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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Dynamique de l’holobionte corallien et plasticité transcriptomique : variabilité interindividuelle, interpopulationnelle et interspécifique / Dynamics of the coral holobionte and transcriptomic plasticity : variability inter individual, inter populational and interspecific

Brener-Raffalli, Kelly 09 November 2017 (has links)
Dans le contexte du réchauffement climatique, les récifs coralliens subissent des stress thermiques de plus en plus fréquents et intenses. Dans le but de mieux comprendre les mécanismes de la thermo­tolérance des coraux, j’ai développé une approche intégrative sur l’holobionte corallien (méta­organisme composé de l’hôte corallien, son algue symbiotique etson microbiote). Pour cela, j’ai réalisé une expérience de stress thermique écologiquement réaliste sur une espèce de corail, Pocillopora damicornis. Cette espèce étant présente dans l’ensemble de l’Indo­Pacifique, j’ai pu comparer la réponse de deux populations dont la thermotolérance est différente puisqu’elles sont soumises à des régimes thermiques contrastés. J’ai analysé, pour chacune d’entre­elles, la réponse de l’hôte corallien (par RNAseq), ainsi que la structure et les changements au niveau des microbiotes algaux et bactériens (par métabarcoding). Les résultats obtenus montrent qu’alors que la structure du microbiote n’est pas influencée par le stress, le corail y répond de façon très différente selon la population étudiée. La population issue d’un environnement plus fluctuant met en place une réponse plus efficace et plus plastique, probablement grâce à l’intervention de mécanismes épigénétiques. Une autre étude réalisée sur différentes populations de P. damicornis dans le cadre de cette thèse montre que la composition du microbiote est influencée par le génome de l’hôte ainsi que par le régime thermique. Un des clades de l’algue symbiotique connu pour améliorer la thermo­ tolérance de l’hôte corallien semble plus sensible aux basses températures que les autres. / In the context of global warming, coral reefs are experiencing thermal stresses which are becoming more frequent and intense. In order to get a better understanding of the mechanisms of coral thermo­tolerance, I developed an integrative approach on the coral holobiont (meta­ organism composed of the coral host, its symbiotic algae and microbiota). For this, I performed an ecologically realistic thermal stress experiment on a coral species, Pocillopora damicornis. This species is widespread in the Indo­Pacific area. I compared the response of two populations whose thermotolerance is different since they are subjected to contrasting thermal regimes. I analyzed, for each of them, the response of the coral host (by RNAseq), as well as the structure and changes in the algal and bacterial microbiota (by metabarcoding). The results show that,while the structure of the microbiota is not influenced by stress, coral responds very differently depending on the population studied. The population from a more fluctuating environment displays a more effective and more plastic response, probably thanks to the involvement of epigenetic mechanisms. Another study carried out on different populations of P. damicornisshowed that the composition of the microbiota is influenced by the host genome and the thermal regime. One of the clades of the symbiotic algae, known to improve the heat­tolerance of the coral host, appears more sensitive to low temperatures than the others.
2

Subsystemmethodik für die Auslegung des niederfrequenten Schwingungskomforts von PKW

Angrick, Christian 16 January 2018 (has links) (PDF)
Um eine zielgerichtete Ableitung von Fahrzeugeigenschaften in frühen Entwicklungsphasen zu ermöglichen, ist eine Subsystemebene erforderlich, die eine konzeptunabhängige Auslegung des Gesamtfahrzeugverhaltens zulässt. In der vorliegenden Arbeit wird daher eine neue Methodik zur Auslegung von Fahrkomfort-Kennwerten auf Basis von Subsystemeigenschaften vorgestellt. Neben der Entwicklung eines geeigneten Modellansatzes, in dem die Subsysteme des Gesamtfahrzeugs durch Greybox-Modelle ohne Komponentenbezug miteinander verknüpft werden, stehen dabei auch dessen Parametrierung sowie die Integration der Methodik im Entwicklungsprozess im Vordergrund. Zur Ableitung der damit verbundenen physikalisch-mechanischen Zusammenhänge werden statische und dynamische Achsprüfstände sowie Simulationen eingesetzt. Die Anwendung der Methodik lässt eine gezielte Eigenschaftsableitung zwischen Gesamtfahrzeug-, Subsystem- und Komponentenebene im Fahrkomfort zu, bei der die Subsystemebene als neue Referenz für die Ableitung von Komponenteneigenschaften dient. Weiterhin erlaubt das Vorgehen eine eigenschaftsbasierte Vorauswahl optimaler Komponentenkonzepte sowie detaillierte Wettbewerbsanalysen. Dadurch wird eine nachhaltige Steigerung der Effizienz im Entwicklungsprozess des Fahrkomforts ermöglicht.
3

