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Mélanges biochar-compost : interactions et impacts sur la séquestration du carbone
No full textIn the context of global challenge, innovative organic amendment strategies could be used to improve soil agronomic properties in addition to increasing carbon (C) sequestration in soil. The combination of highly stable biochar with compost, a nutrient-rich material containing labile C, may be a solution to improve C sequestration while enhancing soil fertility in the context of a circular economy. Aim of the thesis was to examine if there are biochar-compost interactions and if yes, what are the mechanisms determining their effect on C and nitrogen (N) dynamics and plant growth, at different time scales. To this end we used laboratory and field experiments and analyzed for biological and thermal stability. The thermal stability of biochar was affected by biocharcompost interactions, which may already occur during their blending. Artificial weathering influenced the biological stability of both materials. Under field conditions, these processes did not significantly influence the carbon dynamics of the mixture, while biochar friability and N dynamics were affected by biochar-compost interactions. We conclude that biochar and compost interactions may occur at different time scales and affect their material properties and performance as soil amendment.Dans le contexte actuel des enjeux environnementaux, des stratégies innovantes d’amendement organique peuvent être utilisées afin d’améliorer les propriétés agronomiques du sol, tout en augmentant la séquestration du carbone (C) dans le sol. La combinaison de biochar hautement stable avec du compost, matériau riche en nutriments et contenant du C labile, pourrait être une de ces stratégies, dans un contexte d’économie circulaire. L’objectif de la thèse était d’étudier l’existence d’interactions entre biochar et compost et le cas échéant, de déterminer les mécanismes responsables de leurs effets sur la dynamique du C et de l’azote, ainsi que sur les plantes, à différentes échelles de temps. Pour ce faire, nous avons réalisé des expériences au laboratoire et au champ et analysé les stabilités thermiques et biologiques. La stabilité thermique du biochar a été affectée par les interactions biochar-compost, survenant dès leur mélange. L’altération artificielle a induit des changements sur la stabilité biologique des deux composants. Dans les conditions au champ, les processus induits par les interactions biochar-compost n’ont pas impacté significativement la dynamique du C des mélanges, contrairement à leurs effets sur la friabilité du biochar et la dynamique de l’azote. En conclusion, les interactions entre biochar et compost peuvent se produire à différentes échelles de temps et affecter significativement les propriétés des matériaux ainsi que leur performance en tant qu’amendement organique
Response to systemic therapies in granulomatous cheilitis : Retrospective multicenter series of 61 patients
No full textInternational audienc
Clebsch-Gordan Harmonic Decomposition of Tensors: Application to the Mechanics of Architectured Materials
No full textSéminaire de mécanique à d’Alember
Impact de faibles doses de cannabidiol sur la douleur neuropathique et les symptômes de type anxio-dépressifs chez la souris
No full textNeuropathic pain is defined as a long-lasting pain caused by an injury or a disease of the somatosensory system. It is associated with numerous comorbidities such as anxiety and depressive disorders. First-line treatments fail in 15-20 % of patients due to adverse effects, so the search for alternative treatments is essential. Cannabidiol (CBD) has analgesic, anxiolytic and antidepressant properties, but the mechanisms of action are not fully elucidated. In this context, this veterinary thesis is part ofMarion Gaborit's university thesis, a project with two objectives. The first goal was to determine whether the δ-opioid receptor is required to observe these properties in mice suffering from neuropathic pain (sciatic nerve compression model) using genetically modified male and female mice expressing this receptor or not. Behavioral tests were performed to measure mechanical allodynia and anxio-depressive-like behaviors. The second goal was to map by immunohistochemistry the neuronal co-localization of the δ-opioid and CB1-cannabinoid receptors in neuropathic mouse brains. This will provide a better understanding of their functional interactions in the neuropathic context. Our preliminary results in males suggest that the analgesic effect of CBD requires the δ-opioid receptor because the effect was not observable in its absence. For now, we cannot conclude whether CBD has an effect on anxio-depressive-like behaviors or not. Finally, we observed co-localized