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Opinion note on nonlinearity in induced polarization
No full textInternational audienceThe extension of direct current resistivity methods to induced polarization methods has enriched the tools available for subsurface exploration. This enrichment involves an increase in the number of parameters used in the models, as well as addressing different physical phenomena than those observed with direct current. Accounting for nonlinearities, if they exist, can further enhance the sophistication of our models. Nonlinearities are often observed, particularly in laboratory experiments. However, we question their origin, and the experiment described here suggests that the nonlinearities observed under typical experimental conditions may be artifacts related to the electrodes, rather than reflecting the actual response of the subsurface. Indeed, we first replaced the polarizable injection electrodes with non-polarizable electrodes. The nonlinearities observed due to the presence of harmonics were significantly reduced. Then, we replaced the voltage control with a current control, which completely eliminated the nonlinearities still present. We know that it is impossible to prove the non-existence of a phenomenon that does not exist. This fundamental epistemological principle (as pointed out by Russell and Popper) means that we are not claiming that nonlinearity does not exist. We are simply describing an experiment that can raise doubts about its existence
Tree water status behavior of two common European urban species using dendrometric measurements and remote sensing imagery.
No full textInternational audienceWith growing urban populations and rising heatwaves, urban trees are increasingly valued for their cooling benefits through transpiration and shading. However, water stress can limit transpiration, and the effects of urban environment and species-specific traits on tree water status remain understudied. This work investigates how meteorology, soil imperviousness and species influence tree water status behavior, and how vegetation indices derived from remote sensing relate to tree water status, at both seasonal and individual tree scales. Eleven mature Acer platanoides and Tilia x euchlora trees (two common European urban species) growing under varying soil imperviousness levels in a medium-sized French city were monitored. For summer 2023 and spring 2024, two dendrometric indicators of water status - maximum daily shrinkage (MDS) and tree water deficit (TWD) - were calculated, and vegetation index NDVI was extracted from SuperDove imagery. Results show that TWD, more than MDS, effectively assessed tree water status and was closely linked to vapor pressure deficit and relative humidity. Higher soil imperviousness increased water deficit in both seasons, particularly for trees in pits. Acer platanoides exhibited a more isohydric strategy than Tilia x euchlora. NDVI was strongly correlated with TWD in summer 2023 (R² = -0.43), and with MDS in spring 2024 (R² = 0.40). These findings underline the value of dendrometric measurements in urban environments for understanding tree water status, and highlight the potential of very high spatio-temporal resolution satellite data to assess individual tree water status across cities, supporting improved management to maximize the cooling benefits of urban trees
Crisis, breakdown and reorganization: The end of the Old Kingdom and the First Intermediate Period (2200-2050 BC)
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Temperate phage evolve to integrate host stress and quorum signals in lysis-lysogeny decisions
No full textInternational audienceTemperate phage can transmit both horizontally (lytic cycle) and vertically (lysogenic cycle). Many temperate phage have the ability to modify their lysis/lysogeny decisions based on various environmental cues. For instance, many prophage are known to reactivate when SOS stress responses of their host are triggered. Temperate phage infecting Bacilli can also use peptide signals (“arbitrium”) to control their lysis/lysogeny decisions. However, information from the arbitrium and SOS systems can be potentially conflicting, and it is unclear how phage integrate information carried by these two different signals when making lysis–lysogeny decisions. Here, we use evolutionary epidemiology theory to explore how phage could evolve to use both systems to modulate lysis/lysogeny decisions in a fluctuating environment. Our model predicts that it can be adaptive for phage to respond to both host SOS systems and arbitrium signaling, as they provide complementary information on the quality of the infected host and the availability of alternative hosts. Using the phage phi3T and its host Bacillus subtilis , we show that during lytic infection and as prophage, lysis–lysogeny decisions rely on the integration of information on host condition and arbitrium signal concentrations. For example, free-phage are more likely to lysogenise a stressed host, and prophage are less likely to abandon a stressed host, when high arbitrium concentrations suggest susceptible hosts are unavailable. These experimental results are consistent with our theoretical predictions and demonstrate that phage can evolve plastic life-history strategies to adjust their infection dynamics to account for both the within-host environment (host quality) and the external environment that exists outside of their host (availability of susceptible hosts in the population). More generally, our work yields a new theoretical framework to study the evolution of viral plasticity under the influence of multiple environmental cues
