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魏晋南北朝历法的电子化重构与以城市为中心的知识体系
No full textInternational audienceIn 2023, I launched a long-term project to translate all astronomical procedure texts (历法) from the Wei-Jin-Nanbei chao (魏晋南北朝) period into both English and Python code, gradually constructing executable, verifiable, and modifiable 'living translations'. By converting the original narrative descriptions of these texts into explicit computational steps, I have been able to systematically compare their choices of astronomical constants, the internal structure of constant systems, parallel relationships between different texts and procedures, and the relative computational workload and complexity of each calendar system.In my 2021 research, I argued that the history of astronomy during the Wei-Jin-Nanbei chao period can no longer be narrated using dynastic succession as the basic unit. With multiple regimes occupying different cities, the exchange among astronomers exhibited strong regional characteristics, and the transmission and accumulation of knowledge often followed city-lineage networks rather than 'dynastic lines'.In this presentation, I attempt to combine these two research threads to propose a new analytical framework. Mathematical processing of the procedure texts reveals that when we shift the method of comparing astronomical constants from decimal values to fractional equivalence, the borrowing relationships that were 'masked' by traditional constant systems composed of integer resonance periods become clearly visible. The isomorphism of these constant systems often corresponds closely to specific cities, political environments, and scholarly lineages. Analysis of the procedure texts reveals another transmission trajectory: their modular compositional features (similar to what Assyriologists call 'System A' and 'System B' in cuneiform astronomy) repeatedly appear across different texts, independent of differences in constant systems.Through the digital and computational reconstruction of texts and procedures, we can simultaneously track the evolution of both \textbf{constant systems} and \textbf{procedure systems}, thereby reorganising the mathematical literature of this period along 'city-region-lineage' lines rather than by 'dynasty'. This digital humanities approach provides a more explanatory framework for the overall structure of astronomical traditions in the Wei-Jin-Nanbei chao period.2023 年，我启动了一个长期计划：将魏晋南北朝时期的全部历法以英文与 Python 代码的双重形式重新表述，逐步构建可执行、可检验、可修改的"活体翻译"（living translations）。通过把历法文本的原始叙述转换为明确的计算步骤，我得以系统比较其天文常数的选择、常数体系的内部结构、不同文本与术式之间的平行关系，以及各套历法在具体计算上的相对工作量与复杂度。在此之前，我在 2021 年的研究中提出：魏晋南北朝时期的天文学史不能再以朝代更替为基本单位来叙述。由于多个政权分据不同城市，天文学家的交流呈现强烈的地域性特征，知识的传递与累积往往沿着城市—传承的网络而非"王朝线"展开。在本次报告中，我尝试把上述两条研究线索结合起来，提出一个新的分析框架。对历法文本进行数学化处理显示：当我们将天文常数的比较方式从十进制转为分数等价形式时，传统以一组整数谐振搭配构成的常数体系所"掩蔽"的借用关系便清晰显现出来。这些常数体系的同构性往往与特定的城市、政治环境与学术传承密切对应。对历法术文的分析则揭示出另一种传播轨迹：其模块化组合特征（类似楔形文字天文学中所谓的 "系统 A" 与 "系统 B"）在不同文本间反复出现，但不以常数体系的差异为转移。通过对文本与程序的电子化、计算化重构，我们可以同时追踪常数体系与程序体系的演变，从而以"城市—区域—传承线"而非"朝代"来重新组织这一时期的历法文献。这样的数字人文方法，为魏晋南北朝天文传统的整体结构提供了一个更具解释力的框架
Millennial-scale climatic variability and fire regimes and their impacts on vegetation in Gran Canaria since 28 cal ka BP
No full textInternational audienceThe influence of climate change and fire regimes on vegetation in the Canary Islands at the millennial scale remains largely unknown. This study presents the longest continuous palaeoecological record from the archipelago, spanning the last 28,000 years from Vega de Arucas in Gran Canaria. Using a multiproxy approach, we analysed charcoal particles for fire frequency reconstruction, fossil pollen and non-pollen palynomorphs (NPPs) for vegetation change, sedimentology for changes in material deposited, branched glycerol dialkyl glycerol tetraethers (brGDGTs) for air temperature, and pollen climate modelling for temperature, precipitation, and relative humidity estimates. We document different changes in vegetation and fire regimes linked to regional and global climatic transitions. Before the Last Glacial Maximum (LGM), pollen and charcoal data indicate local presence of a laurel forest taxa (e.g., Morella faya) at low elevations (c. 200–300 m above sea level), subjected to infrequent fires, suggesting wetter conditions and cooler temperatures. During the LGM, the laurel forest was replaced by a dry pine forest, indicative of lower than previous temperatures and reduced water availability. This transition from laurel to pine forest coincides with an increase in fire frequency. During the last deglaciation (Bølling-Allerød and Younger Dryas), a rapid shift occurred from pine forest to thermophilous woodland (e.g., Juniperus sp., Phoenix canariensis), reflecting warmer conditions with continued climate oscillations and more frequent fire activity. Although pollen preservation was poor during the Holocene and hampers current understanding of vegetation changes throughout this period, charcoal records indicate frequent fires. While previous views have proposed that islands may have been buffered from climatic changes due to the regulating influence of the ocean, our study confirms a scenario of direct influence of global and regional climatic variations in local vegetation distribution and fire regimes. This has important implications for understanding vegetation resilience and landscape management in the face of future climatic changes
