Dispositifs tout-fibre pour le démultiplexage en longueur d'onde

Équations d'onde et modes -- Multiplexeur/démultiplexeur obtenu avec un coupleur 2X2 -- Filtres spectraux à partir de fibres effilées -- Structures composées -- Coupleur cascadé avec un filtre -- L'interféromètre de Mach-Zehnder -- Composants à réseaux de Bragg -- Différentes conceptions de démultiplexeurs avec des réseaux -- Réalisation de réseaux de Bragg dans la partie centrale du coupleur 2X2 fusionné

Mise en forme de composites carbone/PEEK dans le domaine caoutchoutique

Les matériaux composites à matrices thermoplastiques renforcées de fibres longues sont étudiés de manière intensive pour leur introduction dans les prochaines générations de pièces structurales aéronautiques. Par ses performances thermomécaniques, l’unidirectionnel carbone/PEEK apparait comme un candidat possible, toutefois les procédés actuels de formage ne semblent pas en mesure de réaliser des pièces épaisses avec ce matériau. Ce travail a pour objectif de proposer un procédé innovant capable de réaliser des pièces composites carbone/PEEK épaisses de types cornières structurales en L ou en U. Le coeur du concept est la réalisation de l’étape de mise en forme dans le domaine caoutchoutique pour favoriser le glissement inter-plis et éviter ainsi la formation de défaut de type plissement quelle que soit l’épaisseur. Dans un premier temps, la fenêtre de processabilité adaptée à l’obtention d’une préforme a été définie en se basant sur les propriétés physiques de la matrice PEEK. Puis, la santé matière et les performances des pièces réalisées par ce nouveau procédé ont été mesurées, la comparaison à des pièces obtenues par un procédé conventionnel de formage valide le procédé proposé

Effect of interfacial crystalline growth on autohesion of PEEK

This work aims to clarify the role of the crystalline growth on the autohesion strength of amorphous PEEK below its melting temperature. The self-bonding strength versus temperature, pressure and time has been measured by lap shear test on 250-micron thick amorphous PEEK assembled at various conditions. The effect of the crystalline growth on the adhesion strength has been established at 155°C, 200°C and 250°C. Autohesion is temperature dependent, whereas pressure at less than 1 MPa and time up to 3 h, have less impact on the adhesion strength. Nevertheless, the evolution of the crystalline morphology with time results in increasing the interfacial strength: a gain of 40% is noticed between 1 and 3 h at 250 °C to reach 0.9 MPa. The degree of crystallinity is higher at the interface than elsewhere in the material, the interface acting as nucleating agent. The evolution of the crystalline morphology at the interface with time shows the refinement of the primary lattice when the temperature is higher than or equal to the previous crystallization temperature, corresponding to the highest temperature seen by the polymeric material. The crystalline growth has an ambivalent effect on the autohesion of PEEK: it reduces the mobility of the macromolecular chains and thus their interdiffusion through the interface and at the same time, it is observed that the improvement of its crystal lattice reinforces the interfacial strength

Healthcare equity analysis: applying the Tanahashi model of health service coverage to community health systems following devolution in Kenya

Background: Universal health coverage (UHC) is growing as a national political priority, within the context of recently devolved decision-making processes in Kenya. Increasingly voices within these discussions are highlighting the need for actions towards UHC to focus on quality of services, as well as improving coverage through expansion of national health insurance fund (NHIF) enrolment. Improving health equity is one of the most frequently described objectives for devolution of health services. Previous studies, however, highlight the complexity and unpredictability of devolution processes, potentially contributing to widening rather than reducing disparities. Our study applied Tanahashi's equity model (according to availability, accessibility, acceptability, contact with and quality) to review perceived equity of health services by actors across the health system and at community level, following changes to the priority-setting process at sub-national levels post devolution in Kenya.Methods: We carried out a qualitative study between March 2015 and April 2016, involving 269 key informant and in-depth interviews from different levels of the health system in ten counties and 14 focus group discussions with community members in two of these counties. Qualitative data were analysed using the framework approach.Results: Our findings reveal that devolution in Kenya has focused on improving the supply side of health services, by expanding the availability, geographic and financial accessibility of health services across many counties. However, there has been limited emphasis and investment in promoting the demand side, including restricted efforts to promote acceptability or use of services. Respondents perceived that the quality of health services has typically been neglected within priority-setting to date.Conclusions: If Kenya is to achieve universal health coverage for all citizens, then county governments must address all aspects of equity, including quality. Through application of the Tanahashi framework, we find that community health services can play a crucial role towards achieving health equity

Polymerization study and rheological behavior of a RTM6 epoxy resin system during preprocessing step