L’apogée de la médecine occidentale ancienne : Galien et son héritage
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Co-defining research priorities to address knowledge gaps for future management: A participatory framework for species prioritisation in small-scale coral reef fisheries
No full textInternational audienceEffective governance of small-scale, multi-species coral reef fisheries requires integrating diverse knowledge systems while addressing critical data gaps. Yet, despite increasing calls for participatory approaches, existing species prioritisation frameworks remain largely expert-driven, with limited application in data-limited, multi-species contexts and minimal involvement of fishers in shaping research agendas. This gap reduces the legitimacy, feasibility, and uptake of management-oriented research. We propose a structured, participatory framework for species prioritisation that strategically addresses knowledge gaps to support future research and management. The framework combines three criteria – species vulnerability, operational feasibility, and fishers’ priorities – through a three-phase, stakeholder-inclusive process. We apply it to a French Polynesian coral reef fishery, a context marked by ecological diversity, limited data, and ongoing transitions toward participatory governance. Results highlight the governance challenges inherent to species prioritisation, including ensuring broad fisher representation, balancing power dynamics, and managing trade-offs between ecological objectives and feasibility constraints. While the process successfully integrated fishers’ knowledge into decision-making, it also underscored the resource demands of participatory engagement and the need for adaptive monitoring to prevent effort displacement or the marginalisation of non-prioritised species. Beyond French Polynesia, the framework’s transferability depends on regional conditions: it may be facilitated in island settings with strong community ties but will require broader representation mechanisms in more densely populated contexts. By embedding participation at the earliest stages of research design, this framework contributes to operationalising inclusive, knowledge-based fisheries governance and offers a replicable tool for data-limited, multi-species fisheries seeking to balance ecological sustainability, socio-economic realities, and governance legitimacy.
Northernmost record in the Bay of Biscay (northeastern Atlantic) of two leptothecate hydroids (Cnidaria: Hydrozoa) of southern affinity
No full textInternational audienceTwo leptothecate hydroids of southern affinity, Sertularella ornata Broch, 1933 and Sertularelloides cylindritheca (Allman, 1888) were collected in the southern sector of the Bay of Biscay off Saint Jean de Luz (France). The latter was also seen during several ROV surveys on rocky communities along the Cantabrian Sea and northwestern Spain. Each of the two species is herein described and illustrated and their worldwide distribution, bathymetric ranges and reproductive periods, revised; additionally, we allocate them in their biocoenological context, providing in situ images. The northern boundary limits are extended for both hydroids, which are new records for the Atlantic coast of France; the latter belongs to a genus previously unrecorded in the French mainland fauna. We also discuss the importance of having inventories of the sessile fauna of the exceptional sites at study, for the sake of their protection and detection of future modifications due to climate change
Legal arguments against emotions - how the law silences militant disillusionment with the identity evolution of a non-religious organisation
No full textInternational audienceThis article aims to show how the law can be used to silence the emotions of activists and counter any opposition to the strategic and doctrinal evolutions of a French non-religious organisation.At the end of the 1980s, France's biggest confederation of associations, the Ligue de l'enseignement, shifted its doctrinal base from a secularism closed to any dialogue with religions to a recognition of their importance as a cultural fact. Discussions have been held with leaders of the main religions present in France, the teaching of religion (in historical and sociological perspectives) has been advocated, and reflections on Islam have been carried out. But this evolution was initiated by the sole organisation's leaders and not by the whole confederation. Some militants have expressed skepticism, disillusionment and even incomprehension about these changes. Others rejected the organisation's positions, particularly on the issue of the veil. However, to counter this militant “unhappiness” and the divisions within the movement, those in charge put forward the legislative argument: the Goblet law of 1886 was put forward as a reminder of the long-standing legal recognition of religious establishments; the law on religious signs passed in 2004 was mobilized to silence opposition on the issue
