed sources and were not available for all countries, increasing the statistical uncertainty of our estimates.Interpretation: This study provides a comprehensive picture of the potential impact of suboptimal diet on NCD mortality and morbidity, highlighting the need for improving diet across nations. Our findings will inform implementation of evidence-based dietary interventions and provide a platform for evaluation of their impact on human health annually.
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| 4. |
- Ahlman, Daniel, et al.
(författare)
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Direct numerical simulation of mixing in a plane compressible and turbulent wall jet
- 2005
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Ingår i: 4th International Symposium on Turbulence and Shear Flow Phenomena. ; , s. 1131-1136
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Konferensbidrag (refereegranskat)abstract
- Direct numerical simulation (DNS) is used to simulate the mixing of a passive scalar in a plane compressible and turbulent wall jet. The Mach number of the jet is M = 0.5 at the inlet. The downstream development of the jet is studied and compared to experimental data. Mixing in the inner and outer shear layers of the wall jet is investigated through scalar fluxes, the probability density function of the scalar concentration and the joint probability density function of the wall normal velocity fluctuation and the scalar concentration
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| 5. |
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| 6. |
- Andersson, Jan-Erik, et al.
(författare)
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Robot control for wood carving operations
- 2001
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Ingår i: Mechatronics (Oxford). - 0957-4158 .- 1873-4006. ; 11:4, s. 475-490
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to implement sensor control in wood carving operations. The introduction of wood carving is a step towards the development of a new manufacturing method for the wood manufacturing industry, where wood carving would facilitate increased freedom of the design choice. A control method that improves robot control and supports simpler programming, based on using an industrial robot equipped with a wrist mounted force/torque-sensor. is proposed for the wood carving process. This paper describes the structure and control algorithm of the system and how different machining parameters affect the cutting forces. The evaluation of the system showed that it is possible to control the cutting depth at speeds up to 7.5 mms by adjusting the rake angle of the tool to obtain a nominal force.
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| 7. |
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| 8. |
- Asenjo, Felipe A., et al.
(författare)
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Semi-relativistic effects in spin-1/2 quantum plasmas
- 2012
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 14, s. 073042-
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Tidskriftsartikel (refereegranskat)abstract
- Emerging possibilities for creating and studying novel plasma regimes, e. g. relativistic plasmas and dense systems, in a controlled laboratory environment also require new modeling tools for such systems. This motivates theoretical studies of the kinetic theory governing the dynamics of plasmas for which both relativistic and quantum effects occur simultaneously. Here, we investigate relativistic corrections to the Pauli Hamiltonian in the context of a scalar kinetic theory for spin-1/2 quantum plasmas. In particular, we formulate a quantum kinetic theory for the collective motion of electrons that takes into account effects such as spin-orbit coupling and Zitterbewegung. We discuss the implications and possible applications of our findings.
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| 9. |
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Att välja trä
- 2020. - 10
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Samlingsverk (redaktörskap) (populärvet., debatt m.m.)
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| 10. |
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| 11. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - 2050-084X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.522.7) and 16.5 cm (13.319.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 12. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3– 19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8– 144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 13. |
- Brethouwer, Gert, et al.
(författare)
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Turbulence and cyclic bursts in rotating channel flow
- 2020
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Ingår i: ETC 2013 - 14th European Turbulence Conference. - : Zakon Group LLC.
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Konferensbidrag (refereegranskat)abstract
- DNS have been performed of turbulent channel flow with spanwise rotation and bulk Reynolds number Re up to 30000. At moderate rotation rates Ro the flow on one side of the channel is approximately laminar, or has turbulent patches or oblique turbulent-laminar patterns. Intense cyclic bursts of turbulence with long time intervals are in some cases observed at sufficiently high Re and Ro. A linear analysis indicates that the turbulence bursts are initiated by a linear instability of plane waves aligned with the rotation axis. This linear instability can develop even if parts of the flow are strongly turbulent.
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| 14. |
- Brethouwer, Gert, et al.
(författare)
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Turbulence, instabilities and heat transfer in rotating channel flow simulations
- 2012
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Ingår i: Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer. - : Begell House Inc.. ; , s. 703-706
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Konferensbidrag (refereegranskat)abstract
- Direct numerical simulations of fully developed turbulent channel flow rotating about the spanwise direction are performed over a wide range of Reynolds numbers and rotation speeds. A scalar is also included to examine rotation effects on heat transfer. The Reynolds number based on the bulk mean velocity is up to 30 000, which is higher than in previous studies of rotating channel flow. The flow partly or completely relaminarizes on the stable channel side at sufficiently high rotation speeds, leading to distinct turbulent-laminar patterns in certain cases. Strong cyclic bursts of turbulence are observed at higher rotation speeds and sufficiently high Reynolds numbers. Further analysis showed that the burst are caused by plane spanwise waves with a rapidly growing amplitude, which become unstable after some time and break down into intense turbulence. Rotation strongly affects the direction of the turbulent scalar flux and significantly reduces the turbulent Prandtl number.
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| 15. |
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| 16. |
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| 17. |
- Do-Quang, Minh, et al.
