Science & Mathematics

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Pour se protéger des fortes illuminations, les cyanobactéries ont développé un mécanisme de photo-protection nommé qEcya. Sous forte lumière, il diminue la formation d'espèces dérivées de l'oxygène très réactives et dangereuses, en augmentant la dissipation de l'énergie absorbée sous forme de chaleur. L'énergie provenant des phycobilisomes (PBS, les antennes externes des cyanobactéries) atteignant les centres réactionnels est ainsi diminuée. Le mécanisme est induit par l'absorption de la lumière bleue-verte par une protéine photoactive soluble qui attache un caroténoïde : l'Orange Carotenoïd Protein (OCP). Le processus est accompagné d'une diminution de fluorescence réversible. Dans une étude sur les mécanismes de photo-protection sous carence en fer, nous avons montré que le large quenching de fluorescence induit par la lumière bleue-verte est associé à l'OCP et au mécanisme qEcya. Et qu'il n'est pas associé à la protéine IsiA induite sous carence en fer comme cela avait été suggéré dans le passé. Ensuite, j'ai montré que l'OCP et son mécanisme de photo-protection associé sont répandus chez les cyanobactéries à phycobilisomes. Alors que les cyanobactéries contenant l'OCP augmentent leur dissipation d'énergie au niveau des phycobilisomes pour diminuer l'énergie arrivant aux centres réactionnels, il est apparu que les quelques cyanobactéries ne contenant pas l'OCP ont développé une autre stratégie basée sur la dégradation rapide de leurs phycobilisomes en condition de stress. Des résultats préliminaires sur les interactions OCP-PBS sont aussi décrits dans ce travail. Des PBS incubés en présence de l'OCP ont été co-isolés en complexes OCP-PBS dans un gradient de saccharose, même quand seulement des cœurs de PBS ont été mis en présence de l'OCP. Ces résultats suggèrent fortement que l'OCP et les PBS interagissent. Cependant le mécanisme qEcya n'a pas pu être induit in vitro sur ces complexes OCP-PBS purifiés. Le résultat principal de cette thèse est la découverte d'un nouvel acteur essentiel au mécanisme qEcya: une protéine de 13kDa fortement attachée à la membrane. Nous l'avons nommée la Fluorescence Recovery Protein, FRP, car elle est impliquée dans la récupération de l'émission de fluorescence des phycobilisomes dans le mécanisme qEcya après une forte illumination de lumière bleue-verte. La caractérisation de son gène, slr1964, a montré qu'il est conservé en aval du gène de l'OCP chez les cyanobactéries, et qu'il peut être transcrit indépendamment ou co-transcrit avec le gène de l'OCP. De plus, notre étude suggère fortement que l'OCP et la FRP interagissent.

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Swirling flow has been shown to increase heat transfer in heat exchangers. However, producing swirl while not presenting a severe pressure drop can be a challenge. In this paper, a desired shape of guidance blades for laminar swirl flow is determined by numerical simulation in OpenFOAM. Emphasis is on the mesh technique, where a predefined blade shape is formed by mesh twisting, or morphing. The validity of numerical simulations on a twisted mesh is shown by comparing it to the theoretical solution of laminar flow in a pipe without swirl and guidance blades. A sensitivity study shows that a cell size ratio of 0.025 of diameter is sufficient and affects the solution minimally. To determine the desired shape of guidance blades previously found optimal swirl decay and velocity profile for laminar swirling flow are utilized. Three blade shapes are explored: (I) with a twist angle that varies with axial location only; (II) having a deviation angle matching the theoretical deviation angle for laminar swirling flow; (III) same as II but with a hollow center. Simulations are performed for Re = 100 and swirl number S = 0.2 . Case II is able to sustain swirl longest while maintaining a low pressure drop and is therefore a desired swirler shape profile as predicted theoretically.

