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Structure-Guided Automated Reasoning
No full textInternational audienceAlgorithmic meta-theorems state that problems definable in a fixed logic can be solved efficiently on structures with certain properties. An example is Courcelle's Theorem, which states that all problems expressible in monadic second-order logic can be solved efficiently on structures of small treewidth. Such theorems are usually proven by algorithms for the model-checking problem of the logic, which is often complex and rarely leads to highly efficient solutions. Alternatively, we can solve the model-checking problem by grounding the given logic to propositional logic, for which dedicated solvers are available. Such encodings will, however, usually not preserve the input's treewidth. This paper investigates whether all problems definable in monadic second-order logic can efficiently be encoded into \Lang{sat} such that the input's treewidth bounds the treewidth of the resulting formula. We answer this in the affirmative and, hence, provide an alternative proof of Courcelle's Theorem. Our technique can naturally be extended: There are treewidth-aware reductions from the optimization version of Courcelle's Theorem to MaxSAT and from the counting version of the theorem to \#SAT. By using encodings to SAT, we obtain, ignoring polynomial factors, the same running time for the model-checking problem as we would with dedicated algorithms. Another immediate consequence is a treewidth-preserving reduction from the model-checking problem of monadic second-order logic to integer linear programming (ILP). We complement our upper bounds with new lower bounds based on ETH; and we show that the block size of the input's formula and the treewidth of the input's structure are tightly linked
Polynuclear tantalum(v) coordination complexes: from dinuclear {Ta<sub>2</sub>O} to octanuclear {Ta<sub>8</sub>O<sub>12</sub>} oxo species connected through aryl monotopic carboxylate linkers
No full textfffInternational audienceA series of monocarboxylic ligands (benzoic acid, 1-naphtoic acid, 2-naphtoic acid, antracene-9-carboxylic acid and 4′-methylbiphenyl-4-carboxylic acid) has been used to react upon mild heating with the pentavalent ethoxide tantalum(V) precursor Ta(OEt)5 in isopropanol solvent. Five new molecular coordination compounds were isolated from crystallization upon cooling of the reactant's mixtures at room temperature. The different systems crystallized in dimeric {Ta2O} (compound 1 and 2), tetrameric {Ta4O4} (compound 3 and 4) or octameric {Ta8O12} (compound 5) metal-oxo units stabilized by a combination of monocarboxylic ligands and isopropanolate solvent molecules. The five molecular samples were characterized in solid state by single-crystal and powder X-ray diffraction analyses, infrared spectroscopy, scanning electron microscopy (SEM) and thermogravimetric (TG) analysis. The chemical properties of compounds 1 & 5 have been tested for the catalytic conversion of dihydroxyacetone, showing Brønsted acidity
Dry Methane Reforming over Alumina Supported Molybdenum Carbide Catalysts Promoted with Nickel
No full textInternational audienceNickel-promoted molybdenum carbide (Mo2C) catalysts supported on γ-Al2O3 were synthesized via incipient wetness impregnation and evaluated for dry methane reforming (DMR). Comprehensive physicochemical characterizations including XRD, SEM-EDS, H2-TPR, XPS, TPSR, and TG-DSC were conducted to elucidate structure-performance relationships. Non-promoted Mo2C exhibited poor catalytic stability due to oxidation during DMR. The incorporation of nickel significantly enhanced catalytic activity and stability by promoting the in-situ re-carburization of oxidized Mo species and facilitating methane activation. The optimized Ni/Mo molar ratio of 1:1 led to the formation of a stable Ni-Mo synergistic phase, which exhibited superior resistance to sintering and deactivation
François da Rocha Carneiro, Les Bleus et la Coupe : de Kopa à Mbappé
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Isolation and structure elucidation of cell surface polysaccharides from Oenococcus oeni
No full textInternational audienceThe Gram-positive bacterium Oenococcus oeni is a major player in wine malolactic fermentation. In O. oeni, cell wall polysaccharides are considered putative receptors for bacteriophages, virus predators that lead to fermentation failures. In this study, we have developed an efficient stepwise extraction protocol to extract polysaccharides from the cell wall of O. oeni IOEBS277, which were analyzed by methylation, 1D, 2D-NMR spectroscopy, and MALDI-QIT-TOF mass spectrometry. The chemical structures of the two major purified polysaccharides were elucidated. The first one is a heteropolysaccharide with repeating units consisting of a branched hexasaccharide and one glycerol residue, linked by phosphodiester bonds. The second one consists of a →6)-β-Galf-(1→ galactofuranan chain partially substituted on the C-2 hydroxyl with β-Glcp. HR-MAS NMR analysis of intact O. oeni cells indicated that both polysaccharides are exposed to the bacterial surface