(författare)
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Simulation of finite-size fibers in turbulent channel flows
- 2014
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755 .- 1550-2376. ; 89:1, s. 013006-
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Tidskriftsartikel (refereegranskat)abstract
- The dynamical behavior of almost neutrally buoyant finite-size rigid fibers or rods in turbulent channel flow is studied by direct numerical simulations. The time evolution of the fiber orientation and translational and rotational motions in a statistically steady channel flow is obtained for three different fiber lengths. The turbulent flow is modeled by an entropy lattice Boltzmann method, and the interaction between fibers and carrier fluid is modeled through an external boundary force method. Direct contact and lubrication force models for fiber-fiber interactions and fiber-wall interaction are taken into account to allow for a full four-way interaction. The density ratio is chosen to mimic cellulose fibers in water. It is shown that the finite size leads to fiber-turbulence interactions that are significantly different from earlier reported results for point like particles (e.g., elongated ellipsoids smaller than the Kolmogorov scale). An effect that becomes increasingly accentuated with fiber length is an accumulation in high-speed regions near the wall, resulting in a mean fiber velocity that is higher than the mean fluid velocity. The simulation results indicate that the finite-size fibers tend to stay in the high-speed streaks due to collisions with the wall. In the central region of the channel, long fibers tend to align in the spanwise direction. Closer to the wall the long fibers instead tend to toward to a rotation in the shear plane, while very close to the wall they become predominantly aligned in the streamwise direction.
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| 18. |
- El Khoury, George K., et al.
(författare)
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Turbulent pipe flow : New DNS data and large-scale structures
- 2020
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Ingår i: ETC 2013 - 14th European Turbulence Conference. - : Zakon Group LLC.
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Konferensbidrag (refereegranskat)abstract
- Large-scale fully resolved direct numerical simulations (DNSs) have been performed with a high-order spectral element method to study the flow of an incompressible viscous fluid in a smooth circular pipe of radius R and axial length 25R in the turbulent flow regime at four different friction Reynolds numbers Reτ = 180, 360, 550 and 1000. The new data is compared to other simulation data sets, obtained in pipe, channel and boundary-layer geometry. The pressure is the variable that differs the most between the cases; a significantly higher mean and fluctuating pressure are observed in boundary layers that is linked to a stronger wake region. Critical assessment of the available DNS data is conducted in order to determine which difference or correspondence between the data sets are real and caused by physics, and which discrepancies are likely due to statistical or numerical inaccuracies. Furthermore, two-dimensional spectra of axial/streamwise velocity show an imprint of the large-scale motions from the outer layer in all canonical flows, however with different amplitude.
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| 19. |
- Grahn, Sten, et al.
(författare)
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Spring-assisted gantry robots versus conventional gantry robots: spring constant optimization and work minimization
- 2002
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Ingår i: Industrial robot. - : Emerald. - 0143-991X .- 1758-5791. ; 29:1, s. 53-60
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Tidskriftsartikel (refereegranskat)abstract
- The spring-assisted gantry robots, described in this paper, were designed primarily for the rapid transfer of lightweight objects from one point to another, e.g. to pick objects from a conveyor belt and to place them in a box. The average amount of work required for pick-and-place operations carried out by a conventional gantry robot was decided. Springs were added to conserve the kinetic energy of the main bar, which slides in the X-direction and the work of the same pick-and-place operation was decided. A theoretical study showed that when the spring constant was optimized the required motor work of the spring-assisted robots were 42-95 percent less than the required work of the conventional robot. The conceptual robot exists in mathematical models in Matlab and SIMULINK.
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| 20. |
- Grigoriev, Igor A., et al.
(författare)
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A realizable explicit algebraic Reynolds stress model for compressible turbulent flow with significant mean dilatation
- 2013
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Ingår i: Physics of fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 25:10, s. 105112-
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Tidskriftsartikel (refereegranskat)abstract
- The explicit algebraic Reynolds stress model of Wallin and Johansson [J. Fluid Mech. 403, 89 (2000)] is extended to compressible and variable-density turbulent flows. This is achieved by correctly taking into account the influence of the mean dilatation on the rapid pressure-strain correlation. The resulting model is formally identical to the original model in the limit of constant density. For two-dimensional mean flows the model is analyzed and the physical root of the resulting quartic equation is identified. Using a fixed-point analysis of homogeneously sheared and strained compressible flows, we show that the new model is realizable, unlike the previous model. Application of the model together with a K - omega model to quasi one-dimensional plane nozzle flow, transcending from subsonic to supersonic regime, also demonstrates realizability. Negative "dilatational" production of turbulence kinetic energy competes with positive "incompressible" production, eventually making the total production negative during the spatial evolution of the nozzle flow. Finally, an approach to include the baroclinic effect into the dissipation equation is proposed and an algebraic model for density-velocity correlations is outlined to estimate the corrections associated with density fluctuations. All in all, the new model can become a significant tool for CFD (computational fluid dynamics) of compressible flows.
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| 21. |
- Grigoriev, I. A., et al.
(författare)
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Explicit algebraic and differential Reynolds stress model application to homogeneously sheared and compressed turbulence
- 2015
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Ingår i: Proceedings - 15th European Turbulence Conference, ETC 2015. - : TU Delft.
