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Understanding the interactions of nanoparticles and dissolved organic matter at the molecular level by 1H 2D Multi-Exponential Transverse Relaxation NMR Spectroscopy
No full textInternational audienceThe interaction between humic acid (HA) and engineered nanoparticles (NPs) is critical in environmental sciences, especially for understanding the behavior of NPs in natural waters. This study employs 1H 2D Multi-Exponential Transverse Relaxation (METR) NMR spectroscopy to examine the molecular-level interactions between Pahokee Peat humic acid (HA) and carboxyl-functionalized iron oxide nanoparticles (NPCO). First, 1H 2D METR NMR spectroscopy allowed not only the identification of HA in terms of its chemical composition but also the separation of molecules with the same chemical shift values but different rates of molecular tumbling. Then, using solutions with varying NPCO concentrations (0, 10, 40, and 100 µM), we observed significant changes in the T2 relaxation times of HA components, indicating interactions between HA and NPCO. Analysis showed the biggest effect on two chemical shift regions, corresponding to lipids and carbohydrates, revealing that smaller molecules within these regions exhibit the most significant changes in T2 values upon the addition of NPCO. This suggests that these molecules are the initial sites of interaction, with the entire HA system being affected at higher NPCO concentrations. These findings highlight the utility of METR NMR spectroscopy in studying complex environmental mixtures and provide insights into the behavior of HA and NPs, essential for understanding the fate of NPs in the environment
Du banal à l’extra-ordinaire : les pratiques touristiques vues par les traces numériques
No full textInternational audienceThe search for a tourist experience is characterised by the desire to experience extra-ordinary moments in an environment other than that of ordinary places. Visitor surveys generally focus on these highlights and the ’high points’ of the tourist experience. However, the development of methodologies for collecting digital footprints offers the promise of identifying moments and places considered to be more banal (breaks, detours, transit, etc.). So how can we qualify these places and times of practice using mixed methods that combine the collection of digital traces with more qualitative devices? To answer this question, we draw on two case studies. First, using the case of Biarritz, we analyse the footprints collected on the digital social network Instagram and compare them with field observations. Then, based on the case of La Rochelle, we study GPS data collected using an ad hoc application, then enhanced by a series of interviews with visitors using the map of their digital traces as a means of elicitation. This leads us, in particular, to show the gap between the story and tourism practice.La recherche d’une expérience touristique se distingue par le souhait de vivre des moments extra-ordinaires dans un environnement autre que celui des lieux de l’ordinaire. Les enquêtes menées auprès des visiteurs se font généralement l’écho de ces moments forts et des « hauts lieux » de l’expérience touristique. Or, le développement de méthodologies de recueil de traces numériques offre la promesse d’une identification des moments et des lieux considérés a priori comme plus banals (pauses, détours, transit, etc.). Dès lors, comment qualifier ces lieux et ces temps de la pratique grâce à des méthodes mixtes combinant la collecte de traces numériques avec des dispositifs plus qualitatifs ? Pour répondre à cette question, nous nous appuyons sur deux études de cas. Nous analysons, d’abord, à travers le cas de Biarritz, les traces collectées sur le réseau social numérique Instagram que nous confrontons à des observations de terrain. Puis, à partir du cas de La Rochelle, nous étudions des traces GPS, récoltées grâce à une application ad hoc, puis enrichies par une série d’entretiens auprès des visiteurs utilisant la carte de leurs traces numériques comme support d’élicitation. Cela nous conduit notamment à montrer le décalage entre le récit et la pratique touristique
La justice climatique : un projet de justice sociale ?
