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Understanding extracellular polymeric substances (EPS)-based hydrogel formation and properties at the nanoscale through MP-SPR and QCM-D techniques
No full textInternational audienceComprehensive investigation into the hydrogel formation and properties of structural extracellular polymeric substances (EPS) at the nanoscale
Data-driven PINN inference of oocyte dynamics in fish ovaries
No full textEarly oogenesis in juvenile fish establishes the ovarian reserve and thus conditions lifelong reproductive capacity. This process is regulated by local hormonal feedback mechanisms, mainly involving Anti-Müllerian Hormone (AMH). In this work, we develop a mechanistic size-structured population model describing the dynamics of precursor germ cells and growing oocytes in ovary, incorporating an AMH feedback exerted on the precursor germ cells renewal. Using repeated cross-sectional observations of oocyte size distributions in fish ovaries, we formulate and solve a nonlinear inverse problem with Physics-Informed Neural Networks (PINNs) to infer the size-dependent oocyte growth rate, the AMH-regulated renewal rate of precursor cells, and the recruitment rate of new oocytes. The proposed framework enables flexible, data-driven identification of biological rates under minimal prior assumptions. Once calibrated, the model provides in silico access to key unobservable quantities, including cell transit times, the impact of AMH perturbations such as invalidation conditions, and the mechanisms underlying inter-individual variability in the establishment of the pool of small oocytes. This work presents a novel application of PINNs to inverse problems for size-structured partial differential equation models with nonlocal interaction terms, and establishes a quantitative framework for studying early oogenesis in juvenile fish
Thirty years of nitrogen dynamics in European agri-food systems: a territorial metabolic perspective
No full textInternational audienceEuropean agri-food systems face the dual challenge of reducing their environmental footprint, particularly nitrogen losses, while meeting the demands for both food and non-food biomass. Because future responses will have to build on the legacy of past trajectories, addressing this challenge requires a sound, fine-grained understanding of those trajectories. In the present study, we address this challenge by compiling a dataset (1990–2019) quantifying nitrogen flows across the agri-food systems of 120 European territories. Using this dataset, we apply the generalized representation of agri-food systems framework to classify agri-food systems into six types representing different degrees of specialization. Our results show that agricultural systems became increasingly specialized, rising from 22% of specialized territories in 1990 to 36% in 2019, indicating a growing reliance on external feed and fertilizer inputs. Most of these transitions occurred in eastern Europe, predominantly toward stockless cropping systems. Although these evolutions unfolded within broader processes of market liberalization, transition patterns also displayed clear path-dependency effects rooted in the material configuration of agri-food systems. This is evidenced by the analysis of transition frequencies, which shows that some transitions occurred repeatedly while others never occurred, pointing to the influence of initial system configurations on subsequent trajectories. By contrast, changes in agro-environmental performance were only weakly linked to system transitions. The increases in nitrogen use efficiency (from 0.57 to 0.70) and declines in nitrogen surplus (from 68 to 49 kg N ha −1 ) rather coincided with higher yields and increased nitrogen input application rates, pointing to the dominant role of factors not explicitly captured here, such as shifts in agronomic practices and pedo-climatic conditions. Taken together, these findings provide both a critical dataset and a robust understanding of recent territorial agri-food trajectories, thereby offering a solid empirical basis for anticipating future transitions and developing scenario-based analyses
Making soils into carbon sinks. A sociology of soil carbon quantification
