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The Středa Formula for Floquet Systems: Topological Invariants and Quantized Anomalies from Cesàro Summation
No full textInternational audienceThis work introduces a general theoretical framework, which expresses the topological invariants of two-dimensional Floquet systems in terms of tractable response functions: Building on the Sambe representation of periodically-driven systems, and inspired by the Středa formula for static systems, we evaluate the flow of the unbounded Floquet density of states in response to a magnetic perturbation. This Floquet-Středa response, which is a priori mathematically ill-defined, is regularized by means of a Cesàro summation method. As a key outcome of this approach, we relate all relevant Floquet winding numbers to simple band properties of the Floquet-Bloch Hamiltonian. These general relations indicate how the topological characterization of Floquet systems can be entirely deduced from the stroboscopic time-evolution of the driven system. Importantly, we identify two physically distinguishable contributions to the Floquet-Středa response: a quantized flow of charge between the edge and the bulk of the system, and an 'anomalous' quantized flow of energy between the system and the driving field, which provides new insight on the physical origin of the anomalous edge states. As byproducts, our theory provides: a general relation between Floquet winding numbers and the orbital magnetization of Floquet-Bloch bands; a local marker for Floquet winding numbers, which allows to access Floquet topology in inhomogeneous samples; an experimental protocol to extract these Floquet winding numbers from density-measurements in the presence of an engineered bath; as well as general expressions for these topological invariants in terms of the magnetic response of the Floquet density of states, opening a route for the topological characterization of interacting Floquet systems
The Emergence of Traditions through the Transmission of Names: Tracing the Onomastic Legacy of Yi Yin 伊尹
No full textInternational audienceThis paper explores the onomastic evolution of Yi Yin 伊尹, the celebrated minister of Cheng Tang 成湯, by analyzing the many names, titles, and epithets attributed to him from the Shang period to the Han dynasty. Through a close philological and historical analysis of both excavated and transmitted sources— including oracle bone inscriptions, bronze vessel texts, bamboo manuscripts, and classical literature—it argues that each variation of Yi Yin’s name reflects a stage in the transformation of his image and function across different ritual, political, social, and philosophical contexts.The inquiry begins with the earliest mentions of Yi Yin in oracle-bone inscriptions, where he appears under fifteen names, suggesting a complex cultic status and a unique place within the Shang pantheon. These appellations reveal a figure who, though nominally an official (yin 尹), was venerated like an ancestral deity. Under the Western Zhou, only the name Yi Yin survived, but it was reinterpreted in light of Zhou political ideals. Texts from this era introduce variants such as Bao Heng 保衡 and E Heng 阿衡, presenting him as an embodiment of the Mandate of Heaven and a moral counterpart to the Duke of Zhou.During the Warring States period, new names and narrative roles emerged. Yi Yin was reimagined as the archetype of the loyal and capable minister, often referred to by a name retrospectively applied to emphasize his supposedly humble origins (Xiaochen 小臣). Sometimes designated by his office (yin 尹), he also appears under the enigmatic name Yi Zhi 伊摯, especially in texts portraying him as a military strategist. These shifts reflect a broader pattern of historical reappropriation, as successive generations reworked his image to serve their own philosophical and political agendas.Ultimately, the paper shows that the names of Yi Yin are not merely linguistic variants, but active agents in shaping a fluid and evolving legendary identity. His onomastic plurality offers a lens through which to examine the interplay between memorial construction, sociopolitical imperatives, and textual transmission in early Chinese history
Lettre ouverte de professionnels de la santé publique et mentale et de neurobiologistes pour mettre fin à la famine provoquée par l’homme à Gaza
No full textNous, professionnels de la santé publique et mentale et chercheurs en neurosciences du monde entier, appelons les gouvernements internationaux à faire pression sur le gouvernement israélien pour qu'il se conforme à l’avis de la Cour Internationale de Justice (CIJ) du 22/10/2025 demandant de faciliter l’acheminement de l’aide humanitaire à Gaza (1), et ainsi mettre fin à la famine qui y sévit. Cette famine, qui selon l’ONU est provoquée par l'homme, risque d'avoir des conséquences dramatiques à long terme sur la santé physique et mentale de la population civile, en plus des décès immédiats. Tout en condamnant clairement toutes les attaques contre les civils des deux côtés, nous considérons que ce double prix payé par la population civile palestinienne ne peut être moralement ni légalement acceptable en tant que stratégie de représailles
It is cool to be clear: transparency induces a thermal cost in clearwing butterflies
No full textInternational audience1. In butterflies, wing transparency raises the question of potential costs for vital functions, such as thermoregulation. The thermal melanism hypothesis posits that darker colorations enable higher absorption of solar radiation, leading to the prediction that such colorations should be favoured in colder environments. This prediction extends to the near-infrared range, a large component of solar radiation.2. Here, we assess the implications of wing transparency for light absorption and thermal properties in 42 species of clearwing butterflies (Ithomiini) and examine the distribution of such optical and thermal properties in relation to climatic conditions across different elevations.3. As expected, we find that transparent wings are less efficient than opaque wings to absorb light across ultraviolet, visible and near-infrared ranges, and are poorer at collecting heat. However, the proportion of transparent wing areas and the proportion of transparent species increase with elevation and decrease with temperature, going strongly against the predictions of the thermal melanism hypothesis in terms of species distribution with regard to climatic conditions. 4. Our results suggest that factors other than adaptation to climate, such as predation pressure, physiology or behaviour, may have driven the evolution of wing patterns in Ithomiini.</p
