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« The Expression of Power in the Chanson de Geste in French (Twelfth to Thirteenth Centuries) »
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Effects of La2O3 on structure and mechanical properties of sodium borosilicate glass
No full textInternational audienceTo develop rare-earth-doped borosilicate glasses with enhanced mechanical properties, lanthanum sodium borosilicate glasses were successfully synthesized using a fusion method. The glass composition was (mol.%): 55SiO2 - 25B2O3 – (20-x)Na2O - xLa2O3 (x = 1, 2, 3, 4, and 5). The primary aim was to investigate the impact of Na2O substitution by La2O3 on the structural and mechanical characteristics of the glasses. X-ray diffraction analysis confirmed the amorphous nature of the samples, while Raman and Fourier-transform infrared spectroscopy indicated a conversion of BO3 to BO4 units. Additionally, differential thermal analysis revealed an increase in both glass transition and crystallization temperatures with higher La2O3 content. The inclusion of La2O3 enhanced the glass density, Vickers hardness, fracture toughness, and Young's modulus, owing to the larger ionic radius of La3+ compared to other components. In summary, the incorporation of an optimal concentration of La2O3 significantly improves the mechanical properties of these sodium borosilicate glasses, making them more suitable for applications involving the containment of actinides in nuclear fuel reprocessing
Influenza epidemics in France
No full textAnnual incidence of influenza-like illness since 1984, computed from the weekly incidence data provided by the "Réseau Sentinelles".This is a toy example of a data analysis using the HyperDoc framework. It reuses data and code from another HyperDoc (the "data paper") and is itself reusable, in addition to being explorable and undstandable
-Griffiths polynomials: Bispectrality and biorthogonality
No full textInternational audienceWe introduce a generalization of bivariate Griffiths polynomials depending onan additional parameter . These -Griffiths polynomials arebivariate, bispectral and biorthogonal. For two specific values of theparameter , they become orthogonal. One of the value is related to theusual bivariate Griffiths polynomials, while the second value produces neworthogonal bivariate polynomials
Tutorial lecture : The chemistry of cryogenic etching
No full textInternational audienceEven if it seems counterintuitive, cooling the substrate to very low temperatures can favor chemical reactions and significantly increase the etch rate (ER). Cryogenic etching has been studied for silicon deep etching, but it has also been applied to low-K material etching and Atomic Layer Etching (ALE). More recently, HF-based plasmas with high energy ion bombardment have been successfully developed to etch SiO2 and Si3N4 at low temperatures. In-situ characterizations of plasma-surface interaction at cryogenic temperature will be presented for different fluorine-based chemistries
On the equatorial dayside ionosphere of Saturn – In-situ observations give evidence for a dynamic and layered structure in disequilibrium
No full textInternational audienceThe Cassini observations of Saturn's ionosphere during the proximal orbits 288–293 in the altitude range 1450–4000 km (above 1-bar level) are revisited. A thorough re-analysis is made of all 159 available Langmuir probe sweeps of the Radio & Plasma Wave Science (RPWS) measurements. We relate them to the RPWS plasma wave inferred electron number densities and compare them with the available Ion Neutral Mass Spectrometer (INMS) measurements of the H+ and H3+ number densities. Different analysis methods are used by RPWS to provide consistent electron number density values for the whole measured altitude interval. Consistent RPWS electron number density (ne) and INMS positively charged ion number density (ni+) profiles are derived for altitudes above ~2200 km. Below this altitude the inability of INMS to measure ions above 8 amu at the 34 km/s flyby speed lead us to infer the presence of heavy ions (> 8 amu) and a negatively charged ion component, presumably related to infalling material from the D-ring of Saturn with its associated local ion-molecule-aerosol chemistry. This lower altitude region shows a highly time variable layered structure. The Langmuir probe data in this region are strongly affected by secondaries emitted from the spacecraft and sensor surfaces when traversing a molecule-rich atmosphere at 34 km/s. There are clear signatures of secondary electron and ion emissions from the spacecraft and sensor surfaces in the data. In the Langmuir probe sweep analysis, we correct for the effect of such impact-generated products. This gives corrected total ion number densities that can be compared to the INMS ion number densities and the electron number densities. From this analysis the number of negative ions and/or nm-sized aerosol/dust particles can be constrained. A clear ionospheric peak is not identified, not even at the lowest observed altitude of approximately 1450 km. There are clear latitudinal variations and temporal evolving structures, which we infer are representative of the difference in infalling material from different regions of the D-ring. In addition, there are indications of a strong heating source for the ambient electrons that are well above expected thermal equilibrium levels (up to 4000 K). The cause of this heating is unknown but may be linked to collisional deacceleration of infalling ring material. The observational profiles presented here can be used for ionosphere theory/model comparisons in the future
Objects in vista space are misrepresented to be closer in a spatial updating task
No full textInternational audienceSpatial updating describes the ability to correctly determine one’s position and orientation in the environment after a location change that cannot be observed. We hypothesized that observers misrepresent a far target as being located closer to them than it actually is, in action space rather than in vista space. In a first experiment, participants were presented with a target at distances between 1 m and 200 m. After being blindfolded, they were led away from the target at a 90° angle and indicated the target’s location by pointing to it while walking. Participants overestimated the smallest distances but underestimated larger ones. As hypothesized, they pointed further backward, that is overcompensated, as the target distance increased. However, this spatial updating error may have been influenced more by the awkward pointing angle than by the target distance. To investigate this potential confound, we devised a similar between-subjects experiment in which participants looked at a target at one of 4 distances (2.6 m, 8.6 m, 17.9 m, and 41.2 m). They were then blindfolded and guided to a spot 15 meters away from the target in a 90° angle. At this point, they were asked to turn with their entire body and both arms stretched out in front of their chest until they perceived themselves to be pointing back at the target. For distances up to 17.9 m, there was no difference between the blindfolded and a seeing control condition. However, participants in the group with the farthest target placement (41.2 m) erred farther away from the target when blindfolded - in the hypothesised direction. We conclude that observers base their spatial updating of far targets in vista space on the assumption that the object is indeed closer at the edge of action space
A multi-objective optimization to characterize the diffusion of nanocavities in tungsten
No full textInternational audienceWe characterize the diffusion properties of nanocavities and their uncertainties by designing a multi-objective optimization approach. In this work, the nanocavity diffusion on the 0.3–4 nm size range is the input of a multi-scale simulation that is adjusted to reproduce experimental results of a systematic study of nanocavity growth with temperature up to 1773 K. Under irradiation, in the material microstructure, the damage evolution results from a complicated interplay of the defects and their clusters (formed from the vacancies and self-interstitials created) which diffuse, recombine and grow. The simulation of the whole experiment, based on an Object Kinetic Monte Carlo algorithm, can take several hours per condition which is a strong limitation for the optimization scheme. We describe the method that succeeds for our problem. Starting from a rough and random sampling of the space of parameters, we then consider that each simulation is one point of the hypersurface in the high dimensional space formed by the optimized parameters and objectives. We iteratively improve the characterization of this hypersurface where the objectives are optimum thanks to a systematic search of patterns formed by points on the coordinate planes. The non-dominated solutions, i.e. the equally good solutions, also named the Pareto front, are finally characterized. They draw two “valleys” in the subspace of parameters, delimiting the uncertainties on the searched diffusion properties, which cannot be reduced with the experimental data and the model in their current form
