Scientific Publications of the University of Toulouse II Le Mirail
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Les frontières du sacré. Matérialiser les seuils dans l’architecture, de l’Antiquité à la fin du Moyen Âge
No full textLes historiens de l’art et les archéologues travaillant sur les édifices religieux s’intéressent à des techniques, des formes et des décors, mais ils tentent aussi de restituer les rituels qui s’y déroulaient, les circulations qui les animaient, ainsi que les croyances qui les encadraient. L’édifice et sa périphérie constituent un espace sacré, délimité par une frontière, matérielle ou symbolique, marquant la séparation avec l’espace profane. L’expérience de l’espace sacré est, pour ceux qui le fréquentent, régie par un ensemble de normes et d’usages, et contrainte par ses différents degrés de sacralité, finement hiérarchisés. C’est dans cette approche anthropologique que s’inscrivent les neuf articles réunis dans ce dossier de Frontière·s, creusant un sillon qui, depuis quelques décennies, a permis de structurer des approches pluridisciplinaires fécondes
Counting distinct multivariate self-similarity parameters using a bootstrap-driven graph clustering approach
No full textInternational audienceIn various modern fields, the multiplicity of sensors in applications may result in potentially numerous scale-free time series that jointly characterize one same system. Multivariate self-similarity analysis tackles the challenge of studying these systems by providing as many self-similarity parameter estimates as available time series. The possibly large amount of self-similarity parameters raises the major issue of identifying the number of actually distinct self-similarity parameters. The present work attains this goal by designing an adapted graph to perform a spectral clustering-type procedure. The proposed graph is weighted using pairwise equality test p-values estimated by a multivariate time-scale block-bootstrap scheme combined with wavelet random matrix eigenanalysis for self-similarity parameter estimation. Numerical experiments on synthetic multivariate data show a very satisfactory performance of the clustering strategy
Far-reaching hunter-gatherer networks during the Last Glacial Maximum in Western Europe
No full textInternational audienceSocial networking is an essential feature of hunter-gatherer societies. It fosters the circulation of goods and information and enables kinship ties across different scales, including long-distance contacts. While such behaviors are known since at least the Upper Palaeolithic, evidence for geographically extensive social networks remains scarce. This evidence is limited to indirect inferences based on shared cultural traits, “art” styles, and symbolic items, while lithic raw material movements are mostly local and regional, with few cases exceeding 300 kilometers. We provide geochemical evidence for the largest confirmed distance between the source and discard location of a knapped lithic object in Palaeolithic Europe. Solutrean artifacts discarded at Peña Capón, Central Iberia, were sourced in Southwest France, 600 to 700 kilometers away. This demonstrates social networks of unprecedented geographic scale maintained during ∼1400 years during the Last Glacial Maximum. It also suggests that stone tools were exchanged as symbolic items to solidify social contacts and sustain far-reaching networks as risk-buffering mechanisms among widely dispersed hunter-gatherers
La fondation du campus de la faculté des sciences de Rangueil : un projet-pilote
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Lessons from Formally Verified Deployed Software Systems
No full textInternational audienceThe technology of formal software verification has made spectacular advances, but how much does it actually benefit the development of practical software? Considerable disagreement remains about the practicality of building systems with mechanically-checked proofs of correctness. Is this prospect confined to a few expensive, life-critical projects, or can the idea be applied to a wide segment of the software industry? To help answer this question, the present survey examines a range of projects, in various application areas, that have produced formally verified systems and deployed them for actual use. It considers the technologies used, the form of verification applied, the results obtained, and the lessons that the software industry should draw regarding its ability to benefit from formal verification techniques and tools. Note: this version is the extended article, covering all the systems identified as relevant. A shorter version, covering only a selection, is also available
Zones Ateliers, un réseau de recherches collaboratives, situées et engagées: Un réseau de recherches collaboratives, situées et engagées