No full textInternational audienceSince COP21 in 2015, carbon neutrality targets have emphasized the enhancement of various carbon sinks, including soils, to help sequester carbon away from the atmosphere. What does it take to make soils into carbon sinks? This article focuses on a digital model of soil carbon cycling (AMG), which quantifies soil carbon stocks and their evolution under various agricultural practices. We examine how AMG circulates and transforms within a loosely connected network of actors and organizations involved in agricultural development, climate research, land-use planning public administrations, and carbon commodification. We show how the model evolves into three distinct yet interconnected regimes of carbon quantification – in climate academic research, local public action, and carbon markets – that contribute to building and expanding a sociotechnical infrastructure for quantifying soil carbon sequestration potential. Our findings contribute to literature on environmental quantification and knowledge infrastructures by calling for a shift from viewing knowledge infrastructures as stable and fixed toward an approach that emphasizes open-ended, flexible, and ongoing processes of infrastructuring. We also contribute to the literature on soil/human relationships by emphasizing how the model fosters a new focus on the active role of soils in the global carbon cycle and climate change mitigation
Je t’aime moi non plus ! Notre lien complexe à la fiscalité
No full textNational audienceTrop d'impôt tue l'impôt », dit la célèbre phrase de l'économiste états-unien Arthur Laffer. Et si pour la France, c'était plus compliqué que cela ? N'y a-t-il pas d'autres considérations sociales, affectives ou morales
OsbHLH064, an IVb bHLH Transcription Factor, Regulates Iron Homeostasis and Enhances Grain Fe Accumulation in Rice
No full textInternational audienceIron (Fe) is an essential micronutrient for plant growth and development. The maintenance of Fe homeostasis relies on sophisticated regulatory networks where bHLH transcription factors play a key role. However, how these factors coordinate to regulate this vital process is not fully understood. Here, we characterise OsbHLH064, a previously unstudied IVb bHLH transcription factor, and reveal its critical role in iron homeostasis in rice. Loss of OsbHLH064 results in constitutive activation of Fe homeostasis-related genes under Fe-sufficient conditions, whereas its overexpression strongly suppresses their expression. Remarkably, OsbHLH064 overexpression leads to excessive Fe accumulation in roots, shoots and brown rice. Under Fe deficiency, it also triggers ROS overproduction, highlighting its essential role in balancing Fe homeostasis and oxidative stress. Mechanistically, OsbHLH064 forms heterodimers with IVc bHLH transcription factors, and these interactions facilitate its nuclear localisation. OsbHLH064 represses OsIRO2 and OsIRO3 by competing with or sequestering IVc activators at shared promoters, thereby limiting downstream transcriptional activation. Furthermore, OsbHLH064 directly binds not only canonical IVb/IVc targets but also a broader set of genes involved in Fe uptake, translocation and signalling. Collectively, these findings establish OsbHLH064 as a central upstream regulator integrating multiple pathways to maintain Fe homeostasis and suggest its potential as a target for biofortification strategies aimed at enhancing iron content in rice grains
Brain imaging correlates of food addiction: A systematic review with methodological recommendations
No full textInternational audienceBackgroundFood addiction (FA) affects a significant proportion of the general population and could contribute to excess weight and its related complications. This phenomenon has been well described in terms of behavior, but little is known about its neurological determinants. The primary aim of this systematic review is to identify the neuroimaging characteristics associated with FA, using the Yale Food Addiction Scale (YFAS) as a validated assessment tool.MethodsA systematic search was conducted in PubMed and ScienceDirect databases from 2009 to July 2024 in accordance with the PRISMA 2020 guidelines. Studies were included if they investigated associations between the YFAS and neuroimaging outcomes. A descriptive analysis was conducted due to the methodological heterogeneity between the included articles.ResultsOf the 528 records identified, 25 studies were included in the review, representing 3081 participants in total. Functional magnetic resonance imaging (fMRI, n = 18) and structural MRI (n = 9), were the most commonly used imaging techniques. Studies reported associations between YFAS scores and altered resting-state functional connectivity or brain responses to cognitive tasks, especially in caudate, putamen, amygdala, insula, nucleus accumbens, orbitofrontal cortex, thalamus and precuneus. Yet, numerous neuroimaging findings related to FA presented discrepancies across studies.DiscussionThere is some evidence of altered activation and functional connectivity in brain areas involved in reward and cognitive control among individuals with FA. However, neuroimaging outcomes related to FA remain highly inconsistent across studies, partly due to heterogenous methodologies. Methodological recommendations are provided to improve consistency of future neuroimaging research in the context of FA
Adaptive effects of geographic origin on tree ring width and radial growth -climate relationships in Pinus nigra Arnold, the European black pine