δ and CB1 receptors in the rostral ventromedial medulla (RVM), a structure involved in the descending modulation of pain, and in the dorsal raphe nucleus, involved in mood regulation.La douleur neuropathique est définie comme une douleur persistante causée par une lésion ou une maladie du système somatosensoriel. Elle est associée à de nombreuses comorbidités telles que des troubles anxio-dépressifs. Les traitements de première ligne échouant chez 15 à 20 % des patients à cause des effets indésirables, la recherche de traitements alternatifs est donc essentielle. Le cannabidiol (CBD) possède des propriétés analgésiques, anxiolytiques et antidépressives, mais ses mécanismes d'actions ne sont pas tous élucidés. Dans ce contexte, cette thèse vétérinaire s'inscrit dans le projet de thèse universitaire de Marion Gaborit, avec deux objectifs. Le premier est de déterminer si le récepteur opioïde ჾ est nécessaire à l'observation de ces propriétés chez la souris souffrant de douleur neuropathique (modèle de compression du nerf sciatique) en utilisant des souris mâles et femelles génétiquement modifiées pour exprimer ou non ce récepteur. Des tests comportementaux furent réalisés pour mesurer l'allodynie mécanique et les comportements de type anxio-dépressif. Le second objectif était de cartographier par immunohistochimie la co-localisation neuronale des récepteurs opioïde ჾ et cannabinoïde CB1 dans des cerveaux de souris neuropathiques afin de mieux comprendre leurs interactions fonctionnelles dans ce contexte neuropathique. Nos résultats préliminaires chez les mâles suggèrent que l'effet analgésique du CBD nécessiterait le récepteur opioïde ჾ; car l'effet n'était pas observable en son absence. Nous ne pouvons conclure à ce jour sur l'effet du CBD sur les comportements de type anxio-dépressif. Enfin, nous avons observé une co-localisation des récepteurs opioïdes ჾ et cannabinoïde CB1 au sein notamment de la moelle rostrale ventromédiale (RVM), une structure impliquée dans la modulation descendante de la douleur, et du noyau dorsal du raphé impliqué dans la régulation de l'humeur
Trottoirs: un ordre hybride à Mexico et dans son aire métropolitaine
No full textInternational audienceThe sidewalk is so commonplace that it has not been of much importance to urban policy and urban design until recent years. It is part of the street, so it is a priori a public space, but what complicates the subject considerably is that it serves as an interface between the private space of buildings and the roadway. It is the support of many uses that do not always coexist harmoniously and corresponds today to important urban and metropolitan issues in terms of accessibility for all to the city, spatial justice, and the promotion of sustainable mobility, especially on foot. The way in which governments consider or do not consider sidewalks is significant of their relationship with city dwellers.In the Mexico City metropolitan area, who designs, builds, cleans, sanitizes, beautifies, etc., sidewalks? This seemingly simple question is much more difficult to answer than it appears. The sidewalk involves a complex set of human actors (shopkeepers, pedestrians, musicians, service companies, etc.) and non-human actors (lampposts, telephone booths, planters, parked vehicles, legal and regulatory devices, sometimes numerous, sometimes rickety, etc.). We have selected ten different sites in the metropolis, sidewalks that are either "model" or abandoned, or appropriated by the private sector, etc. These sites are located in Mexico City: Alameda central, downtown Coyoacán, a residential street in the Roma Sur neighborhood, commercial streets in the popular consolidated neighborhood of Santo Domingo, the sidewalk of an office building in Santa Fe, the square in front of a subway station in Iztapalapa, and the sidewalk of a shopping center in the municipality of Gustavo Madero. On the other hand, in the suburbs of the State of Mexico: the border zone of the popular periphery between Nezahualcóyotl and Chimalhuacán, the new city of Ciudad Satélite in Naucalpan, the tourist center of Tepotzotlán.Rather than an analysis restricted to the causes of the mismanagement of sidewalks in the city or the lack of universal accessibility, we focused on the actors, governance, formal and informal regulations and how they shape our daily lives, uses, forms of appropriation, conflicts, and challenges of managing sidewalks. In this perspective, the sidewalk appears as the result and support of a hybrid order, negotiated and blurred, between the public and the private, the formal and the informal, the residential and the commercial, the fleeting and the permanent, etc. This hybrid dynamic contradicts the static conception and state monopoly of sidewalks that prevails in global urbanism and especially in the