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Sökning: WFRF:(Schippers Stefan)

  • Resultat 1-6 av 6
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1.
  • Kepp, Kasper P., et al. (författare)
  • Panel stacking is a threat to consensus statement validity
  • 2024
  • Ingår i: Journal of Clinical Epidemiology. - : Elsevier. - 0895-4356 .- 1878-5921. ; 173
  • Tidskriftsartikel (refereegranskat)abstract
    • Consensus statements can be very influential in medicine and public health. Some of these statements use systematic evidence synthesis but others fail on this front. Many consensus statements use panels of experts to deduce perceived consensus through Delphi processes. We argue that stacking of panel members toward one particular position or narrative is a major threat, especially in absence of systematic evidence review. Stacking may involve financial conflicts of interest, but nonfinancial conflicts of strong advocacy can also cause major bias. Given their emerging importance, we describe here how such consensus statements may be misleading, by analyzing in depth a recent high-impact Delphi consensus statement on COVID-19 recommendations as a case example. We demonstrate that many of the selected panel members and at least 35% of the core panel members had advocated toward COVID-19 elimination (Zero-COVID) during the pandemic and were leading members of aggressive advocacy groups. These advocacy conflicts were not declared in the Delphi consensus publication, with rare exceptions. Therefore, we propose that consensus statements should always require rigorous evidence synthesis and maximal transparency on potential biases toward advocacy or lobbyist groups to be valid. While advocacy can have many important functions, its biased impact on consensus panels should be carefully avoided.
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2.
  • Nikolić, Dragan, et al. (författare)
  • Dielectronic recombination resonances in Na8
  • 2004
  • Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : The American Physical Society. - 1050-2947 .- 1094-1622. ; 70:6
  • Tidskriftsartikel (refereegranskat)abstract
    • The electron-ion recombination spectrum of the Li-like Na8+ ion in the energy range 0.0–0.5 eV is presented. Experimental results obtained by storage-ring techniques are compared with a calculated spectrum, based on a combination of relativistic many-body methods and complex rotation, and the agreement is found to be very good. The deviations between measured and calculated dielectronic recombination resonance energies are usually below about 2 meV with a maximum difference at 5.5 meV, while the theoretical cross sections deviate by at most 20% from the experiment. The recombination spectrum in the investigated energy region is determined by the 2pj7ℓj′ Rydberg manifold of dielectronic recombination resonances, comprising 61 states within half an eV above the ground state of Na8+. The theoretical resonance parameters of all contributing states are provided.
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3.
  • Aumayr, Friedrich, et al. (författare)
  • Roadmap on photonic, electronic and atomic collision physics : III. Heavy particles
  • 2019
  • Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 52:17
  • Tidskriftsartikel (refereegranskat)abstract
    • We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. Roadmap III focusses on heavy particles: with zero to relativistic speeds. Modern theoretical and experimental approaches provide detailed insight into the wide range of many-body interactions involving projectiles and targets of varying complexity ranging from simple atoms, through molecules and clusters, complex biomolecules and nanoparticles to surfaces and crystals. These developments have been driven by technological progress and future developments will expand the horizon of the systems that can be studied. This Roadmap aims at looking back along the road, explaining the evolution of the field, and looking forward, collecting nineteen contributions from leading scientists in the field.
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4.
  • Grumer, Jon, et al. (författare)
  • The effect of an external magnetic field on the determination of E1M1 two-photon decay rates in Be-like ions
  • 2013
  • Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 88
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work we report on ab initio theoretical results for the magnetic-field-induced 2s 2p 3P0 → 2s2 1S0 E1 transition for ions in the beryllium isoelectronic sequence between Z = 5 and 92. It has been proposed that the rate of the E1M1 two-photon transition 2s 2p 3P0 → 2s2 1S0 can be extracted from the lifetime of the 3P0 state in Be-like ions with zero nuclear spin by employing resonant recombination in a storage ring. This experimental approach involves a perturbing external magnetic field. The effect of this field needs to be evaluated in order to properly extract the two-photon rate from the measured decay curves. The magnetic-field-induced transition rates are carefully evaluated, and it is shown that, with a typical storage-ring field strength, it is dominant or of the same order as the E1M1 rate for low- and mid-Z ions. Results for several field strengths and ions are presented, and we also give a simple Z-dependent formula for the rate. We estimate the uncertainties of our model to be within 5% for low- and mid-Z ions and slightly larger for more highly charged ions. Furthermore we evaluate the importance of including both perturber states, 3P1 and 1P1, and it is s
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6.
  • Ueda, Kiyoshi, et al. (författare)
  • Roadmap on photonic, electronic and atomic collision physics : I. Light-matter interaction
  • 2019
  • Ingår i: Journal of Physics B. - : IOP PUBLISHING LTD. - 0953-4075 .- 1361-6455. ; 52:17
  • Tidskriftsartikel (refereegranskat)abstract
    • We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap I, we focus on the light-matter interaction. In this area, studies of ultrafast electronic and molecular dynamics have been rapidly growing, with the advent of new light sources such as attosecond lasers and x-ray free electron lasers. In parallel, experiments with established synchrotron radiation sources and femtosecond lasers using cutting-edge detection schemes are revealing new scientific insights that have never been exploited. Relevant theories are also being rapidly developed. Target samples for photon-impact experiments are expanding from atoms and small molecules to complex systems such as biomolecules, fullerene, clusters and solids. This Roadmap aims to look back along the road, explaining the development of these fields, and look forward, collecting contributions from twenty leading groups from the field.
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  • Resultat 1-6 av 6

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