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Dynamics of the 2021 Fagradalsfjall Eruption (Iceland) Revealed by Volcanic Tremor Patterns
No full textInternational audienceAbstract Co‐eruptive volcanic tremor during the 2021 Fagradalsfjall eruption in Iceland (19 March–18 September 2021) is characterized using seismic and visual data recorded close to the eruption site and across the Reykjanes Peninsula. An automatic seismic network‐based approach reveals several tremor patterns associated with seven phases of the eruption, including (a) continuous tremor located beneath the eruption site and attributed to pressure changes in the shallow vent system(s) in phases I, III, and VII, and (b) two patterns of minute‐ and hour‐long intermittent tremor in May (phase II) and July–August (phases IV–VI), respectively. The first intermittent pattern of minute‐long tremor bursts associated with pulsating lava fountains in May is attributed to magma degassing in a shallow reservoir (top 100 m) connected to a top‐conduit. The progressive enlargement of both the top‐conduit and shallow reservoir with time is estimated quantitatively using a collapsing foam model. Sudden changes of their geometries, as detected from tremor characteristics, are systematically associated with observed crater collapse events. The second intermittent pattern of cyclic hour‐long tremor episodes associated with episodic effusive activity in July–August is attributed to magma flowing and cooling in the feeder dike connected to a sill at 5 km depth. The sill is fed by a constant influx of magma from the deeper plumbing system and stores magma during low discharge periods. The observed cyclicity of both the eruptive activity and the tremor is interpreted quantitatively with a sill‐dike model accounting for magma cooling and induced cyclic viscosity changes in the dike
Relations entre les fonctions exécutives et l’apprentissage autorégulé en premier cycle d’études universitaires
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The effect of seismic air gun shots on physiology and behaviour of fish lake communities
No full textInternational audienceAlterations in the acoustic environment owing to anthropogenic sound are recognised as global pollution and strengthening studies in freshwater. This study focuses on the impact of lake seismic surveys on fish. First, we measured individual stress responses, i.e. cortisol levels and oxidative stress, morphological parameters, and stomach contents of juvenile roaches (Rutilus rutilus) captured by trawling prior to and during the seismic survey. Second, using hydroacoustics, we analysed individual fish and school behaviour before, during, and after the shots. We collected environmental DNA (eDNA) and analysed the concentrations of three species to assess their littoral refuge. Finally, using hydroacoustics, we assessed pelagic fish density before, during, and after the shots. We demonstrated that the shots noticeably impacted juvenile roaches, from the molecular and cellular level to individual morphological characteristics. During the seismic shots, changes in school characteristics were observed. At the onset of the seismic survey, a sharp decrease (> 30%) in pelagic fish density was observed, and no increase in fish density in the littoral area was noted for the three species. These responses suggest that sound disturbances due to air gun shots affect fish in multiple ways (physiology, morphology, behaviour, and habitat use) and across multiple biological scales.</div
Search for H production and constraints on the Yukawa couplings of light quarks to the Higgs boson
No full textInternational audienceA search for H production is performed with data from the CMS experiment at the LHC corresponding to an integrated luminosity of 138 fb at a proton-proton center-of-mass collision energy of 13 TeV. The analysis focuses on the topology of a boosted Higgs boson recoiling against a high-energy photon. The final states of H and H 4 are analyzed. This study examines effective HZ and H anomalous couplings within the context of an effective field theory. In this approach, the production cross section is constrained to be 16.4 fb at 95% confidence level (CL). Simultaneous constraints on four anomalous couplings involving HZ and H are provided. Additionally, the production rate for H 4 is examined to assess potential enhancements in the Yukawa couplings between light quarks and the Higgs boson. Assuming the standard model values for the Yukawa couplings of the bottom and top quarks,the following simultaneous constraints are obtained: = (0.0 1.5) 10, = (0.0 7.1) 10, = 0, and = 0.0. This rules out the hypothesis that up- or down-type quarks in the first or second generation have the same Yukawa couplings as those in the third generation, with a CL greater than 95%
Results of a Geant4 benchmarking study for bio‐medical applications, performed with the G4‐Med system