cities of Europe and other developed countries. The adoption of the notion of a hybrid order could provide stakeholders with an opportunity to reinvent the way sidewalks are planned and managed, giving more space to uses and users, and to the creativity of practitioners.La banqueta (acera) es algo tan común que no importó mucho a las políticas urbanas ni a los estudios urbanos hasta hace unos años. Es parte de la calle, por lo que es a priori un espacio público, pero es especialmente la interfaz entre el espacio privado de los edificios y las vías públicas, lo que complica considerablemente el problema. Hoy en día, incorpora importantes desafíos urbanos y metropolitanos en términos de accesibilidad para todos a la ciudad, justicia espacial, promoción de la movilidad sustentable, especialmente a pie, pero sobretodo es el soporte de muchos usos que no coexisten siempre de manera armoniosa. La manera en que los gobernantes consideran o no las banquetas es significativa de su relación con sus gobernados.¿Quién diseña, construye, limpia, embellece, etc. las banquetas de la Zona Metropolitana del Valle de México? Esta pregunta aparentemente simple es mucho más difícil de contestar de lo que parece. La acera es de hecho un conjunto complejo de actores humanos (comerciantes, peatones, músicos, empresas de servicios, etc.) y no humanos (postes de luz, cabinas telefónicas, jardineras, vehículos estacionados, dispositivos legales y reglamentarios, a veces numerosos y a veces raquíticos, etc.). Fuimos “interrogando” diez banquetas de la metropoli, banquetas “modelo”, banquetas abandonadas, banquetas sobre intervenidas por el sector privado, etc. Estos sitios se encuentran tanto en la Ciudad de México (Alameda central, centro de Coyoacán, una calle residencial de la colonia Roma Sur, calles comerciales de la colonia popular consolidada Santo Domingo, la banqueta del edificio inteligente de oficinas Calakmul en Santa Fe, banqueta a un costado de una estación de metro en un pueblo de Iztapalapa y una banqueta transformada por los desarrolladores de plazas comerciales en la alcaldía de Gustavo Madero) como en el Estado de México (una zona limítrofe de la periferia popular entre los municipios de Nezahualcóyotl y Chimalhuacán, la Zona Azul de Ciudad Satélite en Naucalpan, el pueblo mágico de Tepotzotlán).Más que un análisis de las causas de la mala gestión de las aceras en la ciudad o de la falta de accesibilidad universal, nos hemos centrado en los actores, la gobernanza, los reglamentos formales e informales y la manera en que dan forma a nuestra vida diaria, a los usos, formas de apropiación, conflictos, retos de la gestión de banquetas. Bajo esta perspectiva, la banqueta aparece como el resultado y el soporte de un orden híbrido; negociado y borroso, entre lo público y lo privado, lo formal y lo informal, lo residencial y lo comercial, lo fugaz y lo permanente, etc. Esta dinámica hibrida contradice la concepción estática y el monopolio estatal que prevalecen sobre las banquetas en el urbanismo global y especialmente en las ciudades de Europa y otros países desarrollados. Asumir el orden híbrido podría ofrecer al urbanismo la oportunidad de reinventar las formas de planificación y gestión de las banquetas, dando más lugar a los usos y a los usuarios y a la creatividad de los profesionales.Le trottoir est tellement banal qu'il n'avait pas beaucoup d'importance pour la politique urbaine et les études urbaines jusqu'à ces dernières années. Il fait partie de la rue, c'est donc a priori un espace public, mais ce qui complique considérablement le sujet est qu'il sert d'interface entre l'espace privé des bâtiments et la voirie. Il est le support de nombreux usages qui ne coexistent pas toujours harmonieusement et correspond aujourd'hui à d'importants enjeux urbains et métropolitains en termes d'accessibilité pour tous à la ville, de justice spatiale, de promotion de la mobilité durable, notamment à pied. La manière dont les gouvernants considèrent ou non les trottoirs est significative de leur relation avec les citadins.Dans la zone métropolitaine de Mexico, qui conçoit, construit, nettoie, assainit, embellit, etc. les trottoirs ? Cette question apparemment simple est beaucoup plus difficile à répondre qu'il n'y paraît. Le trottoir suppose en effet un ensemble complexe d'acteurs humains (commerçants, piétons, musiciens, sociétés de services, etc.) et d'acteurs non humains (lampadaires, cabines téléphoniques, jardinières, véhicules stationnés, dispositifs légaux et réglementaires, parfois nombreux, parfois branlants, etc.) Nous avons sélectionné dix sites différents de la métropole, des trottoirs "modèles", ou abandonnés, ou appropriés par le secteur privé, etc. Ces sites se trouvent d'une part dans la Ville de Mexico: Alameda central, centre de Coyoacán, rue résidentielle