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Experimental and numerical investigation of the impact force generated by cylindrical ice water pellets
No full textInternational audienceThis study focuses on the force-time response of cylindrical water ice specimens subjected to impact loadings. Spherical specimens are traditionally used to characterize the impact behavior of water ice. However, they cannot be used to study the geometric effects induced by a cylindrical shape. Impact tests were carried out on a Hopkinson bar at 30 m.s -1 . These tests have demonstrated the importance of the impact angle in terms of both the increase in the load and the peak force at impact. Contrarily to what was observed for tensile spalling test, porosity has no noticeable impact on the maximum peak force measured here. The importance of the impact angle is illustrated by comparing the mechanical response of ice spheres with pellet cylinders for equivalent kinetic energies and temperatures
Integrative assessment of biohydrogen and biomethane production from Brittany and Caribbean Sargassum (Ochrophyta, Fucales)
No full textInternational audienc
Diplômes des immigrés et des descendants d'immigrés : progrès intergénérationnels et persistance des inégalités
No full textDocument de travailInternational audienceCe document de travail livre des résultats sur les diplômes atteints par les immigré·es et les descendant·es d’immigré·es en fonction de la génération, de l’origine et du genre, à partir de la nouvelle enquête Trajectoires et Origines 2 (INED-INSEE). L’intérêt d’une approche générationnelle dans l’étude des parcours des immigré·es et de leurs descendant·es a été démontré depuis longtemps, notamment aux Etats-Unis (Rumbaut 1997, 2004), mais aussi par les analyses issues de la précédente édition de l’enquête TeO (Beauchemin, Hamel & Simon, 2015). La notion de « génération », telle que nous l’utilisons ici, renvoie à « la distance à la migration, fonction du lieu de naissance de l’individu, de celui de ses deux parents et de son âge d’entrée en France s’il n’y est pas né » (Silberman & Fournier 2006 : 27). Cette perspective, qui insiste sur l’éloignement progressif par rapport à l’évènement migratoire, permet de rendre compte de l’hétérogénéité interne aux immigré·es de différentes origines en termes d’âge à l’arrivée en France, d’une part, et, d’autre part, aux descendant·es d’immigré·es en termes de mixité du couple parental (Myers, Gao & Emeka 2009 ; Kalmijn 2015). Dans ce chapitre, nous distinguons quatre « générations » qui n’ont pas été socialisées en France au même degré : la G1 (individus arrivés adultes en France), la G1.5 (individus arrivés jeunes en France), la G2 (individus nés en France de deux parents immigrés) et la G2.5 (individus nés en France d’un seul parent immigré). Les questions suivantes guident les analyses : un lien plus éloigné à la migration est-il associé à une augmentation du niveau de diplôme ? La structure des diplômes diffère-t-elle selon l’âge à la migration ? Les descendant·es de couples mixtes se rapprochent-ils·elles de la population majoritaire ? Si oui, cela vaut-il pour toutes les origines et quel que soit le genre
Decision analysis rooted in Indigenous and Western scientific knowledge identifies cost‐effective strategies for managing hyperabundant deer to restore keystone places
No full textInternational audienceThe hyperabundance of herbivores—a result of altered human relationality with the land and the extirpation of predators—is leading to large‐scale degradation of keystone ecosystems across the globe. Designing and implementing socially acceptable and cost‐effective strategies that meaningfully reduce herbivore populations while allowing for the recovery of ecological function and cultural relationality is an inherently complex issue. As a result, decision paralysis is common, leading to delayed or avoided action and continued ecosystem loss and degradation. Using a structured decision‐making process that incorporated expert elicitation, population modelling and cost‐effectiveness analyses while honouring multiple knowledge systems, we identified five discrete and four portfolio strategies for managing hyperabundant black‐tailed deer ( Odocoileus hemionus columbianus ) in the Southern Gulf Islands of British Columbia, Canada, with consideration to benefit, feasibility and cost objectives. Hunting led by local Indigenous Nations was ranked the most cost‐effective strategy when benefits considered well‐being of peoples and place holistically, and accounted for both Indigenous and Western science worldviews. When only Western perspectives were included, increased licensed hunting by local communities and hiring professional deer reduction specialists were ranked the most cost‐effective. However, while increased licensed hunting had a >50% likelihood of project uptake and success (i.e. feasibility), the strategy had <50% likelihood of achieving any benefit objective. In comparison, Indigenous‐led hunting, professional deer reduction specialists, and all portfolio strategies had >50% likelihood of meeting at least one benefit objective, although only Indigenous‐led hunting also had >50% likelihood of achieving feasibility objectives. Synthesis and applications . We provide a roadmap for decision‐makers across the globe to robustly and transparently assess the problem of herbivore hyperabundance and inform solutions within their context. Within the Salish Sea, our work highlights the need to support hunting, and in particular, Indigenous‐led hunting, as cost‐effective strategies to promote revitalization of well‐being of peoples and place. Read the free Plain Language Summary for this article on the Journal blog