The gut-brain vagal axis governs mesolimbic dopamine dynamics and reward events
No full textAbstract Reward-related processes have traditionally been ascribed to neural circuits centered on the dopamine (DA) system. While exteroceptive stimuli, such as food and drugs of abuse, are well-established activators of DA-neuron activity, growing evidence indicates that interoceptive signals also play a critical role in modulating reward. Among these, the gut-brain vagal axis has emerged as a key pathway, yet its precise contribution to mesolimbic DA-dependent signaling, dynamics and behaviors remains poorly defined. Here, we combine complementary ex vivo and in vivo approaches across multiple scales to investigate how the gut-brain vagal axis regulates DA dynamics and reward-related behaviors. We show that gut-brain vagal tone is essential for gating mesolimbic DA system activity and functions, modulating DA-dependent molecular and cellular processes, and scaling both food- and drugs-induced reinforcement. These findings challenge the traditional brain-centric view of reward processing, supporting a more unified and integrated model in which gut-derived and vagus-mediated interoceptive signals are pivotal in intrinsically shaping motivation and reinforcement. By uncovering the influence of gut-brain vagal communication on mesolimbic DA functions, this work offers new insights into the neurobiological mechanisms underlying both adaptive and maladaptive reward processes, with broad implications for eating disorders and addiction
GW241011 and GW241110: Exploring Binary Formation and Fundamental Physics with Asymmetric, High-spin Black Hole Coalescences
No full textInternational audienceWe report the observation of gravitational waves from two binary black hole coalescences during the fourth observing run of the LIGO–Virgo–KAGRA detector network, GW241011 and GW241110. The sources of these two signals are characterized by rapid and precisely measured primary spins, nonnegligible spin–orbit misalignment, and unequal mass ratios between their constituent black holes. These properties are characteristic of binaries in which the more massive object was itself formed from a previous binary black hole merger and suggest that the sources of GW241011 and GW241110 may have formed in dense stellar environments in which repeated mergers can take place. As the third-loudest gravitational-wave event published to date, with a median network signal-to-noise ratio of 36.0, GW241011 furthermore yields stringent constraints on the Kerr nature of black holes, the multipolar structure of gravitational-wave generation, and the existence of ultralight bosons within the mass range 10–10 eV
Beyond the classics: exegetical schools as vectors of scientific knowledge
No full textInternational audienceStarting in the Han, the biographies of ru 儒 ('classicists' or 'Confucians') emphasize the concepts of jiafa 家法 (lineage methods), shifa 師法 (master's methods), as well as the person from whom the subject 'received' (shou 受) these methods and those to whom they were 'given' (shou 授) or 'transmitted' (chuan 傳). Often, the subject of the biography is described as 'going to' (jiu 就) a master to 'follow' (cong 從), 'serve' (shi 事), or listen to their 'lectures' (jiang 講), implying a necessarily oral and in-person transmission. In the biography, these details serve as qualifications, since an individual's academic authority primarily rests on that of the community from which he originates, and their recurrence is such that, collectively, they enable scholars like Ye Chunfang 葉純芳 to map detailed transmission networks across generations. This interpersonal infrastructure, initially designed for classical studies, is not limited to this function alone. In this presentation, I will discuss how exegetical transmission networks served as a foundation for the dissemination of the exact sciences, and how the jia 家 of these sciences derive from classicist schools
« La méthode diplomatique n’arrive plus à embrayer sur la réalité et a besoin de se réinventer » : retour sur quarante années de négociations diplomatiques sensibles avec Pierre Vimont
No full textInternational audienceHow do diplomats negotiate to end an armed conflict? How do they work to (re)establishdialogue that includes armed groups and ‘demonized’ actors? What practices are used toavoid long-lasting rounds of negotiations between inflexible interlocutors? What impact dothe timing and venue of negotiations have on interactions? These questions were asked toa French diplomat experienced in complex negotiations. Pierre Vimont joined the French Ministry of Foreign Affairs at the end of the 1970s and held some of the most prestigious diplomatic positions (London, Brussels, Washington). Throughout his career, he served as chief of staff to several foreign affairs ministers, French representative to the European Union, ambassador to the United States, architect of the creation of the European External Action Service, and special envoy of the President to Russia. He was involved in critical issues such as negotiations on Iran’s nuclear program, France’s opposition to the Iraq war, the release of civilian hostages, and the Israeli-Palestinian negotiations.Comment les diplomates négocient-ils pour tenter de résoudre un conflit armé ? En premier lieu, comment procèdent-ils pour (r)établir un dialogue entre belligérants lorsque ces derniers sont perçus comme « infréquentables » ? Quelles sont les pratiques mises en œuvre pour éviter que les négociations ne s’éternisent entre des interlocuteurs inflexibles ? Le choix du lieu et du moment de la négociation peuvent-ils jouer sur les interactions entre les acteurs ? Ces questions ont été abordées avec un diplomate français habitué aux négociations compliquées. Intégré au Quai d’Orsay à la fin des années 1970, Pierre Vimont a occupé les postes les plus prestigieux de la diplomatie française (Londres, Bruxelles, Washington). Au cours de sa carrière, il fut successivement directeur de cabinet de plusieurs ministres des Affaires étrangères, représentant de la France auprès de l’Union européenne, ambassadeur aux États-Unis, artisan de la mise en place du Service européen pour l’action extérieure et envoyé spécial du Président de la République en Russie. À ces différents titres, il s’est impliqué personnellement sur des dossiers périlleux tels que l’ouverture des négociations sur le programme nucléaire iranien, l’opposition de la France à la guerre en Iraq, la libération d’otages ou encore la relance des négociations israélo-palestiniennes
