Wikipédia, un projet hors normes ?

International audienceWikipedia and the International Standards Organization both represent a crystallisation of knowledge : of know-how in the case of ISO standards and of encyclopaedic knowledge in the case of Wikipedia. Both are based on reaching a consensus and on collaboration in the form of written texts. From the start, Wikipedia adopted strict rules, in particular its five founding principles. The need for standards has grown with the size of the encyclopaedia.Wikipédia et l'ISO représentent toutes deux une cristallisation du savoir. que ce soit savoir-faire (ISO) ou savoir encyclopédique (Wikipédia). Toutes deux sont fondés sur la recherche de consensus et la collaboration sous forme de textes écrits. Dès le départ Wikipédia a adopté des règles, avec ses cinq principes fondateurs. La montée en puissance a conduit au développement d'un espace méta (ex. page de discussion) dont le fonctionnement a nécessité une codification

Temperature and nutrient effects on the relative importance of brown and green pathways for stream ecosystem functioning: A mesocosm approach

In addition to global warming, aquatic ecosystems are currently facing multiple global changes among which include changes in nitrogen (N) loads. While several studies have investigated both temperature and N impacts on aquatic ecosystems independently, knowledge on their interactive effects remains scarce. In forested headwater streams, decomposition of leaf litter represents the main process ensuring the transfer of nutrients and energy to higher trophic levels, followed by autochthonous primary production, mainly ensured by phototrophic biofilms. The main aim of this study was to disentangle the independent and combined effects of temperature increase and nutrient availability on the relative importance of brown and green processes involved in stream functioning. We hypothesised that water temperature and nutrients would lead to a general increase in leaf‐litter decomposition and primary production, but that the intensity of these effects would be largely modulated by competitive interactions arising between microorganisms as well as by the top‐down control of microorganisms by macro‐invertebrates. Macro‐invertebrates would, in turn, be bottom‐up controlled by microbial resources quality. To test these hypotheses, we conducted a 56‐day experiment in artificial streams containing leaf litter, microbial decomposers and biofilm inoculum, and an assemblage of macro‐invertebrates. Two water inorganic N:phosphorus (P) ratios (33 and 100, molar ratios) and two temperatures (ambient, +2°C) were manipulated, each treatment being replicated three times. Fungal and biofilm growth as well as leaf‐litter decomposition and primary production were quantified. Top‐down impacts of invertebrate primary consumers on brown and green compartments were evaluated using exclosures while bottom‐up control was evaluated through the measurement of resource stoichiometry and fatty acid profiles, as well as quantification of macro‐invertebrate growth and survival. Contrary to expectations, microbial decomposition was not significantly stimulated by nutrient or temperature manipulations, while primary production was only improved under ambient temperature. In the + 2°C treatment with high N:P, greater biofilm biomass was associated with lower fungal development, which indicates competition for nutrients in these conditions. Temperature increased macro‐invertebrate growth and leaf‐litter consumption, but this effect was independent of any improvement of basal resource quality, suggesting that temperature mediated changes in consumer metabolism and activity was the main mechanism involved. Most of our hypotheses that were based on simplified laboratory observations have been rejected in our semi‐controlled mesocosms. Our study suggests that the complexity of biological communities might greatly affect the response of ecosystems to multiple stressors, and that interactions between organisms must be explicitly taken into account when investigating the impacts of global change on ecosystem functioning

(Plasticized) polylactide/clay nanocomposite textile : thermal, mechanical, shrinkage and fire properties

peer reviewedVarious quantities of Cloisite® 30B (from 1% to 4% in weight) have been added to a polylactide matrix by melt blending to produce polylactide-based nanocomposites. Then, these blends have been melt-spun to produce multifilaments yarns. It is demonstrated that it is necessary to use a plasticizer to spin a blend with 4% in weight of Cloisite® 30B. The properties of these yarns have been studied (dispersion of the clay, thermal, mechanical and shrinkage properties). A decrease of the tensile properties is observed when the quantity of Cloisite® 30B increases, but an improvement of the thermal and shrinkage properties is highlighted. These multifilaments have been knitted and the flammability studied using cone calorimeter at 35 kW/m2. A strong decrease, up to 38%, of the heat release rate has been measured

