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Nanostructured W–Cr Janus Heterojunctions Prepared by Glancing Angle Deposition for Gas Sensing
No full textInternational audienceIn this paper, a nanostructured W–Cr Janus thin film was synthesized using the GLancing Angle Deposition cosputtering technique. The film was elaborated using pure W and Cr targets positioned at equal and fixed deposition angles of 80°, resulting in vertically aligned bicomponent nanocolumns. The morphological and crystallographic properties of the W–Cr Janus thin film were studied before and after annealing treatment in air, as high as 500 °C. Investigations revealed that annealing induces the formation of a fully oxidized surface envelope composed of p-type Cr2O3 and n-type WO3, which nonuniformly covers the Janus nanocolumns. The chemical gas sensor based on the annealed W–Cr Janus thin film demonstrated promising sensing performances, achieving detection limits of approximately 37 ± 5, 26 ± 5, and 36 ± 5 ppb for benzene, formaldehyde, and propanol, respectively. Beyond representing a technical advancement in the field of cosputtered thin films, this study underscores the potential of this bicomponent heterojunction structure for the detection of trace-level air pollutants
Solitons stationnaires dans les méta-structures intelligentes : un cadre de conception pour la récupération d’énergie vibratoire basé sur l’Équation de Schrödinger en présence de désordre
No full textSince John Scott Russell’s first observation of solitary waves over 190 years ago, solitons have become an important field of nonlinear physics. Their use in mechanical engineering, however, has only recently gained attention. The main goal of this thesis is to exploit the robustness and stability of standing nonlinear waves, particularly those governed by the Nonlinear Schrödinger Equation (NLSE), to enable energy management and Vibration Energy Harvesting (VEH). The first part of the work establishes a design methodology for perfectly periodic chains of damped oscillators. A three-dimensional stability diagram is derived, and a design algorithm is proposed to control both the oscillation amplitude intensity and the spatial allocation of localized modes according to engineering requirements. To overcome the absence of analytical solutions under external excitation, an artificial intelligence metamodel is developed, providing accurate predictions of damped solitons at a fraction of the computational cost of conventional approaches. The NLSE is then generalized into the Disordered Damped Nonlinear Schrödinger Equation (DDNLSE), capturing realistic structural imperfections. Results show that impurities can nucleate stationary solitons, enlarge stability domains in highly damped regimes, and mitigate chaotic responses, with a hierarchy of parameter uncertainties identified. The second part of the work focuses on multiphysical lattices, where the DDNLSE is reformulated to incorporate piezoelectric coupling. The analysis is conducted in the frequency domain, revealing stability windows near resonance and enabling parameter optimization through heuristic strategies. Finally, the theoretical framework is validated experimentally through a clamped–clamped beam array with magnetic coupling. Measurements confirm the predictive capability of the DDNLSE, showing consistent agreement with the space-frequency energy distribution of the lattice. The experiments demonstrate that disorder can be intentionally exploited to trigger solitons, outperforming individual oscillators in harvested power, operational bandwidth, and robustness. Altogether, this thesis provides the first theoretical and experimental demonstration of soliton-based VEH. Beyond the main application, the proposed soliton-guided framework offers promising perspectives for vibration control, sensing, and the development of multifunctional metastructures resilient to uncertainties, and wave dispersion.Depuis la première observation des ondes solitaires par John Scott Russell il y a plus de 190 ans, les solitons sont devenus un domaine important de la physique non-linéaire. Cependant, leur utilisation en ingénierie mécanique n’a attiré l’attention que récemment. L’objectif principal de cette thèse est d’exploiter la robustesse et la stabilité des ondes non-linéaires stationnaires, en particulier celles régies par l’Équation de Schrödinger non-linéaire (NLSE), afin de permettre la gestion et la récupération d’énergie vibratoire (VEH). La première partie du travail établit une méthodologie de conception pour des chaînes parfaitement périodiques d’oscillateurs amortis. Un