Locating a weak change using diffuse waves (LOCADIFF) : theoretical approach and inversion procedure

We describe a time-resolved monitoring technique for heterogeneous media. Our approach is based on the spatial variations of the cross-coherence of coda waveforms acquired at fixed positions but at different dates. To locate and characterize a weak change that occurred between successive acquisitions, we use a maximum likelihood approach combined with a diffusive propagation model. We illustrate this technique, called LOCADIFF, with numerical simulations. In several illustrative examples, we show that the change can be located with a precision of a few wavelengths and its effective scattering cross-section can be retrieved. The precision of the method depending on the number of source receiver pairs, time window in the coda, and errors in the propagation model is investigated. Limits of applications of the technique to real-world experiments are discussed.Comment: 11 pages, 14 figures, 1 tabl

AeroMAPS: a framework for performing multidisciplinary assessment of prospective scenarios for air transport

AeroMAPS is an open-source software, also available as a web application, for performing multidisciplinary assessment of prospective scenarios for air transport. Such investigations are a significant challenge for aviation stakeholders but are required to explore and evaluate different transition strategies for the sector. The framework presented in this paper aims to provide these stakeholders with a standardised methodology for simulating prospective scenarios. Developed using the Python programming language and easy to use via Jupyter Notebooks or graphical user interfaces, it enables the rapid exploration of various decarbonisation strategies for research or decision-making audiences. Several scientific computing packages are used to facilitate the modular assembly of models and solve complex numerical problems. The framework is structured around various models derived from the academic literature and newly developed ones. In particular, it can be used to model various components of the air transport system (air traffic, aircraft fleet, energy carriers), assess its environmental (climate and energy resources) and cost impacts, and perform environmental sustainability analyses. An application is proposed in this paper in order to understand the capabilities, interests and limits of the software. Future developments are planned to improve existing models, complete environmental analyses and continue extending to other disciplinary fields (economics, regulation, sociology), in order to make AeroMAPS a systemic and holistic aviation integrated assessment model.

La protéine Tat du VIH-1 active la voie TLR4 : effets sur l'expression des facteurs immunosuppressifs IL-10, PD-L1 et IDO

