HAL-ENS-LYON
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Les relations familiales dans Ourika, Édouard et Olivier ou le secret : Impasses du moment 1800
No full textInternational audienceWhether through blood ties or marriage, through vertical lines of descent or horizontal lines of kinship, family relationships are the primary determinant of Claire de Duras' characters. Thus, in Ourika, Édouard and Olivier ou le secret, even in broken families, ‘duty’, as the law of the father, continues to characterise family relationships. This sombre game of families, a space of duty and dead ends, reveals the tragic condition of women and men in the 1800s.Que ce soit dans le lien du sang ou de l’alliance, dans la lignée verticale de la filiation ou horizontale de l’adelphie, la relation familiale constitue le premier déterminant des personnages de Claire de Duras. Ainsi, dans Ourika, Édouard et Olivier ou le secret, quoique dans des familles démembrées, le « devoir », comme loi du père, continue à caractériser la relation familiale. Ce funèbre jeu des familles, espace du devoir et des impasses, révèle la condition tragique de la femme et de l’homme au moment 1800
Global stability and periodicity in a delay differential model
No full textSimple form delay differential equation (DDE) is considered as a mathematical model of several biological processes. The problems of the global asymptotic stability (GAS) of the unique positive equilibrium and the existence of periodic solutions slowly oscillating about this equilibrium are studied. Sufficient conditions for the GAS are derived in terms of the global attractivity of the unique fixed point of induced interval maps, one set being delay independent conditions and the other one dependent on the size of the delay. Slowly oscillating periodic solutions always exist when the linearized about the equilibrium DDE is unstable. The theoretical results are demonstrated by extensive numerical simulations
Towards the metamorphic control of chiroptical properties using Boranils
No full textInternational audienceConstructing sophisticated luminescent dyes around a tetrahedral boron(III) center is a particular approach that has fueled the creativity of chemists motivated by their use in organic electronics and applied photonics or as molecular probes in biomedical analysis, sensors and materials science. Among these dyes, Boranils have attracted particular interest over the past decade with potential application for energy transfer, protein labeling, or NLO imaging. More recently, these dyes have been used to trigger photoinduced electron transfer to viologen-based acceptors (4,4'-bipyridinium salts). This strategy has proven effective in controlling conformational changes at the molecular level or the degree of organization of gel-forming supramolecular assemblies. We are also working on developing switchable materials for circularly polarized luminescence (CPL). Preliminary results on new chiroptical fluorophores based on Boranils will be described. We plan to use these new structures to develop bistable CPL-active metamorphic materials for which stimulation changes the organization of supramolecular self-assembled monolayers on surfaces
Secrets de théâtre et héros "en déshabillé", de la comédie des Lumières au drame romantique
No full textInternational audienc
Régimes de turbulence du bord ouest dans les gyres océaniques
No full textOcean gyres are basin-wide patterns of horizontal circulation driven by surface wind stress. They feature energetic currents at the western boundaries of oceanic basins, a phenomenon known as western intensification. Western boundary currents produce chaotic flow that we here refer to as western-intensified turbulence. However, the fate of this turbulence remains unclear: How is it dissipated? Why does it sometimes self-organize into eastward jets in certain basins but not in others? This thesis aims to bridge the gap between modern modeling capabilities of western-intensified turbulence and our physical understanding of it by investigating western-intensified turbulence across a hierarchy of ocean models of increasing complexity. First, using a barotropic model, we show that the energy of western-intensified turbulence can be dissipated at a fixed rate, independent of the smallness of viscosity. The dissipation occurs in nonlinear vortices generated at the coasts but populating the entire ocean basin, while the time-averaged gyre pattern remains remarkably close to the linear response of the model to the applied wind forcing. Coherent jets are absent in the barotropic model, but we show that they emerge in a reduced-gravity model when the density stratification is sufficiently weak. In that case, both eastward and westward jets are present. In a two-layer model, we find that baroclinic instability disintegrates the westward jets into westward-drifting vortices but leaves the turbulent eastward jets intact. We identify key nondimensional parameters related to the density stratification and map out a phase diagram describing the emergence of coherent eastward jets. In the final part of this thesis, we leverage these results to study how altered stratification profiles in different climates may impact Atlantic eastward jets. Using a realistic ocean circulation model, we show that intensified stratification leads to major changes in the properties of the Gulf Stream jet and the formation of a novel eastward jet detaching from the Brazil Current.Les gyres océaniques sont des courants océaniques