Designing of polylactide/clay nanocomposites for textile applications: effect of processing conditions, spinning and characterization

peer reviewedAn experimental study was carried out to design polylactide (PLA)-clay nanocomposites for developing fibers. PLA and 1-10 wt % of a selected organomodified bentonite (Bentone® 104-B104) were melt mixed to examine the effect of processing conditions (temperature, shear, residence time) on the morphology of performed polymer nanocomposites (PNC). Because of a good compatibility with PLA matrix, the dispersion of B104 occurred under different conditions without difficulty, and a similar morphology was obtained. The results obtained showed that at low temperature of mixing, the shear stress exerted on polymer has a key role on the extent of intercalation and delamination. Upscale experiments were further performed using optimized conditions and 4 wt % B104 was added to PLA matrix by melt blending to produce PNC for spinning. Then, the recovered PNC were melt spun to produce multifilaments yarns, and it was demonstrated that surprisingly, it is not necessary to use a plasticizer to spin a blend with 4 wt % B104. The properties of the yarns have been studied in terms of clay dispersion as well as thermal, mechanical, and shrinkage properties. B104 could be added up to 4 wt % into PLA without detrimentally sacrificing the tensile strength of melt-spun filaments, especially at high draw ratio. Interestingly, the PNC-based multifilaments were knitted and the flammability studied using cone calorimeter at 35 kW/m2. A strong decrease, up to 46%, of the heat release rate was measured

Sex differences in post-acute neurological sequelae of SARS-CoV-2 and symptom resolution in adults after COVID-19 hospitalization: an international multicenter prospective observational study

Although it is known that coronavirus disease 2019 can present with a range of neurological manifestations and in-hospital complications, sparse data exist on whether these initial neurological symptoms of coronavirus disease 2019 are closely associated with post-acute neurological sequelae of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2; PANSC) and whether female versus male sex impacts symptom resolution. In this international, multi-centre, prospective, observational study across 407 sites from 15 countries (30 January 2020 to 30 April 2022), we report the prevalence and risk factors of PANSC among hospitalized adults and investigate the differences between males and females on neurological symptom resolution over time. PANSC symptoms included altered consciousness/confusion, fatigue/malaise, anosmia, dysgeusia and muscle ache/joint pain, on which information was collected at index hospitalization and during follow-up assessments. The analysis considered a time to the resolution of individual and all neurological symptoms. The resulting times were modelled by Weibull regression, assuming mixed-case interval censoring, with sex and age included as covariates. The model results were summarized as cumulative probability functions and age-adjusted and sex-adjusted median times to resolution. We included 6862 hospitalized adults with coronavirus disease 2019, who had follow-up assessments. The median age of the participants was 57 years (39.2% females). Males and females had similar baseline characteristics, except that more males (versus females) were admitted to the intensive care unit (30.5 versus 20.3%) and received mechanical ventilation (17.2 versus 11.8%). Approximately 70% of patients had multiple neurological symptoms at the first follow-up (median = 102 days). Fatigue (49.9%) and myalgia/arthralgia (45.2%) were the most prevalent symptoms of PANSC at the initial follow-up. The reported prevalence in females was generally higher (versus males) for all symptoms. At 12 months, anosmia and dysgeusia were resolved in most patients, although fatigue, altered consciousness and myalgia remained unresolved in >10% of the cohort. Females had a longer time to the resolution (5.2 versus 3.4 months) of neurological symptoms at follow-up for those with more than one neurological symptom. In the multivariable analysis, males were associated with a shorter time to the resolution of symptoms (hazard ratio = 1.53; 95% confidence interval = 1.39–1.69). Intensive care unit admission was associated with a longer time to the resolution of symptoms (hazard ratio = 0.68; 95% confidence interval = 0.60–0.77). Post-discharge stroke was uncommon (0.3% in females and 0.5% in males). Despite the methodological challenges involved in the collection of survey data, this international multi-centre prospective cohort study demonstrated that PANSC following index hospitalization was high. Symptom prevalence was higher and took longer to resolve in females than in males. This supported the fact that while males were sicker during acute illness, females were disproportionately affected by PANSC

Vaccine breakthrough hypoxemic COVID-19 pneumonia in patients with auto-Abs neutralizing type I IFNs

