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Parures amérindiennes en pierre en Martinique et dans les Antilles : du cas particulier de Vivé à l'analyse archipélique
No full textInternational audienceLes productions de parures lapidaires très diverses, tant par le style que par les matières premières, constituent l'une des spécialités reconnues de l'artisanat amérindien pour la période céramique ancienne dans la zone des Antilles et sont réputées moins nombreuses et diversifiées aux périodes suivantes. En Martinique en particulier, le site exceptionnel de Vivé (Le Lorrain) a fourni la collection la plus documentée et diversifiée avec 37 objets. Ils sont réalisés en diverses roches et minéraux, dont une bonne part est souvent reconnue exogène, issue d’échanges ou attestant des déplacements des populations. Nous proposons ici une vision exhaustive de ces objets, avec une identification complète des matériaux par des analyses spectroscopiques permettant de s’affranchir d’une partie des anciennes déterminations minéralogiques parfois hasardeuses, en particulier pour les « roches vertes ». L’étude technologique de ces objets apporte des informations sur l’investissement apporté à ces réalisations à forte valeur culturelle et permet de replacer Vivé dans les schémas d’acquisition de ces parures à l’échelle de la Caraïbe
Topiques de la découverte et figures de l’émerveillement : les lieux communs de la fulgurance savante à l’épreuve de l’histoire des sciences
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Numerical investigation of the effect of defect population on the fatigue strength anisotropy of alloys fabricated by L-PBF
No full textInternational audienceThis study investigates the impact of defects on the fatigue strength anisotropy of Ti-6Al-4V alloy fabricated by Laser Powder Bed Fusion (L-PBF). Finite element simulations are performed to analyze two defect populations, lack of fusion (LoF) defects and gas pores, under multiaxial proportional loading conditions. Results demonstrate that fatigue strength is highly sensitive to the polar angle representing the defect orientation with respect to the mechanical loading and is primarily influenced by defect morphology, transitioning from low sphericity (LoF defects) to high sphericity (gas pores). The anisotropic behavior is particularly pronounced under tensile loading, where the morphology of LoF defects and loading directions exhibit a notable influence. Shear loading exhibits reduced sensitivity to these factors. The proposed statistical methodology allow to determine the fatigue strength anisotropy for any multiaxial loading configuration and defect population. The numerically obtained fatigue strength anisotropy matches the one obtained experimentally in the literature and non-local analysis smoothens the fatigue strength surface response, leading to a reduction in the anisotropic factor ()
Data Complexity of Querying Description Logic Knowledge Bases under Cost-Based Semantics
No full textInternational audienceIn this paper, we study the data complexity of querying inconsistent weighted description logic (DL) knowledge bases under recently-introduced cost-based semantics. In a nutshell, the idea is to assign each interpretation a cost based upon the weights of the violated axioms and assertions, and certain and possible query answers are determined by considering all (resp.\ some) interpretations having optimal or bounded cost. Whereas the initial study of cost-based semantics focused on DLs between and , we consider DLs that may contain inverse roles and role inclusions, thus covering prominent DL-Lite dialects. Our data complexity analysis goes significantly beyond existing results by sharpening several lower bounds and pinpointing the precise complexity of optimal-cost certain answer semantics (no non-trivial upper bound was known). Moreover, while all existing results show the intractability of cost-based semantics, our most challenging and surprising result establishes that if we consider ontologies and a fixed cost bound, certain answers for instance queries and possible answers for conjunctive queries can be computed using first-order rewriting and thus enjoy the lowest possible data complexity (). </div
Aluminum incorporation lowers the intrinsic mechanical properties of single-chain calcium silicate hydrate
No full textInternational audienceIn blended cement systems, the principal hydration product is calcium (alumino) silicate hydrate (C-(A-)S-H). The investigation into how aluminum incorporation affects its mechanical properties is essential for optimizing the formulation and properties of cementitious materials. This study employs high-pressure X-ray diffraction to explore the intrinsic mechanical properties of nanocrystalline single-chain C-A-S-H (Ca-to-Si ratio 1.6), resembling chemical compositions of C-A-S-H in blended cement systems. Increasing aluminum incorporation softens all unit cell axes, with basal planar incompressibility governed by the aluminum coordination number, showing an increasing order of Al(IV) < Al(VI) < Al(V). The softening of the basal plane arises from the longer Alsingle bondO bond length relative to Sisingle bondO bond, and the different distortion indexes in AlOx polyhedra. The hydrogen bond numbers and angles relative to the basal plane within per unit cell influence the basal planar incompressibility of single-chain C-A-S-H. Aluminum-uptake-induced expansion in basal space contributes to a softened c-axis
L'idée de « Sciences « humaines. » »
