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Les sols en partage (Discours de soutenance de thèse de doctorat)
No full textDiscours de soutenance de la thèse de doctorat de Charles Claron. Prononcé au CIRED le 8 décembre 2025.International audienceDiscours (et support de présentation) de la soutenance de thèse de Charles Claron intitulée « L’intégration des valeurs des sols dans la gouvernance foncière en France », soutenue le 8 décembre 2025, au Centre international de recherche sur l'environnement et le développement (CIRED) en présence de : Franck-Dominique Vivien, Professeur à l’Université de Reims (REGARDS) | Président ; Hélène Rey Valette, Maîtresse de conférences à l’Université de Montpellier (CEE-M) | Rapporteure ; Jean-David Gerber, Professeur à l’Université de Berne (Institut de géographie) | Rapporteur ; Nathalie Blanc, Directrice de recherche au CNRS (LADYSS) | Examinatrice ; Maylis Desrousseaux, Maîtresse de conférences à l’École d’urbanisme de Paris (Lab’urba) | Examinatrice ; Olivier Coutard, Directeur de recherche au CNRS (LATTS) | Co-Directeur ; Harold Levrel, Professeur au MNHN (CESCO) | Co-Directeur ; Philippe Billet, Professeur à l’Université Lyon 3 (Institut de droit de l’environnement) | Co-Encadran
The influence of grain crushing and pore collapse on the formation of faults
No full textDuring an earthquake, slip occurs in a localised shear zone that features a heavily granulated fault core that can be characterised as a shear band. We study the formation of this fault core in a granular rock such as sandstone by developing a model of crushable granular media within the framework of Breakage Mechanics. This model accounts for the evolution of the grain size distribution, while also accounting for the co-evolution of the solid fraction. An enrichment with the Cosserat continuum allows for the model to predict finite-width shear bands. The model is then calibrated against experimental data taken from tests on Bentheim sandstone, and a parametric study of the mechanical parameters is conducted using linear stability analysis. We find that for deeply-buried rocks the shear bands have a compactive component, and the initial value of the solid fraction does not play a strong role in the initial band thickness, but can influence the rate of delocalisation of the band. Post-localisation behaviour is studied with the finite element method, which shows the formation of zones of dilation outside the band in addition to the compaction within the band. Using a modified Kozeny--Carman permeability law, it is shown that within the band the permeability reduces by several orders of magnitude, but can increase outside the band. Our results highlight the importance of modelling grain size and solid fraction evolution as they exert a controlling influence on hydromechanical properties that play an important role in fault formation and seismic slip.Document submitted to Journal of Geophysical Research: Solid Eart
Olympic and Paralympic Games (OPG) : which issues for tourism stakeholders and how promoting local tourism in Paris and Seine-Saint-Denis ?”
No full textInternational audienceChappelet (1996) discusses the Gigantism of the Games, each new edition increase the number of sports disciplines, participants, venues, and costs. In addition, the mega-events involve major expenditure on hosting and bidding (Hall, 1989) and are part of regional planning.How can the Olympic and Paralympic Games (OPG), a global event, help to develop local tourism and how can this new image diffused by the event have a positive effect on the destination?We're wondering about the actions taken by the City of Paris and the collaboration with Seine-Saint-Denis to meet the current tourism challenges (sustainable and resilient tourism) in the run-up to the Games. We will analyse the public policies accelerated by the OPG and the relationships between stakeholders.This research is in line with current research on mega-events by examining the organisational legacy of the OPG for local stakeholders from a tourism and heritage point of view.The Games are an opportunity to transmit to the whole world the image that local actors want to give their city (Thanh et al., 2014, Pappas, 2004). However, image effects are possible but not systematic (Muller, 2014). As Houiller-Guibert (2022) points out, events make it possible to make places attractive while using the image of the territories, while partially modifying it. Questionnaire surveys show that 42% of respondents believe that the Seine-Saint-Denis neighbourhoods hosting the events will be enhanced with the Games (Gignon and Delaplace, 2021).Also, OPG are associated with the eviction of tourists: the scale of the event and the anticipated congestion can discourage leisure visitors and professionals from coming to the host city during this period (Matheson, 2006, Preuss, 2011). As part of this mega-event, the tourism stakeholders in these host cities are seeking to respond to local issues. The Office de Tourisme et des Congrès de Paris (OTCP) estimates that 43% of visitors will be from the Paris region.This intervention is based on a thesis that uses a qualitative methodology with semi-directive interviews. We are relying on an immersion in a department of the City of Paris between January 2020 and April 2023, which was carried out as part of a CIFRE thesis. Once we had completed our interviews, we transcribed them and then analysed them using MaxQDA software, which enables us to identify elements by assigning them a code by theme. Thematic analysis followed Braun and Clarke’s (2006) six phases: transcription, data familiarisation, initial coding, theme identification and revision, detailed analysis, and selection of illustrative examples linked to the research question. The ex-ante observations (direct and participant) took place at meetings and through informal interactions, the findings being recorded in field notebooks.A typology of stakeholders has been developed to identify those who should be surveyed. It comprises three main