ED Sciences Chimiques
Transport dynamics of sap in vascular plants : microfluidics approach
by Julien RENAUDEAU (Laboratoire du Futur)
The defense will take place at 14h00 - Amphithéâtre CRPP Centre de Recherche Paul Pascal 115 Avenue du Dr Albert Schweitzer, 33600 Pessac, France
in front of the jury composed of
- Jean-Baptiste SALMON - Directeur de recherche - Université de Bordeaux - Directeur de these
- Jean-Christophe BARET - Professeur - Centre de Recherche Paul Pascal - Examinateur
- Sylvie DINANT - Directrice de recherche - Institut Jean-Pierre Bourgin - Examinateur
- Abraham STROOCK - Professeur - Cornell University - Examinateur
- Cécile COTTIN-BIZONNE - Directrice de recherche - Institut Lumière Matière - Rapporteur
- Yoel FORTERRE - Directeur de recherche - Institut Universitaire des Systèmes Thermiques Industriels - Rapporteur
Sap transport in vascular plants relies on passive mechanisms. In particular, the transport of photosynthesized sugars in the phloem is commonly described by the Münch mechanism. Despite its importance for plant functioning, quantitative investigations of this mechanism remain challenging due to the limited accessibility of the phloem. In this context, this thesis adopts a bio-inspired approach aimed at developing microfluidic devices capable of reproducing and studying sugar transport in the phloem. The main objective of this work is to design microfluidic chips integrating hydrogel membranes directly within the channels, thereby enabling local characterization of transport. First, microfabrication methods based on the extit{in situ} photopolymerization of poly(ethylene glycol) diacrylate (PEGDA) hydrogels were developed to integrate membranes with controlled shapes into PEGDA microfluidic devices. These systems were then used to characterize the membranes. In the dilute regime, the analysis of transient osmotic flows enabled the determination of the transport parameters of the hydrogels. In the concentrated regime, local concentration measurements obtained by confocal Raman spectroscopy revealed the limitations of conventional transport models and led to the development of a unified framework describing transport in both dilute and concentrated conditions. Finally, a multi-membrane microfluidic chip reproducing key features of phloem–xylem coupling was developed. This device enabled the generation of steady osmotic flows within an extit{artificial phloem}. This work provides an original experimental toolbox for fundamental studies of osmotic transport through membranes, and represents a step towards the reproduction of sap transport in plants.
ED Sciences de la Vie et de la Santé
Clinical and neuroscientific applications of symptom networks: semiology, dynamics, intervention, and explanation
by Christophe GAULD (Sommeil, Addiction et Neuropsychiatrie)
The defense will take place at 9h00 - Module 1.2 (au niveau du restaurant universitaire) Université de Bordeaux, Site de Carreire,146 rue Léo Saignat, 33000 Bordeaux
in front of the jury composed of
- Jean-Arthur MICOULAUD-FRANCHI - Professeur des universités - praticien hospitalier - Université de Bordeaux - Directeur de these
- Bruno FALISSARD - Professeur des universités - praticien hospitalier - Université Paris Saclay - Rapporteur
- Jasmina MALLET - Professeure des universités - praticienne hospitalière - Université d'Orléans - Examinateur
- Yannick MORVAN - Professeur des universités - praticien hospitalier - Université Paris Nanterre - Examinateur
- Carmen SCHRODER - Professeure des universités - praticienne hospitalière - Université de Strasbourg - Rapporteur
This thesis explores the clinical and neuroscientific contributions of a translational approach aimed at articulating clinical practice, neuroscientific and medical symptomatology data. It is based on tools provided from computational sciences, and in particular on relational analyses of symptoms, to propose a framework for structuring medical symptomatology beyond traditional nosology. Starting from the observation of the explanatory and practical limits of diagnostic categories, and by conceptualizing disorders as systems of interacting symptoms, this work seeks to formally analyze symptom relations, temporal dynamics, responses to interventions, and their links with neurobiological mechanisms. Four central dimensions of symptomatology are examined through empirical applications across different medical fields. First, the relational dimension is explored in sleep health in order to identify central and stable symptoms across age and sex. Second, the dynamic dimension is examined in addiction medicine using ecological momentary assessment data, with a focus on the role of craving within different symptom trajectories. Third, the interventional dimension is addressed in psychiatry through the study of catatonia, aiming to characterize the semiological impact of pharmacological treatments acting on the sleep-wake axis. Finally, the explanatory dimension is illustrated in epileptology through the integration of semiological networks and electrophysiological data. By articulating computational modeling, clinical practice, and neuroscience, this thesis finally advances the idea of a “science of symptoms”, built on dynamical system theories, and proposes a minimal explanatory model intended to support a more precise and individualized clinical practice.
ED Sociétés, Politique, Santé Publique
Study of the conditions under which parenting support services provide an ecological approach that fosters parental empowerment.
by Mélanie BREMONT (Bordeaux Population Health Research Center)
The defense will take place at 14h30 - salle 1K 35 place Pey-Berland, 33000 Bordeaux
in front of the jury composed of
- Delphine COULON - Professeure assistante - Haute école de santé - Rapporteur
- François ALLA - Professeur des universités - praticien hospitalier - CHU, Centre Inserm, Université de Bordeaux - Examinateur
- Carl LACHARITé - Professeur émérite - Université du Québec à Trois-Rivières - Rapporteur
- Olivia TROUPEL - Maîtresse de conférences - Université de Toulouse - Examinateur
This thesis is situated within the field of health promotion and explores the conditions that support the development of parental empowerment from pregnancy to the child's third year of life. In a context marked by growing attention to early childhood and social health inequalities, numerous parenting support services and programmes have emerged in France. However, these interventions often remain primarily focused on parenting practices and skills, while paying less attention to the social, relational and institutional environments in which parenting takes place. This research therefore aims to understand under what conditions parenting support interventions can foster parental empowerment from an ecological perspective, considering parents as situated actors whose possibilities for action are shaped by their living environments. This study is based on a realist multi-case evaluation conducted across nine parenting support interventions in France, covering the period from pregnancy to the child's third year of life. Fifty-four semi-structured interviews were conducted with parents and twenty-eight with professionals involved in these interventions. Data were analysed using Context–Mechanism–Outcome (CMO) configurations in order to identify the mechanisms activated within different intervention contexts. The findings show that the development of parental empowerment relies on the activation of different mechanisms within specific ecological environments. Three major functions of supportive environments emerged from the analysis: (1) the socio-emotional regulation of the parenting experience, through mechanisms of belonging, recognition and security; (2) the process of consciousness-raising action, through reflective processes, a sense of competence and a sense of parental efficacy; and (3) the development of capabilities, through a sense of freedom and a sense of being supported, contributing to broadening parents' scope for action. A fourth mechanism of parental transformation emerged as a cumulative and temporal dynamic resulting from the articulation between these different functions. These mechanisms are embedded within contexts that may either support or constrain parents' power to act. Four structural pillars were identified: relational, community, organisational and societal. Together, they constitute essential levers for creating environments that support parental empowerment. This thesis therefore proposes an ecological model of parental empowerment, highlighting that the parenting experience relies on the dynamic articulation between social, relational and institutional contexts. It invites a reconsideration of parenting support not as an isolated intervention, but as a social ecology fostering social connectedness, accessibility of resources, parental participation and the reduction of social health inequalities from early childhood onward. The “village” surrounding parents thus emerges as a configuration of relational, social and institutional conditions enabling parents to feel supported, recognised and capable of acting. From this perspective, the question may no longer simply be “how can we help parents?”, but rather “how can we create the conditions that make parental empowerment possible?”