du quartier Roma Sur, rues commerciales du quartier populaire consolidé de Santo Domingo, trottoir d'immeuble de bureaux à Santa Fe, parvis d'une station de métro d'Iztapalapa, trottoir d'un centre commercial dans la municipalité de Gustavo Madero. D'autre part, dans les banlieues de l'État de Mexico: zone frontalière de la périphérie populaire entre Nezahualcóyotl et Chimalhuacán, ville nouvelle de Ciudad Satélite à Naucalpan, centre touristique de Tepotzotlán.Plutôt qu'une analyse restreintes aux causes de la mauvaise gestion des trottoirs dans la ville ou du manque d'accessibilité universelle, nous nous sommes concentrés sur les acteurs, la gouvernance, les réglementations formelles et informelles et la manière dont elles façonnent notre quotidien, les usages, les formes d'appropriation, les conflits, les défis de la gestion des trottoirs. Dans cette perspective, le trottoir apparaît comme le résultat et le support d'un ordre hybride, négocié et brouillé, entre le public et le privé, le formel et l'informel, le résidentiel et le commercial, le fugace et le permanent, etc. Cette dynamique hybride contredit la conception statique et le monopole de l'État qui prévalent sur les trottoirs dans l'urbanisme mondial et surtout dans les villes d'Europe et d'autres pays développés. L'adoption de la notion d'ordre hybride pourrait offrir aux parties prenantes l'occasion de réinventer les modes de planification et de gestion des trottoirs, en donnant plus de place aux usages et aux utilisateurs, ainsi qu'à la créativité des praticiens
A general meta-ecosystem model to predict ecosystem function at landscape extents
No full textThe integration of meta-ecosystem processes over large spatial extent is critical to predicting whether and how global changes might impact biodiversity and ecosystem functions. Yet, there remains an important gap in meta-ecosystem models to predict multiple ecosystem functions (e.g., carbon sequestration, elemental cycling, trophic efficiency) across different ecosystem types (e.g., terrestrial-aquatic, benthic-pelagic). We derive a generic meta-ecosystem model to predict ecosystem function at landscape extents by integrating the spatial dimension of natural systems as spatial networks of different habitat types connected by cross-ecosystem flows of materials and organisms. This model partitions the physical connectedness of ecosystems from the spatial flow rates of materials and organisms, allowing the representation of all types of connectivity across ecosystem boundaries as well as the interaction(s) between them. The model predicts that cross-ecosystem flows maximize the realization of multiple functions at landscape extent. Spatial flows, even the ones that significantly reduce the overall amount of nutrients in the meta-ecosystem, can reallocate nutrients to more efficient ecosystems, leading to greater levels of productivity at both local and regional scales. This ‘cross-ecosystem efficiency hypothesis’ is a general and testable hypothesis emphasizing the complementarity and interconnectedness among ecosystems and the importance of addressing ecosystem diversity for meta-ecosystem function
Intracellular silicification by early-branching magnetotactic bacteria
No full textInternational audienceBiosilicification—the formation of biological structures composed of silica—has a wide distribution among eukaryotes; it plays a major role in global biogeochemical cycles, and has driven the decline of dissolved silicon in the oceans through geological time. While it has long been thought that eukaryotes are the only organisms appreciably affecting the biogeochemical cycling of Si, the recent discoveries of silica transporter genes and marked silicon accumulation in bacteria suggest that prokaryotes may play an underappreciated role in the Si cycle, particularly in ancient times. Here, we report a previously unidentified magnetotactic bacterium that forms intracellular, amorphous silica globules. This bacterium, phylogenetically affiliated with the phylum Nitrospirota, belongs to a deep-branching group of magnetotactic bacteria that also forms intracellular magnetite magnetosomes and sulfur inclusions. This contribution reveals intracellularly controlled silicification within prokaryotes and suggests a previously unrecognized influence on the biogeochemical Si cycle that was operational during early Earth history
Mechanochemical synthesis of pseudobinary Ti-V hydrides and their conversion reaction with Li and Na
No full textLithium-ion batteries (LiBs) based on insertion electrodes reach intrinsic capacity limits. Performance improvements and cost reduction require alternative reaction mechanisms and novel battery chemistries such as conversion reactions and sodium-ion batteries (NaBs), respectively. We here study the formation of Ti1-xVxH2 hydrides (0 0.7) alloys. Na-ion half-cell measurements prove the reactivity between (V,Ti)H2 hydrides and sodium, albeit with significant kinetic limitation
