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Quelques modes d'ondes stationnaires : cordes, membrane rectangulaire et circulaire, cavité cylindrique, cavité sphérique, modes transverses électriques et magnétiques
No full textMasterNous présentons dans ce cours de niveau variable selon les parties traitées (L2 à M1) quelques modes d'ondes stationnaires pouvant survenir au sein de structures à 1 dimension (cordes, modes électromagnétiques TEM), 2 dimensions (membranes rectangulaires ou circulaires) ou 3 dimensions (cavités cylindriques ou sphériques, mode transverse électrique TE ou magnétique TM au sein d'une cavité). Les modes d'ondes stationnaires sont présents dans la vie courante (vibration des cordes), dans l'enveloppe des étoiles comme le Soleil ou encore dans les cavités laser et accélératrices. Leur étude met en jeu l'équation d'Helmoltz et des outils nombreux de fonctions spéciales (Bessel, Legendre, harmoniques sphériques) dont les propriétés sont détaillées en annexes, et s'applique aux vibrations de quantités scalaires (élongation, pression) ou vectorielles (champs électromagnétiques)
Approaching Kasteleyn transition in frustrated quantum Heisenberg antiferromagnets
No full textWe show that the Kasteleyn transition, the abrupt proliferation of infinite strings of defects in classical dimer and related models, can also be relevant for frustrated 2d quantum magnets. This is explicitly demonstrated in a phase of the spin-1/2 Heisenberg diamond-decorated honeycomb lattice where a family of exact eigenstates built as products of dimer and plaquette singlets can be mapped onto the dimer coverings of the honeycomb lattice. The low-temperature properties of this phase are accurately described by an effective dimer model with anisotropic activities and a small, tunable density of monomers, leading to an arbitrarily sharp crossover version of the Kasteleyn transition. The generalization to other geometries and the possibility to realize this model in organo-metallic compounds are briefly discussed
L'ÉDUCATION EN LIGNE À L'ENVIRONNEMENT À TRAVERS LE JEU AU PRISME DES COURANTS PÉDAGOGIQUES
No full textInternational audienceThis research focuses on games available on museum websites, in connection with environmental education through the prism of learning pedagogies. It is based on an analysis and presents the pedagogical and playful devices adopted to the environment in crisis.Cette recherche porte sur les jeux disponibles sur les sites Web de musées, en lien avec l'éducation relative à l'environnement au prisme des pédagogies de l'apprentissage. Elle repose sur une analyse et présente les dispositifs pédagogiques et ludiques adoptés à l'environnement en crise.</div
Planetary, Solar and Heliospheric Radio Emissions X
No full textInternational audienceThe 10th edition of the international workshop on "Planetary, Solar and Heliospheric Radio Emissions” was held in June 2025 in Marseille, France, in continuation of a series of previous workshops successively held in Graz (Austria) in 1984, 1987, 1991, 1996, 2001, 2005, 2010 and 2016 and in Ireland (Dublin) in 2022. The proceedings of this workshop have been double peer-reviewed under the responsability of a scientific editorial committee composed of L. Lamy, C. K. Louis, G. Fischer, D. Morosan and P. Zarka and are published as a digital book entitled “Planetary, Solar and Heliospheric Radio Emissions X”
Chiral-sensitive frequency mixing in valley-excited two-dimensional semiconductors
No full textInternational audienceTwo-dimensional (2D) semiconductors endowed with valley degree of freedom offer potential applications in next-generation petahertz valleytronics and photonics for emerging quantum technologies. We experimentally and theoretically uncover striking signatures of nonperturbative nonlinear optical response in valley-selective photodoped monolayer molybdenum disulfide, highlighting the interplay between strong-field dynamics and valley polarization. The interplay of valley-assisted excitation and circularly polarized probe leads to chiral-sensitive sum and difference frequency mixing of the pump and probe photons, appearing as sidebands in the high-harmonic spectra. Interestingly, the sideband's strength depends on the photodoped valley's chirality and the weaker pump's helicity. Additionally, a circular dichroic signal results from valley-selective photodoping when the pumps's helicity is changed. Sensitivity of the sideband's strength on the pump–probe delay bears an imprint of the temporal aspect of the electron–hole coherence in 2D semiconductors
Terahertz Imaging of Early Stage Thermal Transformations in Oil Shale
No full textInternational audienceThe characterization of oil shales is essential for evaluating their quality and industrial potential. Existing techniques, such as X-ray tomography (XCT), scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS), infrared (IR) and Raman spectroscopies, and nuclear magnetic resonance (NMR), provide valuable information. However, none of these methods offer millimetric/sub-millimetric-scale resolution with direct sensitivity to simultaneous changes in both water and organic matter within a bulk sample. To address this limitation, terahertz (THz) imaging has previously been applied to oil shales; however, no studies have explored its use under varying temperature conditions of the sample. This is particularly relevant, as heating the samples at low temperatures (<200 °C) can provide new insights into their structural and compositional evolution. Thus, in this work, we acquired THz images after sequential heating an oil shale sample at 40, 150, and 200 °C for 15 h each, in order to monitor its change during thermal evolution. The results revealed, for the first time, changes in the THz images arising from the evaporation of free water, the release of bound water from clays, and transformation of organic matter. These findings were validated and explained by complementary analyses, including X-ray diffraction (XRD), XCT, and Rock-Eval pyrolysis. Furthermore, a first effective absorption and refractive index model was proposed, which enabled the estimation of free and bound water evaporation
