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- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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| 5. |
- Bickerton, A. S. T., et al.
(författare)
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Adipose tissue fatty acid metabolism in insulin-resistant men
- 2008
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 51:8, s. 1466-1474
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis Increased NEFA production and concentrations may underlie insulin resistance. We examined systemic and adipose tissue NEFA metabolism in insulin-resistant overweight men (BM1 25-35 kg/m(2)). Methods In a cohort study we examined NEFA concentrations in men in the upper quartile of fasting insulin (n = 124) and in men with fasting insulin below the median (n 159). In a metabolic study we examined NEFA metabolism in the fasting and postprandial states, in ten insulin-resistant men and ten controls. Results In the cohort study, fasting NEFA concentrations were not significantly different between the two groups (median values: insulin-resistant men, 410 mu mol/l; controls, 445 2 mu mol/l). However, triacylglycerol concentrations differed markedly (1.84 vs 1.18 mmol/l respectively, p<0.001). In the metabolic study, arterial NEFA concentrations again did not differ between groups, whereas triacylglycerol concentrations were significantly higher in insulin-resistant men. Systemic NEFA production and the release of NEFA from subcutaneous adipose tissue, expressed per unit of fat mass, were both reduced in insulin-resistant men compared with controls (fasting values by 32%, p=0.02, and 44%, p=0.04 respectively). 3-Hydroxybutyrate concentrations, an index of hepatic fat oxidation and ketogenesis, were lower (p=0.03). Conclusions/interpretation Adipose tissue NEFA output is not increased (per unit weight of tissue) in insulin resistance. On the contrary, it appears to be suppressed by high fasting insulin concentrations. Alterations in triacylglycerol metabolism are more marked than those in NEFA metabolism. and are indicative of altered metabolic partitioning of fatty acids (decreased oxidation, increased esterification) in the liver.
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| 6. |
- Dahlman, Ingrid, et al.
(författare)
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A unique role of monocyte chemoattractant protein 1 among chemokines in adipose tissue of obese subjects
- 2005
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Endocrine Society. - 0021-972X .- 1945-7197. ; 90:10, s. 5834-5840
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Tidskriftsartikel (refereegranskat)abstract
- Context: Low-grade inflammation in adipose tissue may contribute to insulin resistance in obesity. However, the roles of individual inflammatory mediators in adipose tissue are poorly understood. Objectives: The objective of this study was to determine which inflammation markers are most overexpressed at the gene level in adipose tissue in human obesity and how this relates to corresponding protein secretion. Design: We examined gene expression profiles in 17 lean and 20 obese subjects. The secretory pattern of relevant corresponding proteins was examined in human sc adipose tissue or isolated fat cells in vitro and in vivo in several obese or lean cohorts. Results: In ranking gene expression, defined pathways associated with obesity and immune and defense responses scored high. Among seven markedly overexpressed chemokines, only monocyte chemoattractant protein 1 (MCP1) was released from adipose tissue and isolated fat cells in vitro. In obesity, the secretion and expression of MCP1 in adipose tissue pieces were more than 6- and 2-fold increased, respectively, but there was no change in circulating MCP1 levels. There was no net release of MCP1, but there was a net release of leptin, in vivo from adipose tissue into the circulation. Conclusions: Obesity is associated with the increased expression of several chemokine genes in adipose tissue. However, only MCP1 is secreted into the extracellular space, where it primarily acts as a local factor, because little or no spillover into the circulation occurs. MCP1 influences the function of adipocytes, is a recruitment factor for macrophages, and may be a crucial link among chemokines between adipose tissue inflammation and insulin resistance.
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