Au cours de l'infection par le virus de l'immunodéficience humaine de type 1 (VIH-1) on observe une augmentation progressive de l'expression des molécules inhibitrices du système immunitaire (IL-10, PD-L1 et IDO) principalement par les cellules présentatrices d'antigènes (CPA) telles que les cellules dendritiques (DCs). Ces molécules agissent négativement sur la réponse immunitaire anti-VIH et sont associées à la persistance du virus et à l'évolution de la maladie vers le stade SIDA. Une des protéines virales impliquée dans ce mécanisme est la protéine Tat. En plus de son rôle direct dans la transactivation du génome viral, Tat est sécrétée par les cellules infectées et se retrouve à des concentrations de l'ordre du nanomolaire dans le sérum des patients. Dans la circulation, Tat interagit avec les cellules immunitaires et module l'expression de nombreux facteurs incluant des facteurs immunosuppressifs. Les travaux précédents du laboratoire, ont montré que Tat agit au niveau membranaire, par son domaine N-terminal 1-45, afin de stimuler l'expression des cytokines pro-inflammatoires TNF-a, et immunosuppressives IL-10 par les monocytes et les macrophages humains. Plus récemment, la recherche du récepteur membranaire recruté par Tat a permis de mettre en évidence l'implication du TLR4/MD2 dans l'interaction avec Tat. Objectifs : Mon projet de thèse qui s'inscrit dans la continuité des travaux du laboratoire a pour objectif 1) de caractériser davantage le rôle du TLR4 comme récepteurs de Tat en utilisant une approche basée sur des modèles murins invalidés (KO) pour le TLR4 ou ses partenaires moléculaires (CD14, MD2, MyD88, TRIF) 2) d'étudier l'effet de la protéine Tat et de son interaction avec le TLR4 sur la modulation de la fonction des DCs incluant : la production de cytokines, la maturation, l'expression des facteurs immunosuppressifs et la capacité à activer/inhiber les lymphocytes T. Résultats : L'utilisation du modèle de souris KO nous a permis de confirmer le rôle central du TLR4/MD2 comme récepteur de la protéine Tat ainsi que de mieux comprendre le mécanisme moléculaire mis en jeu par Tat pour induire la production de l'IL-10 et du TNF-a impliquant le TLR4 mais également les cofacteurs CD14 et MD2 ainsi que l'activation des deux voies de signalisation MyD88 et TRIF dépendantes. L'étude des effets de l'interaction Tat-TLR4 sur la modulation de la réponse immunitaire des DCs nous a permis de montrer que i) Tat induit la production des cytokines pro-inflammatoires IL-6, IL-12 et des IFN-a et IFN-? en plus de l'IL-10 et du TNF-a ; ii) Tat induit la maturation des DCs en augmentant l'expression de CD83, CD80, CD86 ; iii) Tat stimule l'expression des facteurs immunosuppressifs IL-10, PD-L1 et IDO associées à une inhibition de la prolifération des LT ; iv) l'ensemble de ces effets sont abolis ou inhibés en bloquant l'interaction Tat-TLR4. Conclusions : Nos résultats suggèrent que le VIH-1, par l'intermédiaire de sa protéine Tat, détourne le TLR4 à la surface des CPA pour induire la production de facteurs pro-inflammatoires et stimuler l'expression des molécules immunosuppressives directement associées à la perte de fonction du système immunitaire. Il n'est donc pas exclu que Tat, à cause de son expression précoce, contribue à instaurer un état immunosuppressif très tôt après l'infection et serait aussi impliquée dans l'affaiblissement du système immunitaire et la persistance virale.Human immunodeficiency virus type 1 (HIV-1) infection is associated with a gradual increase in the expression of inhibitory molecules including IL-10, PD-L1 and IDO essentially by antigen presenting cells (APCs) such as dendritic cells (DCs). These molecules act negatively on the anti-HIV immune response and are associated with viral persistence and disease progression towards AIDS. One of the viral protein involved in this mechanism is Tat. In HIV-1 infected patients, Tat is secreted in the sera at nanomolar levels. In addition to its role in viral cycle, Tat interacts with immune cells to modulate the expression of many host genes including immunosuppressive factors. Previous work from our laboratory have shown that Tat protein, by acting at the membrane level, via its 1-45 N-terminal domain, stimulates the expression of pro-inflammatory cytokines TNF-a, and immunosuppressive IL-10 production in human monocytes and macrophages. More recently, we have shown the involvement of TLR4/MD2 in the interaction with Tat. Aim of the study: The objective of my thesis was to 1) Further characterize the implication of TLR4/MD2 as potential receptor of Tat protein. To this end mouse models invalidated (KO) for TLR4 or its molecular partners (CD14, MD2, MyD88, TRIF) were used 2) Study the effect of Tat protein and its interaction with TLR4/MD2 on the modulation of DCs functions including cytokine production, maturation, and the expression of immunosuppressive factors and their effects on the stimulation or inhibition of T cells activation. Results: The use of knockout mouse models has allowed us to confirm the central role of TLR4/MD2 as receptor for Tat protein and to better understand the signalling pathways recruited by Tat to stimulate the production of IL-10 and TNF-a. Our results showed the importance of CD14 and MD2 in addition to TLR4 and demonstrated that Tat activates both TRIF and MyD88-dependent pathways. In parallel, the study of the effects of Tat-TLR4 interaction on the modulation of the immune response of DCs allowed us to show that i) Tat induces the production of pro-inflammatory cytokines IL-6, IL-12 and IFN-a and IFN-? in addition to IL-10 and TNF-a ii) Tat induces the maturation of DCs by increasing the expression of CD83, CD80, CD86 and iii) Tat stimulates the expression of immunosuppressive factors IL-10, PD-L1 and IDO in association with the inhibition of T cells proliferation. iv) All these effects were abolished or inhibited following the blockade of Tat-TLR4 interaction. Conclusions: Our results suggest that HIV-1 by its Tat protein hijacks TLR4 pathway in APCs to induce the production of pro-inflammatory and immunosuppressive factors which are associated with the impairment of immune functions. It is therefore possible that, because of its early expression, Tat may help to establish an immunosuppressive state early after infection and thus contributed in the weakening of the immune system and viral persistence

Compilation of an open-source traffic and CO2 emissions dataset for commercial aviation

The study of the environmental transition of the aviation sector calls for prospective traffic scenarios. Detailed traffic and emissions inventories are often needed to refine the available analyses and to enable the simulation of regionalised scenarios. In the past studies, these are generally based on commercial, proprietary traffic data, making their dissemination problematic and reducing the reproducibility of the science produced. Open-source alternatives do exist, but with limited geographical coverage. This paper presents a method to aggregate different sources of flight information, in order to obtain an open-source air traffic dataset for 2019. Then, missing flight information is identified and completed using an airline route database built from Wikipedia parsing and related socio-economic data. After that, several reference datasets are used to evaluate the accuracy of the extended open-source dataset. Despite varying accuracy for different routes, major traffic flows are reasonably well estimated at the country and continental levels.Finally, the CO2 emissions are obtained using an existing aircraft performance surrogate model, and the accuracies are examined compared to the results from previous studies