Nature-based solutions for water management: Pluridisciplinary state-of-the-art and research needs
No full textInternational audienceNature-based Solutions (NbS) offer a way to preserve, manage and restore ecosystems so as to better meet today's societal challenges, by combining benefits for society and the environment, including biodiversity. They are a response to current climate change-related challenges for water management. However, various barriers exist to the implementation of NbS, such as a lack of appropriation of the concept, as well as needs for knowledge and know-how. Focusing on societal challenges linked to water, we highlight the importance of implementing pluridisciplinary and transdisciplinary projects when trying to implement NbS projects. This requires new approaches in research, practice, and governance. This discussion allows identifying levers for a widespread use of NbS for water management
Seasonal dynamics of mudflat foraminifera linked to diatom species and traits
No full textInternational audienceThe trophic ecology of benthic foraminifera in intertidal mudflats is closely linked to diatoms, a dominant component of the microphytobenthos (MPB). Although experimental studies and metabarcoding have clarified foraminiferal diets, in situ assessments of the temporal dynamics of diatoms and foraminifera remain limited. In this study, we examined the seasonal dynamics of adult (> 150 µm) foraminiferal species over a notable 3.5-year monthly monitoring period at the La Coupelasse mudflat (Bay of Bourgneuf, French Atlantic coast). We related these dynamics to 25 environmental variables and to diatom assemblages, focusing on their traits (size, shape, and life-form). La Coupelasse exhibited a clear seasonal pattern driven by bay hydrodynamics, which regulated the availability of redox-sensitive metals, nutrients, and MPB biomass, thereby shaping the environmental context for benthic communities. Diatom traits, whether considered individually or in combination (“size + shape + life-form”), revealed distinct seasonal strategies that complemented species-level analyses. While species-level data provided a detailed understanding of foraminiferal temporal dynamics, combining diatom traits offered a more effective way to identify seasonal dietary shifts. The four dominant foraminiferal species occupied different seasonal niches, with Ammonia confertitesta and Haynesina germanica showing synchronized biannual peaks in spring and autumn, but differed in dietary responses, as H. germanica responded only to diatom shape. Elphidium oceanense displayed a single annual peak in early autumn, corresponding to a broader trophic flexibility across diatom traits, while Elphidium selseyense showed a late spring peak and remained enigmatic regarding its diatom food preferences. Overall, using combined diatom traits outperformed both species identity and MPB biomass in predicting foraminiferal patterns, highlighting their potential to simplify diatom–foraminifera trophic ecology by overcoming diatom taxonomic constraints. These findings shed light on our understanding of benthic ecology and suggest that trait-based approaches, when integrated with spatial and microbiome data, can enhance predictions of ecosystem responses to environmental change
Tertiary Lymphoid Structures Are Associated with Enhanced Macrophage Activation and Immune Checkpoint Expression and Predict Outcome in Cervical Cancer
No full textInternational audienceCervical tumors are usually treated using surgery, chemotherapy, and radiotherapy and would benefit from immunotherapies. However, the immune microenvironment in cervical cancer remains poorly described. Tertiary lymphoid structures (TLS) were recently described as markers for better immunotherapy response and overall better prognosis in patients with cancer. We evaluated the cervical tumor immune microenvironment, specifically focusing on TLS, using combined high-throughput phenotyping, soluble factor concentration dosage in the tumor microenvironment, and spatial interaction analyses. We found that TLS presence was associated with a more inflammatory soluble microenvironment, with the presence of B cells as well as more activated macrophages and dendritic cells (DC). Furthermore, this myeloid cell activation was associated with the expression of immune checkpoints, such as PD-L1 and CD40, and the proximity of activated conventional type 2 DCs to CD8+ T cells, indicating better immune interactions and tumor control. Finally, we associated TLS presence, greater B-cell density, and activated DC density with improved progression-free survival, substantiating TLS presence as a potential prognostic marker. Our results provide evidence that TLS presence denotes cell activation and immunotherapy target expression
Ploidy-dependent modulation of DNA replication kinetics in Xenopus: DNA replication dynamics in polyploid Xenopus