Principles of mathematics
No full textThis is an introduction to mathematics, with emphasis on geometric aspects. We first discuss numbers, counting, fractions and percentages, and their basic applications. Then we get into plane geometry, with a study of triangles and trigonometry, followed by coordinates and complex numbers. We then go into functions and analysis, with a detailed discussion of the polynomials, the basics of continuity explained, and with the derivatives and integrals discussed too. Finally, we provide an introduction to vector calculus, space geometry, linear algebra and basic mechanics
Euclid Quick Data Release (Q1): From spectrograms to spectra: the SIR spectroscopic Processing Function
No full textInternational audienceThe Euclid space mission aims to investigate the nature of dark energy and dark matter by mapping the large-scale structure of the Universe. A key component of Euclid's observational strategy is slitless spectroscopy, conducted using the Near Infrared Spectrometer and Photometer (NISP). This technique enables the acquisition of large-scale spectroscopic data without the need for targeted apertures, allowing precise redshift measurements for millions of galaxies. These data are essential for Euclid's core science objectives, including the study of cosmic acceleration and the evolution of galaxy clustering, as well as enabling many non-cosmological investigations. This study presents the SIR processing function (PF), which is responsible for processing slitless spectroscopic data. The objective is to generate science-grade fully-calibrated one-dimensional spectra, ensuring high-quality spectroscopic data. The processing function relies on a source catalogue generated from photometric data, effectively corrects detector effects, subtracts cross-contaminations, minimizes self-contamination, calibrates wavelength and flux, and produces reliable spectra for later scientific use. The first Quick Data Release (Q1) of Euclid's spectroscopic data provides approximately three million validated spectra for sources observed in the red-grism mode from a selected portion of the Euclid Wide Survey. We find that wavelength accuracy and measured resolving power are within requirements, thanks to the excellent optical quality of the instrument. The SIR PF represents a significant step in processing slitless spectroscopic data for the Euclid mission. As the survey progresses, continued refinements and additional features will enhance its capabilities, supporting high-precision cosmological and astrophysical measurements
Évaluer l'inclusivité d'un dispositif numérique dans l'éducation (GTnum #EvalNumInclus) : état de l'art
No full textInternational audienceThis literature review is one component of the research project entitled “Evaluating the Inclusivity of a Digital Tool in Education: A Multidisciplinary and Systemic Approach” (GTnum #EvalNumInclus), which falls within the framework of the 2021-2025 GTnum projects led by the Directorate for Digital Education (French Ministry of National Education). This state-of-the-art review is based on a collection of scientific works in France and internationally, aiming to highlight the distribution of literature across different categories of inclusive uses. The extraction methodology and sorting criteria are presented, as well as the analytical categories defined a priori. The distribution of products across three main types of uses, defined in terms of their inclusive operationality, is characterized chronologically and didactically. The emergence of french-language research focusing on the inclusiveness of digital tool uses opens up perspectives for the evolution of practices.Cette revue de littérature constitue l'un des volets de la recherche intitulée Évaluer l'inclusivité d'un dispositif numérique dans l'éducation, approche pluridisciplinaire et systémique (GTnum #EvalNumInclus), qui s'inscrit dans le cadre des GTnum 2021-2025 portés par la Direction du numérique pour l'éducation (ministère de l'Éducation nationale). Cet état de l'art s'appuie sur une collecte de travaux scientifiques en France et à l'international en vue de mettre en évidence la répartition des produits de la littérature entre différentes catégories d'usages inclusifs. La méthodologie d'extraction et les critères de tri sont présentés ainsi que les catégories d'analyse définies a priori. La distribution des produits entre trois principaux types d'usage, définis au regard de leur opérationnalité inclusive, est caractérisée chronologiquement et didactiquement. L'émergence de travaux francophones s'intéressant à l'inclusivité des usages de l'outil numérique ouvre des perspectives d'évolution des pratiques