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Synthesis of Si@Au core-shell particles for directional light scattering
No full textInternational audienc
Integration of bright color centers into arrays of silicon carbide nanopillars
No full textInternational audienceSilicon carbide (SiC) is a wide-bandgap semiconductor combining mature fabrication processes with the ability to host optically active point defects, called color centers, making it ideal for quantum technologies. This study focuses on silicon vacancy defects in 4H-SiC, integrated into nanopillar arrays fabricated via ion implantation, e-beam lithography, and reactive ion etching. SiC nanopillars with a height of 1.4 μm are formed and arrays with varying pillar diameters and spacings are obtained. Cathodoluminescence measurements at 80 K reveal a two to four times improvement in light collection efficiency from the defects compared to unstructured SiC. The cathodoluminescence intensity increases with a smaller pillar spacing and a larger diameter. These findings demonstrate the potential of SiC nanopillar arrays as scalable platforms for enhancing quantum photonic device performance
Silica’s role in creating vivid structural color
No full textInternational audienceNanostructured surfaces and repeating layers of two or more materials (Bragg stacks, Figure 1) can be used to generate color via the dimensions and organization of their structure. These colors span the whole visible spectrum and are always iridescent, as the length of the light’s pathway through the material is dependent on the angle of incidence and the position of the observer, and thus changes the way interference attenuates some frequencies. The hue and saturation of the color depends to some degree on the properties of the Bragg stacks: the refractive index of each individual layer, its thickness and how many times the stack is repeated. Silica has a refractive index (n) across the visible of ~1.4. In order to generate structural color, it must be coupled with materials with a significantly different refractive index, such as silicon (n ~4.0) and titania (n ~2.2).Not only can colors be generated with structure, but other aspects of appearance can also be created or modified, such as haze, polish, clarity, gloss, radiosity, whiteness, opacity, and texture. Moreover, the iridescent color transitions depend on both the materials selected and their structure, both in terms of the number of colors observed between a set range of observation angles and which colors are detected. We have studied ways of controlling these multiple aspects of appearance, both in Bragg stacks and by adding structured silica or particles to the material surface. Silica structures have been applied in two ways: through a phase separation technique leading to a disordered or partially disordered perforated surface; and through nanoimprint lithography, which generates highly regular perforations in the silica layer. We have studied the impact of organized versus disorganized silica structures on color stability. Finally, we have shown that the density of particles on a silica layer can change the haze and gloss of the surface without impacting the color. Silica is a useful material in tuning appearance thanks to its refractive index, stability and easy processability
Strategic Investment for Healthcare System Resilience: A Scenario-Based Optimization Approach
No full textInternational audienceHealthcare systems are essential to society but face numerous challenges in maintaining their resilience and long-term viability. Disruptions, much like those experienced in supply chains—can significantly hinder operational continuity. To mitigate such risks, strategic investments can be made to reduce the likelihood of service interruptions. However, given the constraints of a limited protection budget, it is crucial to allocate resources efficiently to enhance the resilience of selected critical facilities. The objective of this research is to develop an optimal protection strategy that minimizes both patient travel distances for accessing care and the number of patients left without timely treatment due to disruptions. Since accurately predicting facility failures remains difficult, robust optimization provides a valuable framework. In particular, a scenario-based robust decision-making approach allows for the evaluation of multiple plausible disruption scenarios, ensuring that the selected strategy performs well under various conditions. Our methodology leverages scenario analysis to identify the most effective investment strategy for sustaining healthcare system performance over time. Each scenario corresponds to a different allocation of protective investments, and we assess their respective impacts on system resilience. By analyzing the relationship between the fortification of specific facilities and overall system performance, we generate insights to inform budget allocation decisions aimed at maximizing resilience. This process helps quantify the relative importance of each facility, enabling an optimized distribution of resources within fixed budgetary limits
Enhancing healthcare system resilience: Optimization of strategic investments portfolio
No full textInternational audienceHealthcare systems are facing growing challenges such as the shortage and unequal distribution of healthcare professionals, a rise in demand due to an aging population and a rise in chronic diseases but also daily disruptions. At a facility level, various mitigation strategies against everyday challenges can be implemented. Each mitigation strategy comes with its own costs and outcomes. These investments will strengthen the day-to-day resilience of healthcare facilities, thereby reducing the risk of service disruptions, but not all mitigation strategies are possible due to limited budget. Our research focuses on developing a model to identify an optimal investment strategy aimed at enhancing the resilience of healthcare systems. The aim of this bi-objective model is to simultaneously minimize the distances traveled by patients and the number of treatments deferred due to system disruptions. The probability of a patient accessing a facility on his preferred list is strongly impacted by the investment portfolio. To meet this challenge, we propose a new approach for evaluating the probability that a patient will choose a facility based on a Markov chain model. Moreover, the problem uses level-based fortification and probabilistic facility failures. The addressed problem is solved using a dedicated Non-dominated Sorting Genetic Algorithm (NSGA-II). The effectiveness and the robustness of the proposed approach are analyzed through a large experimental and a sensitivity analysis campaign