Curing process and rheological behaviors of a monocomposant epoxy resin used in structural aeronautic applications are investigated. This study helped settle the basic parameters in order to optimize the infusion process of carbon fibers in an epoxy matrix. The effect of carbon nanotube dispersion during the preinjection step is also studied to improve electrical behavior of composite parts. The curing process has been analyzed at isothermal temperature using differential scanning calorimetry technique. Viscosity measurements were achieved with a Couette geometry, suitable for low viscosity resin. A shear-thinning effect caused by adding CNTs in the epoxy matrix is detected. It is more pronounced at high temperature for increasing CNT mass content

CAGIRE: a wide-field NIR imager for the COLIBRI 1.3 meter robotic telescope

The use of high energy transients such as Gamma Ray Bursts (GRBs) as probes of the distant universe relies on the close collaboration between space and ground facilities. In this context, the Sino-French mission SVOM has been designed to combine a space and a ground segment and to make the most of their synergy. On the ground, the 1.3 meter robotic telescope COLIBRI, jointly developed by France and Mexico, will quickly point the sources detected by the space hard X-ray imager ECLAIRs, in order to detect and localise their visible/NIR counterpart and alert large telescopes in minutes. COLIBRI is equipped with two visible cameras, called DDRAGO-blue and DDRAGO-red, and an infrared camera, called CAGIRE, designed for the study of high redshift GRBs candidates. Being a low-noise NIR camera mounted at the focus of an alt-azimutal robotic telescope imposes specific requirements on CAGIRE. We describe here the main characteristics of the camera: its optical, mechanical and electronics architecture, the ALFA detector, and the operation of the camera on the telescope. The instrument description is completed by three sections presenting the calibration strategy, an image simulator incorporating known detector effects, and the automatic reduction software for the ramps acquired by the detector. This paper aims at providing an overview of the instrument before its installation on the telescope.Comment: Accepted by Experimental Astronom

Priority setting for health in the context of devolution in Kenya: implications for health equity and community-based primary care

Devolution changes the locus of power within a country from central to sub-national levels. In 2013, Kenya devolved health and other services from central government to 47 new sub-national governments (known as counties). This transition seeks to strengthen democracy and accountability, increase community participation, improve efficiency and reduce inequities. With changing responsibilities and power following devolution reforms, comes the need for priority-setting at the new county level. Priority-setting arises as a consequence of the needs and demand for healthcare resources exceeding the resources available, resulting in the need for some means of choosing between competing demands. We sought to explore the impact of devolution on priority-setting for health equity and community health services. We conducted key informant and in-depth interviews with health policymakers, health providers and politicians from 10 counties (n = 269 individuals) and 14 focus group discussions with community members based in 2 counties (n = 146 individuals). Qualitative data were analysed using the framework approach. We found Kenya’s devolution reforms were driven by the need to demonstrate responsiveness to county contexts, with positive ramifications for health equity in previously neglected counties. The rapidity of the process, however, combined with limited technical capacity and guidance has meant that decision-making and prioritization have been captured and distorted for political and power interests. Less visible community health services that focus on health promotion, disease prevention and referral have been neglected within the prioritization process in favour of more tangible curative health services. The rapid transition in power carries a degree of risk of not meeting stated objectives. As Kenya moves forward, decision-makers need to address the community health gap and lay down institutional structures, processes and norms which promote health equity for all Kenyans

Multiorgan MRI findings after hospitalisation with COVID-19 in the UK (C-MORE): a prospective, multicentre, observational cohort study

