Portail HAL du Collège de France
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Trois histoires d’Aśoka dans le Za piyu jing 雜譬喻經 (T. 205): Three stories of Aśoka in the Za piyu jing 雜譬喻經 (T. 205)
No full textThree stories related to Aśoka
pousser une étude textuelle traditionnelle vers les humanités numériques
No full textInternational audienc
The authigenic and detrital neodymium isotopic composition in the modern Mediterranean Sea: implications for paleocirculation proxy
No full textInternational audienceNeodymium isotopic composition (143Nd/144Nd or εNd) has been used as a tracer of water mass provenance in the modern and the past oceans. However, recent studies have questioned its reliability because some phases of detrital sediments are reactive and a partial dissolution of these phases could alter the initial authigenic signals through porewater Nd. We examined this possibility using core-top sediments from the Mediterranean Sea, an ideal region, because the water circulation and the εNd distribution of seawater and detrital fractions are relatively well constrained. Furthermore, smectite, one of the most reactive minerals, is abundant in the easternmost basin due to Nile sediment input. We obtained paired authigenic (leachates and foraminiferal tests) and detrital εNd signatures from core-top sediments along the zonal transect from 2°W to 33°E. The authigenic εNd values generally agreed with the bottom water signals, except in the easternmost Levantine and the Aegean Seas, where they were higher than the water values. These areas are characterised by high smectite abundance and enclosed nature, making local Nd source influence more visible. The authigenic εNd values in these areas were stable at about −5 to −4, while the corresponding detrital values ranged between −10 and −4. The compilation of modern seawater and detrital εNd values shows that seawater εNd covaries with detrital signals at 0–200 m water depth, and that the correlation is insignificant at depths greater than 1500 m. These results argue against a ubiquitous control of bottom water εNd by the benthic flux in the present Mediterranean Sea. Sensitivity tests suggest that the εNd values of Mediterranean Sea water are affected by the isotopic composition of Atlantic inflow, deep-water formation zones and local benthic sources, as well as by the size of the Atlantic inflow flux, deep-water formation and zonal water exchange. These results support the use of Nd isotopic composition as a tracer of water mass provenance in the Mediterranean Sea although a combination of isotopic data from various basins is required to distinguish the influence of these factors
Drosophila’s sensory responses to bacterial peptidoglycan integrates positive and negative signals
No full textInternational audienceInteractions between animais, including humans, and surrounding microbes are governed by a delicate balance, crucial for survival. Animais must distinguish and respond adequately to beneficial and harmful microbes to maintain homeostasis. Recent research suggests that bacterial components such as lipopolysaccharide and peptidoglycan {PGN) influence hast behavior by modulating neuronal activity. PGN detection by specific neurons can prompt infected female flies to reduce oviposition or trigger avoidance behaviors via gustatory neurons. Using behavioral assays and calcium imaging, we found that PGNs can also act as attractants, activating the sweet taste circuit in a concentration-dependent manner. Our findings demonstrate that flies integrate PGN-derived positive and negative signais to make ad hoc decisions. This dual response underlines the need for Drosophila to distinguish between different concentrations of compounds in their environment, integrating sensory data to navigate efficiently in microbe-co-inhabited environments
Du maître de sagesse à la canonisation : la représentation de Confucius entre le IVe siècle avant notre ère et le Ier siècle de notre ère, à la lumière des sources transmises et exhumées
No full textInternational audienceLa tradition lettrée chinoise présente Confucius (v. 551-479 av. n. è.) comme le maître par excellence, le désignant souvent par la simple appellation « Maître » (zi 子). Confucius revêt aussi le rôle de patriarche de la classe des lettrés-fonctionnaires, qui formait une sorte d’entité organique ayant assuré la cohésion politique, idéologique, spirituelle, culturelle et éducative de l’empire chinois pendant plus de deux millénaires. Néanmoins, de même que son enseignement fut constamment réinterprété à travers les âges, la représentation de Confucius dans la mémoire collective – loin d’être uniforme – ne cessa d’évoluer en fonction du contexte historique propre à chaque époque. La phase initiale dans la transformation du portrait du penseur se produisit durant les siècles qui précédèrent