diagramme de stabilité tridimensionnel est dérivé et un algorithme de conception est proposé afin de contrôler à la fois l’intensité de l’amplitude d’oscillation et l’allocation spatiale des modes localisés selon les exigences de l’ingénierie. Pour surmonter le problème de l’absence de solutions analytiques sous excitation externe, un métamodèle d’intelligence artificielle est développé, fournissant des prédictions précises des solitons amortis, avec une réduction drastique du coût de calcul par rapport aux méthodes conventionnelles. La NLSE est ensuite généralisée en l’Équation de Schrödinger non-linéaire amortie et désordonnée (DDNLSE), en tenant compte des imperfections structurelles réalistes. Les résultats montrent que les impuretés peuvent nucléer des solitons stationnaires, élargir les domaines de stabilité dans des régimes fortement amortis et atténuer les réponses chaotiques, avec une hiérarchisation des incertitudes des paramètres identifiée. La deuxième partie du travail se concentre sur les réseaux multiphysiques, où la DDNLSE est reformulée pour intégrer le couplage piézoélectrique. L’analyse est menée dans le domaine fréquentiel, révélant des fenêtres de stabilité proches de la résonance et permettant l’optimisation des paramètres par des stratégies heuristiques. Enfin, le cadre théorique est validé expérimentalement à travers un réseau de poutres encastrées–encastrées avec couplage magnétique. Les mesures expérimentales confirment la capacité prédictive de la DDNLSE, montrant une concordance constante avec la distribution spatio-fréquentielle de l’énergie dans le réseau. Les expériences démontrent que le désordre peut être intentionnellement exploité pour déclencher des solitons, surpassant les oscillateurs individuels en termes de puissance récupérée, de bande passante opérationnelle et de robustesse. Dans l’ensemble, cette thèse fournit la première démonstration théorique et expérimentale de VEH basé sur les solitons. Au-delà de l’application principale, le cadre guidé par les solitons proposé offre des perspectives prometteuses pour le contrôle des vibrations, la détection et le développement de méta-structures multifonctionnelles résilientes face aux incertitudes et à la dispersion des ondes
Responsive adaptations to traffic congestion: A matter of habit?
No full textInternational audienceThis chapter combines survey data on drivers' responsive adaptations to congestion with the theoretical framework of the force of driving habit. It proposes to adopt a broader definition of the notion of habit, structured around four points. Firstly, habit differs from simple repetition of a behavior. Secondly, habit is distinguished from reflex. Thirdly, habit is based on incorporated and internalized operational schemas and allows for a liberation of cognitive resources that can be mobilized for other activities in parallel, which may sometimes be much more reflexive. Finally, habit is not limited to gestures but is linked to a set of schemas of action and thought. The chapter seeks to distinguish between drivers with a strong driving habit and those with a weak driving habit. To identify the distribution within this continuum between these two groups, specific methods and tests can be used, notably those from transport psychology
Diet and clinical remission in patients with inflammatory bowel disease: A multicenter cross-sectional study
No full textInternational audienceBackground: Diet and risk of developing inflammatory bowel disease (IBD) has been extensively studied.Aims: To investigate the association between diet and IBD activity.Methods: Consecutive outpatients in 40 French and Belgian centers completed diet and IBD activity questionnaire between April and May 2023 in a cross-sectional study. Associations between diet and clinical remission were adjusted for gender, age, body mass index, education, smoking, and past CD-surgery.Results: Among 2514 patients included, 1715 had Crohn's disease (CD) and 799 had ulcerative colitis (UC). Overall, the mean age was 42.4 years, 52.3 % were women, and 56.4 % were in clinical remission. Among CD patients, clinical remission was associated with a higher intake of fruits (aOR 1.60 [1.20-2.14]) and coffee (aOR 1.57 [1.17-2.11]). Among UC patients, clinical remission was associated with a higher intake of fruits (aOR 1.72 [1.15-2.56]) and salad (aOR 1.73 [1.12-2.66]). A higher adherence to a Mediterranean diet was associated with CD (aOR 1.39 [1.06-1.84]) but not UC remission. A higher adherence to a healthy diet was not associated with either CD nor UC remission.Conclusions: CD remission was associated with higher intakes of fruits, coffee and a Mediterranean diet, while UC remission was associated with higher intakes of fruits and salad. As this was a cross-sectional study, the main limitation was the possibility of reverse causality