groups. Firstly, tourism stakeholders, divided into: institutional tourism development stakeholders, hospitality stakeholders and other tourism developers. Secondly, the stakeholders of the OPG, divided into those preparing the event and direct participants. Thirdly, the indirect Olympic stakeholders involved in the preparation of the event, including those hosting the Games and non-tourism stakeholders indirectly involved in the organisation.Our analysis highlights the involvement of local stakeholders and their active role. We examine both the similarities and the specificities of each. Paris' objective is not to increase the number of tourists, but to improve the quality of the visitor experience. Excursionists and local visitors have been put at the centre of attention, and efforts have been made to attract them. Stakeholders are seeking to promote a positive image of the region. One of Paris' main objectives is to use the Games to promote more sustainable tourism, as highlighted by Visitors Bureau.The analysis we have carried out shows how an event can accelerate local public tourism policies. In the case of the 2024 Games, the attractiveness of Greater Paris through the hosting of the Olympic Games will require the acceleration of public policies, as part of an overall approach to increasing "the attractiveness of metropolises [...] by improving their accessibility and diversifying their urban offer" (Houllier-Guibert, 2021).Seine-Saint-Denis is a key contributor to the event, with built, temporary and existing venues.Tourism stakeholders have taken advantage of this opportunity to develop their ambitions, and visits to construction sites in the run-up to the Games have enabled local residents to discover an area that is undergoing transformation and is culturally diversified.Seine-Saint-Denis aim is to use Games to showcase the region and improve local tourism. A local stakeholder explained that the challenge is to raise awareness of the quality of the local tourism offering. There is a major image issue because of the department's poor image in the collective imaginationWe can see the importance of stakeholder involvement in the development of the territory and how the event helps to accelerate public policies in support of sustainable and resilient tourism
Creep monitoring of adhesively bonded joints using acoustic emission
No full textInternational audienceAs an alternative to invasive methods such as welding and riveting, adhesive bonding offers advantages, particularly adapted for the connexion of composite materials. However, its long-term effectiveness in terms of creep behaviour and mechanical resistance remains poorly studied. The work carried out in this study aims at assessing the potential of acoustic emission for creep damage monitoring of an adhesive joint. In order to study more specifically the behaviour of the adhesive joint, investigations were carried out on steel-to-steel adhesively bonded assemblies. The Arcan geometry was used under quasi-static and creep conditions allowing studying three loading modes: tensile, shear, and tensile-shear combinations. Creep investigations were carrued out up to failure and monitored using local displacement sensors and acoustic emission sensors. In this study, only a single adhesive was used, i.e. a methacrylate adhesive used in offshore applications. First, the experimental test setting will be more precisely described. Then, the obtained results will be presented and analyzed using acoustic emission methodology (observing failure modes, comparing displacement measurements with acoustic emission results, studying different acoustic parameters). Finally, a discussion will be raised regarding the ability of acoustic emission to monitor creep of adhesively bonded joints, the influence of the loading mode on the obtained results, and the needed additional developments
Designing safer climbing pads: The role of foam, covers, and trapped air in pad performance
No full textInternational audienceBouldering is a climbing discipline in which falls are cushioned by pads composed of foam encased in a PVC fabric shell, reducing injury risk. While foam behavior is well-documented, the combined effect of the foam, PVC cover, and trapped air in the pad remains poorly understood. To design safer bouldering pads, this study aims to investigate the distinct roles of the foam, the cover, and the trapped air in pad behavior.Compression tests, including quasistatic and drop tests, were performed on two types of square samples: uncovered foam blocks (either open-cell or closed-cell) and foam blocks covered with a PVC shell. Force, displacement, and internal pressure (within the cover) were measured. The effects of foam type, PVC cover, and trapped air were assessed on stress, strain, strain rate, and absorbed energy.During quasistatic compression, both covered and uncovered samples exhibited similar behavior with low, stable internal pressure; the addition of the PVC cover resulted in only a modest increase in stress (1.25 times higher) due to its stiffness. This emphasizes the foam's dominant mechanical contribution under quasistatic conditions. In drop tests, the behavior of covered samples changed considerably compared to uncovered ones: at 40% strain, the stress in closed-cell covered sample was approximately nine times higher, and the energy absorption per cubic meter was five times greater (14 kJ/m³ vs. 2.7 kJ/m³). Concurrently, a substantial rise in internal pressure was observed throughout the compression process, suggesting that trapped air plays a critical role in the pad's response under high-speed loading.</div
Hydrogen Sulfide Induced Biodeterioration of Mortars and Cement Paste: A Multi-Scale Investigation using laboratory accelerated test
