Vers le développement d'une station de télécommunication aérienne pour le milieu isolé

RÉSUMÉ : Le projet de recherche « Développement d'une station de télécommunication aérienne pour le milieu isolé » est basé sur la problématique de la quasi-absence de solutions de télécommunication pour le milieu isolé à part les tours de télécommunication, déployées partiellement, la fibre optique très onéreuse et présente dans de petits secteurs isolés et le satellite avec des coûts d'utilisation assez importants. Pourtant, lorsque l'on prend l'exemple du nord du Québec, la population, mais aussi certains secteurs industriels comme les mines ou le fret ferroviaire revendiquent la nécessité d'avoir des solutions de télécommunication innovantes ou à défaut simplement adéquates. La thèse, après avoir balayé en détail et évalué toutes les solutions de télécommunication existantes, propose une solution innovante : le ballon captif de télécommunications. Cette solution avec peu de ballons répartis sur un vaste secteur isolé permet de lui apporter une couverture radio totale. Cette solution est autonome en alimentation électrique et est déployable rapidement sur site. Les ballons captifs associés à des nanosatellites en plein essor de nos jours permettront d'apporter au milieu isolé les dernières technologies de télécommunication comme l'internet des objets, réservées pour le moment au milieu urbain. Ce projet de développement d'une solution de ballons captifs-nanosatellite pour le milieu isolé est en réalité un vaste projet dans lequel s'insère la thèse. Cette dernière vise donc à développer et à valider des concepts pour le milieu isolé qui seront utilisés lorsque, plus tard, les ballons et les nanosatellites se parleront dans le milieu isolé. L'un de ces concepts, la géolocalisation, constitue une des problématiques majeures en milieu isolé avec de multiples applications: la géolocalisation de personnes comme les employés travaillant dans les mines, la géolocalisation de trains nordiques, la géolocalisation de matériel, ou la géolocalisation d'animaux pour évaluer leur parcours migratoire par exemple. La thèse s'articule donc autour des thématiques de milieu isolé, de paramètres d'un système de télécommunication, de l'internet des objets, de techniques de géolocalisation avec estimateurs. Quatre études de cas sont mises en œuvre dans cette thèse, en utilisant pour chacune d'elles des techniques de modélisation, de simulations et bien évidemment de validations expérimentales. La première étude de cas a permis de développer avec succès un système de sécurité ferroviaire, pour des employés d'une compagnie ferroviaire travaillant sur des voies ferrées au nord du Québec en milieu isolé, donc sans connexion internet ni réseau électrique, avec la mise en œuvre d'un système de télécommunication basé sur le protocole IEEE 802.15.4. La seconde étude de cas a consisté à étudier la portée d'un système de télécommunication internet des objets utilisant le protocole LoRaWAN dans le cadre du milieu isolé: un résultat de 25 km a été établi. La troisième étude de cas, fondamentale dans un environnement isolé est concentrée sur l'optimisation de l'autonomie en énergie d'un nœud LoRa, donc pour l'internet des objets: une autonomie de 5 ans sur batterie lithium-ion a été obtenue. Enfin la dernière étude de cas met en œuvre un système de géolocalisation par l'internet des objets avec étude de différents estimateurs : une précision de 20 cm sur la géolocalisation d'un nœud LoRa a été obtenue. Ce projet de recherche a permis d'apporter des résultats fort intéressants et très prometteurs sur des concepts très présents dans les thématiques de recherche actuelles. Ces contributions scientifiques ont d'ailleurs débouché sur la publication d'un article et la soumission d'un autre, mais surtout, elles se manifesteront par un potentiel de soumission de 3 articles sous peu. Enfin, ce travail de recherche démontre la pertinence de l'association entre ballons captifs et nanosatellites pour le milieu isolé et il pose les bases du développement de cette solution innovante. -- Mot(s) clé(s) en français : milieu isolé, systèmes de télécommunication sans il, ballons captifs, photovoltaïque, internet des objets, LoRaWAN, géolocalisation, estimateurs, nanosatellites. -- ABSTRACT : "Development of an aerial telecommunication station for the isolated environment" research project is based on the problem of the lack of telecommunication solutions for the isolated environment apart from the telecommunication towers, partially deployed, the very expensive optical fiber located in small isolated areas and the satellite with fairly high operating costs. However, when we take the example of northern Quebec, the population but also certain industrial domains such as mining or rail freight claim the need for innovative or, by default, simply adequate telecommunication solutions. The thesis after having swept in detail and evaluated all the existing telecommunication solutions proposes an innovative solution: the tethered telecommunication balloon. This solution with few balloons distributed over a large isolated sector provides a high radio coverage. This solution is autonomous in terms of power supply and can be quickly deployed on the site. The tethered balloons associated with nanosatellites which is booming nowadays will bring to the isolated environment the latest telecommunication technologies like the internet of things reserved for the moment for urban environments. This project consisting to associate tethered balloons with nanosatellites for the isolated environment, is actually a vast project in which the thesis is part. Therefore, the thesis aims to develop and validate concepts for the isolated environment that will be used later, when tethered balloons and nanosatellites will talk to each other in the isolated environment. One of these concepts, the geolocalization, is one of the major issues in isolated environment with lots of applications: the geolocalization of people such as employees working in mines, the geolocalization of Nordic trains, the geolocalization of equipments, or the geolocalization of animals to assess their migratory journey, for example. Therefore, the thesis revolves around the themes of an isolated environment, of parameters for telecommunication systems, of the Internet of Things, of the geolocalization technics with estimators. Four case studies are implemented in this thesis, each using modeling, simulations and obviously experimental validation technic. The first case study made it possible to successfully develop a railway safety system, for employees of a railway company working on railways in northern Quebec in isolated areas therefore without internet connection or neither electrical network: the solution which has been developed was based on a telecommunication system working with the IEEE 802.15.4 protocol. The second case study consisted of studying the range of an Internet of Things telecommunication system based on the LoRaWAN protocol in the isolated environment context: a result of 25 km was established. The third case study, very important in an isolated sector, focuses on optimizing the energy autonomy of a LoRa node therefore for the Internet of Things: a 5-year autonomy on lithium-ion battery was obtained. Finally, the last case study implements a geolocalization system via the Internet of Things with a study of different estimators: a LoRa node geolocalization accuracy of 20 cm was obtained. This research project has made it possible to obtain very interesting and very promising results on concepts very present in current research themes. These scientific contributions result in the publication of one article and the submission of another one, but more importantly, there will be a potential submission of 3 articles. Finally, this research job demonstrates the relevance of the combination of tethered balloons and nanosatellites for isolated environments and it gives the foundations for the development of this innovative solution. -- Mot(s) clé(s) en anglais : isolated environment, wireless telecommunication systems, tethered balloons, photovoltaics, internet of things, LoRaWAN, geolocalization, estimators, nanosatellites