L’autre visage du progrès: Regards croisés sur les vulnérabilités liées à la santé
No full textNational audienceSi la médecine sait guérir des maladies autrefois mortelles, elle peut aussi, sans le vouloir, générer chronicité, handicap secondaire ou dépendance. Ces vulnérabilités liées à la santé échappent souvent à une médecine centrée sur l’urgence, la technicité et l’efficacité, au détriment de l’accompagnement des situations qu’elle a contribué à créer.Y répondre suppose d’écouter la personne, de respecter son autonomie, de valoriser ses capacités et d’adapter les organisations à sa réalité. Cela implique une approche interdisciplinaire mobilisant médecine, droit, sciences humaines et sciences dures, afin de saisir l’individu dans toute sa complexité.C’est l’ambition de l’Institut pour la Prévention des Vulnérabilités liées à la Santé (IPVS) et des voix réunies ici : promouvoir un soin global, où prévention et accompagnement sont centraux, tout en interrogeant la responsabilité sociale de la médecine et de la société
La topographie de Sens et de Troyes durant l’Antiquité tardive
No full textInternational audienceArchaeological evidence shows the transformation of Sens/Senones and Troyes/Tricasas during Late Antiquity. The urban area shrank in the second half of the 3rd century AD and both cities had a city wall by the middle of the 4th century AD. The fortifications do not seem to constitute a clear urban limit in the 4th century AD, the distribution of finds suggesting the coexistence of extra muros settlements developing along roads exiting the city wall. Small finds from Sens suggest a strong presence of the militia intra muros, which could explain the presence of extra muros districts in the 4th and early 5th centuries AD.Les données de l’archéologie montrent la transformation de Sens/Senones (Yonne) et de Troyes/Tricasas (Aube) durant l’Antiquité tardive. L’aire urbaine diminue dans la seconde moitié du IIIe s. apr. J.-C. et les deux villes disposent d’une enceinte au milieu du IVe s. au plus tard. Les fortifications ne semblent pas constituer une limite urbaine nette au IVe s. apr. J.-C., car la répartition des découvertes suggère la coexistence de quartiers extra muros se développant le long de rues sortant de l’enceinte. Les découvertes de Sens suggèrent une forte présence de la militia intra muros, ce qui pourrait expliquer la présence de quartiers extra muros au IVe et au début du Ve s. apr. J.-C
Quels sont les freins et les leviers à la prise de responsabilités au sein d'associations ?
No full textInternational audienceCette présentation revient sur un travail de recherche et de formation par la recherche effectué en 2025 par des chercheur.e.s de Laboratoire de Sociologie et d'Anthropologie, et des étudiants de M2 "Politiques publiques" (promotion 2024/2025) de l'Université Marie et Louis Pasteur. Ce travail a été mené en partenariat avec le Mouvement Associatif BFC et visait à mieux comprendre les freins et les leviers à la prise de responsabilités au sein des associations. A partir d'un recueil de données qualitatives (environ 40 entretiens) et quantitatives (107 répondants), nous montrons d'une part, que le manque de temps, d'informations, de reconnaissance et de transparence dans la gouvernance sont les principales dimensions évoqués pour expliquer l'absence de prise de responsabilités ; et d'autre part, que la clarification des rôles et missions disponibles, la valorisation de l'investissement, l'innovation dans la gouvernance et l'anticipation dans la transmission des places sont des leviers qui pourraient permettre d'en partie y remédier
Au royaume de Carnac (Morbihan) au milieu du Ve millénaire : les haches polies en fibrolite ibérique
