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Efficient UV Organic Solid‐State Lasers with Ultra‐Short Wavelengths Based on Dispirofluorene‐Indenofluorene Isomers
No full textInternational audienceThe development of efficient UV organic solid‐state lasers (OSLs) remains a significant challenge, yet it is crucial for enabling advanced photonic technologies. This study investigates two dispirofluorene‐indenofluorene regioisomers, (2,1‐a)‐DSF(tBu)4‐IF (DSFIF‐syn) and (1,2‐b)‐DSF(tBu)4‐IF (DSFIF‐anti), to elucidate the impact of subtle structural differences on their solid‐state photophysical and lasing properties. Through a combination of experimental techniques and theoretical approaches, including comprehensive optical characterization and molecular dynamics simulations, it is demonstrated that DSFIF‐syn exhibits significantly reduced intermolecular aggregation compared to DSFIF‐anti, resulting in enhanced optical performance in solid‐state thin films. Remarkably, amplified spontaneous emission (ASE) is achieved at a record‐short wavelength of 365 nm with a low threshold of 4.5 µJ cm−2 (5000 W cm−2) in a PMMA blend film. Moreover, distributed feedback (DFB) laser devices incorporating a blend film of DSFIF‐syn dispersed in polystyrene (PS) enabled lasing at an unprecedentedly short wavelength of 358.5 nm, as well as a low lasing threshold of 0.7 µJ cm−2 (780 W cm−2) at 363.3 nm. These results demonstrate that dispirofluorene‐indenofluorene derivatives are highly promising UV laser dyes, highlighting isomeric control as a valuable molecular design strategy for advancing high‐performance organic lasers
"Le contexte deux fois"
No full textInternational audienceThe aim of this chapter is to review twenty years of research on the relationship between theory and “field” in order to show that ‘context’ can intervene “twice” in research. When seeking to develop an audiovisual pragmatics that takes into account, in its own way, the “field,” this dual approach allows for a better understanding of the respective roles of the observer (the researcher), the viewers (the observed), the corpus involved in the analysis (the films and audiovisual documents), and the “fields” of investigation. Paradoxically, fieldwork teaches us that context is not raw data that semiotization reworks, but rather material that is itself embedded in semiotization.L’objectif de ce chapitre est de revenir sur une vingtaine d’années de recherches traversées par la question des rapports entre théorie et « terrain », afin de montrer que le « contexte » peut intervenir «deux fois » dans la recherche. Lorsqu’on cherche à mettre au point une pragmatique de l’audiovisuel qui tienne compte, à sa manière, du « terrain », cette double entrée permet de mieux comprendre la part respective de l’observateur (le chercheur), des spectateurs (les observés), du corpus mis en jeu par l’analyse (les films et documents audiovisuels) et des « terrains » d’enquête. Paradoxalement, le terrain enseigne que le contexte n’est pas un donné brut que la sémiotisation retravaille mais un matériau lui-même pris dans la sémiotisation
Comparisons of Nutri-Score and NutrInform Battery on consumer preferences, objective understanding, and food choices among Portuguese consumers
No full textInternational audienceFront-of-pack nutrition labels (FoPLs) are a cost-effective measure to inform consumers about the nutritional values of foods and to help them make healthier food choices at the point of purchase. This study compared the preference and performance—objective understanding and food choices—of Portuguese consumers for two FoPLs: Nutri-Score and NutrInform Battery. An experimental study was conducted in 2022 on a representative sample of 1014 Portuguese adults (mean age = 45.1 ± 13.8 years; 49% women). Participants were randomly allocated to either the Nutri-Score or the NutrInform Battery group and asked to complete an online questionnaire testing their objective understanding of the label and the effect on purchase intentions for three food categories as well as perceived helpfulness and perception of the FoPL. In terms of participants' ability to identify the most nutritionally favourable foods, Nutri-Score outperformed NutrInform Battery in all categories, with the highest performance observed for the identification of the three foods of higher nutritional value within the breakfast product category (OR = 27.8 [19.4–39.9], P < .0001). Overall, with Nutri-Score, participants were more likely to intend to purchase more nutritionally favourable products than with NutrInform Battery (OR ranging from 2.01 [1.50–2.68] for breakfast cereals to 14.6 [10.2–20.9] for added fats, P < .0001). In terms of preference, Nutri-Score was more appreciated, and perceived as easier to use, more reliable, and more informative than NutrInform Battery. The Nutri-Score appeared to be a more appreciated and effective tool than NutrInform Battery for helping Portuguese consumers to choose foods with a better nutritional composition
