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Specific carbon fluxes in rivers from long-term monitoring
No full textInternational audienceThe transfer of carbon from land to rivers and ocean is a key part of the carbon cycle, yet it is poorly quantified. The amount of carbon transported by inland waters is comparable with the amount of carbon stored on land, but large variations exist depending on the climatic, lithologic and land-use characteristics of watersheds. In the framework of the Carbonium project, a target project in the FairCarboN national project, we focus on bridging this gap. In a first stage, we aim at quantifying carbon fluxes in rivers, both dissolved and particulate as well as organic and inorganic. In a second stage, these fluxes will be related to river and watershed characteristic such as the maximum discharge, average slope, land use, or lithologic features. A data base comprising for now data from 30 sites belonging to the French research networks OZCAR (Observatoires de la Zone Critique: Applications et Recherche) and RZA (Réseau Zones Ateliers). These sites exhibit long term data sets of liquid discharge, suspended sediment concentrations (SSC) and Carbon concentrations covering a large diversity of lithologies, land use, and meteorological forcing. Most of them are located on the metropolitan territory of France, but data from overseas and foreign countries is also available. Dissolved organic carbon (DOC) vary from very low concentrations (close to 0.1 mgC/L) to concentrations up to 73 mgC/L in tropical rivers. Particulate organic carbon (POC) concentrations are mostly comprised between 0.5 and 22 mgC/L, with occasional events resulting in concentrations as high as 500 mgC/L in the Gier River, a tributary of the Rhône, or the Isère River.This represents carbon contents from 2 to 15%, occasionaly much higher. Specific carbon fluxes vary from 10-2 kg/km2/year in the Bernadouze or in the Gardon to 4x103 kg/km2/year, in the Galabre or in Isère Rivers, with larger rivers such as the Rhône displaying fluxes around 1x103 kg/km2/year. However, estimations of fluxes are subject to high uncertainty related to the availability of data, its frequency and the proxies used to obtain continuous temporal series of DOC and POC concentrations. As a matter of fact, measured parameters do not often include the concentration of DOC and POC. However, each river has a distinct relationship between SSC or turbidity, and POC; while the DOC concentration can be linked to the water flow. The second step of the analysis is therefore to test and select an appropriate method to establish these relationships when low frequency data is available. For example, the field stations of the Rhône River in Arles (south of France), the Coët-Dan River in Naizin (Brittany), or the Mule Hole observatory in India, are suitable candidates because they dispose of high frequency records of flow, turbidity, SSC, and carbon concentrations. In addition, appropriate method of fluxes computation must be chosen depending on the frequency of data measurement
Reliability of Elementary Ultrasonographic Lesions in Psoriatic Arthritis and Development of an Atlas: results Ofthe Echo-Apache Study
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Les atteintes à la liberté académique par l’administration centrale et rapprochée
No full textInternational audienceFrench universities, being public institutions, are under the supervision of the Ministry of Higher Education and Research. This oversight explains why a national legal framework applies uniformly to all higher education institutions. When setting these national rules, the central administration is not always inclined to prioritize academic freedom. A example can be given by the adoption of the "climate plan" by the ministry and the implementation of the "competency-based approach," initiated by the ministry and encouraged by the High Council for the Evaluation of Research and Higher Education. Thus, while the centralization of higher education is beneficial, particularly as it ensures equal treatment among institutions, it can also present disadvantages. These could be mitigated by the institutional autonomy enjoyed by universities: by using the freedom it grants, the "proximate administration," composed mainly of faculty members, should serve as an effective safeguard against threats to academic freedom. However, two examples cast doubt on this: the establishment of a prior authorization regime for the publication of research results by certain laboratories and the decision within a university to prohibit emeritus professors from chairing thesis committees.Las universidades francesas, al ser instituciones públicas, están bajo la supervisión del Ministerio de Enseñanza Superior e Investigación. Esta supervisión explica por qué un marco legal nacional se aplica de manera uniforme a todas las instituciones de enseñanza superior. Al establecer estas reglas nacionales, la administración central no siempre está dispuesta a dar prioridad a la libertad académica. Esto se ilustra con la adopción del "plan climático" por parte del ministerio y el despliegue del "enfoque basado en competencias", iniciado por él y fomentado por el Alto Consejo para la Evaluación de la Investigación y la Enseñanza Superior. Así, aunque la centralización de la enseñanza superior es positiva, especialmente porque asegura un trato igualitario entre instituciones, también puede presentar inconvenientes. Estos podrían ser relativizados por la autonomía institucional de la que gozan las universidades: al hacer uso del margen de maniobra que les concede, la "administración cercana", compuesta mayoritariamente por académicos, debería constituir un baluarte eficaz contra las amenazas a la libertad académica. Sin embargo, dos ejemplos permiten dudar de ello: la implementación de un régimen de autorización previa para la publicación de resultados de investigación por parte de ciertos laboratorios y la decisión, dentro de una universidad, de prohibir la posibilidad de que los profesores eméritos presidan los jurados de tesis.Les universités françaises étant des établissements publics, elles sont placées sous la tutelle du ministère de l'Enseignement supérieur et de la Recherche. Cette tutelle explique qu’un cadre juridique national s’applique de la même façon à l’ensemble des établissements d’enseignement supérieur. En arrêtant ces règles nationales, l’administration centrale n’est pas toujours encline à faire prévaloir la liberté académique. C’est ce qu’illustrent l’adoption du « plan climat » par le ministère et le déploiement de « l’approche par compétences », initiée par lui et encouragée par le Haut Conseil de l’évaluation de la recherche et de l’enseignement supérieur (HCERES). Ainsi, même si la centralisation de l’enseignement supérieur est positive, notamment en ce qu’elle assure une égalité de traitement entre établissements, elle peut aussi présenter des inconvénients. Ces derniers pourraient être relativisés par l’autonomie institutionnelle dont jouissent les universités : en usant de la marge de manœuvre qu’elle lui accorde, « l’administration rapprochée », composée majoritairement d’universitaires, devrait constituer un rempart efficace contre les atteintes à la liberté académique. Deux exemples permettent pourtant d’en douter : la mise en place d’un régime d’autorisation préalable à la publication des résultats de travaux par certains laboratoires et la décision, au sein d’une université, d’interdire la possibilité pour les professeurs émérites de présider les jurys de thèse