PAR-2-induced colonic inflammation does not depend upon paracellular permeability and lymphocyte infiltration

PAR-2-induced colonic inflammation does not depend upon paracellular permeability and lymphocyte infiltration. 10th United European Gastroenterology Wee

The food contaminant deoxynivalenol, decreases intestinal barrier permeability and reduces claudin expression

The gastrointestinal tract represents the first barrier against food contaminants as well as the first target for these toxicants. Deoxynivalenol (DON) is a mycotoxin that commonly contaminates cereals and causes various toxicological effects. Through consumption of contaminated cereals and cereal products, human and pigs are exposed to this mycotoxin. Using in vitro, ex vivo, and in vivo approaches, we investigated the effects of DON on the intestinal epithelium. We demonstrated that, in intestinal epithelial cell lines from porcine (IPEC-1) or human (Caco-2) origin, DON decreases trans-epithelial electric resistance (TEER) and increases in a time and dose-dependent manner the paracellular permeability to 4 kDa dextran and to pathogenic Escherichia Coli across intestinal cell monolayers. In pig explants treated with DON, we also observed an increased permeability of intestinal tissue. These alterations of barrier function were associated with a specific reduction in the expression of claudins, which was also seen in vivo in the jejunum of piglets exposed to DON-contaminated feed. In conclusion, DON alters claudin expression and decreases the barrier function of the intestinal epithelium. Considering that high levels of DON may be present in food or feed, consumption of DON-contaminated food/feed may induce intestinal damage and has consequences for human and animal health