Magnetotactic bacteria for nanobiotechnological applications
No full textInternational audienceMagnetotactic bacteria (MTB) are a heterogeneous group of prokaryotic organisms with ubiquitous distribution and some common, specific attributes (1,2) used in the medical field, namely, targeted and personalized medicine, improved treatment efficacy, long-term survival rates, treatment for hard-to-treat diseases and development of new drug classes (3, 4). As expected, magnetic nanoparticles from magnetotactic bacteria (MTB-NPs) are much more promising nanomaterials for biodiagnosis and therapeutics than synthetic nanoparticles (MNPs), mainly due to their improved characteristics in terms of biocompatibility, functionalization and sustainability (5). In such a context, this poster focuses on the general and particular characteristics of MTB in closecorrelation with their utility in the medical field, as well as on summarizing the characteristics of magnetic nanoparticles, emphasizing their importance and the significant role of MTB-NPs in rapid and specific applications in nanomedicine
Les gloses à l'épreuve de la conception d'une plateforme de lecture-écriture savante
No full textInternational audienceLa conception (design) de logiciels est un révélateur des impensés d'un domaine. En effet, chaque zone de l'écran doit être nommée, une apparence et un comportement doivent lui être assignés, des gestes possibles lui être associés. Ainsi, concevoir une plateforme hypertextuelle à destination notamment des ethnographes et des traducteurs nous a permis d'interroger les notions de glose, de source, de document, de rubrique, de passage, de fragment, de scholie, de signet et même de lutrin ou d'étagère. C'est finalement tout l'univers matériel de l'érudit qui se retrouve passé au crible d'une sorte d'interrogatoire.Là où la langue permet une certaine souplesse, la conception logicielle oblige à repérer les ambivalences et à trancher pour une signification ou pour une autre, donc à prendre un certain risque d’être contredit par les futurs usages. Par exemple, la glose est-elle le commentaire ponctuel de quelques mots ou bien l'ensemble de ces commentaires qui, quand ils sont articulés entre eux, peuvent être considérés comme une nouvelle œuvre ? La conception requiert également d'identifier, de nommer, de faire exister ce qui n'avait peut-être pas de nom. Par exemple, dans une édition bilingue, le texte, pour être traduit, est découpé en unités. Cette unité est-elle toujours un paragraphe, et si non, comment l’appeler ? Peut-on considérer que ce nouvel objet désigne à la fois l'unité du texte original et sa traduction ? Quelles conséquences pratiques et théoriques ce choix pourrait avoir ?Par ailleurs, pour ce qui est de l'apparence et du comportement des objets à l'écran, le concepteur a toute latitude. En particulier dans le domaine des hypertextes, il peut faire le choix du changement radical, à grand renfort de 3D et de graphes (Nelson et al., 2007 ; Hall, 2015), ou celui de la continuité avec une tradition multi-millénaire : lire côte-à-côte un document source et sa glose, écrire dans la marge, utiliser la couleur rouge pour ajouter des repères dans la source sans l'altérer, référencer les passages selon les codifications couramment utilisées (ex : 15:62, 45a ou 16.11a), commenter un fragment précis d'un de ces passages en faisant précéder le commentaire de la reprise des mots du fragment, etc. Nous avons opté pour la deuxième approche, afin de bénéficier à la fois de la connaissance préalable par les usagers de ces « conventions de lecture » mais aussi de l'expérience sédimentée dans ces conventions de la conservation d'un patrimoine intellectuel, multi-culturel, sur le temps long (malgré les changements de civilisation, de techniques, etc.). Notons cependant que mettre en cohérence des éléments épars issus de la tradition n'est pas toujours facile. Par exemple quel statut donner aux hexaples dans un système construit autour de la métaphore de la marge ?Les principes de conception exposés ont fait et continuent de faire l'objet de mises à l'épreuve de natures diverses : celle de leur faisabilité (commencé fin-2022, le logiciel a été mis en production en juillet 2024), celle de son usage encadré (une soixantaine d'étudiants l’utilisent chaque semaine depuis septembre 2024) et de son usage en autonomie totale (par des collègues chercheurs à l'étranger). Même s’il ne s’agit pas de réfutations au sens fort, nous rendrons compte des incompréhensions, des cas non anticipés et des manques bloquants, ainsi que des adaptations déjà mises en œuvre ou envisagées à plus ou moins long terme
Physical and electrical characterization of wide band gap for power electronic application
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"I do not see the point of using the system". Understanding a Broken Policy Knot in the Primary Care Sector
No full textInternational audienceThis paper explores the implementation of a policy promoting new cooperative practices in the primary care sector. Through a two-year multi-sited ethnographic study of Multi-Professional Healthcare Centers (MPHCs) and their coordination mechanisms, we highlight the gaps between the coordinative protocols that prescribe how these structures operate, and the certified Health Information System (HIS) that has been defined by public authorities to support the new practices. These gaps make us say that the policy knot - that entangles policy, practice, and design - broke. To understand why, we studied the biography of the certified HIS and identified that it is based on the practice of general medicine only. Without simply concluding that public policy has failed because of the system's shortcomings, we reveal the human effort involved in compensating for the HIS's inability to support the articulation work required for multi-professional coordination. Based on this empirical contribution, we offer the policy-oriented technological frame as a concept to make sense of IT in public health, and the congruence loop as a guideline to avoid the breakage of a policy knot
Enhancing the Sense of Connectedness in Participatory Systemic Workshops through Embodied Narrative
No full textThis position paper explores how embodied narrative can enhance participants’ sense of connectedness in participatory systemic workshops, particularly within the context of sustainable transportation. Drawing from a preliminary travel diary workshop, the paper outlines how bodily experiences and personal stories can be leveraged to foster mutual understanding and systemic insight