Introduction: The multiorgan impact of moderate to severe coronavirus infections in the post-acute phase is still poorly understood. We aimed to evaluate the excess burden of multiorgan abnormalities after hospitalisation with COVID-19, evaluate their determinants, and explore associations with patient-related outcome measures. Methods: In a prospective, UK-wide, multicentre MRI follow-up study (C-MORE), adults (aged ≥18 years) discharged from hospital following COVID-19 who were included in Tier 2 of the Post-hospitalisation COVID-19 study (PHOSP-COVID) and contemporary controls with no evidence of previous COVID-19 (SARS-CoV-2 nucleocapsid antibody negative) underwent multiorgan MRI (lungs, heart, brain, liver, and kidneys) with quantitative and qualitative assessment of images and clinical adjudication when relevant. Individuals with end-stage renal failure or contraindications to MRI were excluded. Participants also underwent detailed recording of symptoms, and physiological and biochemical tests. The primary outcome was the excess burden of multiorgan abnormalities (two or more organs) relative to controls, with further adjustments for potential confounders. The C-MORE study is ongoing and is registered with ClinicalTrials.gov, NCT04510025. Findings: Of 2710 participants in Tier 2 of PHOSP-COVID, 531 were recruited across 13 UK-wide C-MORE sites. After exclusions, 259 C-MORE patients (mean age 57 years [SD 12]; 158 [61%] male and 101 [39%] female) who were discharged from hospital with PCR-confirmed or clinically diagnosed COVID-19 between March 1, 2020, and Nov 1, 2021, and 52 non-COVID-19 controls from the community (mean age 49 years [SD 14]; 30 [58%] male and 22 [42%] female) were included in the analysis. Patients were assessed at a median of 5·0 months (IQR 4·2–6·3) after hospital discharge. Compared with non-COVID-19 controls, patients were older, living with more obesity, and had more comorbidities. Multiorgan abnormalities on MRI were more frequent in patients than in controls (157 [61%] of 259 vs 14 [27%] of 52; p<0·0001) and independently associated with COVID-19 status (odds ratio [OR] 2·9 [95% CI 1·5–5·8]; padjusted=0·0023) after adjusting for relevant confounders. Compared with controls, patients were more likely to have MRI evidence of lung abnormalities (p=0·0001; parenchymal abnormalities), brain abnormalities (p<0·0001; more white matter hyperintensities and regional brain volume reduction), and kidney abnormalities (p=0·014; lower medullary T1 and loss of corticomedullary differentiation), whereas cardiac and liver MRI abnormalities were similar between patients and controls. Patients with multiorgan abnormalities were older (difference in mean age 7 years [95% CI 4–10]; mean age of 59·8 years [SD 11·7] with multiorgan abnormalities vs mean age of 52·8 years [11·9] without multiorgan abnormalities; p<0·0001), more likely to have three or more comorbidities (OR 2·47 [1·32–4·82]; padjusted=0·0059), and more likely to have a more severe acute infection (acute CRP >5mg/L, OR 3·55 [1·23–11·88]; padjusted=0·025) than those without multiorgan abnormalities. Presence of lung MRI abnormalities was associated with a two-fold higher risk of chest tightness, and multiorgan MRI abnormalities were associated with severe and very severe persistent physical and mental health impairment (PHOSP-COVID symptom clusters) after hospitalisation. Interpretation: After hospitalisation for COVID-19, people are at risk of multiorgan abnormalities in the medium term. Our findings emphasise the need for proactive multidisciplinary care pathways, with the potential for imaging to guide surveillance frequency and therapeutic stratification

Mise en forme de composites carbone/PEEK dans le domaine caoutchoutique

Thermoplastic composite materials based on long carbon fibers are extensively studied to prepare their introduction in the next generation of structural parts in aerospace industry. Because of its thermomechanical properties, unidirectional carbon/PEEK appears as a potential candidate, however the current forming processes do not appear able to manufacture thick parts with this material. The aim of my PhD thesis is to propose an innovative process to produce thick carbon/PEEK parts of L-shape and U-shape profiles. The heart of the concept is to carry out the step of deformation when the matrix is in the rubbery state to promote inter-ply sliding and thus avoiding the formation of wrinkling defect whatever the thickness. In a first step, the processing window suitable to obtain a preform was defined based on the physical properties of the PEEK matrix. The implementation of the proposed method, based on the results collected, has highlighted the complexity of the deformation mechanisms under these specific conditions. A better understanding of these mechanisms has been provided by a modeling and simulation approach. Finally, the material properties and the performance of the parts produced by this new process have been measured, the comparison with parts obtained by a conventional forming process validates the proposed process.Les matériaux composites à matrices thermoplastiques renforcées de fibres longues sont étudiés de manière intensive pour leur introduction dans les prochaines générations de pièces structurales aéronautiques. Par ses performances thermomécaniques, l’unidirectionnel carbone/PEEK apparait comme un candidat possible, toutefois les procédés actuels de formage ne semblent pas en mesure de réaliser des pièces épaisses avec ce matériau. Ce travail de thèse a pour objectif de proposer un procédé innovant capable de réaliser des pièces composites carbone/PEEK épaisses de types cornières structurales en L ou en U. Le cœur du concept est la réalisation de l’étape de mise en forme dans le domaine caoutchoutique pour favoriser le glissement inter-plis et éviter ainsi la formation de défaut de type plissement quelle que soit l’épaisseur. Dans un premier temps, la fenêtre de processabilité adaptée à l’obtention d’une préforme a été définie en se basant sur les propriétés physiques de la matrice PEEK. La mise en application du procédé proposé, faite à partir des résultats collectés, a mis en évidence la complexité des mécanismes de déformation dans ces conditions spécifiques. Une meilleure compréhension de ces mécanismes a pu être apportée par une approche de modélisation et de simulation. Enfin, la santé matière et les performances des pièces réalisées par ce nouveau procédé ont été mesurées, la comparaison à des pièces obtenues par un procédé conventionnel de formage valide le procédé proposé