Un essayeur incompétent. L'affaire Reyslander, Sainte-Marie-aux-Mines, 1571-1572
No full textInternational audienceDans les exploitations minières modernes, l’essai des minerais a joué un rôle majeur dans les relations entre mines et fonderies. Il était exigé de l’officier essayeur des qualités morales et techniques devant assurer des résultats représentatifs et reproductibles. Les plaintes de concessionnaires et l’embarras de l’administration minière mettent en évidence l’exigence du savoir-faire requis et la rareté des personnes qualifiées dans le massif vosgien du second XVIe siècle
Evolution of the oxidation of V zigzag nanostructures on Si: Prime conditions to reach uniform thermochromic VO2(M) thin films
No full textInternational audienceThis article reports on the oxidation of 100 nm-thick vanadium layers achieved by sputtering glancing-angle deposition on silicon, with opposite oblique columns creating a zigzag-like morphology, using a small overpressure continuous flow of air and an infrared lamps furnace. In addition, the study focuses on the stepwise investigation of the nanostructure and the oxidation progress of the layer by electron microscopy, verifying a monotonic incorporation of oxygen with time, which results in a linear rise of the VOx overlayer volumes. This characterization is correlated with Raman spectra quickly collected in a wide wavenumber range. In consequence, we claim a methodology based on the comparisson of the relative intensities of such Raman bands to track the kinetic dynamics of these systems, evidencing the participation of three main phases: VO2(M) alone or mixed with either V or V2O5. For the optimum conditions, high-quality vanadium dioxide layers are achieved, attending to their nanostructure and outstanding optical response (over 90% of relative transmittance modulation at a wavelength of 3000 nm). Vis-NIR spectrophotometry and Raman spectroscopy, both carried out at variable temperature, allow exploring the different thermochromic characteristics of the samples at different oxidation stages
Three-axis inertial sensing based on a valley topological phononic metamaterial
No full textInternational audienceWe propose an electrostatically coupled valley phononic metamaterial for three-axis inertial sensing (two accelerations, one rotation), which consists of unequal masses on the lattice sites to break the inversion symmetry. Different combination constructions of the metamaterials can form three types of interfaces hosting the valley edge states with distinct dispersion relations. A design strategy of assembling various interfaces is introduced to tailor the overall structure of a metamaterial for achieving three-axis inertial sensing. Critically, the acceleration induces the energy localization of the valley edge modes and the Coriolis force introduces additional phase differences into the vibration phase of masses. Hence, a three-axis inertial-sensing method based on the valley phononic metamaterial is proposed by tracking the mode shape shifts and the variation of phase difference between masses. The maximum cross-axis sensitivities of the sensing method are all below 0.4%, underscoring the capability of three-axis independent sensing. The proposed valley phononic-metamaterial-based sensing method provides promising perspectives and avenues for the design of multiaxis inertial sensors
Soft elastomeric optical fibers for oxygen change measurements of blood and living tissues: a thermoplastic polyurethane assessment
No full textInternational audienceThis paper discusses the design, fabrication, and use of thermoplastic polyurethane optical fibers intended for oxygen saturation measurements. It includes an evaluation of the fiber attenuation and the creation of two probes for the measurement assessment. For comparison, a third probe is made using conventional glass optical fibers. The assessment is conducted in two stages: first, absorption measurements are performed using a mixture of methylene blue and intralipid diluted in deionized water; second, a measurement with human blood is conducted to demonstrate the effectiveness of such fibers in measuring blood oxygen saturation. Additionally, a comprehensive study of measurement stability is provided
Preserving Optics Heritage at the University of Franche-Comté
No full textInternational audienceAn effort to safeguard the legacy of optics includes a museum of historical instruments, some dating to 1845.
An equivalent plate model for assessing the dynamic behavior of highly damped sandwich plates
No full textInternational audienceThis article presents an equivalent plate modeling approach for assessing the dynamic behavior of highly damped multilayered plates, with a focus on adaptive structures with shape memory polymer core. The mechanical properties of these structures vary with frequency and temperature, and exceptional damping values are obtained near the glass transition temperature of the shape memory polymer. By modeling the system as an equivalent homogeneous and isotropic thin plate, the effective properties are analytically determined by retaining the real parts of the bending, shear (transverse) and extension (quasi-longitudinal) waves. Unlike other equivalent plate models, the damping loss factor is estimated using a power balance formulation accounting for the significance of multiple waves types, improving the description of the dissipation mechanism. The results show good agreement with the damping estimates obtained using the power input method and the full order finite element model of the sandwich plate. For a 4% damping value, the equivalent plate finite element model accurately predicts the vibroacoustic indicators of the adaptive sandwich plate, while significantly reducing the modeling complexity. Even at exceptionally high damping levels (55% and 77%), the equivalent plate model captures the overall dynamic behavior of the structure. This proposed equivalent model offers a practical method for evaluating the vibroacoustic performance of highly damped multilayered plates and can be used to explore various behaviors of adaptive sandwich plates. Its reduced computation time makes it especially suitable for optimization problems, such as determining optimal temperatures for damping and stiffness control