| 61. |
- Gudbjartsson, Daniel F., et al.
(författare)
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Sequence variants affecting eosinophil numbers associate with asthma and myocardial infarction
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 41:3, s. 342-347
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Tidskriftsartikel (refereegranskat)abstract
- Eosinophils are pleiotropic multifunctional leukocytes involved in initiation and propagation of inflammatory responses and thus have important roles in the pathogenesis of inflammatory diseases. Here we describe a genome-wide association scan for sequence variants affecting eosinophil counts in blood of 9,392 Icelanders. The most significant SNPs were studied further in 12,118 Europeans and 5,212 East Asians. SNPs at 2q12 (rs1420101), 2q13 (rs12619285), 3q21 (rs4857855), 5q31 (rs4143832) and 12q24 (rs3184504) reached genome-wide significance (P = 5.3 x 10(-14), 5.4 x 10(-10), 8.6 x 10(-17), 1.2 x 10(-10) and 6.5 x 10(-19), respectively). A SNP at IL1RL1 associated with asthma (P = 5.5 x 10(-12)) in a collection of ten different populations (7,996 cases and 44,890 controls). SNPs at WDR36, IL33 and MYB that showed suggestive association with eosinophil counts were also associated with atopic asthma (P = 4.2 x 10(-6), 2.2 x 10(-5) and 2.4 x 10(-4), respectively). We also found that a nonsynonymous SNP at 12q24, in SH2B3, associated significantly (P = 8.6 x 10(-8)) with myocardial infarction in six different populations (6,650 cases and 40,621 controls).
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| 62. |
- Ha, Hojin, et al.
(författare)
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In-vitro and In-Vivo Assessment of 4D Flow MRI Reynolds Stress Mapping for Pulsatile Blood Flow
- 2021
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Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media S.A.. - 2296-4185. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Imaging hemodynamics play an important role in the diagnosis of abnormal blood flow due to vascular and valvular diseases as well as in monitoring the recovery of normal blood flow after surgical or interventional treatment. Recently, characterization of turbulent blood flow using 4D flow magnetic resonance imaging (MRI) has been demonstrated by utilizing the changes in signal magnitude depending on intravoxel spin distribution. The imaging sequence was extended with a six-directional icosahedral (ICOSA6) flow-encoding to characterize all elements of the Reynolds stress tensor (RST) in turbulent blood flow. In the present study, we aimed to demonstrate the feasibility of full RST analysis using ICOSA6 4D flow MRI under physiological conditions. First, the turbulence analysis was performed through in vitro experiments with a physiological pulsatile flow condition. Second, a total of 12 normal subjects and one patient with severe aortic stenosis were analyzed using the same sequence. The in-vitro study showed that total turbulent kinetic energy (TKE) was less affected by the signal-to-noise ratio (SNR), however, maximum principal turbulence shear stress (MPTSS) and total turbulence production (TP) had a noise-induced bias. Smaller degree of the bias was observed for TP compared to MPTSS. In-vivo study showed that the subject-variability on turbulence quantification was relatively low for the consistent scan protocol. The in vivo demonstration of the stenosis patient showed that the turbulence analysis could clearly distinguish the difference in all turbulence parameters as they were at least an order of magnitude larger than those from the normal subjects.
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| 63. |
- Ha, Hojin, et al.
(författare)
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In vitro experiments on ICOSA6 4D flow MRI measurement for the quantification of velocity and turbulence parameters
- 2020
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Ingår i: Magnetic Resonance Imaging. - : ELSEVIER SCIENCE INC. - 0730-725X .- 1873-5894. ; 72, s. 49-60
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To perform comprehensive in vitro experiments using six-directional icosahedral flow encoding (ICOSA6) 4D flow magnetic resonance imaging (MRI) under various scan conditions to analyze the robustness of velocity and turbulence quantification. Materials and methods: In vitro flow phantoms with steady flow rates of 10 and 20 L/min were scanned using both conventional 4D flow MRI and ICOSA6. Experiments focused on comparisons between ICOSA6 and conventional four point (4P) methods, and the effects of contrast agents, velocity encoding range (Venc), and scan direction on velocity and turbulence quantification. Results: The results demonstrated that 1) ICOSA6 improves the velocity-to-noise ratio (VNR) of velocity estimation by 33% (on average) and results in similar turbulent kinetic energy (TKE) estimation as the 4P method. 2) Measurements with a contrast agent resulted in more than a 2.5 fold increase in average VNR. However, the improvement of total TKE quantification was not obvious. 3) TKE estimation was less affected by Venc and the scan direction, whereas turbulence production (TP) estimation was largely affected by these measurement conditions. The effects of Venc and scan direction accounted for less than 11.63% of TKE estimation, but up to 33.89% of TP estimation. Conclusion: The ICOSA6 scheme is compatible with conventional 4D flow MRI for velocity and TKE measurement. Contrast agents are effective at increasing VNR, but not signal-to-noise ratio for TKE quantification. The effects of Venc and scan direction influence total TP more than total TKE.
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| 64. |
- Haddadi, Alireza, et al.