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Konferensbidrag (refereegranskat)abstract
- An explicit algebraic and differential Reynolds stress models (EARSM and DRSM) are used to investigate the influence of homogeneous shear and compression on the behaviour of turbulence in the limit of rapid distortion theory (RDT). EARSM is shown to give realizable results and to preserve RDT regime, unlike the eddy-viscosity model (EVM). The DRSM version of our model is in reasonable agreement with RDT theory.
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| 22. |
- Göransson, Gert, 1967, et al.
(författare)
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Characterisation of pulse plated Ni and Ni-Zn alloys.
- 2014
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 161
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Tidskriftsartikel (refereegranskat)abstract
- Nickel, zinc and nickel-rich NiZn alloys were formed on platinum by galvanostatic pulse plating from aqueous sulfate baths. The alloys were formed in three steps, first in anomalous deposition by a current pulse, secondly by dissolution and oxidation during the open circuit potential in each cycle and finally by anodic stripping of the fully plated sample. The treatment leaves a stable phase with an alloy composition of Ni0.8Zn0.2. The potential-time curves during the plating procedure were used to qualitatively describe the nucleation and growth processes. For Zn a fully covered surface was obtained after one pulse while for Ni and NiZn three-dimensional clusters were obtained in the first pulse. Further growth of these layers involves nucleation on the substrate and deposited clusters. The films were characterized with optical microscopy, SEM/EDX, AFM, XPS, TEM and by electrochemical methods. XPS revealed that the surfaces become gently oxidized by the stripping in the plating solution. For Ni a bi-layer of NiO/Ni(OH)2 was found on the surface while for NiZn mainly the hydroxide was detected. The electrocatalytic properties of the layers toward oxygen reduction in alkaline solution were explored and the NiZn alloy was proven to be an excellent catalyst for hydrogen peroxide production.
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| 23. |
- Heid, Iris M, et al.
(författare)
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Meta-analysis identifies 13 new loci associated with waist-hip ratio and reveals sexual dimorphism in the genetic basis of fat distribution
- 2010
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 42:11, s. 949-960
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Tidskriftsartikel (refereegranskat)abstract
- Waist-hip ratio (WHR) is a measure of body fat distribution and a predictor of metabolic consequences independent of overall adiposity. WHR is heritable, but few genetic variants influencing this trait have been identified. We conducted a meta-analysis of 32 genome-wide association studies for WHR adjusted for body mass index (comprising up to 77,167 participants), following up 16 loci in an additional 29 studies (comprising up to 113,636 subjects). We identified 13 new loci in or near RSPO3, VEGFA, TBX15-WARS2, NFE2L3, GRB14, DNM3-PIGC, ITPR2-SSPN, LY86, HOXC13, ADAMTS9, ZNRF3-KREMEN1, NISCH-STAB1 and CPEB4 (P = 1.9 × 10⁻⁹ to P = 1.8 × 10⁻⁴⁰) and the known signal at LYPLAL1. Seven of these loci exhibited marked sexual dimorphism, all with a stronger effect on WHR in women than men (P for sex difference = 1.9 × 10⁻³ to P = 1.2 × 10⁻¹³). These findings provide evidence for multiple loci that modulate body fat distribution independent of overall adiposity and reveal strong gene-by-sex interactions.
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| 24. |
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| 25. |
- Johansson, Baran, et al.
(författare)
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Writing fluency predicted by reading, linguistic and cognitive skills in L1 and L2 in the writing of bilingual biscriptal Persian-Swedish children
- 2023
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Ingår i: L1-Educational Studies in Language and Literature. - : International Association for Research in L1 Education (ARLE). - 1567-6617 .- 1573-1731. ; 23, s. 1-28
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Tidskriftsartikel (refereegranskat)abstract
- Literacy acquisition in children’s L1 and L2 contributes to academic success, and embraces and supports children’s backgrounds and identity formation. However, limited education can prevent bilingual children from developing their writing fluency on the same level in L1 and L2. An analysis of writing fluency can show aspects that require more or less effort in children’s L1 and L2 writing. Thus, it is important to examine writing fluency and the related reading, linguistic and cognitive skills across children’s languages. Our knowledge is limited regarding the skills that could influence children’s writing fluency. Previous studies have mainly focused on Latin scripts and/or one alphabetic and one non-alphabetic script. Furthermore, English has been the writers’ L1 or L2. This paper investigated reading, linguistic and cognitive skills related to the writing fluency of bilingual biscriptal children in two different alphabetic scripts: Persian (L1) and Swedish (L2) across two different genres: narrative and descriptive. 23 children in years 4–9 (aged 10–15) produced four texts each using the Eye and Pen tool. Standardised tests across both languages were used to explore the participants’ reading, linguistic and cognitive skills. Analyses showed that they were more fluent writers across both genres in L2. Word reading appears to contribute to writing fluency across both languages, whereas vocabulary knowledge only related to writing fluency in L1. No significant relationship was found between working memory and writing fluency in either L1 or L2.
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| 26. |
- Johansson, Mats, 1959, et al.