No full textInternational audienceOn the Morbihan coast, three gigantic mounds each covered a single chamber, made to accommodate a person accompanied by a very rich grave assemblage. This gave rise to the hypothesis that, between 4600 and 4300 BC, the society in the Carnac area was based on a system of religious beliefs that supported an elite dominated by a ‘god-king’.Mané er Hroëck at Locmariaquer is the oldest, and most richly-equipped of these Carnac monuments, containing 12 large polished axeheads and an arm-ring of jade, a long axehead of serpentinite, 49 beads and pendants of variscite and no fewer than 92 polished blades of fibrolite (sillimanitite). Thus we are dealing with an exceptional concentration of extraordinary wealth, with the jades originating in the Alps (Monte Viso, Monte Beigua, Moiry and Gemsstock) and the variscite in Spain (Encinasola). The Morbihan was thus at the heart of a system that drew in precious items from distant sources, 1000 or more kilometres away. We have been able to demonstrate this by comparing the objects of jade and variscite with our raw material reference collections, comprising thousands of samples collected in the Alps and the Iberian peninsula.Pinpointing the sources of axe- and adze-heads of fibrolite is harder. Several more or less significant outcrops are known in Finistère, the Massif central and Spain. However, researchers have only been able to draw conclusions according to the raw material samples at their disposal and the different regional typology of axeheads. Thus, for Alexis Damour in 1865, the fibrolite polished blades from Mané er Hroëck were thought to originate in the Massif central. According to Louis Marsille in 1920, the source was claimed to be the Morbihan coast, where this rock was collected in the form of cobbles. In 1952, Jean Cogné and Pierre-Roland Giot observed that at least four Breton sources could have been exploited, and concluded that this ‘ordinary’ rock would not have had a particular value. In contrast, Charles-Tanguy Le Roux in 1979 underlined the special nature of the ‘Carnac’style’ axe- and adze-heads of fibrolite, which had no convincing match in Brittany.The blades found at Mané er Hroëck (like those from Tumiac at Arzon and Mont Saint-Michel at Carnac) will have been long-distance imports, worthy of inclusion in the grave of a god-king. Since 2000, this hypothesis has been put forward by Serge Cassen, following his comparison of these blades with those from the area around Madrid. Cassen’s suggestion was not, however, followed up by geologists in the interpretation of the results of the mineralogical analyses undertaken since 2009, among which are those for the adzehead found in the chamber of Lannec er Gadouer at Erdeven. Without a raw material reference collection that included specimens from outside Brittany, the identification of potential sources was necessarily biased.In April 2004, we took the next step in fieldwork in order to fill the gap in the raw material reference collection – just as we had done in the case of jades and variscite. Our prospection in the Rincòn basin north of Madrid enabled us to gather nearly 300 samples of fibrolite, then in November, to observe in the Auvergne a further c. 200 axeheads out of fibrolite.As a result it has been possible to open the field of comparison to areas outside of Brittany and seek the closest comparanda for the blades of Mané er Hroëck. A striking resemblance was noted between these axe- and adze-heads in the Morbihan and the samples from Horcajuelo de la Sierra; in contrast, the Massif central can now be ruled out of the list of plausible comparanda. Serge Cassen’s hypothesis has therefore been reactivated – with all the more reason, given his observation that the Spanish and Morbihannais fibrolite axe- and adze-heads share the same ‘archaeological’ characteristics.Thus, the importation of Iberian fibrolite axe- and adze-heads has been confirmed; what remains is to clarify the scale of the phenomenon in France. Currently, nearly 200 polished blades can be shown to have been made of Horcajuelo fibrolite – and, possibly, of fibrolite more broadly from the Guadarrama and North Madrid sierras. Most have come from funerary contexts in the Morbihan. Their cutting edge shows no sign of use; this underlines the status of these adze-heads as being the preserve of a handful of individuals. Spanish fibrolite blades are also found in mounds of more modest proportions in southern Brittany and the Vendée coast. There can be no doubt of the association of these blades with ‘Carnac society’. Outside of the funerary context, Iberian blades are rare. Often they were treated in unusual ways. They have been identified at the foot of an alignment of standing stones, at Groah Denn on the island of Hoëdic. Four miniature axeheads, made by reworking full-sized Carnac blades of fibrolite, have been found at Gavrinis. But a surprise was to demonstrate that at Er Lannic – a so-called workshop for producing blades – numerous fibrolite examples had been imported. Moreover, they had been broken using heavy blows of a stone hammer; it is hard to escape the idea that some kind of sacrifice was going on here, in a religious context underlined by the presence of an extraordinary number of Castellic-style ‘incense burners’.In