Crystallization kinetics of Plagioclase and application to timescale of crystal mush storage

Au cours des dernières décennies, la vision des réservoirs magmatiques a profondément évolué : les grandes chambres magmatiques riches en liquide ont été remplacées par un réseau complexe de dykes et de sills dominés par des mushs cristallins. Cette nouvelle conception a renforcé l’intérêt pour la quantification des échelles de temps magmatiques, essentielles pour comprendre la dynamique volcanique. Parmi les différentes méthodes existantes (datation isotopique, diffusion, modélisation thermique), l’analyse des distributions de tailles de cristaux (CSD), associée à des taux de croissance déterminés expérimentalement, constitue un outil particulièrement précieux, notamment lorsque les minéraux datables sont absents ou que les textures sont altérées. Cette thèse vise à évaluer le potentiel des approches texturales, en particulier la méthode CSD, pour contraindre les temps caractéristiques de l’évolution magmatique, en combinant expériences contrôlées et étude d’échantillons naturels. L’approche expérimentale, comprenant 80 expériences réalisées dans un four vertical sur une andésite basaltique en conditions anhydres, poursuivait deux objectifs principaux : (i) quantifier les taux de croissance du plagioclase au cours de différents chemins de solidification ; et (ii) étudier l’impact du chemin thermique et du prétraitement (surchauffe, élimination des germes) sur la nucléation et les textures cristallines. Les résultats montrent une évolution similaire des taux de nucléation et de croissance, avec un maximum généralement atteint à proximité du liquidus, suivi d’une diminution progressive lors du refroidissement. Les microtextures obtenues constituent un excellent marqueur du taux de refroidissement (et donc du sous-refroidissement), avec une évolution des morphologies allant de formes euédriques à des textures squelettiques puis dendritiques lorsque ce dernier augmente. Toute modification du chemin thermique, en particulier lors du prétraitement (notamment la préchauffe initiale), influence fortement la cristallisation : elle tend à inhiber la nucléation et à favoriser la croissance de grands cristaux présentant des textures de déséquilibre (dendritiques). Les taux de croissance obtenus varient de 10⁻⁹ à 10⁻⁸ cm·s⁻¹ (pour des refroidissements compris entre 1 et 125 °C/h), et atteignent des valeurs de l’ordre de 10⁻⁷ à 10⁻⁶ cm·s⁻¹ lorsque la surchauffe dépasse 15 °C au-dessus du liquidus. Les taux de croissance ainsi établis ont ensuite été utilisés pour interpréter les CSD de 19 échantillons issus de trois stratovolcans actifs de l’arc chilien (Osorno, Calbuco et Villarrica). Ces systèmes, dépourvus de phases accessoires datables et caractérisés par des textures criblées, se prêtent particulièrement bien à cette approche. Les durées de cristallisation estimées s’étendent de quelques jours à environ trois ans, selon les vitesses de croissance retenues et les populations cristallines considérées. Ces durées reflètent trois stades distincts de l’histoire magmatique : les macrocristaux enregistrent un séjour prolongé dans le réservoir principal ; les micro-phénocristaux témoignent d’un temps de résidence dans des réservoirs intermédiaires peu profonds, crucial pour l’évaluation des risques ; les microlites, quant à eux, reflètent la cristallisation lors de l’ascension finale précédant l’éruption. Ces durées, plus courtes que celles obtenues par diffusion ou par les séries de l’uranium, soulignent que chaque méthode chronométrique enregistre une fenêtre temporelle distincte. L’approche CSD, sensible aux taux de croissance considérés, permet d’estimer exclusivement les temps de cristallisation. Elle apparaît néanmoins comme un complément indispensable aux chronomètres géochimiques pour mieux comprendre le stockage et la dynamique du magma dans les arcs volcaniques, en reliant à la fois échelles de temps et processus magmatiques.Over the past decades, the conceptual view of magmatic reservoirs has profoundly evolved: large, liquid-rich magma chambers have been replaced by a complex network of dykes and sills dominated by crystalline mushes. This new paradigm has reinforced interest in quantifying magmatic timescales, which are essential for understanding volcanic dynamics. Among the various existing methods (isotopic dating, diffusion chronometry, thermal modelling), the analysis of crystal size distributions (CSD), combined with experimentally determined growth rates, represents a particularly valuable tool, especially when datable accessory minerals are absent or when crystal textures are altered. This thesis aims to assess the potential of textural approaches, particularly the CSD method, to constrain the characteristic timescales of magmatic evolution by combining controlled experiments with the study of natural samples. The experimental approach, consisting of 80 experiments performed in a vertical furnace on an anhydrous basaltic andesite, pursued two main objectives: (i) to quantify plagioclase growth rates along different solidification paths; and (ii) to investigate the influence of thermal history and pre-treatment (superheating, removal of nuclei) on nucleation behaviour and crystal textures. The results show a similar evolution of nucleation and growth rates, with a maximum generally reached near the liquidus, followed by a progressive decrease during cooling. The resulting microtextures are excellent markers of cooling rate (and thus undercooling), with morphologies evolving from euhedral forms to skeletal and then dendritic textures as undercooling increases. Any modification of the thermal path, particularly during pre-treatment (notably initial superheating), strongly influences crystallization: it tends to inhibit nucleation while promoting the growth of large crystals exhibiting disequilibrium textures (dendritic). The measured growth rates range from 10⁻⁹ to 10⁻⁸ cm·s⁻¹ for cooling rates between 1 and 125 °C/h, and reach values on the order of 10⁻⁷ to 10⁻⁶ cm·s⁻¹ when superheating exceeds 15 °C above the liquidus. The experimentally derived growth rates were then used to interpret the CSDs of 19 samples from three active stratovolcanoes of the Chilean arc (Osorno, Calbuco and Villarrica). These systems, which lack datable accessory phases and commonly display sieve textures, are particularly well suited to this approach. The estimated crystallization durations range from a few days to roughly three years, depending on the growth rates considered and the crystal populations analysed. These timescales reflect three distinct stages of the magmatic history: macrocrysts record prolonged residence in the main reservoir; microphenocrysts correspond to residence times in shallow intermediate reservoirs, which are crucial for hazard assessment; and microlites reflect crystallization during the final ascent prior to eruption. These timescales, shorter than those obtained from diffusion chronometry or U-series dating, highlight that each method records a different temporal window. The CSD approach, inherently sensitive to the growth rates considered, provides estimates of crystallization durations only. Nevertheless, it emerges as an essential complement to geochemical chronometers for improving our understanding of magma storage and dynamics in volcanic arcs, by linking both timescales and magmatic processes