(författare)
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Baroreflex effectiveness index and baroreflex sensitivity predict all-cause mortality and sudden death in hypertensive patients with chronic renal failure
- 2007
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Ingår i: J Hypertens. - 0263-6352. ; 25:1, s. 163-8
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Impaired arterial baroreflex sensitivity (BRS) has been associated with cardiac mortality and non-fatal cardiac arrests after a myocardial infarction. Patients with chronic renal failure (CRF) have a poor prognosis because of cardiovascular diseases, and sudden death is common. The aim of this study was to assess whether BRS or the baroreflex effectiveness index (BEI), a novel index reflecting the number of times the baroreflex is active in controlling the heart rate in response to blood pressure fluctuations, is associated with prognosis in CRF. METHODS: Hypertensive patients with CRF who were treated conservatively, by haemodialysis or peritoneal dialysis were studied. Electrocardiogram and beat-to-beat blood pressures were recorded continuously and BRS and BEI were calculated. Patients were then followed prospectively for 41 +/- 15 months (range 1-64). RESULTS: During follow-up 69 patients died. Cardiovascular diseases and uraemia accounted for the majority of deaths (60 and 20%, respectively), whereas sudden death occurred in 15 patients. In adjunct with established risk factors such as age, diabetes, congestive heart failure and diastolic blood pressure, reduced BEI was an independent predictor of all-cause mortality among CRF patients [relative risk (RR) 0.50, 95% confidence interval (CI) 0.33-0.71 for an increase of one standard deviation in BEI, P < 0.001]. Diabetes and reduced BRS were independent predictors of sudden death (RR 0.29, 95% CI 0.09-0.86 for an increase of one standard deviation in BRS, P=0.022). CONCLUSIONS: Both BEI and BRS convey prognostic information that may have clinical implications for patients with cardiovascular diseases in general.
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| 27. |
- Johansson, Mats, 1959, et al.
(författare)
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Elevated temporal QT variability index in patients with chronic renal failure
- 2004
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Ingår i: Clin Sci (Lond). - 0143-5221. ; 107:6, s. 583-8
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Tidskriftsartikel (refereegranskat)abstract
- Patients with CRF (chronic renal failure) are at increased risk of cardiovascular diseases, and 60% of cardiovascular mortality in CRF is attributed to sudden death. Various abnormalities in myocardial repolarization are associated with the risk of ventricular arrhythmia. The aim of this study was to evaluate an index of temporal myocardial repolarization lability, the temporal QTVI (QT variability index), in patients with CRF. ECGs were recorded in 153 patients with CRF on haemodialysis (n=67), continuous ambulatory peritoneal dialysis (n=43) or conservative treatment (n=43) during 30 min of rest. QTVI was calculated as the logarithm of the ratio between the variances of the normalized QT and RR intervals. Age-matched healthy subjects (n=39) were examined for comparison. QTVI was increased by 47% in CRF patients compared with healthy subjects (-0.82+/-0.56 compared with -1.54+/-0.27 respectively; P<0.01). QTVI did not differ among patients on dialysis or conservative treatment, whereas QTVI was elevated further in patients with diabetes compared with non-diabetic CRF patients (-0.56+/-0.54 compared with -0.94+/-0.52 respectively; P<0.01). In a multiple linear regression analysis, diabetes and a history of coronary artery disease were the only independent predictors of QTVI in the CRF population. The present study demonstrates that elevated QTVI in patients with CRF is associated with diabetes and coronary disease. The present findings are important given that repolarization instability may predispose to ventricular arrhythmia and sudden death, events that occur frequently in CRF patients.
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| 28. |
- Johansson, Mats, 1959, et al.
(författare)
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Reduced baroreflex effectiveness index in hypertensive patients with chronic renal failure
- 2005
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Ingår i: Am J Hypertens. - : Oxford University Press (OUP). - 0895-7061. ; 18:7
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Impaired arterial baroreflex function has been associated with an increased risk of ventricular arrhythmia and sudden death. This has also been suggested for patients with chronic renal failure (CRF) who are at high risk for cardiovascular morbidity. The aim of this study was to investigate the arterial baroreflex function in CRF patients with emphasis on analyzing the time during which the arterial baroreflex is active, the baroreflex effectiveness index (BEI). METHODS: Beat-to-beat blood pressure (measured with Portapres) and electrocardiography were continuously registered during 30 min rest in 216 hypertensive CRF patients on hemodialysis (n=95), continuous ambulatory peritoneal dialysis (n=59), or conservative treatment (n=59). The spontaneous sequence method was used to calculate BRS and BEI. Age-matched healthy subjects (n=43) were examined for comparison. RESULTS: The BRS was reduced by 51% and the BEI by 49% in CRF patients compared with healthy subjects (P<.001 for both). In addition, CRF patients with diabetes showed further reductions compared with patients without diabetes (15% reduction of BRS and 44% of BEI, P<.01 for both). The treatment modality for renal failure had no effect on BRS or BEI. In a multivariate linear regression analysis, age, body mass index, and systolic blood pressure were independent predictors of BRS, whereas age and diabetes were independent predictors of BEI in patients with CRF. CONCLUSIONS: We conclude that BEI, which is markedly reduced in hypertensive patients with CRF, may convey information on arterial baroreflex function that is complementary to BRS.
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| 29. |
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| 30. |
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| 31. |
- Johansson, Patrik, et al.