et suivirent l’avènement de l’empire en l’an 221 avant notre ère. Cette longue phase se divise en trois étapes. Dans un premier temps, plus d’un siècle après sa mort, Confucius était dépeint comme un maître qui, entouré de disciples, se mit en quête d’un souverain sage prêt à instaurer un gouvernement fondé sur la vertu. Dans un second temps, environ un siècle après la fondation impériale, le maître de sagesse fut alors décrit comme un « roi sans couronne », dont l’enseignement fut promu au rang de doctrine impériale officielle. Dans un dernier temps, aux alentours de l’ère chrétienne, une nouvelle image de Confucius se développa, avec l’instauration de son culte officiel qui s’accompagna de sa canonisation. Nous nous proposons d’examiner le processus d’évolution de la représentation de Confucius entre le IVe siècle avant notre ère et le Ier siècle de notre ère, suivant les circonstances politiques, sociales et culturelles spécifiques à chaque période. Notre analyse s’appuiera sur des données issues aussi bien de sources transmises que de sources exhumées textuelles et iconographiques, qui ont refait surface au cours des vingt dernières années
The Close AGN Reference Survey (CARS). Long-term spectral variability study of the changing look AGN Mrk 1018
No full textInternational audienceChanging-look AGNs (CLAGN) are accreting supermassive black hole systems that undergo variations in optical spectral type, driven by major changes in accretion rate. Mrk 1018 has undergone two transitions, a brightening event in the 1980s and a transition back to a faint state over the course of 2-3 years in the early 2010s. We characterize the evolving physical properties of the source's inner accretion flow, particularly during the bright-to-faint transition, as well as the morphological properties of its parsec-scale circumnuclear gas. We model archival X-ray spectra from XMM-Newton, Chandra, Suzaku, and Swift, using physically-motivated models to characterize X-ray spectral variations and track Fe Kalpha line flux. We also quantify Mrk 1018's long-term multi-wavelength spectral variability from optical/UV to the X-rays. Over the duration of the bright-to-faint transition, the UV and hard X-ray flux fell by differing factors, roughly 24 and 8, respectively. The soft X-ray excess faded, and was not detected by 2021. In the faint state, when the Eddington ratio drops to log Lbol/LEdd < -1.7, the hot X-ray corona photon index shows a 'softer-when-fainter' trend, similar to that seen in some black hole X-ray binaries and samples of low-luminosity AGNs. Finally, the Fe Kalpha line flux has dropped by only half the factor of the drop in the X-ray continuum. The transition from the bright state to the faint state is consistent with the inner accretion flow transitioning from a geometrically-thin disk to an ADAF-dominated state, with the warm corona disintegrating or becoming energetically negligible, while the X-ray-emitting hot flow becoming energetically dominant. Meanwhile, narrow Fe Kalpha emission has not yet fully responded to the drop in its driving continuum, likely because its emitter extends up to roughly 10 pc
The OCaml system release 5.4: Documentation and user's manual
No full textThis manual documents the release 5.4 of the OCaml system. It is organized as follows. Part I, "An introduction to OCaml", gives an overview of the language. Part II, "The OCaml language", is the reference description of the language. Part III, "The OCaml tools", documents the compilers, toplevel system, and programming utilities. Part IV, "The OCaml library", describes the modules provided in the standard library. Part V, “Indexes”, contains an index of all identifiers defined in the standard library, and an index of keywords
Decoupled winter and summer climate changes in southern Europe during the Dansgaard-Oeschger cycles
No full textInternational audienceThe marine isotope stage 3 (MIS 3) (similar to 60-30 ka) exhibits large amplitude millennial climatic oscillations, also named Dansgaard-Oeschger (DO) cycles, which are marked by alternation of warm (GIs - Greenland interstadials) and cold phases (GSs-Greenland stadials). Here, we explore the seasonal nature of the DO cycle climate signal in southern Europe using 12 pollen records that allowed us to reconstruct the vegetation types and key climatic parameters such as seasonal temperatures and precipitation. Our results show the development of arboreal vegetation during GIs and non-arboreal vegetation during GSs. They also indicate that vegetation changes were mainly driven by winter precipitation and temperatures, with high and low values during GIs and GSs, respectively. The results tend to demonstrate a decoupling between winter and summer conditions, with relatively stable and warm summer temperatures throughout MIS 3, but large amplitude variations in winter. We infer that the climate over southern Europe was mainly influenced by surface conditions over the North Atlantic driven by stratification due to meltwater discharge, and also possibly by extension/contraction of the subpolar gyre (SPG) through changes in the westerlies' strength, thus impacting the extent of winter sea-ice cover, temperature and moisture availability over southern Europe
