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DyHANE: dynamic heterogeneous attributed network embedding through experience node replay
No full textInternational audienceWith real-world network systems typically comprising a large number of interactive components and inherently dynamic, Graph Continual Learning (GCL) has gained increasing popularity in recent years. Furthermore, most applications involve multiple entities and relationships with associated attributes, which has led to widely adopting Heterogeneous Information Networks (HINs) for capturing such rich structural and semantic meaning. In this context, we deal with the problem of learning multi-type node representations in a time evolving graph setting, harnessing the expressive power of Graph Neural Networks (GNNs). To this purpose, we propose a novel framework, named DyHANE—Dynamic Heterogeneous Attributed Network Embedding, which dynamically identifies a representative sample of multi-typed nodes as training set and updates the parameters of a GNN module, enabling the generation of up-to-date representations for all nodes in the network. We show the advantage of employing HINs on a data-incremental classification task. We compare the results obtained by DyHANE on a multi-step, incremental heterogeneous GAT model trained on a sample of changed and unchanged nodes, with the results obtained by either the same model trained from scratch or the same model trained solely on changed nodes. We demonstrate the effectiveness of the proposed approach in facing two major related challenges: (i) to avoid model re-train from scratch if only a subset of the network has been changed and (ii) to mitigate the risk of losing established patterns if the new nodes exhibit unseen properties. To the best of our knowledge, this is the first work that deals with the task of (deep) graph continual learning on HINs
In vivo imaging nickel-rich laticifers: a breakthrough in metal hyperaccumulation
No full textInternational audienceThe discovery of the nickel-rich latex of the New Caledonian endemic tree Pycnandra acuminata introduced the term ‘hyperaccumulator’ and gave rise to a new field of research. This then instigated a global quest for these unusual hyperaccumulator plants, even while the underlying mechanisms of nickel acquisition, transport, and internal elemental distribution remained unknown for this original laticifer-bearing hyperaccumulator plant. Here we reveal for the first time the distribution of nickel-filled laticifers in the different plant organs of P. acuminata. The pressurised nickel laticifers were imaged multimodally with a combination of synchrotron X-ray fluorescence (XRF) microscopy, microtomography (XRF-μCT) and synchrotron X-ray phase contrast imaging microtomography (PCI-μCT). These advanced synchrotron methodologies allowed for complimentary non-invasive reconstructions of an in-situ model of the laticiferous system in this species. The data shows the distribution of the nickel-rich laticifers within whole plant tissues from roots to apical tip, thus suggesting nickel trafficking in the laticifer network. The extraordinary concentration of nickel within P. acuminata laticifers functions as an effective natural tracer for XRF-μCT and PCI-μCT to probe the structure and organization of these cells, thereby permitting insights into the development and physiological functioning of this unique duct system
Interview de Gauthier Dobiny dans le cadre du séminaire permanent de l'Institut ExposUM: La Plateforme Portuaire de Surveillance Environnementale de Cotonou, Bénin : une initiative mutli-acteur·rice.s pour la gestion des invasions biologiques liés au trafic maritime international. Un exemple concret d’opérationnalisation de la recherche à l’interface science/société
No full textRetrouver cette ressource sur le Canal-U de MSH SUD : https://www.canal-u.tv/chaines/msh-sud/interview-de-gauthier-dobiny-dans-le-cadre-du-seminaire-permanent-de-l-institutLors de cette séance, l'intervenant a partagé son expérience autour de la création de la Plateforme Portuaire de Surveillance Environnementale située dans le Port Autonome de Cotonou, au Bénin, officiellement inaugurée à la fin de l’année 2021. Cette plateforme constitue le premier laboratoire dédié à la surveillance et à l’appui de la gestion des espèces envahissantes, notamment des rongeurs porteurs de vecteurs et d'agents pathogènes, à voir le jour au sein d’un port africain. Sa mise en œuvre est le fruit de nombreuses interactions entre partenaires académiques et non-académiques et constitue un exemple emblématique de l’opérationnalisation possible de la recherche scientifique au service d’enjeux de société
Une histoire de la prospective énergie-économie face au défi du changement structurel
No full textInternational audienceThe origins of energy forecasting in economics are usually traced back to the 1970s. This article focuses on earlier periods, analysing how some economists have examined the future of energy supply and demand since the 19th century. We show that most of the extrapolative and quantitative techniques used from the mid-19th century to the 1970s led to persistent difficulties in addressing structural change (technical progress, changes in energy sources, in consumption behaviours, etc.) and therefore in envisioning relevant energy futures. On the basis of Nicholas Georgescu-Roegen’s 1970s proposals to improve forecasting exercises, we set out two principles for dealing with structural change in the design of energy futures: (i) to pay attention to the emergence of “novelty by combination” in the economy, and (ii) to condition the scenarios to the directions suggested by the principles of thermodynamics, in particular with regard to energy degradation (especially of fossil fuels)
