Archive ouverte HAL de CY Cergy Paris Université
Not a member yet
38365 research outputs found
Sort by
Scaling relations at the central regions of nearby galaxies
No full textInternational audienceScaling relations between galactic parameters (e.g., luminosity, mass, metallicity, etc.) represent key pieces of evidence for investigating the processes of galaxy formation and evolution. In most studies, these relations have been obtained for large portions of the galaxies (i.e., on kiloparsec scales), but it is also important to evaluate these relations in smaller scales. In this work, we used optical data cubes of a subsample of nearby galaxies of the DIVING 3D survey. These allowed us to analyze the scaling relations involving stellar velocity dispersion, stellar population age, and stellar population metallicity at the nuclear and circumnuclear regions of galaxies (within scales from tens to a few hundreds of parsecs). We detected correlations between the stellar velocity dispersion and the age, metallicity, and total stellar mass. These correlations are independent of galaxy inclinations, considering all morphological types, nuclear activity, and the presence or absence of galactic bars. We detected, for the first time, a correlation between the stellar velocity dispersion and stellar metallicity in the nuclear regions of galaxies. It is found to be qualitatively consistent with the well-known stellar mass-metallicity relation, described in previous studies, on kiloparsec scales. We also noted that barred galaxies tend to show younger and less metal-rich stellar populations than unbarred galaxies in the central regions, which may be a consequence of the bar triggering star formation in the nuclear regions of these objects. However, further studies, with larger samples, are necessary for comparisons between barred and unbarred galaxies, with the same mass and morphological types. Some active galactic nuclei (AGNs) in our sample are positioned above the observed correlation between stellar velocity dispersion and stellar population age, suggesting that their nuclear stellar populations are younger than expected. This may be a consequence of positive AGN feedback, triggering star formation. Conversely, starburst galaxies do not show nuclear stellar populations at ages over one billion years
La participation des femmes dans la sphère publique en Bolivie, de la fin de la guerre du Chaco à la Révolution nationale (1935-1952)
No full textInternational audienc
Analyses des pertes fer dans un acier au silicium à température cryogénique
No full textInternational audienc
Le langage corporel dansé avec l’enfant autiste et sa famille
No full textInternational audienceLa clinique de l’autisme confronte à des états d’isolement et des modes de construction psychique solitaires, en apparence en dehors du lien à l’autre. Prendre soin d’un enfant autiste implique de prendre soin aussi de son entourage et des liens qui unissent les membres de la famille. Quand le langage verbal n’est pas l’appui commun, quand le langage non verbal imprégné par la présence des gestes stéréotypés n’est pas facilement lisible non plus, comment un langage corporel peut-il se co-construire et devenir partageable ? À partir d’un dispositif clinique et de recherche fondé sur la médiation danse proposée à de jeunes enfants autistes et leurs parents reçus en groupe, cet article évoque la particularité des accordages aux manières singulières qu’a l’enfant autiste d’habiter son corps et l’espace. Il précise la manière dont ces accordages déployés de manière groupale aident les enfants à se faire interlocuteurs de ceux qui les entourent
Retour d'expériences de services de trains légers innovants en Europe, projet ADEME/SNCF TELLI, rapport final
No full textCe rapport s’attache à présenter la réflexion sur un retour d’expériences des petites lignes ferroviaires en Europe. Dans une première partie, nous présenterons les enjeux de cette recherche et le contexte de notre étude, à savoir la réactivation de petites lignes en milieu rural. Nous développerons ensuite une méthodologie d’évaluation des ressorts qui ont favorisé le développement des petites lignes ferroviaires. Cette accroche scientifique permet, d’une part, de mettre en évidence les freins, les obstacles, les points de vigilance et de les identifier pour pouvoir les contourner, mais aussi les forces « catalysatrices » qui permettent d’avancer. Elle permet également, d’autre part, d’intégrer une dimension plus technique dans l’analyse, en recensant différentes caractéristiques propres à l’exploitation des lignes ainsi qu’au contexte territorial de ces dernières. Dans une deuxième partie, nous mènerons des études des retours d’expériences en Europe où l’on observe de nombreuses réactivations de ligne. Ainsi, nous rendrons compte de nos missions sur place déroulées : en Italie du Nord (Tyrol du Sud), avec l’étude du renouveau de la ligne Merano – Malles, représentant un grand succès, reconnu dans toute l’Europe comme un modèle de relance de petites lignes ; en République tchèque, avec l’étude de la Bechyňka, première ligne électrifiée d’Autriche-Hongrie, et celle des Šumavské lokálky, réseau maillant la Forêt de Bohême, aux confins de la République tchèque, de l’Allemagne et de l’Autriche, tout près de l’ancien Rideau de fer ; en Allemagne, avec la Schönbuchbahn, symbole d’une ligne vouée à l’abandon et conduite ensuite jusqu’au succès de la réactivation, puis la Mainschleifenbahn qui est actuellement une ligne-musée touristique circulant les dimanche et jours fériés de mai à octobre et qui a été choisie pour une relance au transport régional de voyageurs avec un cadencement à l’heure ; enfin, en Autriche, avec la Salzburger Lokalbahn, petite ligne de la région de Salzbourg, totalement intégrée au plan de transport régional. Dans une troisième et dernière partie, nous aborderons des pistes de réflexion permettant d’imaginer des enseignements pour les lignes françaises ainsi que des potentiels de transférabilité de « bonnes pratiques » européennes en la matière