organisés à l'échelle du bassin qui sont forcés par le vent. Ils se caractérisent par des courants énergétiques à l'ouest des bassins océaniques, un phénomène connu sous le nom d'intensification de bord ouest. Ces courants de bord ouest créent des écoulements chaotiques que nous désignons ici par le terme de turbulence du bord ouest. Cependant, la phénoménologie de cette turbulence reste mal comprise : comment est-elle dissipée ? Pourquoi s'organise-t-elle parfois en jets vers l'est dans certains bassins, mais pas dans d'autres ? Cette thèse vise à établir des liens entre les capacités de modélisation actuelles de la turbulence du bord ouest et notre compréhension physique de celle-ci, en l'examinant au sein d'une hiérarchie de modèles océaniques de complexité croissante. Dans un premier temps, à l'aide d'un modèle barotrope, nous montrons que l'énergie de la turbulence du bord ouest peut être dissipée à un taux fini qui ne dépend pas de la valeur de la viscosité. La dissipation s'effectue dans des tourbillons non linéaires générés près des côtes mais présents dans l'ensemble du bassin océanique, tandis que la circulation moyenne du gyre reste remarquablement proche de la réponse linéaire calculée pour un vent donné. Aucun jet cohérent n'émerge dans le modèle barotrope. Nous montrons qu'un jet apparaît dans un modèle à gravité réduite lorsque la stratification verticale est suffisamment faible. Dans ce cas, des jets orientés aussi bien vers l'est que vers l'ouest sont présents. Dans un modèle à deux couches, nous constatons que l'instabilité barocline désintègre les jets vers l'ouest en tourbillons se propageant vers l'ouest, tout en préservant les jets turbulents vers l'est. Nous identifions deux paramètres sans dimension clés liés à la stratification, et établissons un diagramme décrivant l'émergence des jets cohérents vers l'est dans cet espace des paramètres. Dans la dernière partie de cette thèse, nous exploitons ces résultats pour étudier comment des profils de stratification modifiés dans différents climats peuvent influencer les jets de l'océan Atlantique. En utilisant un modèle de circulation océanique réaliste, nous montrons qu'une intensification de la stratification entraîne des changements majeurs dans les propriétés du Gulf Stream et favorise la formation d'un nouveau jet vers l'est se détachant du courant du Brésil
The zircon record of Carboniferous partial melting in Silurian mafic rocks from the Lyonnais metamorphic complex (French Massif Central)
No full textNational audienceWe report the petrological and zircon U-Pb and trace element study of metamafic rocks from the Saint-Joseph massif in the Lyonnais metamorphic complex. The samples are ultrabasic and predominantly composed of garnet–amphibole (up to 75–85%), with plagioclase–quartz (10–15%), titaniferous minerals (5–10%), and clinopyroxene relics (>5%). Some samples show a layering marked by garnet abundance ranging from 0 to 40 %. Plagioclase coats the grain boundaries of garnet and amphibole porphyroblasts, resembling a melt pseudomorph. Thermodynamic modelling of a selected sample indicates that fluid-fluxed melting at 10–12 kbar and 800–900 °C, followed by cooling to ~700 °C, can explain the assemblage garnet–amphibole–plagioclase–quartz–titanite. Separated zircon crystals commonly display a core with oscillatory, or sector zoning, rimmed by domains with complex convolute zoning. This pattern suggests polyphase zircon coupled dissolution-reprecipitation. The analyses of zircon rims show either a flat or a positive slope in the heavy REE pattern, irrespective of the date or intra-grain location. This feature is tentatively attributed to the variable garnet content in the rock layering. Zircon core and rim yield an equivalent smear of apparent ages between c. 360–320 Ma, interpreted as a result of melt-mediated dissolution-reprecipitation. One sample contains an additional zircon zone found as CL-dark cores with oscillatory or featureless zoning, and characterised by an exceptionally high trace-element content, e.g. up to 2000 ppm of U. These cores also yield a smear of apparent, on average, older ages, between c. 425–320 Ma. Nine-spots yield a concordia date of 423.8 ± 4.8 Ma with a MSWD of 0.99 regarded as the age of the magmatic protolith. The occurrence of a Silurian mafic magmatism may be related to mantle melting at the northern Gondwana margin, possibly in a suprasubduction setting. The sample records predominantly a Carboniferous fluid-fluxed partial melting event
Infanticide in a colonial cooperative bird is not associated with direct reproductive benefits
No full textInfanticide, the killing of dependent young by adult conspecifics, is an extreme form of conflict that remains poorly understood. Previous studies suggest that it is associated with reproductive benefits, either by making breeders newly available for reproduction or by increasing offspring care and reducing competition for resources. In addition, infanticide may result from a reproductive trade-off, where parents kill their offspring if environmental conditions compromise their reproductive value. Here, we combine video, genetic and individual-level reproductive data collected over 12 years to describe infanticide in a highly social, cooperative bird, the sociable weaver Philetairus socius and to establish whether direct reproductive benefits or life-history trade-offs are possible motivators for this behaviour. We documented 50 cases of infanticide and identified 27 aggressors with known