| 1. |
- Stroth, U., et al.
(author)
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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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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 62:4
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Journal article (peer-reviewed)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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| 2. |
- Chatzikonstantinou, T, et al.
(author)
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COVID-19 severity and mortality in patients with CLL: an update of the international ERIC and Campus CLL study
- 2021
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In: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 35:12, s. 3444-3454
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Journal article (peer-reviewed)abstract
- Patients with chronic lymphocytic leukemia (CLL) may be more susceptible to Coronavirus disease 2019 (COVID-19) due to age, disease, and treatment-related immunosuppression. We aimed to assess risk factors of outcome and elucidate the impact of CLL-directed treatments on the course of COVID-19. We conducted a retrospective, international study, collectively including 941 patients with CLL and confirmed COVID-19. Data from the beginning of the pandemic until March 16, 2021, were collected from 91 centers. The risk factors of case fatality rate (CFR), disease severity, and overall survival (OS) were investigated. OS analysis was restricted to patients with severe COVID-19 (definition: hospitalization with need of oxygen or admission into an intensive care unit). CFR in patients with severe COVID-19 was 38.4%. OS was inferior for patients in all treatment categories compared to untreated (p < 0.001). Untreated patients had a lower risk of death (HR = 0.54, 95% CI:0.41–0.72). The risk of death was higher for older patients and those suffering from cardiac failure (HR = 1.03, 95% CI:1.02–1.04; HR = 1.79, 95% CI:1.04–3.07, respectively). Age, CLL-directed treatment, and cardiac failure were significant risk factors of OS. Untreated patients had a better chance of survival than those on treatment or recently treated.
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| 6. |
- Gardumi, Francesco, et al.
(author)
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Carrying out a multi-model integrated assessment of European energy transition pathways : Challenges and benefits
- 2022
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In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 258, s. 124329-124329
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Journal article (peer-reviewed)abstract
- With the publication of the European Green Deal, the European Union has committed to reaching carbon neutrality by 2050. The envisaged reductions of direct greenhouse gases emissions are seen as technically feasible, but if a wrong path is pursued, significant unintended impacts across borders, sectors, societies and ecosystems may follow. Without the insights gained from an impact assessment framework reaching beyond the techno-economic perspective, the pursuit of direct emission reductions may lead to counterproductive outcomes in the long run. We discuss the opportunities and challenges related to the creation and use of an integrated assessment framework built to inform the European Commission on the path to decarbonisation. The framework is peculiar in that it goes beyond existing ones in its scope, depth and cross-scale coverage, by use of numerous specialised models and case studies. We find challenges of consistency that can be overcome by linking modelling tools iteratively in some cases, harmonising modelling assumptions in others, comparing model outputs in others. We find the highest added value of the framework in additional insights it provides on the technical feasibility of decarbonisation pathways, on vulnerability aspects and on unintended environmental and health impacts on national and sub-national scale.
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| 7. |
- Jaksic, Z., et al.
(author)
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Gradient-index infrared metamaterials based on metal-dielectric submicrometer pillar arrays
- 2013
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In: 2013 11th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, TELSIKS 2013. - : IEEE. - 9781479909025 ; , s. 21-24
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Conference paper (peer-reviewed)abstract
- This paper presents the design and microfabrication of a two-dimensional metal-dielectric metamaterial structure based on an array of pillars with submicrometer diameters and heights. The diameters of pillars periodically vary along one axis in a sawtooth fashion and are constant along the other. The electromagnetic field distribution within this graded metamaterial was considered utilizing an accurate analytical approach. The pillar arrays were fabricated in photoresist and subsequently covered with a sputter-deposited aluminum film. Structures were defined by direct laser writing in photoresist film. Controlled overexposure has been applied in order to make pillar features smaller than the nominal resolution of the equipment. The structures were characterized by optical and atomic force microscopy and by angle-dependent Fourier Transform infrared spectroscopy. The produced graded frequency-selective surfaces may be used e.g. in sensing.
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| 8. |
- Jakšić, Z., et al.
(author)
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Two-dimensional gradient-index metamaterial with sawtooth profile
- 2013
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In: Microwave Review. - 1450-5835. ; 19:2, s. 96-101
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Journal article (peer-reviewed)abstract
- We investigate theoretically and experimentally a binary metal-dielectric metamaterial with a sawtooth profile. The structure consists of a two-dimensional array of pillars with submicrometer diameters. The pillar diameters linearly vary along one axis and are constant along the other. This furnishes a serrated spatial profile of effective refractive index along a single axis. We first present a set of analytical solutions defining the electromagnetic fields in such a structure. Further we give the results of our experimental fabrication of gradient metamaterial with a sawtooth spatial profile. The basic material for pillars was photoresist. Their geometry was defined using direct laser writing. Resist was overexposed in controlled manner in order to obtain pillars with diameters below the nominal resolution of the laser writer. The microfabricated pillars were coated by a sputter-deposited aluminum film. For characterization we utilized optical and atomic force microscopy and angledependent Fourier Transform infrared spectroscopy. We envision the applicability of our graded metasurfaces in transformation optics.
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