ED Entreprise Economie Société
The future of wetlands in the face of global changes: heritage analysis of socio-ecological compromises in the Brouage and Fier d'Ars marshes (Charente-Maritime, France)
by Clémence DEDINGER (Environnement, Territoires en Transition, Infrastructures, Sociétés)
The defense will take place at 14h00 - Amphithéâtre d'INRAE UR ETTIS - Site de Cestas-Gazinet 50 Avenue de Verdun 33612 Cestas
in front of the jury composed of
- Clarisse CAZALS - Chargée de recherche - INRAE - UR ETTIS - Directeur de these
- Harold LEVREL - Professeur - MNHN - Rapporteur
- Audrey RIVAUD - Maîtresse de conférences - Université Paul-Valéry Montpellier 3, UMR 5281 ART-Dev - CoDirecteur de these
- Franck-Dominique VIVIEN - Professeur des universités - Université de Reims Champagne-Ardenne, EA 6292 REGARDS - Rapporteur
- Marie FERRU - Professeure des universités - Université de Poitiers, UR 13823 RURALITES - Examinateur
- Stéphane GHIOTTI - Directeur de recherche - CNRS, UMR 5281 ART-Dev - Examinateur
- Laure LATRUFFE - Directrice de recherche - INRAE - BSE - Examinateur
The current context of global changes is renewing the challenges of environmental governance. In retro-littoral environments, these changes manifest through an increase in the frequency and intensity of extreme events, such as marine submersions. Under these conditions, the preservation of (retro)littoral wetlands is questioned, which calls for a a reevaluation of existing management approaches. This thesis aims to explore the possible future of these particular areas through the lens of heritage compromises. These compromises reflect, on the one hand, the process of making compatible a diversity of representations of heritage (what actors seek to preserve and transmit, including the use of resources) - what we call compromises in the process of being said. On the other hand, they refer to compromises in the process of being made, i.e., to the actors' practices responding to compromise logics (between exploitation and preservation), which are shape by a set of material, institutional and relational determinants. The originality of our analytical framework is to combine an heritage approach and two complementary theoretical approaches (economics of conventions and practice theory). This framework has been applied to the retro-littoral marshes of Brouage and Fier d'Ars, located in Charente-Maritime (France). Our findings reveal that the heterogeneity of marsh heritage conceptions, defended by the actors (managers and producers), finds a form of compatibility within two dominant "in the process of being said" compromises. Farmers' practices (breeders, salt producers, oyster farmers) generally reflect productive compromises that favor marsh preservation, highlighting the internal coherence of heritage compromises in both regions. This coherence is determined by a set of collective material, institutional and relational dimensions that guide producers' actions to varying degrees. We then show how existing compromises are disrupted by growing oppositions between stakeholders, particularly as concerns over marine flooding have gained prominence. Future compromises will inevitably depend on the capacity of actors to resist shifts in practices. For example, the ecological dependency of production activities limits the flexibility available to farmers for adaptation. The empirical approach adopted in this work, leading to a mixed methodoly and the interweaving of qualitative (discourse analysis) and quantitative (multivariate statistical analysis, social network analysis) methods, represents a methodological advancement for deciphering the diverse drivers of individual and collective action. Furthermore, studying the emergence and dynamics of heritage compromises offers a promising pathway for assessing the adaptive potential of territories in response to global change.
ED Sciences Physiques et de l'Ingénieur
Design, fabrication and characterization of high-speed detectors for future 100 Gbit/s access network
by Risab GNANAMANI (Laboratoire de l'Intégration du Matériau au Système)
The defense will take place at 10h00 - L'Amphithéâtre Jean-Paul Dom du Laboratoire IMS Université de Bordeaux Laboratoire de l'Intégration du Matériau au Système UMR CNRS 5218, 351 cours de la Libération – Bat A31, 33400 Talence, France
in front of the jury composed of
- Cristell MANEUX - Professeure - Université de Bordeaux - Directeur de these
- Fabienne SALIOU - Ingénieure de recherche - Orange - Rapporteur
- Cyril RENAUD - Professeur - Université Collège de Londres - Rapporteur
- Christophe CAILLAUD - Ingénieur de recherche - III-V Lab - Examinateur
In the modern era of rapid digital transformation, optical communication systems have become vital to meeting the ever-growing demand for high-speed and reliable data transmission. At the core of these systems, access networks facilitate connectivity between end-users, such as residential and business subscribers, and wide-area networks, supporting essential services like cloud computing, video conferencing, and remote work. As global data consumption surges driven by mobile communication, internet video services, and increasing reliance on cloud technologies, there is a growing demand for bandwidth, necessitating upgrades to the current Passive Optical Network (PON) systems. However, traditional solutions, such as avalanche photodiodes (APDs), struggle to meet these demands due to their limited gain-bandwidth product, constraining both bandwidth and responsivity. This thesis proposes the integration of a semiconductor optical amplifier (SOA) with a uni-travelling carrier photodiode (UTC-PD) to create a preamplified receiver capable of supporting next-generation access networks with speeds exceeding 100 Gbps. A comprehensive review of existing SOA-UTC technology was undertaken, which led to the fabrication of Optimized SOA-UTCs. These devices demonstrated impressive performance, achieving a responsivity of 140 A/W and bandwidths of 49 GHz without an integrated biasing circuit, and over 110 GHz with one. Challenges in the conventional process, particularly related to photodiode regrowth and waveguide limitations, prompted the development of a novel, Auto-aligned process. This disruptive approach not only simplifies and shortens the fabrication process but also delivers cost-efficiency without compromising the high performance of the integrated components. Through the successful fabrication of SOA-UTCs, the first proof of concept for the Auto-aligned process is presented, demonstrating its potential to enhance future optical access networks.