From colonialism to international aid: Social protection in former French colonies in sub‐Saharan Africa, 1890–2020
No full textInternational audienceThis article examines social protection pathways in the former French colonies in sub‐Saharan Africa. We identify five steps to understanding the patterns and dynamics of social protection in these countries that provide evidence of its exogenous construction. First, we characterize the main developments in social protection systems and policies from their inception, covering the colonial era to the present, underlining the role of colonial legacy and the global social policy framework. Second, we document the similarity of national social protection trajectories and lack of national ownership of the policy problem markedly that characterizes social protection pathways
Natural and human-mediated drivers of microevolution in Neotropical palms: a historical genomics approach
No full textSequencing data (i.e. paired-end reads) are available on the European Nucleotide Archive underaccession PRJEB51800. Bioinformatics codes are available on GitLab under Project ID 34990830 (https://gitlab.com/LouiseBrousseau/palm-capture-bioinformatics). Data and code remains under embargo until formal acceptance of the present article.Microevolution in Amazonia has been far less documented than in temperate regions and still constitutes a major knowledge gap. Moreover, the actual influence of pre-Columbian societies through the Holocene remains unclear, although it could provide interesting insights on the relationship between natural and human-mediated evolutionary processes in driving microevolution. Because they are widespread and traditionally managed since pre-Columbian times, Neotropical palms are choice models to investigate the drivers of microevolution in Amazonia. In this study, we carried out a preliminary exploration of the genomic diversity in two pairs of congeneric palm species in French Guiana ( Astrocaryum spp. and Oenocarpus spp.). We built upon an original sampling design, taking into account both regional climate variations and local-scale pre-Columbian occupation, and designed a new target capture kit of 20,000 molecular probes scattered across exonic regions of more than 5,000 nuclear genes in Arecoïdeae (“ARECO5000+”). Hundreds of palm libraries were sequenced through Illumina sequencing, providing a unique – high-coverage – genomic dataset in these non-model species. We explored patterns of genomic diversity and differentiation within and across populations, bringing state-of-the-art knowledge about the roles of climate adaptation and pre-Columbian domestication. By documenting original cases of “incipient” domestication, these pioneer results open new avenues toward a better understanding of microevolution in Amazonia and of the impact of pre-Columbian societies on present-day biodiversity patterns
Ecosystem engineers shape ecological network structure and stability: A framework and literature review
No full textThe data base used in this review are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.z34tmpgnw.International audience1. Ecosystem engineering is a ubiquitous process where species influence the physical environment and thereby structure ecological communities. However, there has been little effort to synthesize or predict how ecosystem engineering may impact the structure and stability of interaction networks.2. To assess current scientific understanding of ecosystem engineering impacts via habitat forming, habitat modification and bioturbation on interaction networks/food webs, we reviewed the literature covering marine, freshwater and terrestrial food webs, plant-pollinator networks and theory.3. We provide a conceptual framework and identify three major pathways of engineering impact on networks through changes in resource availability and energy flow, habitat heterogeneity and environmental filtering. These three processes often work in concert and most studies report that engineering increases species richness. This is particularly marked for engineers that increase habitat heterogeneity and thereby the number of available niches.4. The response of network structure to ecosystem engineering varies, however some patterns emerge from this review. Engineered habitat heterogeneity leads to a higher number of links between species in the networks and increases link density. Connectance can be negatively or positively affected by ecosystem engineer impact, depending on the engineering pathway and the engineer impact of species richness.5. We discuss how ecosystem engineers can stabilize or destabilize communities through the changes in niche space, diversity, network structure and the dependency on the engineering impact. Theory and empirical evidence need to inform each other to better integrate ecosystem engineering and ecological networks. A mechanistic understanding how ecosystem engineering traits shape interactions networks and their stability will be important to predict species extinctions and can provide crucial information for conservation and ecosystem restoration.Read the free Plain Language Summary for this article: https://fesummaries.wordpress.com/2024/06/13/ecosystem-engineers-shape-communities-and-species-interactions
Lose your teeth but keep your nerve! Lessons from sea cows...