(författare)
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Puumala hantavirus genetic variability in an endemic region (Northern Sweden)
- 2008
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Ingår i: Infection, Genetics and Evolution. - : Elsevier BV. - 1567-1348 .- 1567-7257. ; 8:3, s. 286-296
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Tidskriftsartikel (refereegranskat)abstract
- Puumala hantavirus (PUUV), naturally harboured and shed by bank voles (Myodes [Clethrionomys] glareolus), is the etiological agent to nephropathia epidemica (NE), a mild haemorrhagic fever with renal syndrome. Both host and virus are found throughout much of the European continent and in northern Sweden NE is the second most prevalent serious febrile viral infection after influenza. The reliability of diagnostics by PCR depends on genetic variability for the detection of viral nucleic acids in unknown samples. In the present study we evaluated the genetic variability of PUUV isolated from bank voles in an area of northern Sweden highly endemic for NE. Genetic variability among bank voles was also investigated to evaluate co-evolutionary patterns. We found that the viral sequence appeared stable across the 80 km study region, with the exception of the southernmost sampling site, which differed from its nearest neighbour by 7%, despite a geographical separation of only 10 km. The southernmost sampling site demonstrated a higher degree of genetic similarity to PUUV previously isolated 100 km south thereof; two locations appear to constitute a separate PUUV phylogenetic branch. In contrast to the viral genome, no phylogenetic variance was observed in the bank vole mtDNA in this study. Previous studies have shown that as a result of terrestrial mammals' postglacial re-colonization routes, bank voles and associated PUUV of a southern and a northern lineage established a dichotomous contact zone across the Scandinavian peninsula approximately 100-150km south of the present study sites. Our observations reveal evolutionary divergence of PUUV that has led to dissimilarities within the restricted geographical scale of the northern host re-colonization route as well. These results suggest either a static situation in which PUUV strains are regionally well adapted, or an ongoing process in which strains of PUUV circulate on a geographical scale not yet reliably described. (c) 2008 Elsevier B.V. All rights reserved.
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| 32. |
- Lango Allen, Hana, et al.
(författare)
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Hundreds of variants clustered in genomic loci and biological pathways affect human height.
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 467:7317, s. 832-8
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Tidskriftsartikel (refereegranskat)abstract
- Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P<0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.
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| 33. |
- Lazeroms, Werner, et al.
(författare)
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Explicit algebraic models for turbulent flows with buoyancy effects
- 2020
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Ingår i: ETC 2013 - 14th European Turbulence Conference. - : Zakon Group LLC.
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Konferensbidrag (refereegranskat)abstract
- For turbulent flows that are influenced by an active scalar, the Reynolds stresses and scalar flux are coupled in a complicated way, which makes it difficult to model these flows. A framework has been derived for obtaining explicit algebraic Reynolds-stress and scalar-flux models for two-dimensional mean flows with stratification. For the specific case of stably stratified parallel shear flows, the derived model was shown to give good results. As an extension of these results, two more cases are considered: unstable stratification in a horizontal channel and natural convection in a vertical channel.
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| 34. |
- Lazeroms, Werner, et al.
(författare)
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Nonlinear features in explicit algebraic models for turbulent flows with active scalars
- 2015
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Ingår i: 9th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2015. - : TSFP-9. - 9780000000002
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Konferensbidrag (refereegranskat)abstract
- A detailed discussion of explicit algebraic turbulence models in the case of active scalars is given. In particular, we discuss the appearance of nonlinearities in the models and the need for explicit solutions of the resulting nonlinear equations. Focussing on a recently published model for two-dimensional stratified flows, we present an intuitive way of approximating the solution of a sixth-order polynomial equation for the production-to-dissipation ratio (p + g)/e of turbulent kinetic energy K. This formulation is shown to be consistent for turbulent channel flow with stable and unstable stratification. The result is important for obtaining a robust model with a correct behaviour of the turbulence production in different limits of shear and buoyancy. The results have recently been published in Lazeroms et al. (2015).
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| 35. |
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| 36. |
- Lenaers, Peter, et al.
(författare)
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A new high-order method for the accurate simulation of incompressible wall-bounded flows
- 2015
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Ingår i: 9th International Conference on Direct and Large-Eddy Simulation, 2013. - Cham : Springer Publishing Company. - 9783319144474 ; , s. 133-138
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Konferensbidrag (refereegranskat)abstract
- A new high-order method for the accurate simulation of incompressible wall-bounded flows is presented. In stream- and spanwise direction the discretisation is performed by standard Fourier series, while in wall-normal direction the method combines high-order collocated compact finite differences with the influence matrix method to calculate the pressure boundary conditions that render the velocity field divergence-free. The main advantage over Chebyshev collocation is that in wall normal direction, the grid can be chosen freely and thus excessive clustering near the wall is avoided. Both explicit and implicit discretisations of the viscous terms are described, with the implicit method being more complex, but also having a wider range of applications. The method is validated by simulating fully turbulent channel flow at friction Reynolds number Reτ=395, and comparing our data with existing numerical results. The results show excellent agreement proving that the method simulates all physical processes correctly.
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| 37. |
- Li, Chunliang, et al.
