ED Mathématiques et Informatique
Byzantine-Resilient Peer Sampling for Large-Scale Distributed Systems
by Augusta MUKAM (LaBRI - Laboratoire Bordelais de Recherche en Informatique)
The defense will take place at 14h00 - Amphithéâtre du LaBRI Domaine universitaire, 351 Cours de la Libération, 33405 Talence
in front of the jury composed of
- Laurent REVEILLERE - Professeur des universités - Université de Bordeaux - Directeur de these
- Sonia BEN MOKHTAR - Directrice de recherche - CNRS - Rapporteur
- Yérom-David BROMBERG - Professeur des universités - Université de Rennes - Rapporteur
- Patricia THéBAULT - Professeure des universités - Université de Bordeaux - Examinateur
- Léo MENDIBOURE - Maître de conférences - Université de Pau et des Pays de l'Adour - Examinateur
Peer sampling services are foundational primitives in large-scale distributed systems, providing each node with a continuously refreshed, near-uniform view of the system membership. Gossip-based implementations are particularly well-suited to this task owing to their scalability, self-healing properties, and robustness to churn. However, in open, adversarial environments such as public blockchain networks, Byzantine nodes can systematically bias view exchanges, corrupting the sampling distribution and enabling attacks such as eclipse attacks, denial-of-service attacks, and manipulation of consensus protocols. This thesis addresses the problem of Byzantine-resilient gossip-based peer sampling through three complementary contributions. First, we present Aupe, a Byzantine fault-tolerant peer sampling protocol that combines a frequency-tracking Set Cleaner with a collaborative debiasing mechanism leveraging trusted execution environments. Experimental evaluations show that Aupe maintains optimal fault tolerance in the presence of up to 26% adversarial nodes. Second, we conduct a systematic evaluation of sketch-based frequency estimators, including Count-Min Sketch, Bitmatcher, and several variants, in the context of adversarial peer sampling, and propose evaluation metrics tailored to peer sampling objectives that go beyond standard aggregate measures. Third, we integrate Bitmatcher into Aupe, replacing exact frequency counting with a memory-efficient adaptive sketch. We study the issue of sketch decay or aging when sketches are required to live indefinitely, as in peer sampling services, as well as sketch aggregation in the context of collaborative debiasing. We evaluate the resulting system under adversarial conditions. Together, these contributions advance the state of the art in resilient, scalable, and resource-efficient peer sampling, demonstrating that uniform sampling and compact statistical frequency estimation can be effectively combined in practical distributed systems.
ED Sciences Chimiques
Twisted π-systems for delayed fluorescence, room-temperature phosphorescence, liquid crytals and glasses
by Monike DA SILVA KUTZ (Centre de Recherche Paul Pascal)
The defense will take place at 13h00 - Salle Faruk Nome Rue Eng. Agronômico Andrei Cristian Ferreira, sans numéro. 88040-900, Trindade, Florianópolis - SC, Brésil
in front of the jury composed of
- Harald BOCK - Directeur de recherche - Université de Bordeaux - Directeur de these
- Eduard WESTPHAL - Professeur des universités - Universidade Federal de Santa Catarina - CoDirecteur de these
- Marcelo Henrique GEHLEN - Professeur des universités - Universidade de São Paulo - Rapporteur
- Leandra FRANCISCATO CAMPO - Professeure des universités - Universidade Federal do Rio Grande do Sul - Rapporteur
The development of multifunctional materials for advanced optoelectronics requires the integration of complex optical properties with the capacity for anisotropic emission. This thesis addresses this challenge through the molecular engineering of aromatic cores that synergistically combine dual delayed emission and mesomorphism. The starting point was the polycyclic aromatic hydrocarbon homotruxene (HTX), which, despite exhibiting fascinating photophysical properties, such as persistent room temperature phosphorescence (pRTP) and triplet-triplet annihilation delayed fluorescence (TTA-DF) due to its twisted π-system, proved unsuitable for the formation of liquid-crystalline phases because of its lack of planarity. To overcome this limitation, the molecular core was redesigned, giving rise to monohomotruxene (MHTX). This new core, more rigid and planar, was conceived with the dual purpose of minimizing vibrational relaxation of excited states and promoting intermolecular stacking, laying the foundation for mesomorphic materials with dual delayed emission. In the first chapter, an in-depth spectroscopic investigation revealed that MHTX not only maintains the rich photophysics of HTX (exhibiting blue TTA-DF, green monomeric pRTP, and orange pRTP from J-aggregates) but surpasses it, presenting a higher photoluminescence quantum yield, attributed to its optimized rigidity and symmetry breaking. Additionally, it was demonstrated that each emissive pathway can be selectively accessed by the excitation wavelength. With a promising core established, the research advanced towards the fine control of its properties. The second chapter showed that the HOMO-LUMO energy gap of MHTX can be systematically modulated by inserting electron-donating groups (EDGs) at peripheral positions, while preserving the desired emissive behavior. The next step, explored in the third chapter, was to induce mesomorphism. Here, strategic peripheral functionalization was crucial: while long alkoxy chains suppressed mesophase formation, the introduction of inverted ester groups promoted the necessary molecular segregation, resulting in monotropic nematic phases that could be vitrified near room temperature. Crucially, these same groups acted as steric controllers, inhibiting aggregation in solution and thus preserving the core's intrinsic dual emission. Expanding the molecular scope, the fourth chapter presents the synthesis of monohomotruxenone (MHTK), a discotic core derived from MHTX by introducing carbonyl groups. This modification, by exploring the increased electronic conjugation and the n−π* character of the new groups (according to El-Sayed's rule), shifted the dual emission to the orange region and reduced the excited state lifetimes. Notably, liquid crystalline derivatives of MHTK self-assembled into stable columnar hexagonal mesophases over a wide temperature range, suppressing crystallization even under sub-ambient conditions. Finally, in a last study, discotic materials based on a symmetric core with high triplet energy were developed to act as optically inert anisotropic matrices, capable of molecularly aligning emitters in the blue region. Collectively, this thesis establishes a panoramic and integrated strategy of molecular engineering, from rational core design to electronic modification and steric functionalization, to create organic materials that combine complex photophysics and controlled self-organization. The results not only demonstrate the feasibility of integrating dual delayed emission and mesomorphism but also provide a robust foundational for the development of next-generation multifunctional soft materials for advanced optoelectronic applications.