No full textInternational audienceBackgroundGeant4, a Monte Carlo Simulation Toolkit extensively used in bio‐medical physics, is in continuous evolution to include newest research findings to improve its accuracy and to respond to the evolving needs of a very diverse user community. In 2014, the G4‐Med benchmarking system was born from the effort of the Geant4 Medical Simulation Benchmarking Group, to benchmark and monitor the evolution of Geant4 for medical physics applications. The G4‐Med system was first described in our Medical Physics Special Report published in 2021. Results of the tests were reported for Geant4 10.5. PurposeIn this work, we describe the evolution of the G4‐Med benchmarking system.Methods The G4‐Med benchmarking suite currently includes 23 tests, which benchmark Geant4 from the calculation of basic physical quantities to the simulation of more clinically relevant set‐ups. New tests concern the benchmarking of Geant4‐DNA physics and chemistry components for regression testing purposes, dosimetry for brachytherapy with a source, dosimetry for external x‐ray and electron FLASH radiotherapy, experimental microdosimetry for proton therapy, and in vivo PET for carbon and oxygen beams. Regression testing has been performed between Geant4 10.5 and 11.1. Finally, a simple Geant4 simulation has been developed and used to compare Geant4 EM physics constructors and physics lists in terms of execution times. ResultsIn summary, our EM tests show that the parameters of the multiple scattering in the Geant4 EM constructor G4EmStandardPhysics_option3 in Geant4 11.1, while improving the modeling of the electron backscattering in high atomic number targets, are not adequate for dosimetry for clinical x‐ray and electron beams. Therefore, these parameters have been reverted back to those of Geant4 10.5 in Geant4 11.2.1. The x‐ray radiotherapy test shows significant differences in the modeling of the bremsstrahlung process, especially between G4EmPenelopePhysics and the other constructors under study ( G4EmLivermorePhysics , G4EmStandardPhysics_option3 , and G4EmStandardPhysics_option4 ). These differences will be studied in an in‐depth investigation within our Group. Improvement in Geant4 11.1 has been observed for the modeling of the proton and carbon ion Bragg peak with energies of clinical interest, thanks to the adoption of ICRU90 to calculate the low energy proton stopping powers in water and of the Linhard–Sorensen ion model, available in Geant4 since version 11.0. Nuclear fragmentation tests of interest for carbon ion therapy show differences between Geant4 10.5 and 11.1 in terms of fragment yields. In particular, a higher production of boron fragments is observed with Geant4 11.1, leading to a better agreement with reference data for this fragment.ConclusionsBased on the overall results of our tests, we recommend to use G4EmStandardPhysics_option4 as EM constructor and QGSP_BIC_HP with G4EmStandardPhysics_option4 , for hadrontherapy applications. The Geant4‐DNA physics lists report differences in modeling electron interactions in water, however, the tests have a pure regression testing purpose so no recommendation can be formulated
Electrical Characterization of Modular 3D Packaging Assembled with Compressed Metal Foams
No full textInternational audienceThis paper proposes a novel modular packaging concept based on the 3D integration of 1.2kV SiC MOSFET with metal foams for electrical contacts with pressure assembly. These foams could allow improving the disassembly of switching cells by keeping low electrical resistance and inductance inside the package. Thus, static and dynamic experimental characterizations are carried out to evaluate their impact compared to a massive interconnection represented by copper interposers. Static measurements show that the electrical resistance of the package is 2.3mΩ which represents 7% of the total resistance. Dynamic characterizations demonstrate that the stray inductance of the switching cell is equal to 2.7nH. With results of the massive interconnection close to the ones of foams, the material used for the electrical interconnection have no impact on the electrical performances of the power module. The modification of pressure assembly of the power module shows however a global increase of the packaging resistance and stray inductance of the power module for both solutions. This increase is more important for the massive interconnection due the non-deformable mechanicals properties
Cecilia Vergnano "Alpine Border Conflicts: Migration and Social Polarization in the Everyday Life of Intra-EU Borders", Lanham, Maryland, 2024, 150 p.
No full textInternational audienceL’ouvrage de Cecilia Vergnano, anthropologue à l’Université catholique de Leuven en Belgique, porte sur la (re-)frontiérisation de l’espace alpin depuis 2015. Composé de 150 pages et cinq chapitres, ce livre est le fruit de longs terrains qu’elle a entrepris dans le cadre d’une bourse post-doctorale financée par le programme Marie Skłodowska. Elle y analyse ce processus à partir de trois terrains : deux à la frontière italo-française et un à la frontière italo-autrichienne
The number system in rational base 3/2 and the 3x + 1 problem
No full textTo appear in Comptes Rendus. Mathématique. Académie des Sciences, ParisThe representation of numbers in rational base p/q was introduced in 2008 by Akiyama, Frougny and Sakarovitch, with a special focus on the case p/q = 3/2. Unnoticed since then, natural questions related to representations in that specific base turn out to intimately involve the Collatz 3x+1 function. Our purpose in this note is to expose these links and motivate further research into them