(författare)
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Limonene-derived polycarbonates as biobased UV-curable (powder) coating resins
- 2021
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Ingår i: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 151
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Tidskriftsartikel (refereegranskat)abstract
- The evaluation of poly(limonene carbonate)s (PLCs), derived from orange oils and carbon dioxide, as UV-curable (powder) coating binders is described. PLCs with moderate molecular weight were prepared by copolymerization of limonene oxide with CO2 and a subsequent molecular weight reduction step by transcarbonation with 1,10-decanediol (1,10-DCD). These PLCs were cured with a trifunctional thiol monomer in the presence of a photoinitiator via thiol-ene chemistry to form poly(thioether-co-carbonate) networks. The UV curing of the resins following solvent casting was studied at 130 degrees C using ATR-FTIR, revealing a fast curing and a quick thiol-ene network (TEN) formation, realized by the addition reactions of thiol groups of the curing agent onto pendant isopropenyl groups of PLC. An ene addition enhanced by thiol-ene crosslinking was also observed, known as a 'cage effect', which was discovered for the first time in a UV-curable thiol-ene system. The efficient TEN formation was also evidenced by the high sol fractions in those UV-cured samples and their dynamic mechanical thermal analysis (DMTA). The DMTA results of these TENs showed high Tgs (up to 125.9 degrees C) and a wide range of thermomechanical properties, including rubbery moduli from 4.4-27.5 MPa. The UV-cured powder coating employing PLCs as binders showed outstanding properties such as high transparency, good acetone resistance, high pencil hardness (H-2 H) and high Konig hardness (174-199 s), suggesting their potential as very promising biobased alternatives to conventional powder coating resins.
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| 38. |
- Lundell, Björn, et al.
(författare)
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Addressing Lock-in, Interoperability, and Long-Term Maintenance Challenges Through Open Source : How Can Companies Strategically Use Open Source?
- 2017
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Ingår i: Open Source Systems. - Cham : Springer. - 9783319577340 - 9783319577357 ; , s. 80-88
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Konferensbidrag (refereegranskat)abstract
- This industry paper reports on how strategic use of open source in company contexts can provide effective support for addressing the fundamental challenges of lock-in, interoperability, and longevity of software and associated digital assets. The fundamental challenges and an overview of an ongoing collaborative research project are presented. Through a conceptual model for open source usage in company contexts we characterise how companies engage with open source and elaborate on how the fundamental challenges can be effectively addressed through open source usage in company contexts.
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| 39. |
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| 40. |
- Magnusson, Måns, et al.
(författare)
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Cervical Muscle Afferents Play a Dominant Role over Vestibular Afferents during Bilateral Vibration of Neck Muscles.
- 2006
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Ingår i: Journal of Vestibular Research. - 1878-6464. ; 16:3, s. 127-136
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Tidskriftsartikel (refereegranskat)abstract
- A previous study showed that vibratory stimulation of neck muscles in humans induced short-latency electromyographic (EMG) activation of lower leg muscles, producing postural reactions at the feet. These findings indicated that cervical proprioception contributes to stabilization of stance through rapidly integrated pathways. However, as vibration may excite both proprioceptive and vestibular afferents, and because of the proximity of neck muscles to the vestibular apparatus, neck muscle vibration could also have activated the vestibular system thereby contributing to the effect observed. To investigate any possible contribution of vestibular stimulation, vibratory stimuli were applied bilaterally and separately to the splenius muscles of the neck and the planum mastoideum overlying the vestibular organs. Ten normal subjects, with eyes closed, were exposed to vibratory stimulation of two different amplitudes and frequencies. Responses were assessed by EMG activity recorded from tibialis anterior and gastrocnemius muscles of both legs and by changes in center of pressure as measured by a force platform. Results indicated that vibration induced reproducible EMG and postural responses in the anteroposterior direction, particularly on cessation of vibration. EMG and postural responses were considerably lower and less consistent with mastoid vibration compared with neck muscles vibration. Previous reports suggest that vibratory stimulation could propagate to the vestibular organs and generate a vestibular-induced postural activation. However, our findings indicate that cervical muscles afferents play a dominant role over vestibular afferents when vibration is directed towards the neck muscles.
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| 41. |
- Marouli, Eirini, et al.
(författare)
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Rare and low-frequency coding variants alter human adult height
- 2017
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 542:7640, s. 186-190
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Tidskriftsartikel (refereegranskat)abstract
- Height is a highly heritable, classic polygenic trait with approximately 700 common associated variants identified through genome-wide association studies so far. Here, we report 83 height-associated coding variants with lower minor-allele frequencies (in the range of 0.1-4.8%) and effects of up to 2 centimetres per allele (such as those in IHH, STC2, AR and CRISPLD2), greater than ten times the average effect of common variants. In functional follow-up studies, rare height increasing alleles of STC2 (giving an increase of 1-2 centimetres per allele) compromised proteolytic inhibition of PAPP-A and increased cleavage of IGFBP-4 in vitro, resulting in higher bioavailability of insulin-like growth factors. These 83 height-associated variants overlap genes that are mutated in monogenic growth disorders and highlight new biological candidates (such as ADAMTS3, IL11RA and NOX4) and pathways (such as proteoglycan and glycosaminoglycan synthesis) involved in growth. Our results demonstrate that sufficiently large sample sizes can uncover rare and low-frequency variants of moderate-to-large effect associated with polygenic human phenotypes, and that these variants implicate relevant genes and pathways.
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| 42. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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| 43. |
- Montecchia, Matteo, 1990-, et al.
(författare)
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Capturing Reynolds number effects in the periodic hill flow by using LES with anisotropy-resolving sub-grid scale model
- 2019
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Ingår i: 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11).