No full textRadial growth is an adaptive trait that is expected to vary among forest tree populations when habitat conditions change. Pinus nigra J.F. Arnold (1785), the European black pine, is a forest tree species widely but patchily distributed throughout southern Europe, from isolated locations in north Africa to the Black Sea and Western Asia. While it has been widely used as plantation species since the mid-19 th century because of its strong growth on rather poor soils, the effect of genetic lineages and geographic origins on mean ring widths has not yet need assessed. In this study, we analyze the radial growth performance of sixteen different geographic origins (provenances) of P. nigra growing in four bioclimatically contrasted common gardens in France.Using a tree-ring to climate relationship approach and a 40-year long chronology, we first estimated how variable the effect of monthly climate was on radial growth, depending on phylogenetic or geographic origin, and plantation habitat. We then used the tree ring data to estimate genetic and plasticity effects and to test for the existence of genotype by environment interactions. Lastly, we ranked the growth performance of the different subspecies and provenances measured in each common garden, having in mind a typology for forest management.Results showed few climate effect differences among provenances and subspecies, with late spring minimum temperatures affecting radial growth negatively and early summer precipitations positively, overall. Winter maximum temperatures affected radial growth differently depending on the site, with a negative correlation at the warmest sites and a positive correlation at the coldest one. The provenance effect was stronger than the subspecies effect and radial growth phenotypic plasticity was high across the four sites (up to 50% increase in mean tree ring width from low to high fertility sites). While some provenances of P.n. subsp. pallasiana, P.n. subsp. laricio and P.n. subsp. nigra performed well in all sites, others attributed to the same subspecies displayed significant genotype by environment interactions.Provenances of the subspecies P.n. subsp. salzmannii often displayed the smallest mean ring widths except in the least fertile test site.Provenance variability within subspecies and not just subspecies variability should be considered in plantation forestry, both for restoration and timber production
Orbital stability of monostable waves for reaction-diffusion systems
No full textWe study stability of monostable waves for reaction-diffusion systems. When the solution is initially close to a fast wave profile in optimal topology, we prove convergence to a shifted profile. The proof relies on explicit resolvent kernels estimates, allowing to handle weakly localized perturbations. It allows phase shift construction even when the translational eigenvalue is not associated to a zero of the Evans function.We further discuss distinction between Evans and Fourier eigenmodes when the marginal group velocity are directed towards the wave interface
Nanosecond laser surface texturing of Ti-6Al-4V & Al1050: Overview of induced modifications and relevant characterization techniques for structural bonding applications
No full textInternational audienceLaser surface texturing (LST) using nanosecond pulses is an effective approach to modify the surface properties of metallic alloys. This study provides a synthetic overview of the modifications induced by LST on two materials: titanium alloy Ti-6Al-4V and aluminum alloy Al1050. The main goal is to improve the structural bonding performance of the metals. Untreated, laser-textured, and sandblasted samples are compared, and the most relevant characterization techniques to assess these changes are identified. Significant changes in topography, microstructure, and surface chemistry are observed due to the heating of matter generated by a nanosecond laser. Surface topography was analyzed using scanning electron microscopy, digital microscopy, and x-ray tomography, highlighting increased surface roughness and surface complexity. Microstructural alterations were evaluated using electron backscatter diffraction and x-ray diffraction. Local increases in dislocation density were identified via kernel average misorientation mapping, and in Ti-6Al-4V, the formation of a martensitic α′ phase was observed in the subsurface. The increase in the oxygen concentration near the surface was assessed by x-ray photoelectron spectroscopy, light-discharge optical emission spectroscopy, and Auger electron spectroscopy. This multitechnique approach allows a comprehensive understanding of laser-induced transformations in the metallic substrates, allowing to understand the key properties in improving the adhesive bonding.</p