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A folded gallium 12-MC-4 that encapsulates visible and near-infrared emitting lanthanide ions
No full textInternational audienc
Aquatic metabolism influences temporal variations of water carbon and atmospheric carbon dioxide fluxes in a temperate salt marsh
No full textInternational audienceSalt marshes are blue carbon (C) ecosystems characterized by intense atmospheric CO2 uptake and C sequestration but also by organic and inorganic C exports through the tide. However, uncertainties about the main biotic factors controlling these vertical and horizontal C fluxes imply studying terrestrial and aquatic metabolisms simultaneously at small timescales (diurnal and tidal) to distinguish their contributions to net ecosystem CO2 exchange (NEE). In a temperate salt marsh, four sampling 24 h cycles were performed to measure all water C biogeochemical parameters (including CO2 partial pressures, pCO2), nutrients, and aquatic metabolism simultaneously to NEE from high tide during marsh immersion (imported coastal waters influenced by the continental shelf) to low tide during marsh emersion (exported channel waters influenced by the marsh drainage). At high tide, water CO2 oversaturation (water pCO2 > air pCO2) due to marsh aquatic heterotrophy and CO2-concentrated water inputs from the coastal end-member induced water–air CO2 emissions during marsh immersion. At low tide, water pCO2 in the channel were also mainly controlled by the marsh aquatic metabolism, inducing a water CO2 oversaturation in winter due to dominant heterotrophy and a water CO2 undersaturation in spring and summer due to dominant autotrophy. In winter, the greatest increases in dissolved inorganic carbon (DIC; from 2354 to 3963 µmol kg−1), total alkalinity (TA; from 2508 to 4016 µmol kg−1) and dissolved inorganic nitrogen (DIN; from 27.7 to 68.4 µM) were measured simultaneously during low tide at night, probably due to intense aerobic/anaerobic microbial respiration of organic matter in channel waters and/or sediments resulting in the greatest water pCO2 increase (from 533 to 1461 ppmv). On the contrary, in spring and summer, large water pCO2 decreases (down to 83 ppmv) and dissolved organic carbon (DOC) increases (up to 1040 µM) from high to low tide could be related to intense autochthonous and allochthonous marsh primary production, including benthic microalgae, phytoplankton and macroalgae. This study suggests that the horizontal exchanges of coastal waters with the salt marsh significantly modify water C dynamics and associated water CO2 sink/source state in the channel due to an intense marsh metabolism (production and respiration). At the daily scale, plant and phytoplankton metabolism rates played a major and a minor role, respectively, in the marsh CO2 sink measured by atmospheric eddy covariance at the ecosystem scale (NEE), even during immersion where emerged plants located on the highest marsh levels can maintain a low CO2 uptake, despite aquatic heterotrophy and associated water–air CO2 emissions
Artisanal mining in Africa. Green for Gold?
No full textInternational audienceThe livelihoods of 130 to 270 million people depend on artisanal mining. Artisanal mining is a labour-intensive, often illegal, extractive activity. We combine geological knowledge and a source of exogenous temporal variation to construct the first proxy for artisanal gold mining in Africa—the main form of artisanal mining. We establish that an increase in the potential value of artisanal mining is a significant driver of deforestation. The historical increase in the gold price accounts for 8% of forest loss across the continent and, within the subset of gold-suitable areas, 28 %. In parallel, artisanal mining increases local economic wealth and may provide an alternative livelihood should a weather shock jeopardise agricultural output. Finally, mining-induced deforestation seems rooted more in the direct clearing of trees for the activity than in indirect deforestation triggered by increased local demand
Procédé pour déterminer un parcours optimisé d'un véhicule électrique au regard du temps de parcours et du cout énergétique
No full textL’invention concerne un procédé réalisé par unité de calcul pour déterminer un trajet optimal (TRJ) d’un véhicule électrique sur un itinéraire prédéfini, au regard d'une pondération entre un critère de temps de parcours minimal et un critère de coût énergétique minimal, à l’aide de données de référence comprenant des informations de cartographie routière et des informations relatives à la position et à la puissance installée de stations de recharge, un coefficient de pondération (γ), incarnant une préférence entre le critère de temps de parcours minimal et le critère de coût énergétique minimal, défini par l’utilisateur, l’unité de calcul étant configurée pour identifier un minimum d’une fonction d’optimisation utilisant un coût virtuel de temps passé sur l’itinéraire prédéfini et un coût virtuel ou réel de l’énergie électrique dépensée, par une méthode de programmation dynamique multi domaines ou par une méthode de programmation non linéaire de type point intérieur
High-resolution solid-state 7Li NMR study of lithium incorporation in calcite and aragonite
No full textInternational audienceAbstract In the present study, the chemical composition, mineralogy, and mechanisms of alteration of a cementitious grout based on a CEM III/C with addition of smectite, hydrotalcite, and silica fume, are studied using a combination of chemical and physical methods. This material was designed in the context of geological repository of radioactive wastes, with a twofold aim: first, to fill the technical voids left by drilling operations at the interface between the geological formation and the disposal galleries. Second, to neutralize a potential acidic transient due to pyrite oxidation, and to create an environment that favors low corrosion rates of carbon steels. The grout is mainly composed of calcium silicate hydrates having a Ca/Si ratio of ~0.8, incorporating Al in the bridging site of the Si chains (C-A-S-H), and accounting for 29–36 wt.% of the sample. It also contains silica fume (38–48 wt.%), smectite with interlayer Na (11–17 wt.%), hydrotalcite with interlayer CO 3 2− (3–4 wt.%), and lower amounts of portlandite, calcite, and possibly gibbsite and gypsum. Upon alteration by water in a flow-through reactor, the main modifications affecting the sample are calcite and gypsum dissolution, hence releasing aqueous Ca 2+ that is adsorbed in smectite interlayer by replacing Na + , and stoichiometric C-A-S-H dissolution. The evolution of solution chemistry and of the solid phase composition are reproduced successfully using a thermokinetic model