<b>Leveraging Whole Brain Imaging to Identify Brain Regions Involved in Alcohol Frontloading</b>

Cherish Elizabeth Ardinger (9706763) 03 January 2024 (has links)
<p dir="ltr">Frontloading is an alcohol drinking pattern where intake is skewed toward the onset of access. The goal of the current study was to identify brain regions involved in frontloading using whole brain imaging. 63 C57Bl/6J (32 female and 31 male) mice underwent 8 days of binge drinking using drinking-in-the-dark (DID). Three hours into the dark cycle, mice received 20% (v/v) alcohol or water for two hours on days 1-7. Intake was measured in 1-minute bins using volumetric sippers, which facilitated analyses of drinking patterns. Mice were perfused 80 minutes into the day 8 DID session and brains were extracted and processed for iDISCO clearing and c-fos immunohistochemistry. For brain network analyses, day 8 drinking patterns were used to characterize mice as frontloaders or non-frontloaders using a change-point analysis described in our recent ACER publication (Ardinger et al., 2022). Groups were female frontloaders (n = 20), female non-frontloaders (n = 2), male frontloaders (n = 13) and male non-frontloaders (n = 8). There were no differences in total alcohol intake as a function of frontloading status. Water drinkers had an n of 10 for each sex. As only two female mice were characterized as non-frontloaders, it was not possible to construct a functional correlation network for this group. Following light sheet imaging, ClearMap2.1 was used to register brains to the Allen Brain Atlas and detect fos+ cells. Functional correlation matrices were calculated for each group from log<sub>10</sub> c-fos values. Euclidean distances were calculated from these R values and hierarchical clustering was used to determine modules (highly connected groups of brain regions) at a tree-cut height of 50%. In males, alcohol access decreased modularity (3 modules in both frontloaders and non-frontloaders) as compared to water drinkers (7 modules). In females, an opposite effect was observed. Alcohol access (9 modules) increased modularity as compared to water drinkers (5 modules). These results suggest sex differences in how alcohol consumption reorganizes the functional architecture of networks. Next, key brain regions in each network were identified. Connector hubs, which primarily facilitate communication between modules, and provincial hubs, which facilitate communication within modules, were of specific interest for their important and differing roles. In males, 4 connector hubs and 17 provincial hubs were uniquely identified in frontloaders (i.e., were brain regions that did not have this status in male non-frontloaders or water drinkers). These represented a group of hindbrain regions (e.g., locus coeruleus and the pontine gray) connected to striatal/cortical regions (e.g., cortical amygdalar area) by the paraventricular nucleus of the thalamus. In females, 16 connector and 17 provincial hubs were uniquely identified which were distributed across 8 of the 9 modules in the female alcohol drinker network. Only one brain region (the nucleus raphe pontis) was a connector hub in both sexes, suggesting that frontloading in males and females may be driven by different brain regions. In conclusion, alcohol consumption led to fewer, but more densely connected, groups of brain regions in males but not females, and recruited different hub brain regions between the sexes. These results suggest target brain regions for future studies to try to manipulate frontloading behavior and more broadly contribute to the literature on alcohol’s effect on neural networks.</p>
4

Automotive Powertrain Software Evaluation Tool

Powale, Kalkin 08 February 2018 (has links) (PDF)
The software is a key differentiator and driver of innovation in the automotive industry. The major challenges for software development are increasing in complexity, shorter time-to-market, increase in development cost and demand of quality assurance. The complexity is increasing due to emission legislations, variants of product and new communication technologies being interfaced with the vehicle. The shorter development time is due to competition in the market, which requires faster feedback loops of verification and validation of developed functionalities. The increase in development cost is contributed by two factors; the first is pre-launch cost, this involves the cost of error correction in development stages. Another is post-launch cost; this involves warranty and guarantees cost. As the development time passes the cost of error correction also increases. Hence it is important to detect the error as early as possible. All these factors affect the software quality; there are several cases where Original Equipment Manufacturer (OEM) have callbacks their product because of the quality defect. Hence, there is increased in the requirement of software quality assurance. The solution for these software challenges can be the early quality evaluation in continuous integration framework environment. The most prominent in today\'s automotive industry AUTomotive Open System ARchitecture (AUTOSAR) reference architecture is used to describe software component and interfaces. AUTOSAR provides the standardised software component architecture elements. It was created to address the issues of growing complexity; the existing AUTOSAR environment does have software quality measures, such as schema validations and protocols for acceptance tests. However, it lacks the quality specification for non-functional qualities such as maintainability, modularity, etc. The tool is required which will evaluate the AUTOSAR based software architecture and give the objective feedback regarding quality. This thesis aims to provide the quality measurement tool, which will be used for evaluation of AUTOSAR based software architecture. The tool reads the AUTOSAR architecture information from AUTOSAR Extensible Markup Language (ARXML) file. The tool provides configuration ability, continuous evaluation and objective feedback regarding software quality characteristics. The tool was utilised on transmission control project, and results are validated by industry experts.
5