the Morbihan, the polished blades of Iberian fibrolite must have formed part of the ensemble of long-distance movements, along with items of jades and of variscite. The elite of the Carnac area played a strategic role in the process of attracting and manipulating these objects of wealth. We must, however, try to understand the specific status of the polished blades of fibrolite, as at Mané er Hroëck, where they were grouped separately from the objects of jades and of variscite. One also needs to ask why the axe- and adze-heads of Iberian fibrolite seem not to have featured in the large non-funerary deposits such as that of Bernon at Arzon, which consists entirely of axeheads of Alpine jades.Vers le 46e siècle av. J.-C., le Morbihan a constitué un puissant centre d’attraction d’objets exotiques précieux. Parmi ces signes d’inégalité sociale, les haches en jade alpin et les parures en variscite ibérique illustraient des transferts sur plus de 1 000 km à vol d’oiseau. Dans trois tumulus carnacéens géants, 134 haches polies en fibrolite (sillimanitite) accompagnaient les dotations funéraires consacrées, chaque fois, à un personnage hors du commun.Des sources régionales ont d'abord été supposées. Cependant, dès 2000, considérant à la fois les normes typologiques et les caractères pétrographiques des fibrolites "carnacéennes", Serge Cassen proposait une origine dans la région de Madrid, au centre de l'Espagne. Lorsqu'il a fallu interpréter les résultats des analyses minéralogiques, cette piste n'a pas été suivie ; faute de référentiels en Espagne et dans le Massif central, la question des sources potentielles était donc biaisée.En 2024, les auteurs reprennent la question, avec la même procédure que pour les jades et les variscites. Ainsi, près de 300 échantillons de fibrolite ont été récoltés au nord de Madrid, vers Horcajuelo de la Sierra. Dès lors, la matière première et la typologie des lames polies néolithiques pouvaient être comparées à trois référentiels : Bretagne, Massif central et centre de l’Espagne. Après réexamen des séries néolithiques françaises, un peu plus de 200 exemplaires de haches en fibrolite sont aujourd'hui attribués à cette source située au centre de l'Espagne. Les transferts à longue distance de lames d'origine ibérique sont maintenant pressentis jusqu'en Bretagne. Réalisés au profit d'une élite dominante dans une société théocratique, les lames "carnacéennes" illustrent des manipulations sociales attendues, mais aussi des pratiques rituelles insoupçonnées, comme la destruction des lames polies à Er Lannic
Diamond-saw-diced multi-color ridge Pr,Gd:LiYF 4 waveguide lasers
No full textInternational audienceSingle-crystalline layers of 0.3 at.% Pr, 3.5 at.% Gd:LiYF 4 were grown by liquid phase epitaxy and microstructured using precision diamond-saw dicing, resulting in low-loss (0.16 dB/cm in the red) ridge waveguides with a sub-nm sidewall surface roughness. The continuous-wave red channel waveguide laser generated 504 mW at 639.6 nm with a high slope efficiency of 57.8%, a laser threshold of 34 mW, linearly polarized emission ( σ ), and high beam quality (M 2 = 1.66). Laser operation in the orange and deep-red was obtained. The polarized emission properties of Pr 3+ ions in the epitaxial layers are reported
Vacancy Functionalized MoS<sub>2</sub> Nanolaminated Membranes for Efficient Sieving in Forward Osmosis
No full textInternational audience2D transition‐metal dichalcogenides (TMDs) based nanolaminates are promising candidates for water purification. However, fabricating nanochannels with tunable capillary widths remain a challenge. This study proposed a sulfur vacancy functionalization strategy for fabricating high performance nanolaminate membranes by grafting three kinds of thiol (S‐H) containing molecules (Cysteine, 3‐Mercapto‐1,2‐propanediol, 1‐Propanethiol) on MoS2 nanosheets, in which propanethiol functionalized MoS2 membrane exhibited best salt rejection (99.3%) and water/salt selectivity (800 bar −1 ) in forward osmosis (draw solution: sucrose solution). It is found the capillary width increased from 0.2 Å in pristine MoS 2 to ≈5 Å in propanethiol functionalized MoS2 membranes. Numerical simulations suggest that nanofluidic properties of the functionalized membranes are governed by the fundamental interaction between water and the corresponding S‐H functional group, and the interlayer distance. Importantly, since the S‐H containing molecules can repair MoS2 nanosheets by fitting into the sulfur vacancies, the stability of the membranes is also improved with minimal swelling, which is promising for their practical applications