Spectroscopic Data at High Temperature for Exoplanetary Studies: The e-PYTHEAS Project
No full textInternational audienceThe field of exoplanetary studies has immensely expanded in the past years, and the analysis of the acquired observations necessitates an improved understanding of the radiative properties of hot gaseous media. Our project, e-PYTHEAS, started in 2016 and associates both experimental and theoretical high-temperature spectroscopies of molecular species detected in exoplanets by five French laboratories and international partners to support modeling of exoplanet data. The method we use starts with theoretical research that we support and confirm with laboratory experiments yielding infrared laboratory data of methane, ethane, acetylene and ethylene between 500 and 2500 K. The outcome is then injected into models of the atmospheres of the giant gaseous planets in our solar and other exoplanetary systems helping refine thermal profiles and atmospheric composition. The results will permit to more effectively analyze data and interpret observations of space missions such as ESA's M4 ARIEL, to be launched in 2029
Advances in metal-catalyzed strategies for carbohydrate functionalization
No full textInternational audienceTransition metal catalysis provides a versatile and powerful platform for the construction of structurally complex molecules. In recent years, its application has been successfully extended to the functionalization of carbohydrates, significantly expanding the toolbox of catalytic strategies available for sustainable synthesis. This review offers a comprehensive and up-to-date overview of recent advances in metal-catalyzed carbohydrate transformations, emphasizing key methodological innovations and their relevance to synthetic applications
Universality Classes for Purification in Nonunitary Quantum Processes
No full textInternational audienceWe consider the universal aspects of two problems: (i) the singular value structure of a product M t = m t m t − 1 … m 1 of many large independent random matrices and (ii) the slow purification of a large number of qubits by repeated quantum measurements. The time-evolution operator in the latter case is again a product of matrices m i , representing time steps in the evolution, but the m i are now nontrivially correlated as a result of Born’s rule. Both processes are associated with the decay of natural measures of entropy as a function of time or of the number of matrices in the product. We argue that, for a broad class of models, each process is described by universal scaling forms for purification and that (i) and (ii) represent distinct “universality classes” with distinct scaling functions. Using the replica trick, these universality classes correspond to effective one-dimensional statistical mechanics models for a gas of “kinks,” representing domain walls between elements of the permutation group. This is an instructive low-dimensional limit of the effective statistical mechanics models for random circuits and tensor networks. These results apply to longtime purification in spatially local monitored circuit models on the entangled side of the measurement phase transition
Towards Equity, Peace and Sustainability in Times of Crisis: Proceedings of the ISCAR Southern Europe and West Asia Conference 2025
No full textInternational audienceThe ISCAR 2025 Southern Europe and West Asia (SEWA) Conference proceedings bring together contributions from scholars and practitioners working within sociocultural and activity-theoretical traditions across Southern Europe, West Asia, and other regions. The collected works are situated in a historical moment characterised by intertwined social, environmental, political, and educational crises, which pose profound challenges to human development and social justice. In this context, the proceedings foreground research that critically examines how education, learning, and collective activity can contribute to more equitable, peaceful, and sustainable futures. The intellectual orientation of the proceedings is grounded in a shared axiological commitment to equity, peace, and sustainability, recognising that research is never value-neutral but embedded in historical and ethical conditions. Ontologically, the contributions are informed by a sociocultural understanding of human activity, approaching learning, development, and practice as socially mediated and historically situated processes. Epistemologically, the proceedings embrace pluralism, valuing the coexistence of diverse theoretical frameworks, methodological approaches, and disciplinary perspectives. This pluralistic stance aims to move beyond methodological compartmentalisation by fostering dialogue, openness, and constructive critique as conditions for interdisciplinary knowledge production