No full textInternational audienceLa justice climatique correspond à une attente sociale forte exprimée par la société civile. Elle reflète les attentes légitimes d’États et de populations particulièrement vulnérables aux impacts des changements climatiques. Pour y répondre, les objectifs de lutte contre le cumul des inégalités se déclinent dans les politiques publiques à différentes échelles de territoires et de temps, en visant plus spécifiquement les groupes les plus vulnérables. Sur le plan juridique, la justice climatique repose sur deux piliers : la reconnaissance du droit à un environnement sain, qui impose la protection du système climatique, et la protection de droits sociaux collectifs, en assurant une transition écologique socialement juste. Les leviers et les freins pour réussir une transition écologique socialement juste doivent être clairement identifiés pour opérer des choix dont les coûts ne seront pas plus ou moins directement supportés par les plus démunis
Intra-species differences in impacts of climate change: A case study of the hooded seal (Cystophora cristata)
No full textInternational audienceThe Arctic is warming nearly four times faster than the global average, but the rate of change is not uniform across the region. Wide-ranging Arctic species are exposed to variable environmental conditions across their range, but it remains unclear how different climate change regimes are affecting populations within the same species that have become exposed to different conditions and how each population may respond in the future. In this study, we investigated how environmental changes in the Greenland Sea (GS) have influenced foraging behavior and diet of GS hooded seals (Cystophora cristata) over recent decades, and evaluated how future climate scenarios may affect them. We then compared these findings with recently published results on hooded seals from the Northwest Atlantic (NWA) stock, placing them in the broader context of Arctic ecosystem dynamics. Specifically, we analyzed changes in (1) foraging distribution and habitat use based on a two-decade tracking time series (1992–1993 and 2007–2008) from GS hooded seals and (2) diet, using carbon and nitrogen stable isotopes from blubber samples collected in 2007 and 2022. We also projected future suitable foraging habitats under the SSP5-8.5 climate scenario. Our results show that while GS hooded seals have maintained consistent habitat preferences and diets over the past two decades, their foraging areas have shifted eastward, rather than northward as was seen for the NWA seals—despite northward shifts in their breeding and molting grounds. Suitable foraging habitats of the future are projected to expand and continue shifting eastward. This pattern is unexpected for an ice-associated Arctic species, and contrasts projections for the NWA stock. Although it is uncertain whether hooded seals possess sufficient behavioral or physiological plasticity to cope with future climate-driven changes, our findings underscore the importance of considering population-level behavioral heterogeneity when assessing species-wide responses to environmental change
From Mapping to Shaping the Digital Landscape of Performing Arts: DARIAH-EU Working Group Theatralia
No full textInternational audienceThis article outlines the development of the Working Group Theatralia within DARIAH-EU, focusing on the digital transformation of performing arts practices and research through its two phases of work. First, Theatralia mapped the community's needs and explored existing projects related to the digit(al)ization of theatre operations, digital technologies in performances and digital methodologies for research, as well as archiving. The second phase focused on developing metadata schemas and controlled vocabularies for performing arts archiving, applying the Dublin Core model to ensure interoperability and long-term data preservation. In conclusion, the article highlights Theatralia's continued multifaceted role in fostering interdisciplinary collaboration and advancing digital tools for archiving and analysis in the field of performing arts
The penmen of the Hanse. Functions and agency of the urban secretaries at the Hanse diets (c. 1360–1450)
No full textInternational audienceAccording to the records of the Hanse diets (the recesse) in the 14th and 15th centuries, these meetings were supposed to be opened only to the consuls of the Hanse cities – i.e. to members of the City Council of their home town. The secretaries were explicitly excluded, although they used to be highly engaged in their town’s diplomacy. However, a closer look at the sources reveals that these officers played in fact an important role behind the scenes, and that at certain moments they even had the possibility to plead publicly. This article examines the secretaries’ agency and seeks to show that they could perform multiple and various tasks during the diets: information, message transmission, advice, as well as informal conflict management. Some notaries also played an important role in the drafting and archiving of the recesse. Their agency seems to have depended both on personal qualities and on the involvement of their hometown in the Hanse
Analyse spatiale des vitesses de recul du sommet de falaise : contribution méthodologique par l’utilisation des graphiques à bandes
