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Thousand Years of Nitrogen Oxide Sources in Western Europe: Evidence From Nitrogen Stable Isotopes (δ15N) of Nitrate in a Mont Blanc Ice Core
No full textInternational audienceAbstractNitrogen stable isotopes (δ 15 N) of ice core nitrate (NO 3 -) are often subject to diverse interpretations associated with changes in nitrogen oxide (NO x ) sourcing, atmospheric reactions, and/or postdepositional processes. Here, an ice core from Mont Blanc (French Alps) was analyzed to investigate the δ 15 N (NO 3 -) record over the past 1,000 years. Atmospheric isotopic fractionation, including gas-particle partitioning, introduces a limited and quantifiable effect on δ 15 N(NO 3 -)-up to 2.4 ‰ in extreme cases. Thus, the glaciallyarchived NO 3 -reliably reflects a record of Western European NO x emissions by comparing δ 15 N and concentrations of NO 3 -, and isotope-concentration mixing relationships (Keeling plot) with historical emission inventories. An increase in δ 15 N(NO 3 -) in the 1800s reflects the dominance of NO x emissions from coal combustion. During the 20th century, the δ 15 N(NO 3 -) value substantially decreased, from (4.7 ± 1.5) ‰ in 1900 to (-1.9 ± 1.4) ‰ in 1990, and Keeling plot interpretation attributes this decrease to increasing oil combustion emissions. Between 1750 and 2016, the ice core's δ 15 N(NO 3 -) record generally aligns with existing NO x inventories for Western Europe. However, during the early 20th-century, low ice core δ 15 N(NO 3 -) values suggest that the inventories may have underestimated NO x emissions resulting from agriculture. Since 2000, the decreasing NO 3 -concentrations and δ 15 N(NO 3 -) values highlight the success of mitigation policies in reducing fossil fuel-induced NO x emissions, albeit with a delay of 20 years relative to emission inventories, that can be attributed to gas-particle partitioning and mis-quantification of NO x sources. This work reaffirms the value of alpine ice cores for understanding aerosol sources.Plain Language SummaryThis study aims to understand changes in nitrogen (N) stable isotopes, specifically the enrichment of 15 N/ 14 N (δ 15 N), in atmospheric nitrate. δ 15 N records of nitrate can provide information about its gaseous precursor (nitrogen oxides = NO x ) sources. However, some glacial archives are subject to debate whether they can be interpreted solely as source signals. Here, we analyzed a glacial record from Mont Blanc (French Alps), which preserves the δ 15 N source signal due to the proximity to NO x sources from Western Europe and its high snow accumulation rate. We discuss the evolution of NO x emissions over the past 1,000 years in light of existing NO x emission inventories in Western Europe. Notably, the comparison between δ 15 N record from ice core and NO x emission inventory highlights the rise in fossil fuel combustion over the 20th century, the underestimation of agricultural NO x emissions in the early 20th century, and its more recent emission reductions resulting from mitigation programs
Signaling quality to bridge the ethnic and gender gap: evidence for ethnic women entrepreneurs
No full textInternational audienceCrowdfunding offers a promising avenue to democratize finance, yet persistent biases continue to constrain minority entrepreneurs. This study examines ethnic women entrepreneurs, a group considered underdogs because overlapping gender and ethnic disadvantages create distinct legitimacy deficits in fundraising. Using a novel dataset of 18,123 U.S. Kickstarter campaigns, we analyze how underdog status shapes the effectiveness of internal signals (e.g., education, campaign commitment) and external signals (e.g., Staff Pick endorsements). We address selection bias with a Heckman two-stage procedure and entropy balancing. Results show ethnic women entrepreneurs face disadvantages in attracting local backers, while external signals strongly enhance credibility and fundraising outcomes. Internal signals are more effective with foreign backers, highlighting that the value of signals depends on both entrepreneur identity and backer audience. Signaling thus functions as both an economic and symbolic tool, enabling underdogs to challenge stereotypes and reclaim legitimacy. Ethnic women entrepreneurs can strategically leverage transnational networks to overcome local disadvantages. By integrating insights from signaling theory, underdog strategy, and ethnic entrepreneurship, this study advances understanding of how marginalized entrepreneurs navigate structural barriers in digital finance and offers guidance for more inclusive crowdfunding models
Impact of physical and sensory enrichment on the physiological status and disease resistance of triploid rainbow trout (Oncorhynchus mykiss)
No full textInternational audienceEnvironmental enrichment is increasingly recognised as a practical approach to improve the welfare of farmed fish. In rainbow trout (Oncorhynchus mykiss), a species of high economic and scientific relevance, few studies have simultaneously evaluated multiple dimensions of welfare under different enrichment strategies. Here, we investigated the effects of structural and sensory enrichments on growth, physiology, behaviour, neurochemistry, and disease resistance. Female triploid rainbow trout were reared for eight weeks under eight conditions: neutral control, positive stress control (no enrichment with additional handling stress), structural enrichments (rubber hose, rubber wall, floating grass mat, flexible laminaria), and sensory enrichments (continuous gas bubbles, blue light filter). Growth performance, blood markers of stress (cortisol, glucose, lactate), behavioural indicators, enrichment use, and brain monoamine turnover (5-HIAA/5-HT for serotonin; HVA/L-DOPA for dopamine) were assessed at three time points in eight weeks. To evaluate robustness, fish were subsequently challenged with Aeromonas salmonicida subsp. salmonicida. No significant differences in growth were detected across conditions, showed the highest weight gains, raising the hypothesis that they could provide benefits over longer rearing cycles, a question that will require dedicated long-term trials. Behavioural analyses indicated high use of structural enrichments and reduced stress-related behaviours under the blue filter and rubber hose conditions. Stress physiology revealed condition-specific reductions in lactate or cortisol, but no consistent enrichment effect across markers. Neurochemical analyses demonstrated condition-dependent modulation of serotonergic and dopaminergic turnover, with laminaria increasing both systems, blue filter reducing dopaminergic activity, and bubbles strongly decreasing serotonergic turnover. Infection outcomes showed slower disease progression in rubber hose, laminaria, blue filter, and rubber wall conditions, with rubber hose fish exhibiting the slowest mortality kinetics. Overall, our integrative approach highlights that environmental enrichment modulates multiple welfare dimensions in rainbow trout, with laminaria, blue filter, grass mat, and rubber hose emerging as the most promising strategies. These findings support enrichment as a valuable tool to promote fish welfare and resilience, while underlining the need for long-term and context-specific validation before implementation in aquaculture
Active-passive microwave scattering in the Antarctica wind-glazed region: an analog for icy moons of Saturn
No full textInternational audienceMicrowave radiometry and scatterometry, two complementary modes of sensing the composition and structure of the upper meters to hundreds of meters of the subsurface, are often difficult to reconcile, both on the Earth cryosphere and on icy moons of Saturn. To help interpret and model microwave scattering in porous, high-purity ices, we examine jointly 6.9–89 GHz AMSR2 radiometry in vertical (V) and horizontal (H) polarizations as well as 5.2 GHz ASCAT, 13.4 GHz QuikSCAT, and 13.5 GHz OSCAT scatterometry in the wind-glazed region of the East Antarctic ice sheet. The data are simulated using the Snow Microwave Radiative Transfer (SMRT) model, assuming a simplified snowpack characterized by constant temperature and a continuous increase in grain size (represented by optical radius) and density with depth. For the first time, we show that scatterometry and 6.9–37 GHz radiometry at V polarization can be successfully simulated with a unique simple snowpack model, indicating that incoherent volume scattering on subsurface heterogeneities dominates both the active and passive signals. To also simulate H-polarized radiometry, a thin surface ice layer as observed in the wind-glazed regions is one solution. Additional complexity, such as seasonal temperature variations, surface roughness, or non-continuous density variations, is necessary to explain the 89 GHz data and HH-polarized backscatter. Meanwhile, applying the same approach to simulate simultaneously passive and active Ku-band observations of icy moons improves on previous attempts but remains unable to reproduce the very high backscatter observed, highlighting the importance of coherent scattering and possibly unknown large icy structures (at least millimetric) in the subsurface. More work is still to be done to fully reproduce the microwave signatures of icy surfaces in the solar system
An embryo-derived peptide signal directs endosperm polarity in Arabidopsis
No full textAbstract Angiosperm seed formation requires the coordinated development of the products of double fertilization, the embryo and the endosperm. The endosperm mediates efficient nutrient transfer from surrounding maternal tissues to the developing embryo. This function requires a polarized tissue organization, which manifests as early polar gene expression and polar cellularization dynamics. We show that the receptor kinase HAIKU2 acts in coordination with the transcription factor WRKY10/MINISEED3 to ensure robust endosperm polarity establishment through the activity of the homeodomain transcription factors WUSCHEL-RELATED HOMEOBOX 8 and 9 . This process depends on egg cell fertilization and is mediated through the peptide PATHOGEN-INDUCED PEPTIDE-LIKE 7, which acts as a HAIKU2 ligand. Our results reveal how a molecular paracrine dialogue between the embryo and endosperm ensures optimal seed developmental coordination
Impact of producers behavior in the biocontrol of a pest. The case of the Asian citrus psyllid
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/616818/)International audienceThe Asian citrus psyllid (ACP), Diaphorina citrus, is the main vector of Candi- datus Liberibacter spp., the bacterium that cause Huanglongbing (HLB), the citrus greening disease [1]. This disease is so impacting that many citrus orchards have disappeared in many places, for instance 80% in Florida. Europe and, in particular, the Mediterranean basin is free of HLB, so far. However, it is present in three French overseas departments, including La R´eunion since 2015. Di!erent biocontrol methods have been tested and used with more or less success against the psyllid, using natural predators and parasito¨ıd, like Tamarixia radiata, and enthomopathogenic fungi. La R´eunion is the first and unique place, where biological control of HLB was achieved successfully in the 70s, using parasito¨ıds and mass grubbing [5]. Based on a recent result [2], we aim to take into account the role of producers behavior in the cooperation or not in the pest control. Human behavior is not easy to take into account in models. This has been mainly done for Human disease control (see for instance [3, 4]). Here, we consider a simplified Pest model related to the control of ACP by pheromone trapping [2]. We assume that the control is proportional to the amount of producers that agree to set-up the control. Then, based on pest infestation, the cost of the control, and the ”pressure” from the other producers, we build a socio-economic subsystem coupled to the pest equation. A qualitative analysis is done to derive the long-term behavior of the system, showing the possible existence of stable limit cycles. The results are discussed to derive the best control strategies. Numerical simulations will illustrate or complete our theoretical findings