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WAARDERING VAN BELEGGINGEN BIJ MAATSCHAPPIJEN VAN LEVENSVERZEKERING, BEDRIJFS- EN ONDERNEMINGSPENSIOENFONDSEN

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Vision-based at-home health monitoring is a growing and effective modality for unobtrusively and inexpensively tracking the health of vulnerable people without the kind of sacrifice of autonomy that accompanies residing in a hospital or a care home. The vision modality comes with its own set of unique challenges, principally the preservation of privacy. This paper demonstrates, using three face obfuscation methods, that pose-based actionrecognition is essentially unaffected by privacy-preserving routines.

The research addresses the study of heat exchange between heavy crude oil and the environment during surface pumping, specifically of a crude oil with an API gravity of 17.5, under the particular atmospheric conditions of Eastern Ecuador. The main objective of the study is to evaluate the temperature loss in a 50-meter segment of SCH-80 pipe, with a diameter of 4 inches, used for the transportation of heavy crude. This aims to understand how heavy crude loses temperature and to determine the convective coefficient, knowing that the heat loss from the fluid to the environment occurs mainly by convection. This is to determine what the temperature losses will be in longer pipe sections. For this purpose, a methodology using computational fluid dynamics (CFD) simulation was employed, a key tool for predicting the thermal behavior of crude in interaction with the environment. It was determined that the convective coefficient is 52 W/m2.K, and there is a temperature loss of 3.2 K in the 50-meter section. With this data, future research could evaluate potential heating technologies that facilitate the transport of heavy crude oil. This approach would allow for exploring innovative solutions to improve efficiency and effectiveness in managing heavy crude, facing one of the main challenges in its transport: managing its high viscosity

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Research projects in ecology or biodiversity either start with an area of study or a target species list. Working with these species lists or taxonomic lists is not as straightforward as it seems. The taxonomic names that are considered to be "standard," are surprisingly dynamic. Over time, the names keep changing with ongoing research and advancements in taxonomy. Additionally, they undergo all sorts of reorganization, such as one species being split into multiple species and/or subspecies, the grouping of multiple species into a single species, and the reclassification of species from one genus to another. Compiling a consistent target species list can be very time consuming and tricky. However it is the initial step in most research projects and needs to be completed in order to continue the research.Advancements in biodiversity informatics are helping simplify and automate some of these tasks. There are several web services that provide taxonomic data with either a taxonomic or a geographic focus. An increasing number of experts are opening access to their carefully curated taxonomic lists. Even with the help of these services, a lot of time needs to be spent to create a working list of names that can be linked to data such as Global Biodiversity Information Facility (GBIF) mediated occurrence data. The package "taxotools" (Barve 2021) provides basic taxonomic list processing functions within the R programming environment (R Core Team 2021). Even though it is a work in progress, the functions available so far are applicable to diverse projects. The tools available can be categorized into the following broad areas:Name manipulation: A set of helper functions to check scientific names with global name resolution services like Global Names Architecture (GNA) & GBIF Name Parser, and to construct and deconstruct scientific names to and from components like genus, species and subspecific units.Name matching: Matches names either with global name services or with user-created master taxonomy lists using fuzzy matching, testing combinations of genus level synonyms, subspecies elevation to species, trying to match with higher level taxonomic entities like genus and family, and employing a user-defined lookup table to manually resolve names.List processing: Updates list fields such as unique identifiers (id), higher taxonomy and taxonomic ranks.List matching: Compares user generated lists with each other and finds differences in the two lists, then prepares the lists for merging together to form a masterlist.Format conversion: Converts taxolist to and from formats like HTML and Darwin Core (Wieczorek et al. 2021), which is useful in data exchange or checking the lists manually.Name harvesting functions: Acquires additional names from Integrated Taxonomic Information System (ITIS) and Wikipedia (taxonomy infobox).Detailed function listings under each category are listed in Table 1.This package has been effectively used in several biodiversity studies and projects like Map of Life, ButterflyNet, Terrestrial Parasite Tracker etc. It has been successfully tested on a masterlist constructed with ~1M names from World Flora Online and performs well.The package is available on The Comprehensive R Archive Network (CRAN) [https://CRAN.R-project.org/package=taxotools] and the developmental release is on GitHub [https://github.com/vijaybarve/taxotools].