-
Konferensbidrag (refereegranskat)abstract
- Concerning wall resolved large-eddy simulation (LES), a considerable reduction of computational resources is achievable by employing the Explicit Algebraic subgrid scale model (EAM) (\cite{marstorp2009explicit}).LES of periodic hill is carried out using OpenFOAM with the EAM and a low-diffusive implementation that has been previously tested on a turbulent channel flow. The aim of the present study is to evaluate in a broad sense the influence of the Reynolds number on the flow quantities.
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| 44. |
- Montecchia, Matteo, 1990-, et al.
(författare)
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Improving LES with OpenFOAM by minimising numerical dissipation and use of explicit algebraic SGS stress model
- 2019
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Ingår i: Journal of Turbulence. - : TAYLOR & FRANCIS LTD. - 1468-5248. ; 20:11-12, s. 697-722
-
Tidskriftsartikel (refereegranskat)abstract
- There is a rapidly growing interest in using general-purpose CFD codes based on second-order finite volume methods for Large-Eddy Simulation (LES) in a wide range of applications, and in many cases involving wall-bounded flows. However, such codes are strongly affected by numerical dissipation and the accuracy obtained for typical LES resolutions is often poor. In the present study, we approach the problem of improving the LES capability of such codes by reduction of the numerical dissipation and use of an anisotropy-capturing subgrid-scale (SGS) stress model. The latter is of special importance for wall-resolved LES with resolutions where the SGS anisotropy can be substantial. Here we use the Explicit Algebraic (EA) SGS model [Marstorp L, Brethouwer G, Grundestam O, et al. Explicit algebraic subgrid stress models with application to rotating channel flow. J Fluid Mech. 2009;639:403-432], and comparisons are made for channel flow at friction Reynolds numbers up to 934 with the dynamic Smagorinsky model. The numerical dissipation is reduced by using an OpenFOAM based custom-built flow solver that modifies the Rhie and Chow interpolation and allows to control and minimise its effects without causing numerical instability (in viscous, fully turbulent flows). Different resolutions were used and large improvements of the LES accuracy were demonstrated for skin friction, mean velocity and other flow statistics by use of the new solver in combination with the EA SGS model. By reducing the numerical dissipation and using the EA SGS model the resolution requirements for wall-resolved LES can be significantly reduced.
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| 45. |
- Montecchia, Matteo, 1990-, et al.
(författare)
-
Improving LES with OpenFOAM by minimizing numerical dissipation and use of Explicit Algebraic SGS stress model
-
Tidskriftsartikel (refereegranskat)abstract
- There is a rapidly growing interest in using general-purpose CFD codes based on second order finite volume methods for Large-Eddy Simulation (LES) in a wide range of applications,and in many cases involving wall-bounded flows. However, such codes are strongly affected by numerical dissipation and the accuracy obtained for typical LES-resolutions is often poor. In the present study we approach the problem of improving LES capability of such codes by reduction of the numerical dissipation and use of an anisotropy-capturing sub-grid scale (SGS) stress model. The latter is of special importance for wall-resolved LES with resolutions where the SGS anisotropy can be substantial. Here we use the Explicit Algebraic (EA) SGS model (L. Marstorp, et al., J. Fluid Mech. {\bf 639}, (2009)), and comparisons are made for channel flow at friction Reynolds numbers up to 934 with the dynamic Smagorinsky model.The numerical dissipation is reduced byusing an OpenFOAM based custom-built flow solver that modifies the Rhie \& Chow interpolation and allows to control and minimize its effects without causing numerical instability (in viscous, fully turbulent flows). Different resolutions were used and large improvements of the LES accuracy were demonstrated for skin friction, mean velocity and other flow statistics by use of the new solver in combination with the EA SGS model.By reducing the numerical dissipation and using the EA SGS model the resolution requirements for wall-resolved LES can be significantly reduced.
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| 46. |
- Montecchia, Matteo, 1990-, et al.
(författare)
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Large-eddy simulation of turbulent channel flow using the explicit algebraic subgrid-scale model
- 2015
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Ingår i: Proceedings - 15th European Turbulence Conference, ETC 2015. - : TU Delft.
-
Konferensbidrag (refereegranskat)abstract
- Large-eddy simulation (LES) of turbulent channel flow are performed with a new subgrid-scale (SGS) stress model. The simulations show that with this model we can well predict turbulent wall flows at coarse resolutions and moderately high Reynolds numbers. The commonly used dynamic Smagorinsky model fails at coarser resolutions.