Subsystemmethodik für die Auslegung des niederfrequenten Schwingungskomforts von PKW

Angrick, Christian 14 August 2017 (has links)
Um eine zielgerichtete Ableitung von Fahrzeugeigenschaften in frühen Entwicklungsphasen zu ermöglichen, ist eine Subsystemebene erforderlich, die eine konzeptunabhängige Auslegung des Gesamtfahrzeugverhaltens zulässt. In der vorliegenden Arbeit wird daher eine neue Methodik zur Auslegung von Fahrkomfort-Kennwerten auf Basis von Subsystemeigenschaften vorgestellt. Neben der Entwicklung eines geeigneten Modellansatzes, in dem die Subsysteme des Gesamtfahrzeugs durch Greybox-Modelle ohne Komponentenbezug miteinander verknüpft werden, stehen dabei auch dessen Parametrierung sowie die Integration der Methodik im Entwicklungsprozess im Vordergrund. Zur Ableitung der damit verbundenen physikalisch-mechanischen Zusammenhänge werden statische und dynamische Achsprüfstände sowie Simulationen eingesetzt. Die Anwendung der Methodik lässt eine gezielte Eigenschaftsableitung zwischen Gesamtfahrzeug-, Subsystem- und Komponentenebene im Fahrkomfort zu, bei der die Subsystemebene als neue Referenz für die Ableitung von Komponenteneigenschaften dient. Weiterhin erlaubt das Vorgehen eine eigenschaftsbasierte Vorauswahl optimaler Komponentenkonzepte sowie detaillierte Wettbewerbsanalysen. Dadurch wird eine nachhaltige Steigerung der Effizienz im Entwicklungsprozess des Fahrkomforts ermöglicht.
6

Automotive Powertrain Software Evaluation Tool

Powale, Kalkin 08 February 2018 (has links)
The software is a key differentiator and driver of innovation in the automotive industry. The major challenges for software development are increasing in complexity, shorter time-to-market, increase in development cost and demand of quality assurance. The complexity is increasing due to emission legislations, variants of product and new communication technologies being interfaced with the vehicle. The shorter development time is due to competition in the market, which requires faster feedback loops of verification and validation of developed functionalities. The increase in development cost is contributed by two factors; the first is pre-launch cost, this involves the cost of error correction in development stages. Another is post-launch cost; this involves warranty and guarantees cost. As the development time passes the cost of error correction also increases. Hence it is important to detect the error as early as possible. All these factors affect the software quality; there are several cases where Original Equipment Manufacturer (OEM) have callbacks their product because of the quality defect. Hence, there is increased in the requirement of software quality assurance. The solution for these software challenges can be the early quality evaluation in continuous integration framework environment. The most prominent in today\'s automotive industry AUTomotive Open System ARchitecture (AUTOSAR) reference architecture is used to describe software component and interfaces. AUTOSAR provides the standardised software component architecture elements. It was created to address the issues of growing complexity; the existing AUTOSAR environment does have software quality measures, such as schema validations and protocols for acceptance tests. However, it lacks the quality specification for non-functional qualities such as maintainability, modularity, etc. The tool is required which will evaluate the AUTOSAR based software architecture and give the objective feedback regarding quality. This thesis aims to provide the quality measurement tool, which will be used for evaluation of AUTOSAR based software architecture. The tool reads the AUTOSAR architecture information from AUTOSAR Extensible Markup Language (ARXML) file. The tool provides configuration ability, continuous evaluation and objective feedback regarding software quality characteristics. The tool was utilised on transmission control project, and results are validated by industry experts.

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