No full textInternational audienceSi les sciences humaines posent un certain nombre de problèmes conceptuels, épistémologiques, institutionnels, méthodologiques, normatifs, typologiques, sémantiques, elles posent également de fortes interrogations scientifiques quant à leurs présupposés, leurs histoires, leurs fonctions et la nature des connaissances et des savoirs disciplinaires et interdisciplinaires qu'elles peuvent recouvrir. A leur décharge, les sciences dites « humaines » et les discours scientifiques comme théories et pratiques intellectuelles posent également une multiplicité d’interrogations fondamentales parmi les suivantes : qu’est-ce qui caractérise foncièrement le concept de « pensées scientifiques » ? A quels degrés de certitude, la connaissance, les savoirs et les champs disciplinaires peuvent-ils accéder étant donné les moyens dont nous disposons ? Quelle(s) sorte(s) de vérité(s) proposent-ils ? A partir de quelles caractéristiques et selon quels critères conférons-nous le qualificatif de « science(s) » et d’épithète « humaines » à un genre de la connaissance prétendument relatif à la sphère et aux dimension humaines ? C’est pourquoi, par-delà nos conceptions peu ou prou univoque ou plurivoque de l’idée de science(s) humaine(s), en définitive, le propos de notre communication cherchera fondamentalement à répondre aux questions suivantes : qu'est-ce qu’une « Science(s) dite « humaine(s) » prétend faire en termes de connaissances et quels types de savoirs produit-elle ? Quels sont les modes possibles d’être des choses et des affaires humaines en termes disciplinaires et scientifiques? Dans quelle mesure une science humaine peut-elle ou non enrichir l’ontologie des sciences dites « non ou autre(s) qu’humaine(s) », à l’aune des théories, pratiques, discours et récits expérientiels dont témoigne irréfragablement le caractère humain de toute activité scientifique ? Autrement dit, en quels sens l’idée de « science(s) humaine(s) » peut-elle être conceptualisée, définit et comprise dans ses dimensions de convergence, de divergence et de complémentarité avec ce qui, supposément, ne se définirait pas en termes de discipline comme une « science « humaine » »
Comparative studies of invasive Elodea canadensis Michx. in two climatically different regions
No full textInternational audienceElodea canadensis is a widespread invasive alien aquatic species in Europe. However, there is growing evidence that increasing anthropogenic eutrophication and other factors are leading to a decline in the populations of this species. We compared the structure of plant communities and the phenotypic plasticity of E. canadensis individuals across communities in Ukraine and Portugal to assess whether the species responds similarly to environmental variation, and to identify differences in its distribution, community role, and the environmental factors influencing the formation of morphological traits of the species and biomass. In both countries, E. canadensis preferentially occurs in oligo-mesotrophic and meso-eutrophic waters, forming similar communities, but in Ukraine the communities in lentic water bodies were floristically more diverse. Populations with high biomass of E. canadensis in Ukraine were formed in lentic water bodies with good water exchange, as well as in lotic ecosystems of both Ukraine and Portugal. Environmental clustering revealed a distinct ecological separation among water bodies, with the strongest contrast observed between lower-nutrient, higher-elevation Ukrainian lakes and nutrient-rich, lowland mixed lotic systems in both countries. The morphological traits of E. canadensis differed significantly between these clusters, particularly shoot length and leaf width, highlighting phenotypic responses to environmental gradients. We assume that anthropogenic eutrophication affects E. & scy;anadensis communities, and may lead to their decline or disappearance as trophic levels rise in both countries. Understanding these patterns is important for forecasting invasion dynamics under eutrophication and climate change, and for refining management strategies in freshwater ecosystems
Differences in mean daily intake of macronutrients, caffeine and water by level of mental morbidity
No full textInternational audienceWe investigated macronutrient, caffeine and water intake by mental morbidity level, focusing on pure and comorbid anxiety, insomnia, and eating disorders (ED). This descriptive, cross-sectional study used 2013-2017 data from the NutriNet-Sant & eacute; cohort. Diet was assessed with >= 3 24-hour records; mean daily intake of total energy and % contribution of carbohydrates, proteins, and lipids to total energy; total, simple, complex carbohydrates; total, animal, vegetable protein; total lipids, SFA, MUFA, PUFA; cholesterol; caffeine and water was analyzed. Data were weighted using the 2016 French Census, and ANOVA was performed (N = 23,965). Overall, men presenting all 3 mental disorders had the highest % carbohydrates and the lowest % proteins and lipids. The multimorbidity group had the highest obesity rates and caffeine intake across sex; water intake had no dose-response association with mental morbidity. The findings could help generate hypotheses regarding dietary exposures that might play a role in mental multimorbidity risk
The Strong (2,2)-Conjecture for more classes of graphs
No full textInternational audienceThe Strong -Conjecture asks whether, for all connected graphs different from and , we can assign to edges red and blue labels with value or so that no two adjacent vertices have the same sum of incident red labels or the same sum of incident blue labels. This conjecture, which can be perceived as a generalisation of the so-called 1-2-3 Conjecture, as, thus far, been proved only for a handful number of graph classes. In this work, we prove the Strong -Conjecture holds for more classes of graphs. In particular, we prove the conjecture for cacti, subcubic outerplanar graphs, graphs with maximum average degree less than , and some Halin graphs, among others
Qu’est-ce qui remplit les salles de concerts ? La nostalgie, pardi !
No full texthttps://theconversation.com/quest-ce-qui-remplit-les-salles-de-concerts-la-nostalgie-pardi-272744Sur les scènes françaises, les tournées « best of » ou les « tribute bands » occupent le terrain, remplissent les salles et structurent un véritable marché de la « nostalgie live ». Portés par une demande de réconfort émotionnel et de communion mémorielle, ces spectacles du passé remixés au présent interrogent. Comment comprendre un tel engouement pour ces pastiches et jusqu’où cette économie de la copie peut-elle prospérer sans trop étouffer la création