No full textDNA replication in multicellular organisms follows a tightly regulated spatio-temporal program. Although the mechanisms underlying this replication program remain only partially understood, studies in model systems such as Xenopus laevis have highlighted the importance of titrating low-abundance replication factors. Whole-genome duplications as a consequence of polyploidization introduce additional layers of complexity, yet comparative analyses of replication programs across closely related polyploid species are scarce. Here, we developed an interspecies in vitro replication system using X. laevis egg extracts and sperm nuclei from three Xenopus species with varying ploidy: diploid (X. tropicalis), tetraploid (X. laevis), and dodecaploid (X. eysoole). Replication in diploid X. tropicalis was faster than in tetraploid X. laevis nuclei, due to higher fork density and speed. Surprisingly, dodecaploid X. eysoole replication was also accelerated compared to tetraploid nuclei, suggesting that higher ploidy does not necessarily extend S phase. Since replication genes are highly conserved between these species, these results imply dynamic tuning of replication programs across polyploid species and shed light on the evolutionary adaptability of DNA replication in response to genome duplication
Tara Polaris expeditions: Sustained decadal observations of the coupled Arctic system in rapid transition
No full textThe coupled Arctic system is in rapid transition and is set to undergo further dramatic changes over the coming decades. These changes will lead most likely to an ice-free ocean in summer, expected before mid-century. The Arctic will become more strongly influenced by atmospheric and oceanographic processes characteristic of mid-latitudes, increasing the prevalence of contaminants and new biological species. This ongoing transition of the Arctic to a new state necessitates systematic monitoring of all sentinels (variables that make an essential contribution to characterizing the Earth's state) to improve our understanding of the system, enhance forecasting and support knowledge-based decisions. Here, we describe a sustained multi-decadal observation program to be implemented on the Tara Polar Station between 2026 and 2046. The monitoring program is designed as a series of year-long drift expeditions, called Tara Polaris, in the central Arctic Ocean, covering all seasons. The multidisciplinary data will bridge ecological, geochemical, biological, and physical parameters and processes in the atmosphere, sea ice and ocean. In addition, data collected with consistent methodologies over a 20-year period will make it possible to distinguish long-term trends from seasonal and interannual variability. In this paper, we discuss specific measurement challenges in each compartment (i.e., atmosphere, sea ice and ocean) along key sentinels and the most pressing scientific questions to be addressed. The expected outcomes of the Tara Polaris program will enable us to understand and quantify the main feedbacks of the coupled Arctic system, with their seasonal and interannual trends and spatial variability.</div
Polyploidy modulates the adaptation to water deficit in citrus scion/rootstock associations evaluated under controlled pot condition and relates to specific changes in root and leaf transcriptome
No full textData availability: The RNA-seq data underlying this article are available in Gene Expression Omnibus (GEO) database at: https://www.ncbi.nlm.nih.gov/geo, and can be accessed with the project accession number: GSE255759.International audienceHighlights: • Tetraploid rootstocks with triploid scions enhance drought tolerance in pots. • In pots, 4x rootstocks better regulate water loss under drought conditions. • ABA levels under stress are higher in 4× than in 2× rootstocks. • DEGs involved in transport, stress response and protective barrier formation. • Polyploidy shows strong potential to improve citrus drought resilience.Abstract: Citrus, one of the world's most important crops, is facing significant challenges due to drought events. Previous studies have demonstrated that tetraploid rootstocks may exhibit greater tolerance to abiotic stresses than their diploid counterparts. The effects of combining a tetraploid rootstock with a triploid scion under water deficit conditions have not been thoroughly explored. A water deficit experiment was conducted under controlled pot conditions using four citrus scion/rootstock combinations: diploid and tetraploid Swingle citrumelo rootstocks grafted with diploid Mexican lime and triploid Persian lime. Physiological, biochemical, and transcriptomic analyses under controlled pot condition revealed that tetraploid rootstocks exhibited significantly improved performance under drought stress, with an even greater effect when the scion was the triploid Persian lime. In that condition, the improved resilience was associated with reduced water consumption, higher photosynthesis, increased stomatal conductance and transpiration under water stress conditions. Elevated abscisic acid levels and stronger antioxidant activity in polyploid rootstocks further contributed to the stress response. Transcriptomic data revealed distinct gene expression changes in roots and leaves, influenced by organ ploidy and rootstock-scion interactions. Taken together our results provide insights into drought adaptation mechanisms including osmotic adjustment, oxidative stress protection, sustained photosynthesis, antioxidant enzyme activity and enhanced synthesis of protective barriers. These findings underscore ploidy's role at both rootstock and scion levels in shaping the plant's response to water deficit, revealing useful interactions between rootstock and scion influencing drought resilience