(författare)
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Large-scale Graph Processing on Commodity Systems : Understanding and Mitigating the Impact of Swapping
- 2023
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Ingår i: The International Symposium on Memory Systems (MEMSYS '23). - : Association for Computing Machinery (ACM). - 9798400716447 ; , s. 1-11
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Konferensbidrag (refereegranskat)abstract
- Graph workloads are critical in many areas. Unfortunately, graph sizes have been increasing faster than DRAM capacity. As a result, large-scale graph processing necessarily falls back to virtual memory paging, resulting in tremendous performance losses.In this work we investigate how we can get the best possible performance on commodity systems from graphs that cannot fit into DRAM by understanding, and adjusting, how the virtual memory system and the graph characteristics interact. To do so, we first characterize the graph applications, system, and SSD behavior as a function of how much of the graph fits in DRAM. From this analysis we see that for multiple graph types, the system fails to fully utilize the bandwidth of the SSDs due to a lack of parallel page-in requests.We use this insight to motivate overcommitting CPU threads for graph processing. This allows us to significantly increase the number of parallel page-in requests for several graph types, and recover much of the performance lost to paging. We show that overcommitting threads generally improves performance for various algorithms and graph types. However, we identify one graph that suffers from overcommitting threads, leading to the recommendation that overcommitting threads is generally good for performance, but there may be certain graph inputs that suffer from overcommitting threads.
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| 65. |
- Hansson Concilio, Roberta, et al.
(författare)
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Dynamics and preconditioning in a single drop vapor explosion
- 2007
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Ingår i: Proceedings - 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-12. - 0894480588 - 9780894480584
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Konferensbidrag (refereegranskat)abstract
- In order to develop a mechanistic understanding of the thermal-hydraulic processes in vapor explosion, it is paramount to characterize the dynamics of the hot liquid (melt) drop fragmentation and the volatile liquid (coolant) vaporization. In the present study, these intricate phenomena are investigated by performing well-controlled, externally triggered, single-drop experiments, employing a high-speed digital visualization system with synchronized cinematography and X-ray radiography system called SHARP (Simultaneous High-speed Acquisition of X-ray Radiography and Photography). The processed images, after an elaborate image processing, revealed the internal structure and dynamic evolution of the hot liquid fragmentation and related vaporization of the coolant. Such data gives way to new insights into the physics of the vapor explosion phenomena and quantification of the associated dynamic micro interactions. Analysis of the experimental results shows that, followed an external perturbation (trigger), a high temperature molten material (tin) drop underwent deformation and partial fragmentation already during the first cycle of bubble growth. Analysis of the SHARP data reveals correlation between the drop's dynamics in the first bubble cycle and energetics of the subsequent explosive evaporation in the second cycle. This finding provides a basis to suggest a so-called melt drop preconditioning i.e. deformation/ pre-fragmentation of a hot melt drop immediately following the pressure trigger, being instrumental to the subsequent coolant entrainment and resulting energetics of the so-triggered drop explosion.
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| 66. |
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| 67. |
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| 68. |
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| 69. |
- Hansson, Roberta Concilio, et al.
(författare)
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Dynamics and preconditioning in a single-droplet vapor explosion
- 2009
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Ingår i: Nuclear Technology. - 0029-5450 .- 1943-7471. ; 167:1, s. 223-234
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims to develop a mechanistic understanding of the thermal-hydraulic processes in a vapor explosion, which may occur in nuclear power plants during a hypothetical severe accident, involving interactions of high-temperature corium melt and volatile coolant. Dynamics of the hot liquid (melt) droplet and the volatile liquid (coolant) were investigated in the Micro-Interactions in Steam Explosion Experiments (MISTEE) facility by performing well-controlled, externally triggered, single-droplet experiments, using a high-speed visualization system with synchronized digital cinematography and continuous X-ray radiography, called Simultaneous High-speed Acquisition of X-ray Radiography and Photography (SHARP). After an elaborate image processing, the SHARP images depict the evolution of both melt material (dispersal) and coolant (bubble dynamics) and their microscale interactions. The analysis of the data shows a deficiency in using the bubble dynamics alone to provide a consistent explanation of the energetic behavior. In contrast, the SHARP data reveal a correlation between the droplet's dynamics in the bubble's first cycle and the energetics of the subsequent explosive evaporation in the bubble's second cycle. The finding provides a basis to suggest that a so-called melt-droplet preconditioning, i.e., deformation/prefragmentation of a hot melt droplet immediately following the pressure trigger, is instrumental to the subsequent coolant entrainment, evaporation, and energetics of the resulting vapor explosion.
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| 70. |
- Hansson, Roberta Concilio, et al.
(författare)
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Simultaneous high speed digital cinematographic and X-ray radiographic imaging of a intense multi-fluid interaction with rapid phase changes
- 2009
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Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777 .- 1879-2286. ; 33:4, s. 754-763
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Tidskriftsartikel (refereegranskat)abstract
- As typical for the study of the vapor explosions, the qualitative and quantitative understanding of the phenomena requires visualization of both material and interface dynamics. A new approach to multifluid multiphase visualization is presented with the focus on the development of a synchronized highspeed visualization by digital cinematography and X-ray radiography. The developed system, named SHARP (simultaneous high-speed acquisition of X-ray radiography and photography), and its image processing methodology, directed to an image synchronization procedure and a separate quantification of vapor and molten material dynamics, is presented in this paper. Furthermore, we exploit an intrinsic property of the X-ray radiation, namely the differences in linear mass attenuation coefficients over the beam path through a multi-component system, to characterize the evolution of molten material distribution. Analysis of the data obtained by the SHARP system and image processing procedure developed granted new insights into the physics of the vapor explosion phenomena, as well as, quantitative information of the associated dynamic micro-interactions.
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