Chapter 18 - Hamstring and thigh injuries

editorial reviewe

Effect of focus flood water spreading on recharge in semi-arid climate: case of water spreading weirs in Burkina Faso

peer reviewedIn recent years, water spreading weirs have been implemented on watercourses in West Africa. This study investigates the hydrological impact of water spreading weirs (WSWs) in the semi-arid Wedbila watershed of Burkina Faso, a region challenged by soil degradation and scarce water resources. The study employs an integrated, multidisciplinary approach combining in situ monitoring of surface water levels, soil moisture at multiple depths, and piezometric fluctuations to capture the influence of WSWs on soil water dynamics and aquifer recharge. Comparative analyses between zones impacted by water spreading and control zones provide a robust empirical basis—making this one of the few West African studies to comprehensively combine these measurements in assessing WSW effects on infiltration and groundwater recharge. Results demonstrate that WSWs significantly enhance soil moisture retention near the surface and notable rises in piezometric levels observed during and after flood events. Correlation analysis of monitored parameters indicated that groundwater recharge is dependent on rainfall distribution, surface water levels, and soil properties. Using soil water balance, the annual infiltration calculated in the spreading zone was 568 mm, significantly exceeding that observed outside the spreading zone. Cumulative infiltration during spreading periods accounted for 57 % of annual infiltration. This water spreading weirs positive impact demonstrates, contingent upon spreading duration, topography and soil characteristics. Importantly, the WSWs as a low-cost managed aquifer recharge (MAR) solution suitable for data-poor, semi-arid regions like Burkina Faso. By enhancing the landscape's capacity to capture scarce and erratic rainfall, WSWs contribute to climate resilience and agricultural productivity in vulnerable rural communities facing increasing water scarcity due to climate change. They serve as a complementary technique for raising the groundwater level when conditions are favorable in Burkina Faso.2. Zero hunger13. Climate actio