histories. These were mostly born outside the colonies where they committed infanticide (63%) and there was a bias towards younger individuals. Aggressors were usually not part of the victim’s breeding group (74%), but in two cases infanticide was committed by the breeding female, and in five by helpers. In most cases, aggressors were not reproducing at the time of the infanticide, were not recorded mating with any of the breeders or helpers from the attacked nest, nor occupied the nest from where the chicks were evicted. Only eight of the known aggressors were confirmed as breeders after the attacks, and these mostly reproduced at the colony where the attacks were committed. Overall, we found no evidence for direct reproductive benefits of infanticide in sociable weavers. However, the younger age of aggressors, lack of genetic relatedness to the victims and future breeding at the colony suggest that competition between breeding groups, and hence indirect reproductive benefits, could provide motivation for infanticide in this population. Additional work over longer periods is needed to identify these possible indirect fitness benefits of infanticide
Spin glasses and the Parisi formula
No full text17 pages; contribution to the proceedings of the ICM 202
Operator norm of products of random matrices
No full textWe study the operator norm of products of independent random matrices with independent and identically distributed entries. For -by- matrices whose entries are centered, have unit variance, and have a finite moment of order 4\al for some \al > 1, we find that the operator norm of the product of matrices behaves asymptotically like . The case of products of possibly non-square matrices with possibly non-centered entries is also covered
Séparation de phase et effets de bord pour des gaz sur réseau hors équilibre
No full textOne of the major challenges of modern statistical physics is to build robust tools to study outof-equilibrium microscopic systems (e.g. submitted to thermostats or external fields, active matter) andunderstand their large-scale behavior. Among such tools, the theory of scaling limits of lattice gases, whichhas received in the last decades significant attention from various communities (physics, mathematics, biology)links microscopic stochastic particle systems with their macroscopic limit, typically characterized by apartial differential equation.In this framework, my research work has focused on the the macroscopic behavior of three classes of microscopicmodels:– Active matter models, whose phenomenology is very rich and exhibits both self organization patternsand spontaneous condensation phenomena.– Kinetically constrained lattice gases, with a specific focus on the Facilitated Exclusion Process (FEP), which aremodels for phase separation and transitions in which particle jumps are subject to a local constraint,which distorts their equilibrium states.– Non-equilibrium models, affected by boundary dynamics, which can also exhibit varied behavior, dependingon the microscopic lattice, as well as the microscopic details of both bulk and boundary dynamicsconsidered.This manuscript’s introduction is dedicated to defining the fundamental mathematical objects on which latticegases and their scaling limits are based, and to presenting these three statistical physics thematics in thecontext of their state of the art. The two chapters of the manuscript are then respectively dedicated to describingin more details my works on the macroscopic effect of boundary dynamics and kinetic constraints,on which most of my post-PhD work has focused.l’un des défis majeurs de la physique statistique moderne est de construire des outils robustes pourl’étude des systèmes microscopiques hors-équilibre (e.g. sous l’action de thermostats, influence d’un champextérieur, matière active), permettant de comprendre leur comportement à grande échelle. Parmi ces outils,la théorie des limites d’échelles des gaz sur réseau, qui a reçu ces dernières décennies beaucoup d’attention dansdiverses communautés (Physiciens, Mathématiciens, Biologistes), permet de faire le lien entre un systèmestochastique de particules microscopique, et sa limite d’échelle typiquement caractérisée par une équationaux dérivées partielles.Dans ce cadre général, mes travaux de recherche ont porté en grande partie sur l’étude du comportementmacroscopique de trois grandes familles de modèles microscopiques :– Les systèmes de matière active, qui présentent une phénoménologie extrêmement riche, en particulierdes phénomènes d’auto-organisation et de condensation spontanée.– Les gaz sur réseau cinétiquement contraints, en particulier le processus d’exclusion facilitée (FEP), des modèlesde séparation et de transitions de phase dans lesquels le mouvement des particules est soumis à unecontrainte locale, perturbant leur équilibre.– Les modèles non-équilibre, affectés par des dynamiques de bord, qui eux aussi peuvent avoir des comportementsextrêmement variés selon le réseau, la dynamique de bord et la dynamique de bulk considérée.L’introduction de ce manuscrit définit succinctement les objets mathématiques fondamentaux nécessairesà la construction des gaz sur réseaux et de leurs limites d’échelles, ainsi qu’à la présentation de ces troisthématiques et de leur état de l’art. Les deux chapitres du manuscrit sont ensuite respectivement dédiés àmes travaux sur l’effet macroscopique de contraintes cinétiques, et à celui de dynamiques de bords, qui ontreprésenté la majorité de mes travaux mathématiques post-thèse