Is religiousness a protective resource? A 15-year longitudinal analysis of the link between religious engagement and life-satisfaction across income levels
No full textInternational audienceMany researchers have argued that religiousness serves as a protective resource in the face of adversity. To examine this assumption, we conducted cross-lagged temporal analyses on yearly measured panel responses over a 15-year period and examined the effect of religiousness on life-satisfaction across different income levels. Overall, we found no support for the assumption that religiousness serves as a protective resource. While we did find positive associations between religiousness and life-satisfaction in particular among low-income individuals, we observed these effects only at the between-person level. At the within-person level, temporal effects were small and their directions were not consistent with what would be expected if religion were a protective mechanism that helps coping with adversity. Implications are discussed
Investigating the impact of polyvinyl alcohol on mechanical and thermal properties of expansive soil under freeze–thaw cycles
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Managerial Mood Work: Generating Coordination in Creative, Time‐Pressured Settings
No full textInternational audienceMuch of the literature on coordination engages it as a phenomenon driven by presence of certain facilitating structures, like plans or roles, or arising from members’ past work. In some contexts, however, supplementary mechanisms may be required. We argue that in creative, time‐pressured settings, generating coordination relies on managers’ purposeful emotion‐based manipulation of group moods, which we term managerial mood work . Our argument builds on the observation of stage preparation of Paris fashion shows. We see such shows as particularly valuable empirical exemplars, in that they include time‐pressured technical preparations with both creatively complex and simple outcomes, enabling comparison. This allows us to show how managers purposefully generate coordination in creative, time‐pressured settings via three mechanisms: countering the group mood to trigger coordination, calibrating the group mood to progress coordination forward and settling the group mood to signal temporary resolution to coordination. Our contribution is a conceptualization of managerial mood work as a supporting mechanism for coordination in creative, time‐pressured settings, adding to understanding of the role of emotions and group moods in coordination, and of managers as their facilitators
Leveraging Association Rules for Better Predictions and Better Explanations
No full textWe present a new approach to classification that combines data and knowledge. In this approach, data mining is used to derive association rules (possibly with negations) from data. Those rules are leveraged to increase the predictive performance of tree-based models (decision trees and random forests) used for a classification task. They are also used to improve the corresponding explanation task through the generation of abductive explanations that are more general than those derivable without taking such rules into account. Experiments show that for the two tree-based models under consideration, benefits can be offered by the approach in terms of predictive performance and in terms of explanation sizes
Global and Local Technological Changes with Environmental Factors: Analysis of the Agricultural Sector in the Belt and Road Countries
No full textInternational audienceThe United Nations 2030 Agenda for Sustainable Development necessitates the expansion of green agriculture, which entails the adoption of low-carbon technologies. This study expands the understanding of technological progress by incorporating the consideration of undesirable outputs within the by-production model framework. Convex and nonconvex models are applied to calculate the distance function, from which the Luenberger productivity indicator is obtained and decomposed into economic and environmental efficiencies. Then, this study assesses the contribution of global and local innovation forces to technological progress, taking environmental factors into account. Additionally, it examines the beta-convergence of productivity and identifies some countries as innovators. Analyzing the technological changes in the agricultural sector across 53 Belt and Road nations, the findings indicate advancements in green productivity, efficiency changes, and technological progress, with technological progress in the environmental dimension contributing the most to efficiency improvement. Moreover, 14 out of 53 sample countries experience both global and local technological progress, with global and local innovation forces contributing equally. However, agricultural green development in these countries does not converge. Therefore, the findings of this study suggest that the Belt and Road countries should prioritize environmental technological innovation and agricultural cooperation to foster sustainable development