The mirage of the silver bullet: Exploring the limitations of high-resolution data in flood model validation

peer reviewedValidation of inundation models presents persistent challenges, particularly in urban floodplains where structural complexity often exacerbates discrepancies between model outputs and observation datasets. Findings from the present study suggest that while availability of high-resolution field data can enhance validation efforts, it is not the final piece of the puzzle. The study highlights the (often inseparable) complex combination of observed data limitations, model uncertainties, and structural discrepancies between model and observed datasets, which strongly influence validation outcomes. Using the July 2021 Vesdre Valley flood in Belgium as an illustrative framework, the research evaluates the performance of a high-resolution 2D hydrodynamic model (WOLF). The unprecedented detail of the post-flood survey provides a unique opportunity for rigorous validation. Four so-called ‘reconciliation methods’ are explored to address structural discrepancies (in post-processing) between observation data and computational outcomes, highlighting the effect of the choice of method. At the highest model resolution (2 m), the critical success index (= 0.86) indicates strong spatial agreement across sectors, with a mean absolute error of 0.56 m in modelled maximum flood depths. By proposing and critically evaluating various methods for reconciling inherent differences between observational and computed datasets, this study highlights the complexity of model validation beyond data availability. Additionally, it offers recommendations for refining post-flood survey methodologies to minimise uncertainties associated with the validation process

How grooves control droplet growth, transport and release

Water management on surfaces underpins applications ranging from atmospheric water harvesting to heat exchange and surface cleaning. Many existing strategies rely on chemical coatings or micro-texturing, which can be fragile, costly, or difficult to scale. This thesis explores an alternative approach based on simple geometric features, focusing on whether grooves alone can collect, guide, and release small volumes of water on vertical substrates. We investigate four representative systems that span different flow configurations and degrees of confinement. On fibers and fiber bundles, we show that grooves naturally appearing between strands reorganize droplet dynamics by modifying the film left behind the droplet, reducing dissipation and increasing sliding speed. Under condensation on a vertical plate, we demonstrate that groove spacing selects the drainage pathway: large spacings favor gravitational shedding, while small ones confine droplets to the plateaus and redirect transport into the grooves. At the lower edge of such plates, groove geometry determines the disposition and frequency of droplet dripping. Finally, in a minimal configuration consisting of two parallel grooves, we show that geometry alone can stabilize a thin water film over more than one hundred capillary lengths. At groove termini, the film breaks and releases a droplet through a cyclic sequence of events. Across these systems, a common principle emerges: groove acts as a minimal feature that structures the flow. Grooves define where liquid accumulates, how it moves, and when it detaches, enabling robust control without coatings or complex fabrication. These findings suggest that simple geometric design can serve as the foundation for scalable, passive, and durable water-handling surfaces, and they outline the key operations needed for a future geometry-driven millifluidic platform.Daphnée12. Responsible consumption and production6. Clean water and sanitatio

