HAL-Université de Bretagne Occidentale
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La décohabitation est-elle synonyme d'émancipation ? Expériences étudiantes de la première année à l'université
No full textInternational audienc
Assessing Stimuli Detectability and Pleasantness for Auditory BCI
No full textInternational audienceBrain-Computer Interfaces (BCIs) enable device control by analyzing brain activity. In reactive auditory BCIs based on steady-state auditory evoked potentials, users are exposed to amplitude-modulated sine waves at given frequencies that encode information (i.e. the type of action expected), while their brain activity is analyzed to infer the intended action based on the frequency retrieved. However, listening to sine-wave may be perceived as unpleasant over time. This study compares the use of pure-tones with alternative sounds, including artificial stimuli (such as a Brownian noise) and natural sounds (such as cicada song and cat's purr) by measuring brain responses of 48 subjects to these different stimuli, all amplitude-modulated at 40 Hz. The Signal-to-Noise Ratio (SNR) (i.e. the ratio between the power spectrum of electroencephalographic signals in response to the target stimulus and that in response to a silence stimulus) is computed at 40 Hz for each type of stimulus. It reveals that the 40-Hz modulation frequency is clearly more identifiable when carried by a pure tone than when carried by the other sounds, with an SNR increase up to more than 5 dB. The cicada song stimulus is a promising alternative, still requiring improvement to achieve the level of detectability observed for pure tones. The experiment is conducted at two different sound levels to assess whether increasing the listening level increases the SNR, but the opposite trend is found. Questionnaires indicate that more than half of the participants find pure tones annoying and prefer other sounds, confirming that this study is worth pursuing
La résolution de problèmes en Sciences expérimentales : regards croisés sur les pratiques enseignantes en Europe
No full textInternational audienceCet article propose une analyse comparative de pratiques d'enseignement de la résolution de problèmes en sciences expérimentales au niveau secondaire supérieur en France, aux Pays-Bas et en Italie. Cette étude de cas s’appuie sur des observations en travaux pratiques et convoque trois cadres d'analyse : les fonctions du problème selon Fabre, des éléments de la Théorie Anthropologique du Didactique (praxéologie) et le modèle des connaissances professionnelles des enseignants (PCK). Le but est de modéliser et de comparer les choix pédagogiques (praxis) et les savoirs mobilisés (logos) par les professeurs dans différents contextes institutionnels européens
A Decade of Research on Cloud Storage Systems: A Retrospective
No full textInternational audienceThis presentation looks back on ten years of research on cloud systems. It explores how to improve the management of data and task placement across diverse and heterogeneous environments combining different types of storage and computing resources. The work focuses on developing methods to monitor, analyze, and optimize the use of these resources, relying on models of cost, performance, and prediction. By integrating approaches from operation research and artificial intelligence, the research aims to make cloud infrastructures more efficient, adaptive, and sustainable
Acceleration of implicit schemes for large systems of delay differential equations
No full textInternational audienceThe objective is to accelerate numerical implicit schemes for solving large linear or nonlinear delay differential equations. These schemes require solving large linear or nonlinear systems at each integration step, making effective initial guesses critical for rapid convergence. For nonlinear problems, an inexact Newton method is used, whose efficiency depends heavily on the quality of these initial guesses. To generate them, line search or trust-region algorithms are employed -each involving the solution of large linear systems. These linear systems are solved using a Krylov subspace method. Initial guesses are constructed via a Petrov-Galerkin process applied to low-dimensional approximation subspaces derived from previous steps. Error estimates are provided, linking the accuracy of the initial guesses to the timestep size, the scheme's order, and the subspace dimension. Numerical experiments show speedups of up to two orders of magnitude over standard predictor-based methods, when those converge
Synthèse et perspectives : approches transformatives, changement d'échelle et implications pour l'Enseignement Supérieur et la Recherche
No full textInternational audienc
Zones Ateliers: Un réseau de recherches collaboratives, situées et engagées
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Three-dimensional management needs of deep-sea hydrothermal vent ecosystems
No full textInternational audienceDeep-sea hydrothermal vents form small, unique, and fragile ecosystems that are widely recognized as sites in need of protection. Deep-seabed mining (DSM) is a future threat to hydrothermal ecosystem integrity. In most areas within, and in all areas beyond national jurisdiction, currently proposed protection measures from DSM are unlikely to be sufficient, as only the known active venting sites on the seafloor are intended to be protected from DSM impacts. To ensure effective protection, we propose protecting not only the active vent sites but the entire hydrothermal ecosystems and their transition zones, embracing the seafloor, subseafloor and overlying water column. We discuss how ecological knowledge supports the proposed three-dimensional (3-D) protection. We suggest no DSM extraction or indirect impacts on the seafloor and entire subseafloor within a minimum 50 km diameter (25 km radius) around visible active vents. This will ensure the maintenance of subseafloor connections that are key for ecosystem integrity, as changes in vent fluid conditions can alter all ecosystem functions and services linked to venting activity. In the water column, protection from pollution from the seafloor to surface is suggested to protect vent larvae. This extent spans the entire length of ridges or back-arc basins, with a cross-axial extent of 80 km. We further discuss how international law can contribute to the effective protection of vent ecosystems and transition zones in international waters, and provide guidance for coastal States to safeguard these ecosystems and transition zones within their own maritime areas
Au delà de “Mon cher Shaw” : la correspondance bretonne des Hamon
No full texthttps://bylg.hypotheses.org/5486L’exposition “Mon cher Shaw” qui était présentée dans l’extension de la bibliothèque Yves-Le-Gallo du CRBC en fin d'année 2025 abordait, outre la traduction des œuvres de George Bernard Shaw, la question de la sociabilité de ses traducteurs, le couple Hamon, en Bretagne. Dans la droite lignée de l’exposition valorisant la correspondance, cet article propose de découvrir d’autres aspects du couple Hamon à travers les lettres envoyées à deux personnalités bretonnes dont le CRBC conserve les archives, Francis Even et Yves Le Febvre