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| 47. |
- Montecchia, Matteo, 1990-
(författare)
-
Numerical and modelling aspects of large-eddy and hybrid simulations of turbulent flows
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this study, the explicit algebraic sub-grid scale (SGS) model (EAM) has been extensively validated in wall-resolved large-eddy simulations (LES) of wall-bounded turbulent flows at different Reynolds numbers and a wide range of resolutions. Compared to eddy-viscosity based models, the formulation of the EAM is more consistent with the physics and allows to accurately capture SGS anisotropy,which is relevant especially close to walls.The present work aims to extend the validation of the EAM to larger Reynolds numbers using codes with different orders of numerical accuracy.The first simulations, performed by using a pseudo-spectral code, show that the use of the EAM, compared to the dynamic Smagorinsky model (DSM), leads to significant improvements in the prediction of the first-and second order statistics of turbulent channel flow.These improvements are observed from relatively low to reasonably high Reynolds numbers and with coarse grids.The evaluation of the EAM was continued by implementing and testing of the EAM in the general-purpose finite-volume code OpenFOAM.Several tests of LES of turbulent channel flow have shown thatthe use of the Rhie and Chow (R&C) interpolation in OpenFOAM induces significant numerical dissipation.A new custom-built solver has been utilized in order to minimize the dissipation without generating significant adverse effects. The use of the EAM, together with the new solver, gives a substantially improved prediction of the mean velocity profiles as compared to predictions using the DSM, resulting in roughly 50% reduction in the grid point requirements to achieve a given degree of accuracy. In periodic hill flow, LES with the EAM agreed reasonably well with the reference dataat different bulk Reynolds numbers and reduced the misprediction of the first- and second order statistics observed in LES with DSM.The reduction of the R&C filter dissipation was also shown to be beneficial for the prediction of the mean quantities. An analysis of the skin friction along the lower wall reveals spanwise-elongated, almost axi-symmetric vortical structures generated by the Kelvin-Helmholtz instability. The structures introduced a significant amount of anisotropy.The last part of the study involved the development of a novel hybrid RANS-LES model where explicit algebraic Reynolds stress modelling is applied in both RANS and LES regions.Validations have been conducted on turbulent channel and periodic hill flows at different Reynolds numbers.The explicit algebraic Reynolds stress model for improved-delayed-detached-eddy simulation (EARSM-IDDES) gives reasonable predictions of the mean quantities and Reynolds stresses in both the geometries considered.The use of EARSM-IDDES, compared to the k-omega SST-IDDES model, improves the estimation of the quantities close to the wall.The present work has proven that the use of EAM in wall-resolved LES of wall-bounded flows in simple and complex geometries leads to a substantial reduction of computational requirements both in high-accuracy and general-purpose codes, compared to the use of eddy-viscosity models.In hybrid simulations the EARSM-IDDES shows a clear potential in capturing the physics of wall-bounded flows.
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| 48. |
- Montecchia, Matteo, 1990-, et al.
(författare)
-
Reynolds number effects in periodic hill flow: an LES study using OpenFOAM and the Explicit Algebraic SGS stress model
-
Tidskriftsartikel (refereegranskat)abstract
- Periodic hill channel flow at two different bulk Reynolds numbers of 10595 and 37000 is studied by wall-resolved large-eddy simulations (LES) to investigate the detailed Reynolds number effects of the separation bubble and the associated flow physics.The capability of OpenFOAM is here extended by using a modified solver which considerably reduces the Rhie and Chow (R\&C) interpolation-induced dissipation.The capability of the code is further enhanced by use of the Explicit Algebraic SGS stress model (EAM) (L. Marstorp {\itshape et al.}, J. Fluid Mech. {\bf 639}, (2009)).The EAM was shown to be instrumental for accurate prediction of turbulent structures and anisotropy while still maintaining a moderate amount of grid points.The generation of large-scale, spanwise oriented structures by the shear layer instability and the subsequent breakdown of these structures give an anisotropy state close to the axisymmetry limit followed by a transition to a much more isotropic state. These variations are well captured with the LES with EAM. The Reynolds number dependency of the separation bubble size is also well captured. For both the Reynolds numbers considered, the use of the EAM has significantly enhanced the prediction accuracy of the skin friction and the mean quantities, compared to LES with the Dynamic Smagorinsky model.
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| 49. |
- Montecchia, Matteo, et al.
(författare)
-
Taking large-eddy simulation of wall-bounded flows to higher Reynolds numbers by use of anisotropy-resolving subgrid models
- 2017
-
Ingår i: Physical Review Fluids. - : American Physical Society. - 2469-990X. ; 2
-
Tidskriftsartikel (refereegranskat)abstract
- Properly resolved large-eddy simulations of wall-bounded high Reynolds number flows using standard subgrid-scale (SGS) models requires high spatial and temporal resolution. We have shown that a more elaborate SGS model taking into account the SGS Reynolds stress anisotropies can relax the requirement for the number of grid points by at least an order of magnitude for the same accuracy. This was shown by applying the recently developed explicit algebraic subgrid-scale model (EAM) to fully developed high Reynolds number channel flows with friction Reynolds numbers of 550, 2000, and 5200. The near-wall region is fully resolved, i.e., no explicit wall modeling or wall functions are applied. A dynamic procedure adjusts the model at the wall for both low and high Reynolds numbers. The resolution is reduced, from the typically recommended 50 and 15 wall units in the stream-and spanwise directions respectively, by up to a factor of 5 in each direction. It was shown by comparison with direct numerical simulations that the EAM is much less sensitive to reduced resolution than the dynamic Smagorinsky model. Skin friction coefficients, mean flow profiles, and Reynolds stresses are better predicted by the EAM for a given resolution. Even the notorious overprediction of the streamwise fluctuation intensity typically seen in poorly resolved LES is significantly reduced whenEAMis used on coarse grids. The improved prediction is due to the capability of the EAM to capture the SGS anisotropy, which becomes significant close to the wall.
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| 50. |
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