Taux de retour énergétique du bouquet électrique : l’impact des sources intermittentes
No full textInternational audienceAfin de réduire leur dépendance aux énergies fossiles, de nombreux pays ont engagé des transitions de leurs systèmes énergétiques en déployant notamment des parcs solaires et éoliens. Ceux-ci nécessitent la construction d’un système de flexibilités capable d’intégrer dans le réseau électrique leurs productions fatales et intermittentes. Dans une précédente publication, deux des auteurs ont étudié le dimensionnement de ce système et sa composition possible à partir de productions pilotables, d’effacements de consommation et de stockages. Un autre aspect critique de la transition énergétique est l’évolution du taux de retour énergétique (TRE) du bouquet électrique (Energy Return On Investment — EROI). La littérature fournit des valeurs de l’EROI des sources, c’est-à-dire le rapport de la quantité d’électricité totale produite par une unité de production à l’énergie investie dans son cycle de vie ; d’autres y ajoutent un stockage qui permette de lisser leur production à l’intérieur d’une journée ; mais rares sont les simulations du système de flexibilités nécessaire au fonctionnement sur l’année. C’est ce que nous présentons ici sur le cas français pour deux bouquets électriques envisagés pour 2050. On trouve un EROI voisin de 6,6 pour le bouquet à 50 % de nucléaire et 50 % de renouvelable, et de 2,3 pour le bouquet à 100 % renouvelable, alors qu’aujourd’hui l’EROI du bouquet est autour de 25,5. Ces faibles valeurs sont essentiellement dues à l’impact des stockages associés au développement des énergies intermittentes. Pour savoir si ces bouquets sont soutenables pour notre société, les valeurs obtenues sont comparées aux estimations de la littérature sur l’EROI minimal pour le fonctionnement d’un pays raisonnablement développé
Cluster-diagrammatic D-TRILEX approach to non-local electronic correlations
No full textIn this work, we extend the theoretical approach known as "D-TRILEX", developed for solving correlated electronic systems, to a cluster reference system for the diagrammatic expansion. This framework allows us to consistently combine the exact treatment of short-range correlation effects within the cluster, with an efficient diagrammatic description of the long-range charge and spin collective fluctuations beyond the cluster. We demonstrate the effectiveness of our approach by applying it to the one-dimensional nano-ring Hubbard model, where the low dimensionality enhances non-local correlations. Our results show that the cluster extension of D-TRILEX accurately reproduces the electronic self-energy at momenta corresponding to the Fermi energy, in good agreement with the numerically exact quantum Monte Carlo solution of the problem, and outperforms significantly more computationally demanding approach based on the parquet approximation. We show that the D-TRILEX diagrammatic extension drastically reduces the periodization ambiguity of cluster quantities when mapping back to the original lattice, compared to cluster dynamical mean-field theory (CDMFT). Furthermore, we identify the CDMFT impurity problem as the main source of the translational-symmetry breaking and propose the computational scheme for improving the starting point for the cluster-diagrammatic expansion
Importance scientifique, sanitaire et sociale du microbiome vaginal
No full textInternational audienceThe vaginal microbiome is an ideal study system given the diversity of bacteria it harbors, its communities that can be structured into large, stable types, the ease of sampling, and the well-characterized environment. The microbiome is also dynamic and varying according to life stage, biological mechanisms such as hormonal cycles or menstruation, and specific exposures (e.g.; antibiotics, sexual practices). The associations between vaginal microbiota and health are strong, including its role in sexually transmitted infections, fertility, and general well-being. This raises questions about prevention and therapies, while avoiding the risk of excessive pathologization.Le microbiome vaginal est un objet d’étude idéal avec sa diversité de bactéries limitée, ses communautés qui se structurent facilement selon de grands types stables, son échantillonnage aisé et son environnement bien caractérisé. Il est aussi dynamique, et varie en fonction des périodes de la vie, des mécanismes biologiques tels que les cycles hormonaux ou les menstruations et des expositions particulières (antibiotiques, pratiques sexuelles). Les associations entre le microbiote vaginal et la santé sont très fortes (infections sexuellement transmissibles, fertilité, bien-être général), ce qui pose la question de la prévention et des thérapies, tout en évitant l’écueil d’une pathologisation excessive