Defensive armament in Ugarit: armour, helmets and shields
No full textInternational audienceIn recent decades, several multidisciplinary studies have enabled us to deepen our knowledge of armies and armament in Bronze Age societies in the Near East. The archaeological finds at the sites of Ras Shamra, Minet el- Beida and Ras Ibn Hani are most often taken into account in analyses based on publications by excavators that only record part of the artefacts unearthed. As yet, there is no overall study of armament in Ugarit. One of the objectives of an ongoing research programme conducted by the “Mission archéologique syro-française de Ras Shamra- Ougarit” is to enhance our understanding of the armament of Ugarit and to present previously unpublished material to the scholarly community.There is quite a considerable number of realia that can be associated with armaments, which belong to a wide range of different types. Most of the pieces brought to light in excavations are made of a copper alloy and are classified as offensive weapons. There is very much less armament that is exclusively defensive. It is worth mentioning that this applies to the whole of the Near Eastern archaeological documentation of the Bronze Age. It is quite possible that many pieces made of perishable materials, such as shields made of wood or stretched skin or else body armour made of fabric and leather, have not been preserved.This article offers a comprehensive overview of the defensive armament in Ugarit, structured into three sections addressing armour, helmets, and shields, respec- tively. For each category, the archaeological evidence is examined first, followed by an analysis of relevant textual sources. The final section is devoted to the iconographic documentation
Combined analysis of microfacies of continuous and instantaneous lake deposits to refine the seasonal signal of hydro-gravitational hazards in the southern Alps
No full textInternational audienceLamina-scale investigation of the continuous sedimentation – driven by lake productivity and diffuse runoff – are essential for producing near seasonal-scale records of local environmental changes, such as shifts in climate and land cover. Understanding the information contained in continuous sedimentation also allows for precise characterization of instantaneous sedimentation events by identifying the specific environmental conditions and timing in which they occur (Kämpf et al., 2015; Czymzik et al., 2010). To assess the long-term evolution of hydro-gravitational hazards, it is thus relevant to study instantaneous deposits in relation to continuous deposits to better understand the environmental context of sedimentary deposits.This study focuses on the 15-meters-long composite core LAU21 from Lake Lauzet (890 m a.s.l.), located in the lower Ubaye River valley, which is characterized by finely laminated continuous sedimentation and instantaneous deposits with variable particle-size grading and thickness. Here, we present results from two sediment sections covering the Mid-Holocene period (constrained by 14C dating), based on a multiscale and multiproxy approach combining lithological, granulometric, geochemical, geophysical, micrometric thin sections, and palynological analysis. Three facies characterize the finely laminated continuous sedimentation: a micrite facies, a diatom facies, and a filamentous algal facies. This succession is typical of varved sedimentary sequences in deep, perialpine lakes and may suggest the presence of a seasonal signal. Two types of grain-supported instantaneous layers are intercalated within the continuous sedimentation. These layers (thicknesses ranging from micrometer to centimeter) are interpreted as triggered by flood (i.e. coarse basal unit covered by a finning upward sequence), and debris flow and/or avalanche (i.e. non-graded clastic sequence rich in botanical remains). As an example, the thin section LAU21-S5-124-134 (2500 – 2000 cal. BP) is composed of a succession of 86 laminae of continuous deposits, intercalated with 14 instantaneous deposits, including 6 flood layers and 8 debris flow and/or avalanche layers. In the remainder of the study, it will be possible to distinguish debris flows from avalanches by analyzing grain size distribution, the geomorphological features of the source areas (slope, incision), and the load/discharge ratio. The analysis of seasonal hydrological variability will contribute to their interpretation