No full textInternational audienceCementitious materials in sewer environments are exposed to highly aggressive biogenic sulfuric acid, yet their long-term resistance remains difficult to evaluate without extended field trials. This study validates an accelerated test protocol that reproduces up to 49 months of in situ degradation in only 190 days under controlled microbial and H2S exposure. Three binders (CEM I, CEM V/A, and CAC) were tested in both mortar and cement paste forms. Despite higher total porosity, cement paste consistently outperformed mortar in durability due to its denser pore network and greater buffering capacity, highlighting the key role of microstructural organization. Degradation was monitored using multi-scale analytical techniques, including macroscopic indicators (pH, mass, dimensional change), SEM-EDS, and μ-Raman mapping combined with PCA and MCR-ALS, revealing clear zonation patterns and sulfate-rich biodeterioration fronts. Using different specimen dimensions (2x2x2 cm3 and 4x4x4 cm3), the test demonstrated consistent degradation profiles, confirming its scalability and robustness. Results showed rapid degradation in CEM I, moderate deterioration in CEM V, and exceptional stability in CAC. Across all binders, altered zone thicknesses obtained during these accelerated tests closely matched those observed after 49-month field exposures in real sewer conditions, yielding acceleration factors ranging from 5 to 10, depending on binder type and H2S concentration. This study confirms the predictive ability of the proposed protocol and emphasizes the combined influence of binder composition and microstructural form (mortar vs. paste) on biogenic sulfuric acid resistance. It provides a reliable and time-efficient tool for material selection and durability assessment in wastewater infrastructure design
From Suffering to Growth: A Conceptual Review of Workplace Bullying Through a Logotherapeutic Lens with Organizational Implications
No full textInternational audienceThis paper presents a conceptual review of workplace bullying as a trauma, integrating psychological and existential perspectives on post-traumatic growth. The study offers a conceptual framework for comprehending existential trauma, meaning-making, and healing in the context of workplace bullying by referencing Janoff-Bulman’s shattered assumptions theory and then Calhoun and Tedeschi’s post-traumatic growth model. This theoretical foundation is further expanded through Viktor Frankl’s logotherapy, which emphasizes the value of meaning in the process of transforming suffering. An illustrative case exemplifies the existential dimensions of workplace bullying, including the disruption and reconstruction of meaning, while highlighting how logotherapeutic concepts can facilitate post-traumatic growth. This paper also offers a conceptual framework with organizational implications for future studies
Le lobbying en mutation : lobbying responsable, zones grises et usages des IA génératives
No full textInternational audienceAprès une introduction par Lila Schneider-Beuchat, Responsable de Nexus salle d’innovation pédagogique nouvellement inaugurée de l’HEG, Stéphanie Haesen, présidente de Swissintell, chargée de cours et co-responsable du CAS en Competitive Intelligence à la HEG-Genève et Hélène Madinier, vice présidente de Swissintell ont fait un point sur l'actualité de l’association.Lisa Ferreira Gaspar a ensuite présenté les résultats issus de son travail d'équivalent Licence 3 sur « La veille dans les organisations de Suisse romande : l’état des lieux des pratiques et de modes d’adoption de démarches de veille en 2025 ». Stéphanie Haesen a introduit les intervenantes de la table ronde : Sacra Tomisawa, Consultante en affaires publiques et organisation chez ellips public affairs & consulting, Valérie Bourdin, Déléguée aux affaires fédérales et régionales à la Fédération des Entreprises Romandes (FER) et Lucile Desmoulins, Maîtresse de conférences en Sciences de l’information et communication à l’Université Gustave Eiffel (laboratoire DICEN). Elles ont abordé de manière comparative leur vision de l’évolution des métiers du lobbying, les liens en France et en Suisse entre l’IE et le lobbying et l’écart entre les perceptions des pratiques du lobbying et leur réalité. Les échanges se sont focalisées sur l’évolution des méthodes et des pratiques à l’ère numérique et des IAG, par exemple pour identifier des dynamiques d’influence et y répondre. À partir de leurs connaissances théoriques et pratiques de la réalité des métiers du lobbying, elles ont analysé les initiatives existantes en matière de régulation et de transparence et comment chaque professionnel respecte (ou non) un cadre légal, des principes déontologiques et comment elles choisissent leur manière singulière de faire leur métier ou de former aux métiers de l’influence de manière éthique. Elles ont proposé des exemples sur les questions des libéralités, des incompatibilités dans le choix des clients, et d’usages bien installés ou émergents des IAG
Correction: Opportunistic CT-based osteoporosis screening of the hip: a systematic review of diagnostic accuracy
No full textInternational audienc
Vers un Maps 2.0 - Construire une carte pan-scalaire plus progressive
No full textNational audienceGoogle Maps has established itself as the world's leading navigation tool, but its design is not without flaws. Complex data, in particular, are often either insufficiently, poorly, or not at all generalized across different scales, leading to inconsistencies that can leave users disoriented during navigation. This article proposes a methodology for designing a more progressive pan-scalar map, inspired by the visual style of Google Maps. The goal is to recreate a multi-scale map with particular attention to the progressiveness of the various levels of generalization for each dataset. Recently conceptualized in scientific literature, progressivity in multi-scale cartography had not yet been applied on the scale of an entire map. Progressively generalizing a single dataset vastly differs from generalizing multiple datasets, which interact with one another and evolve at sometimes different rhythms. This article seeks to apply the previously theorized concepts in practice, testing their adaptability through a real example of a multi-scale map