Compilation and Applications of an Open-Source Dataset on Global Air Traffic Flows and Carbon Emissions

The study of the environmental transition of the aviation sector calls for prospective traffic scenarios. Detailed traffic and emissions inventories are often needed to refine the available analyses and to enable the simulation of regionalised scenarios. In the past studies, these are generally based on commercial, proprietary traffic data, making their dissemination problematic and reducing the reproducibility of the science produced. Open-source alternatives do exist but with limited geographical coverage. This study bridges this gap by presenting an innovative open-source dataset detailing 2019\u27s global air traffic flows and associated CO2 emissions. A comprehensive approach that compiles diverse flight data sources is presented. The remaining data gaps are addressed by constructing a route network through systematic Wikipedia parsing and by estimating the related traffic using socio-economic data. Then, an aircraft performance model to estimate CO2 emissions is implemented. This methodology promises reinforced reproducibility and broader data accessibility in aviation environmental research. Several reference datasets are used to evaluate the accuracy of the open-source dataset. Despite various levels of accuracy for individual routes, major traffic flows are well estimated at the country and continental levels, albeit with room for refinement to ensure consistent data reliability. To facilitate the exploration of the dataset, the AeroSCOPE tool has been developed. To initiate research prospects, use cases of this dataset are proposed, concerning the network potential of electric and hydrogen-powered aircraft and inequalities in air transport

Reviews and responses for AeroMAPS: a framework for performing multidisciplinary assessment of prospective scenarios for air transport

See detailed reviews and responses in the PDF file. DOI for the original paper: https://doi.org/10.59490/joas.2023.714

Original Article

The pancreas taken from the frog (Rana nigromaculata) was fixed in 1% OsO_4 and sliced into ultrathin sections for electron microscopic studies. The following observations were made: 1. A great \u27number of minute granules found in the cytoplasm of a pancreatic cell were called the microsomes, which were divided into two types, the C-microsome and S-microsome. 2. Electron microsopic studies of the ergastoplasm showed that it is composed of the microsome granules and A-substance. The microsomes were seen embedded in the A-substance which was either filamentous or membranous. The membranous structure, which was called the Am-membrane, was seen to form a sac, with a cavity of varying sizes, or to form a lamella. 3. The Am-membrane has close similarity to α-cytomembrane of Sjostrand, except that the latter is rough-surfaced. It was deduced that the Am-membrane, which is smooth-surfaced, might turn into the rough-surfaced α-cytomembrane. 4. There was the Golgi apparatus in the supranuclear region of a pancreatic cell. It consisted of the Golgi membrane, Golgi vacuole and. Golgi vesicle. 5. The mitochondria of a pancreatic cell appeared like long filaments, and some of them were seen to ramify. 6. The membrane of mitochondria, i. e. the limiting membrane, consisted of the Ammembrane. The mitochondria contained a lot of A-substances, as well as the C-microsomes and S-microsomes. When the mitochondria came into being, there appeared inside them chains of granules, which appeared like strips of beads, as the outgrowths of the A-substance and the microsome granules attached to the Am-membrane. They are the so-called cristae mitochondriales. 7. The secretory granules originate in the microsomes. They came into being when the microsomes gradually thickened and grew in size as various substances became adhered to them. Some of the secretory granules were covered with a membrane and appeared like what they have called the intracisternal granule of Palade.It seemed that this was a phenomenon attendant upon the dissolution and liqutefaction of the secretory granule. 8. Comparative studies were made of the ergastoplasm of the pancreatic cells from the frogs in hibernation, the frogs artificially hungered, the frogs which were given food after a certain period of fasting, the frogs to which pilocarpine was given subcutaneously, and the very young, immature frogs. The studies revealed that the ergastoplasm of the pancreatic cells greatly varied in form with the difference in nutritive condition and with different developmental stages of the cell. The change in form and structure occured as a result of transformation of the microsomes and A-substance. The ergastoplasm, even after it has come into being, might easily be inactivated if nutrition is defective. The ergastoplasm is concerned in the secretory mechanism, which is different from the secretory phenomenon of the secretory granules. It would seem that structurally the mitochondria have no direct relation to this mechanism

Reviews and responses for Compilation of an open-source traffic and CO2 emissions dataset for commercial aviation

See detailed reviews and responses in the PDF file. DOI for the original paper: https://doi.org/10.59490/joas.2023.720