ED Sciences et environnements
Genetic resources of maritime pine: geographical variability, selection pressures and future adaptation.
by Adélaïde THERAROZ (BIOGECO - BIOdiversité, Gènes & Communautés)
The defense will take place at 14h00 - Airial Salle des Chênaies Airial Salle des Chênaies, INRAE, 69 Route d'Arcachon, 33612, Cestas
in front of the jury composed of
- Santiago GONZALEZ-MARTINEZ - Directeur de recherche - UMR 1202 Biodiversité Gènes & Communautés (BIOGECO) INRAE, Université Bordeaux - Directeur de these
- Juan-Pablo JARAMILLO CORREA - Professeur - Institute of Ecology, National Autonomous University of Mexico (UNAM) - Rapporteur
- Katrin HEER - Professeur - Albert-Ludwigs-University Freiburg Faculty of Environment and Natural Resources - Rapporteur
- Marjana WESTERGREN - Chargée de recherche - Slovenian Forestry Institue (SFI) - CoDirecteur de these
- Stephen CAVERS - Directeur de recherche - UK Centre for Ecology & Hydrology Edinburgh (UKCEH) - Examinateur
- Marta BENITO GARZóN - Directrice de recherche - UMR 1202 Biodiversité Gènes & Communautés (BIOGECO) INRAE, Université Bordeaux - Examinateur
- Julie GAüZERE - Chargée de recherche - Unité de Recherche Écologie des Forêts Méditerranéennes (URFM) - Examinateur
Climate change is already affecting forest ecosystems on all continents, as evidenced by the northward and upward migration of species and the increase of forest dieback in response to not only harsher climate conditions but also to pest and disease epidemics resulting from unprecedented climatic events as well as the intensification of human activities. These phenomena have negative consequences for the functioning of forest ecosystems and the persistence of species and populations, as they threaten the availability of resources, disrupt population dynamics and call into question physiological limits and resistance to pathogens. The future of natural forest tree populations in the face of climate change, given their sessile nature and long generation times, is therefore worrying, whether in terms of extinction, ability to migrate or adapt through genetic change. From a conservation point of view, we need to understand the extent to which forest trees will be able to survive in the face of current and future climate change. The huge amount of genomic data available from next-generation sequencing tools is revolutionising our understanding of the genetic basis of adaptation. In turn, it is accelerating the development of new statistical methods that can predict the genomic vulnerability of forest trees to climate change in space and time, and determine the potential for genetic maladaptation under changing climatic conditions. In this PhD thesis, I used maritime pine (Pinus pinaster Ait.), a long-lived conifer native to the western part of the Mediterranean basin, as a case study to unravel the spatial patterns of genetic variation at the rangewide and regional scales function of different gradients, anticipate population responses to climate change and provide insight into current trends in natural selection. The first chapter aims to understand how, at the scale of the species range, genetic variation, adaptability and the potential for short-term maladaptation to future climatic conditions are distributed from the range core towards the geographical and climatic margins. The second chapter examines the spatial patterns of contemporary natural selection by analysing phenotypic changes in response to current selective pressures, and provides an overview of current trends in local adaptation to climate change for maritime pine in the wild. The third chapter aims to identify the spatial patterns of genetic variation of maritime pine in the Corsica Island, characterized by specific features and constituting valuable genetic resources for the species, and to analyse their current and future adaptive capacities to climate change. Overall, this PhD thesis studies the underlying drivers and potential of maritime pine adaptive responses to changing environmental conditions at different spatial and temporal scales, thus contributing to the development of an integrative framework essential for anticipating population responses to climate change, on the basis of which robust predictions for conservation and management strategies can be developed.