Life-threatening `breakthrough' cases of critical COVID-19 are attributed to poor or waning antibody response to the SARS- CoV-2 vaccine in individuals already at risk. Pre-existing autoantibodies (auto-Abs) neutralizing type I IFNs underlie at least 15% of critical COVID-19 pneumonia cases in unvaccinated individuals; however, their contribution to hypoxemic breakthrough cases in vaccinated people remains unknown. Here, we studied a cohort of 48 individuals ( age 20-86 years) who received 2 doses of an mRNA vaccine and developed a breakthrough infection with hypoxemic COVID-19 pneumonia 2 weeks to 4 months later. Antibody levels to the vaccine, neutralization of the virus, and auto- Abs to type I IFNs were measured in the plasma. Forty-two individuals had no known deficiency of B cell immunity and a normal antibody response to the vaccine. Among them, ten (24%) had auto-Abs neutralizing type I IFNs (aged 43-86 years). Eight of these ten patients had auto-Abs neutralizing both IFN-a2 and IFN-., while two neutralized IFN-omega only. No patient neutralized IFN-ss. Seven neutralized 10 ng/mL of type I IFNs, and three 100 pg/mL only. Seven patients neutralized SARS-CoV-2 D614G and the Delta variant (B.1.617.2) efficiently, while one patient neutralized Delta slightly less efficiently. Two of the three patients neutralizing only 100 pg/mL of type I IFNs neutralized both D61G and Delta less efficiently. Despite two mRNA vaccine inoculations and the presence of circulating antibodies capable of neutralizing SARS-CoV-2, auto-Abs neutralizing type I IFNs may underlie a significant proportion of hypoxemic COVID-19 pneumonia cases, highlighting the importance of this particularly vulnerable population

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Étude de la Structure et des Interfaces des Transistors Organiques Electroluminescents

The organic light-emitting transistor (OLET) has attracted extensive attention from organic electronics research community. Its specificity is the combination of the electronic properties of the field-effect transistor with the light-emitting properties of the light-emitting diodes. Thus, it promises a major step forward to the simplification of circuit engineering in display technologies. The performances shown by OLETs make them potential candidates of the electrically pumped organic laser that still remains as a major challenge. It is in this context that this work of Ph.D. focused on the study of the structure of OLETs and their interfaces. As a first step, a viable architecture with reproducible performances was established through the investigations of different structures and materials. Optimisation on this structure was then carried out by integrating interfacial layers. The roles of hole blocking molecules were compared decoupling electron injection and hole blocking efficacies. OLETs with operating voltage as low as 5 V have been achieved. Cavity effect was observed in these OLETs, thanks to the specific structure where gate and drain both are composed of Al metal. Colour tuning in all visible light was realized simply by changing the emissive layer thickness. Subsequently, optical simulations were carried out to explain these phenomena. Further studies were carried out to enhance the current densities of our OLETs. Molecular doping and substrate temperature-controlled deposition were the two approaches explored. Although higher current densities were obtained, optical performances were not improved. In parallel, the integration of better gain-medium materials for lasing emission was attempted, in which a guest-host system was successfully developed.Le transistor organique électroluminescent (OLET) est l’objet de beaucoup d’attention dans la communauté de recherche en électronique organique. Sa spécificité est la réunion des propriétés électroniques des transistors à effet de champ avec les propriétés d’émission des diodes électroluminescentes. Elle promet donc des avancées majeures dans la simplification de l’ingénierie de circuit dans des application pour les technologies d’affichage. Les performances affichées par les OLETs en font aussi des candidats potentiels pour être l’architecture de base du laser organique pompé électriquement qui est un des grands défis de la recherche en électronique organique. C’est dans cet environnement que ce travail de doctorat trouve sa problématique. Il s’agit de faire une étude assez générale de la structure d’un OLET et des interfaces qui s’y trouvent. Dans un premier temps un travail a été effectué sur la sélection du type de structure et sur les matériaux utilisés pour obtenir un OLET avec des performances reproductibles. Un dispositif de base a pu être mis au point présentant des émissions de l’ordre de la dizaine de mW.cm-2. Un travail d’optimisation a ensuite été consacré à l’ajout de couches aux interfaces importantes. Les effets de différentes couches bloquantes de trous ont été comparés en étudiant les effets de blocage et d’injection de charges. Ainsi des OLETs avec des tensions d’opération de 5V ont été mis au point. Un effet de cavité a pu être observé dans nos OLETs. Cet effet apparaît grâce à la structure spécifique qui se compose d’une électrode de grille et de drain en aluminium. Un ajustement de la couleur dans toute la gamme du visible a pu être effectué juste en changeant l’épaisseur de la couche émissive. Par conséquent des modélisations optiques ont été entreprises pour comprendre le phénomène. D’autre études ont été menées pour améliorer la densité de courant des OLETs. Le dopage moléculaire et le dépôt sur un substrat à la température contrôlée sont deux techniques utilisées. Bien que les effets sur le courant soient positifs, l’émission des dispositifs n’est pas améliorée. En parallèle l’intégration de matériaux qui sont bons milieux à gain pour laser a été tenté. Elle a permis la mise au point réussi d’un OLET utilisant un milieu matrice-invité