Accompagnement obligatoire pour salarié.e sans emploi.: Une « double subordination » analysée dans une perspective de genre
No full textInternational audienceCet article se propose d’analyser les spécificités de l’accompagnement dans un atelier chantier d’insertion (aci), dispositif d’insertion sociale et professionnelle conventionné par l’État, sous l’angle de la caractéristique statutaire des personnes en parcours qui sont à la fois salariées et demandeuses d’emploi. C’est ce que nous désignons ici en termes de « double subordination » des personnes en parcours vis-à-vis du chantier qui les embauche et de Pôle emploi. Après avoir analysé leur investissement subjectif en tant que salarié/demandeur d’emploi, nous proposerons une lecture genrée du rapport au travail en insertion et de sa répercussion sur l’accompagnement vers l’emploi.Le matériel clinique de cet article est fourni par une enquête réalisée en psychodynamique du travail (Dejours, [1980]2008) auprès des professionnel.le.s permanent.e.s et des personnes en parcours d’insertion qui s’est déroulée entre 2018 et 2020. Cette enquête réalisée par S. Mercier-Millot a constitué la base de son travail de thèse de doctorat en psychologie dirigée par P. Molinier et V. Ganem et soutenue en 2022
Heuristic universality detection over regular expressions specified by systems
No full textInternational audienceIn this article, we provide a computational approach for evaluating the expressivity of systems of equations for generating random regular expressions. More concretely, we obtain bounds on the proportion of universal expressions these systems produce. These bounds rely on the heuristic proposed by Koechlin et al., 2021, extended here to more general systems of several equations, which are harder to analyze. We have developed a tool that enables one to automatically test many of them. We discuss the results obtained for several systems from the literature
Faire de la fiction une expérience sociale : le cas des autrices de fanfictions sur les dispositifs spécialisés en ligne.
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Anthropology of Cities in the Arab Countries
No full textInternational audienceThis article aims to present a synthesis of socio-anthropological studies on cities by Arab academics and to examine their theoretical orientations in different Arab countries. It will highlight the key topics which have been studied in different urban and national contexts and will question the extent to which these studies are linked to the epistemological developments in the field of urban anthropology
The role of social transmission in the use of a new behaviour by killer whales in response to fisheries
No full textInternational audienceHuman exploitation profoundly impacts ecosystems but can also provide novel feeding opportunities to which animals may respond by learning new foraging behaviours. Among these, feeding on fisheries catch or byproduct, a behaviour termed ‘depredation’, has been observed in many large marine predator species globally. However, for social species, how social transmission influences both the acquisition of and the level of engagement in such behaviour by individuals within populations remains poorly understood. In this study, we analysed 18 years (2005–2022) of photo-identification data, with a combination of both social and diffusion models, to assess the role of social transmission in the acquisition of depredation by social units of the killer whale population of the Crozet Islands, as well as the extent to which social units engaged in this behaviour once acquired. We found that an increasing number of social units acquired depredation behaviour over time and that they did so through learning from other units and independent learning. We also demonstrate that during the years following this acquisition, their level of engagement in depredation was influenced by social preferences, with closely associated units showing similar levels of depredation and certain units acting as structural key nodes facilitating the transmission of depredation within the network. However, past the year when the entire population had acquired depredation, we found that factors other than social transmission came into play to explain heterogeneity in depredation levels observed across social units. Together, these findings highlight the role of social dynamics in shaping species' response to human-induced changes in their environment and in leading to intrapopulation behavioural heterogeneity that can have major implications for the long-term conservation of top marine predator populations