HAL-Université de Bretagne Occidentale
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Visualiser les proximités à l’aide de l’intelligence artificielle générative : le cas des nomades numériques à Bali, Indonésie
No full textInternational audienceThe paper examines proximity, both physical and digital, within Bali’s digital nomad landscape. Despite the allure of business prospects, unregulated digital nomadism poses challenges. Using AI, an image illustrates physical closeness but underscores social isolation, lacking community bonds. The beach, typically a social hub, appears solitary, reflecting a future depicted by the AI—an interplay of prophecy and uncertainty. This highlights the significance of visual representations in grasping the nuances of proximity, both physical and digital.Cet article propose de s'emparer de l'outil de génération d'image par intelligence artificielle en vue de mettre en perspective les proximités géographiques et organisées, en l'espèce celles des nomades numériques. L'idée générale consiste à analyser comment à partir d'un simple texte, ou prompt, l'on peut offrir une meilleure représentation visuelle et concrète de ces concepts, les rendre utiles et leur donner du sens. L’exemple des nomades numériques nous semble dans ce cadre pertinent car l’une des caractéristiques de ces individus est qu’ils souffrent de solitude (Miguel et al., 2023), forme de distance sociale inhérente à leur forte mobilité. Paradoxalement, ils ont tendance à se rassembler en communauté dans les mêmes destinations comme l’île de Bali en Indonésie (Thompson, 2019)
« Notre naturisme prolétarien fonction éducative » (Freinet, 1934). Commentaires au sujet de la figure de l’éducateur prolétarien naturiste
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A tourist’s guide to regularity structures and singular stochastic PDEs
No full textWe give an essentially self-contained treatment of the fundamental analytic and algebraic features of regularity structures and their applications to the study of singular stochastic PDEs
Le Perroquet Entre Orient et Occident
No full textInternational audienceConnu sous différents noms – psittacus en latin, papegau en ancien français ou papegay en occitan médiéval – et finalement dénommé « perroquet », l’oiseau multicolore porte de riches et nombreuses significations ambiguës. Du côté du sacré, il trône en compagnie de la Vierge ou du Christ. Du côté du profane, il figure auprès d’une jeune femme dénudée ou non, avec une large palette de tonalités, sérieuses, burlesques, parodiques, satiriques. Des contes indiens aux fables sud-américaines, en passant par La Fontaine, Flaubert ou Tintin, l’oiseau qui parle est une invitation au voyage : dans le temps, l’espace, la littérature et la peinture ; dans la réalité comme dans l’imaginaire. L’ouvrage raconte ainsi son histoire culturelle de l’Antiquité à nos jours, de l’Orient à l’Occident, du Nouveau Monde à l’Europe où il se perche désormais sur l’épaule des pirates
The Effects of Unresolved Scales on Analogue Forecasting Ensembles
No full textUsing similar states in a database called “catalogue” such as a reanalysis, analogues provide simple yet efficient ensemble forecasts in atmospheric and ocean sciences. Typically performed on low-resolution images of large-scale atmospheric or ocean circulation, analogue forecasting encounters uncertainties due to unresolved small spatial scales, as the latter contribute to the time-evolution of the circulation but not to the similarity criterion used to search for analogues. Another source of uncertainty are the finite distances between the analogues and the initial target large-scale variables. We disentangle these two sources of uncertainty using a modified version of the Lorenz system, where stochastic terms account for unresolved small spatial scales. For large enough catalogue size and forecast horizon, we show that the analogue forecasting ensemble spread is dominated by the effect of stochastic terms, with only little influence of the initial analogue-to-target distances. Conversely, for short-term forecast and small catalogue size, the analogue ensemble is mostly influenced by initial analogue-to-target distances and not by the effects of unresolved scales. This result calls for adjustments of the classical analogue method for small forecast horizons
Paleoceanographic responses to sea level variability in the East Sea since the last glacial period: Multi-proxy approach
No full textInternational audienceThe oceanographic conditions in the East Sea have significantly changed over glacial-interglacial cycles, but the underlying mechanisms remain poorly understood due to limited data. We present multi-proxy records from three sediment cores along the western margin of the East Sea to reconstruct past oceanic conditions since Marine Isotope Stage (MIS) 5. Our results reveal contrasting conditions between glacial and interglacial periods. First, detrital Nd isotopes provide evidence for provenance changes suggesting a reduced contribution of seawater inflow from the Tsushima Warm Current compared to the local fluvial influx from Japanese islands during the last glacial period, most likely linked to sea level drop. As a result, the East Sea likely experienced surface water freshening, particularly during MIS 2, when seawater exchange through the Korea/Tsushima Strait was (almost) entirely restricted, as evidenced by decreasing oxygen isotope ratios in planktic foraminifers. Authigenic Nd isotopes suggest that this freshening caused strong water column stratification, limiting vertical mixing below ~800 m. Consequently, bottom waters likely became oxygen-depleted, as indicated by decreases in total organic carbon to total sulfur contents and cerium anomalies and an increase in authigenic molybdenum concentrations. The reduced horizontal and vertical water mixing also possibly limited nutrient supply during the last glacial period, resulting in diminished primary productivity. This study emphasizes the distinctive response of the East Sea's oceanographic conditions to climate-driven sea level fluctuations and highlights its potential contribution to the global ocean carbon reservoir during glacial periods
Gonyaulax montresoriae sp. nov. (Dinophyceae) from the Adriatic Sea produces predominantly yessotoxin
No full textInternational audienceYessotoxin is one of the shellfish toxins leading to mussel farm closures in the Adriatic Sea of Italy. Two putative Gonyaulax spinifera strains GSA0501 and GSA0602 are known as yessotoxins producers, but their identities have remained elusive since 2005. To address this gap, we established five Gonyaulax strains by incubating sediments from the Adriatic Sea and subsequently isolating single cells. Both cyst and theca morphology were examined using light and scanning electron microscopy. In addition, LSU and/or SSU rRNA gene sequences were obtained for all strains. Two strains produce cysts resembling Spiniferites mirabilis and one strain was related to S. scabratus. The other two strains are described as Gonyaulax montresoriae sp. nov., characterized by a high cingular displacement and overhang, along with two unequal antapical spines. Cysts of G. montresoriae are pear-shaped, showing a smooth surface and exclusively gonal processes with perforations at the base, the latter similar to S. lazus. LSU rRNA gene sequence comparison suggests that the G. spinifera strain GSA0501 isolated from the Adriatic Sea in 2005 should also be identified as G. montresoriae. Maximum likelihood and Bayesian inference analyses based on LSU and SSU rRNA gene sequences reveal that G. montresoriae is monophyletic, and close to several toxic strains of presumable Gonyaulax spinifera from the Adriatic Sea and New Zealand, whose taxonomic positions are uncertain. One strain of G. montresoriae was examined for yessotoxin production using LC-MS/MS, and found to produce predominantly yessotoxin at a concentration of 3.0 pg cell-1. Our results highlight the rich diversity and risks associated with Gonyaulax species in the Mediterranean Sea