Sensitivity analysis of an aerosol-aware microphysics scheme in Weather Research and Forecasting (WRF) during case studies of fog in Namibia
No full textInternational audienceAerosol-aware microphysics parameterisation schemes are increasingly being introduced into numerical weather prediction models, allowing for regional and case-specific parameterisation of cloud condensation nuclei (CCN) and cloud droplet interactions. In this paper, the Thompson aerosol-aware microphysics scheme, within the Weather Research and Forecasting (WRF) model, is used for two fog cases during September 2017 over Namibia. Measurements of CCN and fog microphysics were undertaken during the AErosols, RadiatiOn and CLOuds in southern Africa (AEROCLO-sA) field campaign at Henties Bay on the coast of Namibia during September 2017. A key concept of the microphysics scheme is the conversion of water-friendly aerosols to cloud droplets (hereafter referred to as CCN activation), which could be estimated from the observations. A fog monitor 100 (FM-100) provided cloud droplet size distribution, number concentration (N t), liquid water content (LWC), and mean volumetric diameter (MVD). These measurements are used to evaluate and parameterise WRF model simulations of N t , LWC, and MVD. A sensitivity analysis was conducted through variations to the initial CCN concentration, CCN radius, and the minimum updraft speed, which are important factors that influence droplet activation in the microphysics scheme of the model. The first model scenario made use of the default settings with a constant initial CCN number concentration of 300 cm −3 and underestimated the cloud droplet number concentration, while the LWC was in good agreement with the observations. This resulted in droplet size being larger than the observations. Another scenario used modelled data as CCN initial conditions, which were an order of magnitude higher than other scenarios. However, these provided the most realistic values of N t , LWC, MVD, and droplet size distribution. From this, it was concluded that CCN activation of around 10 % in the simulations is too low, while the observed appears to be higher reaching between 20 % and 80 %, with a mean (median) of 0.55 (0.56) during fog events. To achieve this level of activation in the model, the minimum updraft speed for CCN activation was increased from 0.01 to 0.1 m s −1. This scenario provided N t , LWC, MVD, and droplet size distribution in the range of the observations, with the added benefit of a realistic initial CCN concentration. These results demonstrate the benefits of a dynamic aerosol-aware scheme when parameterised with observations
SARS-CoV-2 Genomic Characteristics and Clinical Impact of SARS-CoV-2 Viral Diversity in Critically Ill COVID-19 Patients: A Prospective Multicenter Cohort Study
No full textInternational audienceThe SARS-CoV-2 variant of concern, α, spread worldwide at the beginning of 2021. It was suggested that this variant was associated with a higher risk of mortality than other variants. We aimed to characterize the genetic diversity of SARS-CoV-2 variants isolated from patients with severe COVID-19 and unravel the relationships between specific viral mutations/mutational patterns and clinical outcomes. This is a prospective multicenter observational cohort study. Patients aged ≥18 years admitted to 11 intensive care units (ICUs) in hospitals in the Greater Paris area for SARS-CoV-2 infection and acute respiratory failure between 1 October 2020 and 30 May 2021 were included. The primary clinical endpoint was day-28 mortality. Full-length SARS-CoV-2 genomes were sequenced by means of next-generation sequencing (Illumina COVIDSeq). In total, 413 patients were included, 183 (44.3%) were infected with pre-existing variants, 197 (47.7%) were infected with variant α, and 33 (8.0%) were infected with other variants. The patients infected with pre-existing variants were significantly older (64.9 ± 11.9 vs. 60.5 ± 11.8 years; p = 0.0005) and had more frequent COPD (11.5% vs. 4.1%; p = 0.009) and higher SOFA scores (4 [3-8] vs. 3 [2-4]; 0.0002). The day-28 mortality was no different between the patients infected with pre-existing, α, or other variants (31.1% vs. 26.2% vs. 30.3%; p = 0.550). There was no association between day-28 mortality and specific variants or the presence of specific mutations. At ICU admission, the patients infected with pre-existing variants had a different clinical presentation from those infected with variant α, but mortality did not differ between these groups. There was no association between specific variants or SARS-CoV-2 genome mutational pattern and day-28 mortali