| 1. |
- Medina-Gomez, Gema, et al.
(författare)
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The link between nutritional status and insulin sensitivity is dependent on the adipocyte-specific peroxisome proliferator-activated receptor-gamma2 isoform
- 2005
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 54:6, s. 1706-1716
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARgamma) is critically required for adipogenesis. PPARgamma exists as two isoforms, gamma1 and gamma2. PPARgamma2 is the more potent adipogenic isoform in vitro and is normally restricted to adipose tissues, where it is regulated more by nutritional state than PPARgamma1. To elucidate the relevance of the PPARgamma2 in vivo, we generated a mouse model in which the PPARgamma2 isoform was specifically disrupted. Despite similar weight, body composition, food intake, energy expenditure, and adipose tissue morphology, male mice lacking the gamma2 isoform were more insulin resistant than wild-type animals when fed a regular diet. These results indicate that insulin resistance associated with ablation of PPARgamma2 is not the result of lipodystrophy and suggests a specific role for PPARgamma2 in maintaining insulin sensitivity independently of its effects on adipogenesis. Furthermore, PPARgamma2 knockout mice fed a high-fat diet did not become more insulin resistant than those on a normal diet, despite a marked increase in their mean adipocyte cell size. These findings suggest that PPARgamma2 is required for the maintenance of normal insulin sensitivity in mice but also raises the intriguing notion that PPARgamma2 may be necessary for the adverse effects of a high-fat diet on carbohydrate metabolism.
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| 2. |
- Cramer, Bradley D., et al.
(författare)
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Paleobiogeography, high-resolution stratigraphy, and the future of Paleozoic biostratigraphy: Fine-scale diachroneity of the Wenlock (Silurian) conodont Kockelella walliseri
- 2010
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 294:3-4, s. 232-241
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Konferensbidrag (refereegranskat)abstract
- The Wenlock Epoch of the Silurian Period has become one of the chronostratigraphically best-constrained intervals of the Paleozoic. The integration of multiple chronostratigraphic tools, such as conodont and graptolite biostratigraphy, sequence stratigraphy, and delta C-13(carb) chemostratigraphy, has greatly improved global chronostratigraphic correlation and portions of the Wenlock can now be correlated with precision better than +/- 100 kyr. Additionally, such detailed and integrated chronostratigraphy provides an opportunity to evaluate the fidelity of individual chronostratigraphic tools. Here, we use conodont biostratigraphy, sequence stratigraphy and carbon isotope (delta C-13(carb)) chemostratigraphy to demonstrate that the conodont Kockelella walliseri, an important guide fossil for middle and upper Sheinwoodian strata (lower stage of the Wenlock Series), first appears at least one full stratigraphic sequence lower in Laurentia than in Baltica. Rather than serving as a demonstration of the unreliability of conodont biostratigraphy, this example serves to demonstrate the promise of high-resolution Paleozoic stratigraphy. The temporal difference between the two first occurrences was likely less than 1 million years, and although it is conceptually understood that speciation and colonization must have been non-instantaneous events, Paleozoic paleobiogeographic variability on such short timescales (tens to hundreds of kyr) traditionally has been ignored or considered to be of little practical importance. The expansion of high-resolution Paleozoic stratigraphy in the future will require robust biostratigraphic zonations that embrace the integration of multiple chronostratigraphic tools as well as the paleobiogeographic variability in ranges that they will inevitably demonstrate. In addition, a better understanding of the paleobiogeographic migration histories of marine organisms will provide a unique tool for future Paleozoic paleoceanography and paleobiology research. (C) 2010 Elsevier B.V. All rights reserved.
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| 3. |
- Cramer, Bradley D., et al.