No full textInternational audiencePour répondre à la complexité des grands défis contemporains (climat, inégalités, biodiversité, pandémies, etc.), le champ de l’enseignement supérieur et de la recherche (ESR) évolue : les sciences de la soutenabilité, apparues il y a seulement un quart de siècle, en témoignent. En France, le Réseau des Zones Ateliers (RZA), dispositif original du CNRS–Écologie & Environnement, incarne cette dynamique. Infrastructure de recherche socio-écologique, il mobilise des approches inter- et transdisciplinaires pour appréhender la complexité des socio-écosystèmes.Destiné à un large public composé d’étudiants, d’acteurs des territoires et de chercheurs, cet ouvrage adopte une perspective historique. Une introduction retrace la genèse et l’évolution du réseau à travers le prisme de sa plasticité, puis les développements présentent les étapes de l’élaboration des approches inter- et transdisciplinaires, en s’appuyant sur la diversité des problématiques propres à chaque « Zone Atelier ». Enfin, une ouverture propose des perspectives, inscrivant le RZA dans le champ des sciences transformatives et appelant à une profonde transformation de l’ESR lui-même
L'étude des chaînes relationnelles : un domaine de l'analyse de réseau sociaux à développer
No full textInternational audienceThe study of relational chains is one of the approaches used in social network analysis. It consists of documenting the activation of relationships between people in processes of accessing resources or other people. This approach makes it possible to study the phenomena of embeddedness (the dependence of various social activities on networks of relationships between individuals) and, more generally, the overall structure of networks in various socio-historical contexts.L'étude des chaînes relationnelles est l'une des approches utilisées en analyse des réseaux sociaux. Elle consiste à documenter l'activation de relations entre personnes dans des processus d'accès à des ressources ou à d'autres personnes. Cette approche permet d'étudier les phénomènes d'encastrement (la dépendance d'activités sociales diverses relativement aux réseaux de relations entre les personnes) et plus généralement la structure générale des réseaux dans des contextes sociohistoriques variés
Generation and modulation of fully circularly polarized ultrabroadband THz radiation using two-color gas plasma techniques
No full textInternational audienceTerahertz optics enables powerful spectroscopy and imaging thanks to its non-ionizing nature and sensitivity to molecular and material properties. It is also beneficial to next-generation communications, since it offers vast bandwidth for ultra-fast, low-latency data transfer. Polarization control of terahertz waves is vital for applications in chiral spectroscopy, spin dynamics, ultrafast material studies, and communication multiplexing. Despite progress, full polarization control—particularly for ultra-broadband terahertz pulses—remains a challenge. In this work, we introduce a simple method for generating circularly polarized terahertz radiation with an ellipticity of 0.99. By optimizing key parameters—BBO crystal tilt, rotation, position, and pump chirp—we achieve broadband circular polarization across 30 THz, with indications of further extent to 40 THz. This approach advances fundamental studies in terahertz optics and paves the way for adaptive sensing and next-generation terahertz communications
Regret asymptotiquement optimal dans les processus de décision markoviens communicants
No full textIn this paper, we present a learning algorithm that achieves asymptotically optimal regret for Markov decision processes in average reward under a communicating assumption. That is, given a communicating Markov decision process , our algorithm has regret where T is the number of learning steps and is the best possible constant. This algorithm works by explicitly tracking the constant to learn optimally, then balances the trade-off between exploration (playing sub-optimally to gain information), co-exploration (playing optimally to gain information) and exploitation (playing optimally to score maximally). We further show that the function is discontinuous, which is a consequent challenge for our approach. To that end, we describe a regularization mechanism to estimate with arbitrary precision from empirical data
An Accurate Alternative to Hybrid Functionals for Germanium: DFT+α
No full textInternational audienceThe accuracy of bulk-property predictions in density functional theory (DFT) calculations depends on the choice of the exchange-correlation functional. While the Perdew-Burke-Ernzerhof (PBE) functional systematically overestimates lattice parameters and strongly underestimates electronic band gaps, hybrid functionals such as Heyd-Scuseria-Ernzerhof (HSE) offer better overall agreement across a broad range of materials. Using germanium as a critical test case, we challenge the ability of both functionals to capture the semiconductor properties. Although HSE improves PBE's gap error, it fails to reproduce germanium's correct Γ-L indirect and Γ-Γ band gaps simultaneously. Noting that the PBE-underestimated energy separation between the 4p valenceband maximum and 4s conduction-band minimum causes unphysical sp mixing, we propose DFT+α, a semiempirical correction scheme applied selectively to 4s-like orbitals. For germanium, DFT+α restores the proper ordering and orbital character of the band edges and yields accurate lattice constants, bulk modulus, elastic constants, and phonon frequencies at a fraction of hybrid-functional computational cost