No full textInternational audienceThe present study proposes a methodology for the visualization of cliff-top retreat velocity, using maps. This method is applied to the cliffs of La Flotte (Ré Island, France). These cliffs are composed of sedimentary rocks, alternating carbonate, bioclastic limestone, and marl. The retreat at the cliff-top, a key indicator of the erosion of these geomorphological objects, is typically measured through time series analysis employing orthophotographs. However, these linear approaches are unable to adequately represent at once the spatial and temporal variability of the phenomenon. To address this issue, we have developed a methodology for generating strip graphs from multiscalar sources, encompassing both annual (UAV orthophotographs, 2021-2024) and decadal (IGN orthophotographs, 1950-2021) data. These strip graphs are derived from statistical results obtained with DSAS software, which compare cliff-top positions at varying dates. These strip graphs are then segmented to identify recurring areas of active erosion, particularly in the central and western parts of the cliffs studied. Uncertainties (georeferencing, digitizing, and resolution) are taken into account to eliminate unreliable values. This process, however, limits the exploitation of the results, as many transects are located within the periodic error margins. To compensate for this limitation, transects are cross-referenced with external indicators (landslides and scree cones inventories) to overcome uncertainty. A comparison of strip graphs and French regulatory mapping methods reveals that the former provides a more precise and localized assessment of erosive dynamics. However, using strip graphs requires additional information (geological, climatic, and marine characteristics) to explain the underlying mechanisms. This could be accomplished in the future. In conclusion, although subject to methodological constraints, strip graphs analysis is a relevant tool for spatializing medium-term cliff-top retreat velocity hazards, for coastal risk management.Cette étude propose une méthode de visualisation du recul du sommet de falaise à partir de graphiques à bandes (strip graphs). La méthode est ensuite appliquée aux falaises de La Flotte (Île de Ré, France). Ces falaises sont composées de roches sédimentaires, avec une alternance entre des marnes et des calcaires. Le recul du sommet de falaise, principal indicateur de l’érosion de ces objets géomorphologiques, est habituellement mesuré par des analyses diachroniques via des orthophotographies. Or, ces approches linéaires peinent à représenter la variabilité spatiale et temporelle du phénomène. Pour y remédier, les auteurs proposent de générer des graphiques à bandes à partir de sources multiscalaires : annuelle (orthophotographies drone, 2021–2024) et décennale (orthophotographies IGN, 1950–2021). Ces graphiques sont élaborés à partir des résultats statistiques produits avec le logiciel DSAS, en comparant la position du sommet de falaise à différentes dates. Ces graphiques à bandes sont ensuite segmentés ce qui permet de relever des zones récurrentes d’érosion active, notamment au centre et à l’ouest du linéaire étudié. L'intégration des incertitudes (géoréférencement, digitalisation, résolution) permet d’écarter les valeurs peu fiables, bien que cela limite fortement les résultats de l’analyse à l’échelle annuelle. Pour pallier cette limite, des indicateurs externes (inventaire de mouvements gravitaires et des cônes d’éboulis) sont utilisés pour s’affranchir de l’incertitude sur certains transects. Comparés aux cartographies réglementaires (PPRN), les graphiques à bandes offrent une lecture plus fine et localisée des dynamiques érosives. Toutefois, cette méthode nécessite un complément d’information (caractéristiques géologiques, climatiques et marines) pour expliquer les processus sous-jacents. Ces limites pourront faire l’objet d’une analyse ultérieure. En conclusion, bien que soumise à des contraintes méthodologiques, l’analyse par graphique à bandes constitue un outil pertinent pour spatialiser les aléas de recul du sommet de falaise à moyen terme, au service de la gestion du risque côtier
Innovative methodological and analytical developments in the study of plant-soil fauna interactions: the contribution of metabolomics
No full textInternational audiencePlant–soil interactions are modified by both biotic and abiotic factors, and understanding these dynamics is essential to predict ecosystem responses to climate change. Root exudates play a central role in rhizosphere dynamics through the release of primary and specialized metabolites, which are involved in defense mechanisms, competition, and symbiosis. However, the influence of soil fauna on root exudation remains poorly understood. To date, studying root exudation in soil matrices has been technically challenging, and the most commonly used systems hydroponic or hybrid fail to reproduce realistic interactions with soil fauna.Presently, we investigate how soil fauna, specifically nematodes, modulate the quantity and composition of root exudates in Linum usitatissimum, and how these interactions are further influenced by increased temperature. Using the innovative ECOROOTS system, root exudates are collected in situ using nitrocellulose traps placed at the root apex, allowing for high-resolution metabolomic profiling via GC-HRMS (1-2). Additionally, molecular networks based on GC-HRMS data have been developed to support metabolite annotation. Preliminary results indicate that the presence of nematodes significantly alters the exudation profile of Linum usitatissimum, an effect that is further amplified under a +4◦C.This methodology will be further integrated with HPLC-HRMS analyses, providing a robust multiblock approach for the investigation of root exudation in other plant species with allelopathic potential or agronomic relevance.(1) V. Bohm et al., mai 2025, doi: 10.1016/j.jcoa.2025.100205(2) A. Levasseur et al., juin 2025, doi: 10.1016/j.soilbio.2025.109771