Universal Loss Dynamics in a Unitary Bose Gas

The low temperature unitary Bose gas is a fundamental paradigm in few-body and many-body physics, attracting wide theoretical and experimental interest. Here we first present a theoretical model that describes the dynamic competition between two-body evaporation and three-body re-combination in a harmonically trapped unitary atomic gas above the condensation temperature. We identify a universal magic trap depth where, within some parameter range, evaporative cooling is balanced by recombination heating and the gas temperature stays constant. Our model is developed for the usual three-dimensional evaporation regime as well as the 2D evaporation case. Experiments performed with unitary 133 Cs and 7 Li atoms fully support our predictions and enable quantitative measurements of the 3-body recombination rate in the low temperature domain. In particular, we measure for the first time the Efimov inelasticity parameter $\eta$ * = 0.098(7) for the 47.8-G d-wave Feshbach resonance in 133 Cs. Combined 133 Cs and 7 Li experimental data allow investigations of loss dynamics over two orders of magnitude in temperature and four orders of magnitude in three-body loss. We confirm the 1/T 2 temperature universality law up to the constant $\eta$ *

Influence of Language on Colour Perception: A Simulationist Explanation

“How can perception be altered by language?” is the fundamental question of this article. Indeed, various studies have pointed out the influence of colour-related knowledge on object and colour perception, evoked by linguistic stimuli. Here the relevance of the simulationist approach is assumed in order to explain this influence, where the understanding of colour-related words or sentences involves a process of colour simulation that is supported by a neuronal network partially similar to the network involved in colour perception. Consequently, colour-related knowledge and colour perception can interact through a process of pattern interference. In support of this idea, studies are discussed showing priming effects between colour simulation and colour perception, but two limitations are also raised. Firstly, these works all used between-category colour discrimination tasks that allow the intervention of lexical processes that can also explain priming. Secondly, these works control the congruency link between prime and target at the level of ‘colour category’, and no demonstration is made of an influence at the level of specific hues. Consequently, the simulationist view of language/perception interactions seems an interesting way to thinking but more experimens are needed in order to overcome some limitations

Coral bleaching under thermal stress: putative involvement of host/symbiont recognition mechanisms

<p>Abstract</p> <p>Background</p> <p>Coral bleaching can be defined as the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from their cnidarian host. This major disturbance of reef ecosystems is principally induced by increases in water temperature. Since the beginning of the 1980s and the onset of global climate change, this phenomenon has been occurring at increasing rates and scales, and with increasing severity. Several studies have been undertaken in the last few years to better understand the cellular and molecular mechanisms of coral bleaching but the jigsaw puzzle is far from being complete, especially concerning the early events leading to symbiosis breakdown. The aim of the present study was to find molecular actors involved early in the mechanism leading to symbiosis collapse.</p> <p>Results</p> <p>In our experimental procedure, one set of <it>Pocillopora damicornis </it>nubbins was subjected to a gradual increase of water temperature from 28°C to 32°C over 15 days. A second control set kept at constant temperature (28°C). The differentially expressed mRNA between the stressed states (sampled just before the onset of bleaching) and the non stressed states (control) were isolated by Suppression Subtractive Hybridization. Transcription rates of the most interesting genes (considering their putative function) were quantified by Q-RT-PCR, which revealed a significant decrease in transcription of two candidates six days before bleaching. RACE-PCR experiments showed that one of them (<it>PdC-Lectin</it>) contained a C-Type-Lectin domain specific for mannose. Immunolocalisation demonstrated that this host gene mediates molecular interactions between the host and the symbionts suggesting a putative role in zooxanthellae acquisition and/or sequestration. The second gene corresponds to a gene putatively involved in calcification processes (<it>Pdcyst-rich</it>). Its down-regulation could reflect a trade-off mechanism leading to the arrest of the mineralization process under stress.</p> <p>Conclusion</p> <p>Under thermal stress zooxanthellae photosynthesis leads to intense oxidative stress in the two partners. This endogenous stress can lead to the perception of the symbiont as a toxic partner for the host. Consequently, we propose that the bleaching process is due in part to a decrease in zooxanthellae acquisition and/or sequestration. In addition to a new hypothesis in coral bleaching mechanisms, this study provides promising biomarkers for monitoring coral health.</p

Fecal Protease Activity Is Associated with Compositional Alterations in the Intestinal Microbiota

Intestinal proteases carry out a variety of functions in the gastrointestinal (GI) tract. Studies have reported that elevated enteric proteases in patients with GI disease can alter intestinal physiology, however the origin (human vs. microbial) of elevated proteases in patients with GI disease is unclear

Fecal Protease Activity Is Associated with Compositional Alterations in the Intestinal Microbiota

Intestinal proteases carry out a variety of functions in the gastrointestinal (GI) tract. Studies have reported that elevated enteric proteases in patients with GI disease can alter intestinal physiology, however the origin (human vs. microbial) of elevated proteases in patients with GI disease is unclear