No full textInternational audienceSirenians (extant and extinct sea cows) are a well-known example of morphological adaptation to a shallow-water grazing diet characterized by a modified feeding apparatus and orofacial morphology. They are notably characterized by a tooth reduction associated with the development of keratinized pads. These keratinized structures were especially pronounced in the recently extinct Steller’s sea cows, Hydrodamalis gigas, which was completely toothless. In an opposite evolutionary trend, manatees have developed a long row of six to eight molars that exhibit a constant addition of supernumerary teeth at the back of the jaw, which then migrate anteriorly (known as continuous dental replacement). We used a comparative framework of ontogenetic, paleontological, and genetic evidence to trace the evolutionary history of tooth loss in sirenians. We first used μ-CT scans of sirenian skulls to understand how motor-sensor systems associated with tooth innervation responded to innovations such as keratinized pads and continuous dental replacement. To further explore the degree of dental regression in sirenians, we determined the functionality of genes whose proteins are tied to tooth development and maintenance. We obtained nine core dental genes from Trichechus manatus, Dugong dugon, and Hydrodamalis gigas. Our results reveal how patterns of innervation changed with modifications of the dental formula, especially continuous replacement in manatees. Both our morphological and genomic data suggest that the tooth developmental pathway was not completely lost in the edentulous Steller's sea cows. We then argue that the dental neurovascular anatomy was co-opted for innervating and supplying blood to the keratinized pads. Using a long and slow developmental process such as tooth development might constitute a simple way for maintaining the dorsal innervation of keratinous structures in order to preserve sensorial functions of the alveolar region. Such a case of evolutionary tinkering is similar to that observed in other toothless tetrapods, and suggests that the tooth developmental pathway has been recycled multiple times to improve the neurovascularisation of disparate neomorphic keratinized structures, from baleen of mysticetes to beaks of non-avian dinosaurs and keratinized pads of sirenians
Impact of agroecological practices on Phytoseiidae communities in a vineyard of South of France: effect of covercrops and agroforestry
No full textInternational audienceViticulture is characterized by substantial pesticide applications, impacting natural enemies. New pest control strategies and management of plant diversity into agrosystems acting as reservoirs of natural enemies are assumed to limit pesticide use. Various studies support this hypothesis but gaps exist on the effect of diversification on Phytoseiidae mites, generalist predators reported as prevalent and efficient natural enemies in vineyards. This study focuses on the effect of cover crop management (no cover crop, spontaneous cover crops with or without agroforestry) and grape variety (resistant cv. Artaban and cv. Syrah) on predatory mites and prey communities, in a newly planted experimental vineyard in South-East France. Samplings were carried out three times a year on vine, cover crops, and co-planted trees. Phytoseiidae, Tydeiidae, Eriophyidae mites and thrips were characterized. Nine Phytoseiidae species were identified on vine, the main ones being Kampimodromus aberrans, Typhlodromus exhilaratus, Phytoseius finitimus and Euseius gallicus. Kampimodromus aberrans was prevalent on the cv. Syrah, highlighting a strong effect of variety. The low unexpected effect of system management observed outcome could be due to several factors, such as the experimental plot size or the influence of vine stress on Phytoseiidae communities in vines with cover crops. All phytoseiid species present on vine were identifed at least once on cover crops and co-planted trees, suggesting their potential role as reservoirs. Further studies should be performed investigating the evolution of communities in this newly-planted experimental system, as well as potential differences in trophic network interactions