ED Sciences de la Vie et de la Santé
PREDICTIVE METABOLOMICS OF PHENOTYPIC TRAITS OF CAMELLIA CULTIVARS AND THEIR BIOLOGICAL ACTIVITIES FOR DERMOCOSMETIC APPLICATIONS.
by Fafa HOCINI (BFP - Biologie du Fruit et Pathologie)
The defense will take place at 14h00 - Agora Haut-Carré Université de Bordeaux Domaine du Haut-Carré 43 Rue Pierre Noailles 33400 Talence
in front of the jury composed of
- Guillaume TCHERKEZ - Professeur des universités - Université de Angers - Rapporteur
- Jean-Luc WOLFENDER - Professeur des universités - Université de Genève - Rapporteur
- Iuliana POPA - Maîtresse de conférences - Université Paris Saclay - Examinateur
- Nathalie GUIVARC'H - Professeure des universités - Université de Tours - Examinateur
- Florence MEHL - Docteur - Swiss Institute of Bioinformatics - Examinateur
- Stéphanie KRISA - Professeure des universités - Université de Bordeaux - Examinateur
- Pierre PETRIACQ - Directeur de recherche - INRAE - Directeur de these
- Vincent COCANDEAU - Cadre scientifique - Chanel Parfums Beaute - CoDirecteur de these
Native to Asia, the genus Camellia belongs to the Theaceae family and displays a complex taxonomy, with more than 250 described species and around 23,000 cultivars. Several species are widely known and exploited, including Camellia sinensis for tea production, Camellia oleifera as a source of edible oil, and Camellia japonica for its horticultural value. Although the phytochemistry of C. japonica is well documented, metabolic variations associated with floral phenotypes remain poorly explored, particularly using modern untargeted metabolomics approaches. This PhD work focuses on predictive metabolomics applied to the Camellia genus. The first objective is to characterise metabolic diversity among cultivars exhibiting contrasted floral phenotypes, especially flower colour and floral form, using LC-HRMS-based metabolomic profiling. Metabolomic data were associated with phenotypic traits through multivariate statistical models and variable selection approaches, in order to identify predictive metabolic signatures. A second part of the thesis investigates the relationships between the metabolic composition of Camellia extracts and their biological activities evaluated on relevant human skin targets. Overall, this work aims to improve the understanding of metabolic organisation linked to phenotypic traits and observed biological activities, without assuming direct causal mechanisms.
ED Sociétés, Politique, Santé Publique
Physical pain, moral pain: interactions between chronic pain and psychiatric disorders in older people
by Hélène SAINT-MARTIN (Bordeaux Population Health Research Center)
The defense will take place at 13h30 - Amphi P.-A. Louis Université de Bordeaux Site Carreire, Bâtiment ISPED 146 rue Léo Saignat 33000 Bordeaux
in front of the jury composed of
- Isabelle ROUCH - Praticienne hospitalière - Université de Bordeaux - Directeur de these
- Hélène AMIEVA - Professeure des universités - Université de Bordeaux - Examinateur
- Gisèle PICKERING - Professeure des universités - praticienne hospitalière - Université Clermont-Auvergne - Rapporteur
- Jean-Michel DOREY - Maître de conférences - praticien hospitalier - Université Claude Bernard Lyon 1 - CoDirecteur de these
- Gabriel ROBERT - Professeur des universités - praticien hospitalier - Université de Rennes - Rapporteur
- Bernard LAURENT - Professeur émérite - Université de Saint-Etienne - Examinateur
Older patients with psychiatric disorders or neurocognitive disorders may be particularly vulnerable to several health issues – especially chronic pain. These pain symptoms aggravate overall health status and contribute to the reduction in quality of life associated with psychiatric disorders. They may also contribute to cascading decompensations, accelerated aging and reduced life expectancy in patients with psychiatric disorders. This is, at least, what we may hypothesize based on clinical practice; however, the scientific literature remains limited. The first part of our work consists of a literature review on the associations between chronic pain and psychiatric disorders, focusing on older adults (aged 65 and over). This review highlights the frequent comorbidity between chronic pain and anxiety and depressive disorders. Bipolar disorders and schizophrenia may be associated with chronic pain to a lesser extent, but to the same degree as the general population. Regarding neurocognitive disorders, they may constitute a risk factor for chronic pain, and there appears to be an association between pain and behavioral and psychological symptoms of dementia. The second part of our work consists of three experimental studies that aimed to address the scientific gaps identified in our literature review. We will soon publish the results of our last project, the study “Chronic Pain in Older Adults with Psychiatric Disorders” (DoCPPA). The main objective of this study is to determine the prevalence of chronic pain in older adults followed in psychiatric wards. Our next project will consist of a longitudinal follow-up of a large cohort of older adults with psychiatric disorders. This study will help us better understand the dynamics of the emergence and progression of chronic pain in this population. Beyond – and despite – their numerous health problems, our patients face significant barriers in accessing primary care. To address these issues, we suggest that psychiatric wards should integrate somatic care, within a “reverse integration” model. Our future projects will investigate the potential of “plurivalent” treatments, that is, treatments that could address both pain and psychiatric symptoms.