Boosting Effect of Encapsulated Polyoxometalates in the Photocatalytic CO 2 Reduction by MOF-545
No full textInternational audienceAchieving efficient photocatalytic CO2 reduction is a current complex challenge, requiring the development of strategies that optimize not only the capture of photons but also the photoinduced charge separation and electron transfer processes. In this pursuit, we have immobilized polyoxometalates (POMs), specifically [SiW12O40] 4-(SiW12) and [W10O32] 4-(W10), within the Zr-based porphyrinic metal-organic framework (MOF) MOF-545 catalytic material with the purpose of maximizing its CO2 photoreduction activity. The resulting SiW12@MOF-545 and W10@MOF-545 composites were fully characterized by various techniques (IR spectroscopy, powder X-ray diffraction, N2 adsorption isotherms, HADDF-STEM) to confirm the POM's incorporation via impregnation. These characterizations were complemented by simulations in order to locate the POM into the MOF's cavities and identify host/guest interactions. In photocatalytic conditions, i.e. under visible-light irradiation and in CH3CN/TEOA 20:1 solution, the two SiW12@MOF-545 and W10@MOF-545 composites reduced CO2 to formate with 100% selectivity at rates of 669 and 1239 mol gMOF -1 h -1 , respectively. Remarkably, W10@MOF-545 showed around a 3-fold increase in activity compared to its POM-free counterpart. DFT calculations suggest that both POM guests can accept photoexcited electrons from the porphyrin linkers of MOF-545, allowing increased lifetime of the photogenerated holes in the MOF upon illumination, thus boosting TEOA oxidation by the porphyrinic MOF for subsequent CO2 reduction. Moreover, the calculations unveil the origin of the observed superior overall catalytic activity of W10@MOF-545 over SiW12@MOF-545 due to stronger thermodynamic driving force for charge separation, providing rational guidelines for future design of efficient photocatalysts.</div
Mechanochemical and Piezo‐Accelerated Stereoselective Synthesis of Isoindolinones
No full textInternational audienceIn this study, we report on the use of mechanochemistry for the synthesis of trifluoromethylated isoindolinones via a cascade radical sequence involving intermolecular addition/cyclization reactions of ynamides. This minimum solvent approach, involving liquid‐assisted grinding, provides the products in good yields with complete E stereoselectivity, contrasting with the E/Z mixtures obtained under previously reported photoredox conditions. Mechanistic investigations revealed two complementary activation pathways: mechanical activation alone can trigger the radical cascade, while the presence of piezoelectric materials (BaTiO 3 ) significantly accelerates product formation. Furthermore, we identified an unexpected role of Celite® as an abrasive agent that promotes metal leaching and enables alternative activation pathways. This methodology showcases mechanochemistry as a valuable alternative to photoredox catalysis for stereoselective radical transformations, with distinct mechanistic advantages that can be strategically exploited
Wang Anshi (1021-1086), un éducateur au XIème siècle
No full textWang Anshi (1021-1086), an eminent scholar-official of the Northern Song dynasty (960-1127), brought a series of changes during his wide-ranging reforms to government schools and the official recruitment system. This study looks into the origin of these changes that lies in his conception of "xue" (study or learning), an ancient notion that acquired new significations of great profoundness in Wang's thought. Through an original exegetical approach, he incorporated elements of the Taoist tradition into his interpretations of Confucian classics. In this way, he reformulated different dimensions of the act of "xue", from his definition of the ideal scholar and the ideal man as incarnations of the ultimate achievement of learning, to the means of its realization. For Wang, this true learning could lead man to exploit his natural potential to the highest degree while becoming one with the Way, the foundation of the universe. At this stage, actions generated by the mind deeply rooted in the Way could accomplish