Study of the structure and interfaces of an organic light - emitting transistor

Le transistor organique électroluminescent (OLET) est l’objet de beaucoup d’attention dans la communauté de recherche en électronique organique. Sa spécificité est la réunion des propriétés électroniques des transistors à effet de champ avec les propriétés d’émission des diodes électroluminescentes. Elle promet donc des avancées majeures dans la simplification de l’ingénierie de circuit dans des application pour les technologies d’affichage. Les performances affichées par les OLETs en font aussi des candidats potentiels pour être l’architecture de base du laser organique pompé électriquement qui est un des grands défis de la recherche en électronique organique. C’est dans cet environnement que ce travail de doctorat trouve sa problématique. Il s’agit de faire une étude assez générale de la structure d’un OLET et des interfaces qui s’y trouvent. Dans un premier temps un travail a été effectué sur la sélection du type de structure et sur les matériaux utilisés pour obtenir un OLET avec des performances reproductibles. Un dispositif de base a pu être mis au point présentant des émissions de l’ordre de la dizaine de mW.cm-2. Un travail d’optimisation a ensuite été consacré à l’ajout de couches aux interfaces importantes. Les effets de différentes couches bloquantes de trous ont été comparés en étudiant les effets de blocage et d’injection de charges. Ainsi des OLETs avec des tensions d’opération de 5V ont été mis au point. Un effet de cavité a pu être observé dans nos OLETs. Cet effet apparaît grâce à la structure spécifique qui se compose d’une électrode de grille et de drain en aluminium. Un ajustement de la couleur dans toute la gamme du visible a pu être effectué juste en changeant l’épaisseur de la couche émissive. Par conséquent des modélisations optiques ont été entreprises pour comprendre le phénomène. D’autre études ont été menées pour améliorer la densité de courant des OLETs. Le dopage moléculaire et le dépôt sur un substrat à la température contrôlée sont deux techniques utilisées. Bien que les effets sur le courant soient positifs, l’émission des dispositifs n’est pas améliorée. En parallèle l’intégration de matériaux qui sont bons milieux à gain pour laser a été tenté. Elle a permis la mise au point réussi d’un OLET utilisant un milieu matrice-invité.The organic light-emitting transistor (OLET) has attracted extensive attention from organic electronics research community. Its specificity is the combination of the electronic properties of the field-effect transistor with the light-emitting properties of the light-emitting diodes. Thus, it promises a major step forward to the simplification of circuit engineering in display technologies. The performances shown by OLETs make them potential candidates of the electrically pumped organic laser that still remains as a major challenge. It is in this context that this work of Ph.D. focused on the study of the structure of OLETs and their interfaces. As a first step, a viable architecture with reproducible performances was established through the investigations of different structures and materials. Optimisation on this structure was then carried out by integrating interfacial layers. The roles of hole blocking molecules were compared decoupling electron injection and hole blocking efficacies. OLETs with operating voltage as low as 5 V have been achieved. Cavity effect was observed in these OLETs, thanks to the specific structure where gate and drain both are composed of Al metal. Colour tuning in all visible light was realized simply by changing the emissive layer thickness. Subsequently, optical simulations were carried out to explain these phenomena. Further studies were carried out to enhance the current densities of our OLETs. Molecular doping and substrate temperature-controlled deposition were the two approaches explored. Although higher current densities were obtained, optical performances were not improved. In parallel, the integration of better gain-medium materials for lasing emission was attempted, in which a guest-host system was successfully developed