(författare)
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Revised correlation of Silurian Provincial Series of North America with global and regional chronostratigraphic units and delta 13C(carb) chemostratigraphy
- 2011
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Ingår i: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164. ; 44:2, s. 185-202
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Forskningsöversikt (refereegranskat)abstract
- Recent revisions to the biostratigraphic and chronostratigraphic assignment of strata from the type area of the Niagaran Provincial Series (a regional chronostratigraphic unit) have demonstrated the need to revise the chronostratigraphic correlation of the Silurian System of North America. Recently, the working group to restudy the base of the Wenlock Series has developed an extremely high-resolution global chronostratigraphy for the Telychian and Sheinwoodian stages by integrating graptolite and conodont biostratigraphy with carbonate carbon isotope (delta 13C(carb)) chemostratigraphy. This improved global chronostratigraphy has required such significant chronostratigraphic revisions to the North American succession that much of the Silurian System in North America is currently in a state of flux and needs further refinement. This report serves as an update of the progress on recalibrating the global chronostratigraphic correlation of North American Provincial Series and Stage boundaries in their type area. The revised North American classification is correlated with global series and stages as well as regional classifications used in the United Kingdom, the East Baltic, Australia, China, the Barrandian, and Altaj. Twenty-four potential stage slices, based primarily on graptolite and conodont zones and correlated to the global series and stages, are illustrated alongside a new composite delta 13C(carb) curve for the Silurian. Conodont, graptolite, isotope, New York, Ontario, series, Silurian, stage.
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| 4. |
- Meyer, H.F., et al.
(författare)
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Overview of physics studies on ASDEX Upgrade
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation (q 95 = 5.5, ) at low density. Higher installed electron cyclotron resonance heating power 6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with MW m-1 with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently . This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of and E r allow for inter ELM transport analysis confirming that E r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of 'natural' no ELM regimes have been extended. Stable I-modes up to have been characterised using -feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle - measured for the first time - or the cross-phase angle of and fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvénic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.
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| 5. |
- Pickering, John W., et al.
(författare)
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Rapid Rule-out of Acute Myocardial Infarction With a Single High-Sensitivity Cardiac Troponin T Measurement Below the Limit of Detection A Collaborative Meta-analysis
- 2017
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Ingår i: Annals of Internal Medicine. - 0003-4819 .- 1539-3704. ; 166:10, s. 715-724
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Tidskriftsartikel (refereegranskat)abstract
- Background: High-sensitivity assays for cardiac troponin T (hs-cTnT) are sometimes used to rapidly rule out acute myocardial infarction (AMI). Purpose: To estimate the ability of a single hs-cTnT concentration below the limit of detection (<0.005 mu g/L) and a nonischemic electrocardiogram (ECG) to rule out AMI in adults presenting to the emergency department (ED) with chest pain. Data Sources: EMBASE and MEDLINE without language restrictions (1 January 2008 to 14 December 2016). Study Selection: Cohort studies involving adults presenting to the ED with possible acute coronary syndrome in whom an ECG and hs-cTnT measurements were obtained and AMI outcomes adjudicated during initial hospitalization. Data Extraction: Investigators of studies provided data on the number of low-risk patients (no new ischemia on ECG and hs-cTnT measurements <0.005 mu g/L) and the number who had AMI during hospitalization (primary outcome) or a major adverse cardiac event (MACE) or death within 30 days (secondary outcomes), by risk classification (low or not low risk). Two independent epidemiologists rated risk of bias of studies. Data Synthesis: Of 9241 patients in 11 cohort studies, 2825 (30.6%) were classified as low risk. Fourteen (0.5%) low-risk patients had AMI. Sensitivity of the risk classification for AMI ranged from 87.5% to 100% in individual studies. Pooled estimated sensitivity was 98.7% (95% CI, 96.6% to 99.5%). Sensitivity for 30-day MACEs ranged from 87.9% to 100%; pooled sensitivity was 98.0% (CI, 94.7% to 99.3%). No low-risk patients died. Limitation: Few studies, variation in timing and methods of reference standard troponin tests, and heterogeneity of risk and prevalence of AMI across studies. Conclusion: A single hs-cTnT concentration below the limit of detection in combination with a nonischemic ECG may successfully rule out AMI in patients presenting to EDs with possible emergency acute coronary syndrome.
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| 6. |
- Stroth, U., et al.
(författare)
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Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L-H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts.
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