beneficial works in human society. These aspects are analyzed in the central section of our work (chapter III), where we also show that in his writings, he defined a process of progression leading to the fulfillment of "xue", in which self-cultivation and canonical study are arranged in a rigorous order. In Antiquity that he took as a model, schools assured a moral education leading to the supreme realization of man, which was in perfect harmony with the social education for the training of competent officials. His exegetical approach behind the making of this model is analyzed in detail in our work. To better understand the originality of Wang's approach by situating it in historical continuity, this central section is preceded by a preliminary examination (Chapter I) of evolutions in the field of education from the Spring and Autumn period (772-476 BC) to the Tang dynasty (220-907), tracing the major "xue" ideals that have emerged in different social and political contexts. This chapter also presents functions that have been successively conferred on the main educational institutions, which gained an important ritual characteristic by the Song times. We show that these traditions contributed to the shaping of the educational landscape of the Northern Song (chapter II), which nevertheless created complex problems in government schools. While attempts were being made to rectify them, some eminent scholars set out to rethink the true meaning of learning and education, developing pedagogical practices oriented to human perfection. Wang's approach differed clearly from those of his contemporaries, for he placed great emphasis on institutions and regulations in the education and the recruitment of scholar-officials. In chapter IV which focuses on the means of realization of Wang's ideals, we show that, although he explained concrete practices to be followed by the individual to achieve the ultimate goal of "xue" that engage a strongly corporeal aspect, it is principally through the reorganization of the government schools that he carried out his plan. By imposing the New Commentaries on three Confucian classics written under his direction as a nationwide standard school curriculum (a radical measure that aroused bitter controversy in his day), Wang wished to promote a manual that would guide all those who applied themselves to learning by putting them on the right track. We show that these commentaries convey the essential views of "xue" analyzed in Chapter III, as well as some fundamental principles of governance.Wang Anshi (1021-1086), lettré et homme d'État éminent des Song du Nord (960-1127), a apporté une série de changements lors de sa réforme générale aux écoles et aux modalités de sélection en vue du recrutement du personnel administratif. Aux origines de ces changements on trouve sa conception du "xue" (étude ou apprendre), notion très ancienne qui a acquis chez lui des significations nouvelles d'une grande profondeur. Par une approche exégétique originale, il a su incorporer des éléments de sources taoïstes dans sa lecture des classiques confucéens. Ainsi il est arrivé à reformuler les différentes dimensions constitutives de l'acte du "xue", de l'idéal lettré et idéal de l'homme qui en incarnent l'objectif suprême, jusqu'aux moyens de leur réalisation. Cette étude authentique peut selon lui conduire l'homme à exploiter son potentiel naturel au plus haut degré en faisant corps avec la Voie, fondement de l'univers. À ce stade, l'action générée par l'esprit qui s'ancre profondément dans la Voie peut accomplir des œuvres bienfaisantes dans la société humaine. Ces aspects sont analysés dans la partie centrale de notre travail (chapitre III), où nous montrons que se dégage de ses écrits la définition d'un processus de progression conduisant à l'achèvement du "xue", où la culture de soi et l'étude canonique sont rangées dans un ordre rigoureux. Pour Wang, dans l'école de l'Antiquité prise pour modèle, l'éducation morale permettant la réalisation suprême de l'homme était en parfaite harmonie avec l'éducation sociale destinée à former des fonctionnaires compétents. L'approche exégétique derrière la fabrique de ce modèle est analysée en détail dans notre travail. Afin de mieux comprendre l'originalité de la démarche de Wang en la situant dans la continuité historique, cette partie centrale est précédée par un examen préliminaire (chapitre I) consacré aux évolutions intervenues dans le domaine de l'éducation, des Printemps et Automnes (772-476 av. J.