Nigromancie et usages du corps humain aux derniers siècles du Moyen Âge
No full textInternational audienceCette contribution compare le discours doctrinal que les théologiens et les inquisiteurs de la fin du Moyen Âge consacrent à la « nigromancie », où l’accent est mis sur les usages sacrilèges dont il est fait de parties du corps humain, mort ou vivant, en guise de sacrifices aux démons, à celui des textes de magie savante que l’on a conservés, qui donnent une image plus contrastée de ces pratiques, notamment pour ce qui concerne le sang, central dans la doctrine du pacte
Action-Reaction: Study of the behavioural responses adopted by consumers of brands involved in scandals
No full textInternational audienceThe aim of this research is to understand, characterise and classify the behavioural responses of consumers of a brand that has been the subject of a scandal, according to the level of hatred felt. To do this, we carried out a case study in the form of a literature review. The first step was to identify 12 companies from different strategic sectors that had recently faced a major crisis. The most relevant articles recounting these events were searched on the Internet and then consulted, before being analysed to highlight and explain consumers' behavioural reactions. The results obtained make it possible to propose a reading grid proposing to establish links between corporate behaviour, consumer reactions and corporate responses. Our results confirm the literature on corporate behaviour (Makarem and Jae, 2016) and the links between hatred and resistance (Buffaz, Perraud, Rodriguez, 2024). This reading grid makes it possible to recommend that brands implement an appropriate and specific response to each consumer reaction depending on the type of scandal identified
Quelles réponses comportementales de la part des consommateurs vis-à-vis des marques faisant l’objet de scandales ?
No full textInternational audienceUne étude de cas, prenant la forme d’une analyse documentaire, a été réalisée afin de comprendre de caractériser et de classifier les réponses comportementales des consommateurs d’une marque ayant fait l’objet d’un scandale, et ce en fonction du niveau de haine ressentie. Douze entreprises, issues de domaines d’activités stratégiques différents, ayant dû récemment faire face à une crise majeure ont été étudiées pour mettre en exergue et expliquer les réactions comportementales des consommateurs. Une grille de lecture proposant d’établir des liens entre les comportements des entreprises, les réactions des consommateurs et les réponses des entreprises a été établie. Nos résultats confirment la littérature sur les comportements des entreprises (Makarem et Jae, 2016) et les liens entre haine et résistance (Buffaz, Perraud, Rodriguez, 2024) et permettent de recommander aux marques une réponse appropriée et spécifique à chaque réaction des consommateurs en fonction du type de scandale identifié
Les plateformes de SVOD, nouvel opium du peuple ?
No full textInternational audienceAlors qu’elles connaissent un franc succès en France et à travers le monde, les plateformes de SVOD (Subscription Video On Demand) se réinventent pour faire face à l’intensité concurrentielle croissante du secteur et au renouvellement des acteurs historiques de l’audiovisuel. Cette recherche a pour objectifs d’apporter un éclairage sur les perceptions des abonnés vis-à-vis de ces plateformes et de confirmer les valeurs économique (prix), fonctionnelle (performance/qualité), sociale et émotionnelle liées à l’usage d’un tel service. Une étude qualitative exploratoire, prenant la forme d’entretiens semi-directifs, a été conduite en France auprès de 21 individus abonnés à au moins une plateforme de SVOD. Les résultats montrent que les dimensions de la valeur perçue (PERVAL) par Sweeney et Soutar (2001) sont enrichies en leur sein par l’apparition de meso-valeurs et surtout de micro-valeurs que sont le pouvoir, la nostalgie et le réconfort. L’étude montre également que l’engagement (fidélité) des abonnés dépend de la perception de l’offre globale et non de la marque et de sa plateforme. En conséquence, la littérature sur les dimensions de la valeur perçue est enrichie, et les plateformes de SVOD apprennent que le taux de churn pourrait être limité par un approfondissement de la relation client
Contextual cues and stance decision-making in tennis forehand professional tennis players
No full textInternational audienceIn tennis, both open and square stances are used to produce forehands, although few differences have been found between them in terms of biomechanical or ball speed advantages. Hence, it is currently unclear why expert players decide to change their stance during rallies. The objective of this study was to analyze the influence of the context before the stroke on the players’ stance choice. Based on video analysis of men and women professional tennis matches, 2479 stances chosen by twenty players were recorded, considering contextual factors such as “balance of power” and direction of the ball to be played. Results revealed that open stance was used significantly more than square stance in 83.6% of the forehands, with no difference between women and men. These rates varied based on the balance of power, with fewer open stance during favorable situations (65.4%). The direction of the ball played influenced the choice of stance in favorable situations, with fewer open stance being used to play cross court. Taken all together, these results showed an interaction between factors preceding the forehand stroke when adopting a stance in tennis. When players had little time to make a choice, they overwhelmingly used open stances. This choice can be automated, which reduces the attentional load. On the other hand, when they had more time, they varied their type of stance according to the zone being played, with inter-individual differences. The findings could provide valuable insights for coaches to optimize training and improve players’ decision-making efficiency