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Artistes blessés et vétérans de la Grande Guerre. Montrer la guerre / combattre pour la paix
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Intermediation Platforms and Geopolitical Asymmetries, Lessons from a Pandemic
No full textInternational audienceTo a large extent, and particularly before vaccines became available, human societies owed their resilience during the COVID-19 pandemic to non-pharmaceutical interventions, i.e. social distancing combined with more invasive digital systems. In this paper, we consider the digital applications developed during 2020-2021, the two first years of the pandemic. We introduce a typology based on the services offered and the data flows they require, between both public and private actors. A detailed timeline of these developments shows that countries’ strategies have evolved in strong coherence with their overall digital policy. Our study demonstrates that this exogenous crisis has reinforced the critical role of intermediation platforms for maintaining society’s essential functions. Their increased centrality has contributed to intensifying information asymmetries and power imbalances, already at stake before the pandemic, both between platforms and states, as well as between countries, leading to new geopolitical equilibria
Proton beam-induced effects of platinum nanoparticles and their intracellular localization
No full textInternational audienceThis study investigates the effects of platinum nanoparticles (Pt NPs) on breast cancer cell lines (MCF7 and MDA-MB-231) under proton beam irradiation, with a focus on nanoparticle accumulation behavior, cytotoxicity and radiosensitization. Platinum NPs used in this research exhibited a uniform, flower-like morphology with an average size of 26.2 ± 3.9 nm and showed no agglomeration. Cytotoxicity assays revealed that Pt NPs induced time- and concentration-dependent decrease in cell viability, with significant toxic effects observed at concentrations ≥ 0.375 mM. Moreover, holotomographic imaging demonstrated dynamic nanoparticle accumulation in both cell lines, initially localizing at the membrane and progressively internalizing over time. Importantly, no specific accumulation site preference was detected. Quantitative analysis showed that Pt NP uptake by MCF7 cells was approximately twice that of MDA-MB-231 cells, with simulation models aligning closely with experimental data (86 % and 90 % fit, respectively). Proton irradiation studies indicated a marked radiosensitizing effect of Pt NPs, with cell viability reduced by up to 85 % at higher NP concentrations and radiation doses (10 Gy). These findings underscore the potential of flower-like Pt NPs as effective radiosensitizers in proton therapy, owing to their high cellular uptake, surface reactivity and cytotoxicity
Enhancing thermal management of GaN transistors with direct oil jet impingement: Experimental insights for high-power electronics
No full textInternational audienceThis study experimentally investigates the cooling performance of oil jet impingement on high-power GaN transistors, focusing on the effects of nozzle geometry (diameter: 0.5 mm, 1 mm; nozzle-transistor distance: 5 mm, 10 mm) and properties of two fluids (a NewOil-A and Siloil M40). At a flow rate of 80 mL/min, Siloil M40 achieved a heat transfer coefficient of 13 848 W/m2K, reducing junction temperatures to 120 °C under 38 W power dissipation (corresponding to a heat flux density of 135 W/cm2). In contrast, NewOil-A yielded a junction temperature of 90 °C under identical power and heat flux conditions, demonstrating NewOil-A's superior cooling performance. The optimized system enabled a 198 % improvement in power handling compared to uncooled operation. Smaller nozzles (diameter: 0.5 mm) and reduced nozzle-transistor distance (5 mm) enhanced cooling efficiency. Additionally, a novel correlation linking Nusselt, Reynolds, and Prandtl numbers is proposed, offering practical design guidelines for GaN-based power electronics in applications like electric vehicles
Addition of bismuth stimulates photocatalysis by UiO-66/TiO2: synergistic effect between Bi3+ and metallic Bi0
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Not on my plate! Challenges to promote meat substitutes
No full textInternational audienceWe implement an online survey on a sample of 1,088 French respondents to assess their willingness-to-pay (WTP) for meat substitutes and to test the effectiveness of informational treatments aimed at encouraging a switch to these substitutes. Using insights from the mental accounting theory, our treatments inform respondents about the carbon content of the different alternatives. We show that there is no significant difference in the WTP between the veggie and meat-like alternatives, both exceeding the WTP for cultured meat. Second, we detect weak and heterogeneous effects of our informational treatments. Third, our study emphasizes the need for careful consideration in study design, as certain results suggest that respondents’ choices may not exhibit behavioral consistency with the independence of irrelevant alternatives principle
Farming practices induce contrasted effects on parasitic infections in passerine birds in agricultural landscapes
No full textInternational audienceAgricultural intensification has led to landscape changes and the extensive use of synthetic pesticides. Concurrently, a significant decline in biodiversity has been observed, especially for birds that frequent farmlands, which may ultimately affect community structures by altering interspecific relationships. While the contribution of pesticides to bird declines is now widely recognised, their impacts on host-parasite interactions remain largely unexplored. Pesticides may influence the presence and abundance of parasites and/or alter the host's immune system, affecting control over pathogenic infections. We investigated, for the first time to our knowledge, the differences in wild passerines' parasite burden, caught within 10 sites mainly surrounded by conventional farming (CF) and 10 sites mainly surrounded by organic farming (OF), as these landscapes differ in pesticide use. We estimated the number of two ectoparasites (ticks, chewing lice) and two endoparasites (blood parasites Plasmodium, coccidia) in 10 bird species. Our results highlighted a strong effect of the year and bird species on parasitic infections. Nevertheless, farming practices induced contrasted effects on parasitic burdens in birds: ectoparasite burdens were lower in CF, while blood parasite burdens were higher in this environment. This suggests that both farming practices can have a positive or negative effect on avian parasitic infections, and on bird health more generally