-C) jusqu'aux Tang (220-907), pour retracer à grands traits des idéaux du "xue" ayant émergé dans des conditions sociales et politiques différentes. Sont aussi mises en lumière les fonctions conférées successivement aux principales institutions éducatives de l'État, dont l'aspect rituel a acquis un poids majeur. Nous montrons que ces traditions ont contribué à dessiner le paysage de l'éducation sous les Song du Nord (chapitre II), qui étaient en même temps à l'origine des problèmes complexes que comportaient les écoles officielles. Parallèlement à des tentatives destinées à les rectifier, certains lettrés éminents se sont appliqués à repenser le sens même de l'étude et de l'éducation, développant des pratiques pédagogiques orientées vers le perfectionnement de l'homme. L'approche de Wang se distingue fortement de celles de ses contemporains en raison de l'accent qu'il place sur l'institution et les règlements dans la formation et le recrutement des lettrés-fonctionnaires. Dans le chapitre IV, centré sur les moyens de réalisation des idéaux de Wang, nous montrons que, bien qu'il ait explicité des pratiques concrètes à suivre par l'individu qui engagent un aspect fortement corporel, c'est par la réorganisation de l'école officielle que se déploie pleinement son dessein. En imposant les Nouveaux commentaires rédigés sous sa direction sur trois classiques confucéens comme matières d'étude uniformes à l'échelle nationale (mesure radicale qui a suscité d'âpres controverses à son époque), Wang souhaite en effet promouvoir un manuel encadrant tous ceux qui se sont appliqués à l'étude en les mettant sur la bonne voie. Nous montrons que ces commentaires véhiculent les vues essentielles du "xue" analysées dans le chapitre III ainsi que des principes de gouvernement fondamentaux
“The Work of Inspection Cannot be Freed of Confusions and Amalgamations”: Purity, Danger and the Practice of Late Ottoman Statecraft
No full textInternational audienceThis chapter explores the intricacies of late Ottoman administration, focusing particularly on inspection practices and the discourse surrounding them. Through a close reading of a selection of administrative correspondences from the late nineteenth century, the chapter aims to take a “grounded” approach to the historical semantics of corruption, discussing how to distinguish between emic and etic perspectives. At the outset, the chapter focuses on a 1918 ministerial circular dealing with the issue of appointments and highlighting the efforts made by some Ottoman officials to eliminate patronage and favoritism. It then examines various reports which, without explicitly mentioning corruption, deal with issues that may be directly or indirectly related to it. The analysis extends to the role of chemistry and scientific inspection in guaranteeing the integrity of imported goods, revealing the institutional and technical difficulties encountered by the Ottoman authorities. The text concludes with a discussion of the wider implications of “purity control” in Ottoman administrative practices, suggesting that corruption should be understood not only in ethical and political terms, but also in the material context of governance
H i Properties of Field Galaxies at z ≈ 0.2–0.6: Insights into Declining Cosmic Star Formation
No full textInternational audienceAbstract We report statistically significant detection of H i 21 cm emission from intermediate-redshift ( z ≈ 0.2–0.6) galaxies. By leveraging multisightline galaxy survey data from the Cosmic Ultraviolet Baryon Survey and deep radio observations from the MeerKAT Absorption Line Survey, we have established a sample of ≈6000 spectroscopically identified galaxies in 11 distinct fields to constrain the neutral gas content at intermediate redshifts. The galaxies sample a broad range in stellar mass, from log M star / M ⊙ ≈ 8 to log M star / M ⊙ ≈ 11 , with a median of 〈 log M star / M ⊙ 〉 med ≈ 10 and a wide range in redshift from z ≈ 0.24 to z ≈ 0.63 with a median of 〈 z 〉 med = 0.44. While no individual galaxies show detectable H i emission, the emission line signal is detected in the stacked spectra of all subsamples at greater than 4 σ significance. The observed total H i 21 cm line flux translates to a H i mass, M H I ≈10 10 M ⊙ . We find a high H i -to-stellar-mass ratio of M H I / M star ≈ 6 for low-mass galaxies with 〈 log M star / M ⊙ 〉 ≈ 9.3 (>3.7 σ ). For galaxies with 〈 log M star / M ⊙ 〉 ≈ 10.6 , we find M H I / M star ≈ 0.3 (>4.7 σ ). In addition, the redshift evolution of H i mass, 〈 M H I 〉, in both low- and high-mass field galaxies, inferred from the stacked emission-line signal, aligns well with the expectation from the cosmic star formation history. This suggests that the overall decline in the cosmic star formation activity across the general galaxy population may be connected to a decreasing supply of neutral hydrogen. Finally, our analysis has revealed significant 21 cm signals at distances greater than 75 kpc from these intermediate-redshift galaxies, indicating a substantial reservoir of H i gas in their extended surroundings