Usage des états affectifs des congénères pour palier aux changements environnementaux [Pre-print]

peer reviewedAs a result of human-induced environmental change, animals increasingly face challenges that differ from those encountered throughout their evolutionary history. Whilst this has caused dramatic declines for many species, some can persist by gathering information to reduce uncertainty, thereby minimising risks and exploiting new opportunities. The strategic use of social information can be particularly useful in enabling such uncertainty-reduction. Here, we argue that the behavioural and affective states of others provide vital social information for animals to guide evaluations of risks and opportunities. Specifically, attending and responding to indicators of others’ affective states through processes such as emotional contagion may facilitate information transmission. For instance, when exposed to a novel, ambiguous anthropogenic stimulus that could indicate either an opportunity or a threat, animals may use social information about others’ affective states to decide whether to approach or avoid the stimulus. To increase immediate and long-term benefits, individuals might also alter their social behaviour and information use flexibly based on critical early-life experiences, the socio-ecological context, or the behaviour and states of associates in the social network. Finally, given that an individual’s affective state can influence how it copes with changing environments and makes appropriate decisions, we argue that there is a need for greater synergy between animal welfare and conservation efforts. Bridging the gap between ensuring individual-level welfare and population-level resilience will be crucial for ethical policies to protect wild animals responsibly in the face of human-induced rapid environmental change

Mamluk Chancery Papers and Their Formats: A Contribution to the History of Paper

peer reviewe

Baudelaire's clarities

peer reviewedBaudelaire, l’ange du bizarre, est aussi le poète des évidences et des clichés, qu’il perfore autant qu’il les performe. Cartes sur tables, tel est son jeu, à travers une poétique clairement gouvernée par une réflexivité ayant divers points d'accroche et d'embrayage : la progression discursive, tant en prose qu'en poésie (où discours et méta-discours se superposent) ; l'univocité érotique et rhétorique (fétichiste et métonymique) ; l'objectivation pré-sociologique de l'expérience littéraire et une théorie du lieu commun dans laquelle poncif et inventivité s'alimentent réciproquement. Cette réflexivité, qui n’est pas sans point aveugle, est mise en évidence à travers quelques poésies emblématiques (dont « A une passante ») et quelques proses de combat (dont « Conseils aux jeunes littérateurs »).Baudelaire’s poetics is clearly reflexive in many ways: a discursive process constantly biased by a meta-discourse; an erotic and rhetorical balance; a pre-sociological objectivation of literary experiment and a theory of the “lieu commun” in which cliché is given as a path to invention

Post-treatments on carbon xerogels to improve their performance as negative electrodes of Na-ion batteries

peer reviewedA carbon xerogel (CX) with ∼2 μm nodules was synthesized via polycondensation of resorcinol with formaldehyde in water, followed by pyrolysis at 800 °C. The resulting sample underwent surface treatments using Chemical Vapor Deposition (CVD) and/or CO2 activation in order to mask the micropores with a secondary carbon layer or develop additional micropores, respectively. This strategy aimed at understanding the impact of surface modification and closed micropores on the performance of hard carbons as negative electrode materials for Na-ion battery. On the one hand, the coating deposited by CVD was found to display more graphitic-like domains and to close the CX microporosity, leading to enhanced Initial Coulombic Efficiency (ICE) and reversible capacity. On the other hand, due to its very high accessible surface area, the activated sample showed very low ICE (18 %) and reversible capacity (62 mAh g−1). However, once the activated sample was covered with a secondary carbon layer by CVD, the capacity reached 294 mAh g−1 with a high ICE of around 88 %, and an enhanced insertion plateau at low voltage was observed. Additionally, this activated-coated sample showed a high-rate capability and much greater stability than the other samples upon cycling. Such surface treatments provide an effective strategy for both understanding the impact of hard carbon surface properties on Na storage and optimizing their performance for negative electrodes in Na-ion batteries

Validation of supercritical fluid chromatographic methods

peer reviewedMethod validation is the process of proving that an analytical method is acceptable for its intended purpose. The present chapter defines the validation criteria described in regulatory documents, especially focused on the ICH Q2(R2) and Q14 effective in 2024. Despite the abundance of guidelines, the conclusion about method validity remains confused. In this context, the state-of-the-art validation methodology named total error, or combined approach, is briefly explained as the methodology that should be followed for all method validations. Finally, a review of literature presents quantitative development and validation of supercritical fluid chromatography methods considering a wide range of applications and analytical fields