Democracy and innovative governance in French agricultural cooperatives
No full textInternational audienceIn order to answer this question, the chapter is organized in four parts: first, we expose our theoretical framework; second, we detail the qualitative methodology based on four case studies; third, we analyse these cases; and fourth, we synthetize and conclude. Theoretical framework: democratic and innovative governanceWe based our theoretical framework on the concepts of democracy, governance, and innovation in corporate governance, applied to cooperatives, more particularly in the agricultural sector. In the following pages, we will define and develop these concepts, showing that a few studies deal with them and their interactions, proposing a conceptual framework to deal with drivers of governance innovation in terms of democracy. Democracy and governance: from capitalistic firms to cooperativesCompany is an organization with many faces that has been approached in different ways. From the neoclassical conception, according to which the company was considered as a "black box", to the company seen as a system, it is still difficult to grasp its complex reality (Tosi, 2009). Organization theory studies all types of organizations with very diverse points of view, as underlined by Tosi ( 2009): rational/natural models, closed/open system approaches, and considering single-or double-way relationships between environment and structure.According to Pfeffer (1991), this research field frequently took the individual and its behaviour as the unique unit of analysis and did not really consider social structure as relevant, denying the effects of social and mutual interactions among individuals on the firm's management. On the contrary, for Pfeffer (1991, p 801), "organizations are social settings". Social relations are therefore essential and can influence the firm's performance. Some authors went further and considered organization as an open system model where structure and environment are linked, sometimes following an interactive process, dealing with institutions and ecology, and leading to open system natural models (Tosi, 2009).In this perspective, the pervasive power of shareholders, stressed by Jensen and Meckling (1976), is counterbalanced or, at least, influenced by the open system of interactions between internal and external stakeholders, taking into account the commitment to society of the firm, analysed by the stakeholder theory (ST; Freeman, 1984). Democracy is also more concerned, directly or indirectly, considering the firm as an institution where democracy gains ground thanks to increasing openness, activist shareholders (Gomez, 2001) and citizen requirements (Grandori, 2017). This phenomenon led Andreani (1994, p 184) to state, "it is much more difficult to initiate democracy in a party than in a firm". In fact, behind stakeholder and democratic issues, governance is at the heart of operations.Democratic governance (Cornforth, 2004) concerns the essence of agricultural cooperatives as social economy organizations. Since their origin, they have been
L’autonomisation au travail d’éleveurs qui valorisent des milieux semi-naturels par le pâturage
No full textPARTIE II: LES NOUVELLES PRATIQUES AGRICOLESInternational audienc
White-rot fungi as a sustainable pretreatment approach to improve lignocellulosic biomass conversion for biohydrogen production
No full textInternational audienceThe production of biofuels from lignocellulosic biomass is one of the most promising alternatives for generating clean energy. However, various challenges arise when using this recalcitrant biomass in biotechnological processes for the production of biofuels (ethanol, biogas, biohydrogen, and methane), such as low yields due to the structural complexity of lignocellulose. In this sense, this study evaluated a biological pretreatment of a lignocellulosic waste mixture consisting of fruit peels (FRP) and brewer's spent grain (BSG), through solid-state fermentation (SSF) using the white-rot fungi Trametes versicolor and Pleurotus ostreatus. Different pretreatment conditions were assessed, including duration (15, 25, and 35 days), temperature (28 and 32 °C), and fungal strain (T. versicolor and P. ostreatus), to determine their impact on reducing sugars concentration and delignification and improving the bioaccesibility of the biomass in further bioenergy obtention process.The most suitable pretreatment condition was to carry out the SSF with T. versicolor at 28 °C for 25 days, obtaining a delignification of 15 ± 0.14 % and a reducing sugars consumption of 24 ± 0 %. The substrate pretreated under these conditions (TV-H) resulted in a 2.06-fold improvement in hydrogen production (mLH2 L−1) compared to the raw substrate as well as a shift in microbial communities and metabolic pathways involved in comparison to the raw substrate in dark fermentation, demonstrating an improvement in the process when biomass is pretreated with Trametes versicolor