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A one-health approach to non-native species, aquaculture, and food security
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/609253/)International audienceOne-Health is an umbrella term that integrates the health of the environment, humans and non-human animals. This approach is applied here to elucidate the impact of non-native invasive species on aquaculture and food security. Despite inherent biases against these species, a better understanding of their characteristics allows for the identification of those of greatest concern, minimizing the risk of food shortages and infectious diseases. This review summarises the positive and negative impacts of non-native species, delineating the specific areas they may impact. Additionally, this review gives an insight to the expertise and stakeholders that would need to be included if a “One-Health” approach were to be implemented by policymakers to better control non-native species. Detailed examples illustrate the consequences of non-native species on trophic dynamics, ecosystem health, water chemistry, and human health, emphasizing the importance of managing them within a multidimensional framework. The “One-Health” approach is explained, and suggestions are made on how certain non-native species could be used to contribute to food security in low- and middle-income countries. Furthermore, recommendations are made to promote a more inclusive management strategy
Predicting water quality in urban rivers: Linking high frequency monitoring and spatial rainfall
No full textInternational audienc
Development of a New Laboratory Earthquake Setup Featuring a Paraffin oil-based Gel as Analogue Material
No full textInternational audienceIn this study, we present the development of a new experimental setup composed of an analogue fault surrounded by paraffinoil-based gel, which allows us to simulate earthquake-like events in the laboratory. The apparatus is designed to test the possibility ofmitigating earthquake-like instabilities using control theory. We present the physical properties of the paraffin oil-based gel as functionsof strain rate, strain, and temperature. Our results show a linear relation between the stress and strain up to 30% shear strain, along witha low viscosity at high strain rate. Furthermore, we engineered the frictional properties of the analogue fault using 3D-printed patchesplaced along its surface. Finally, an experimental earthquake simulation, using the setup, demonstrates a sudden slip event within the gel,propagating at a speed between cs and 1.41 cs, where cs represents the shear wave velocity of the gel, which is consistent with theoreticaland previous experimental results
Understanding the complex dynamics of zebra mussel invasions over several decades in European rivers: drivers, impacts and predictions
No full textInternational audienceThe zebra mussel Dreissena polymorpha is one of the most successful, notorious, and detrimental aquatic invasive non‐native species worldwide, having invaded Europe and North America while causing substantial ecological and socio‐economic impacts. Here, we investigated the spatiotemporal trends in this species' invasion success using 178 macroinvertebrate abundance time series, containing 1451 records of D. polymorpha collected across nine European countries between 1972–2019. Using these raw (absolute) abundance data, we examined trends and drivers of occurrences and relative abundances of D. polymorpha within invaded communities. Meta‐regression models revealed non‐significant trends both at the European level and for the majority of the invaded countries, except for France (significant decreasing trend) and Hungary (marginally positive trend). At the European level, the number of D. polymorpha occurrences over time followed a flat‐top bell‐shaped distribution, with a steep increase between 1973–1989 followed by a plateau phase prior to significantly declining post‐1998. Using a series of climatic and hydromorphological site‐specific characteristics of invaded and uninvaded sites from two periods (1998–2002; 2011–2015), we found that native richness, non‐native abundance, distance to the next barrier, and elevation were associated with the occurrence of D. polymorpha . We also found that higher native richness and lower latitude were related to lower relative abundances. Using Cohen's D as a measure of D. polymorpha impact, we found that biodiversity within the invaded sites was initially higher than in uninvaded ones, but then declined, suggesting differences in biodiversity trends across invaded and uninvaded sites. While our results emphasise the high invasion success of D. polymorpha , increasing stressors within the context of global change – particularly ongoing climate change – are likely to enhance invasion rates and the impact of D. polymorpha in the near future, exacerbated by the lack of timely and effective management actions
Pathologies animales virales (fièvre aphteuse, clavelée) et traitements végétaux impliqués à Widou Thiengoly (Ferlo Nord)
No full textInternational audienceObjective: The aim of this study was to determine the plant diversity involved in the treatmentfoot-and-mouth disease and sheep pox in Ferlo Nord, a region of Senegal considered to be alivestock production area par excellence, with a wealth of hitherto undocumentedethnoveterinary practices.Methods and results: An ethnobotanical survey was carried out using a semi-structured openinterview guide, targeting mainly older herders. The data collected made it possible to assessone ethnobotanical parameter in particular: the level of fidelity. Two viral pathologies (footand-mouth disease and sheep pox) requiring the use of organs (leaf, root, bark, sap, fruit) fromsix plants following various preparations (crushing, direct use, maceration and drying) and twomodes of administration (local and oral) were listed. Foot-and-mouth disease mainly involvesplants, particularly Acacia nilotica subsp. adstringens (Schum. & Thonn.) Roberty and sheeppox, with little recourse to plants, with species such as Combretum glutinosum Hochst. exA.Rich. also used against foot-and-mouth disease.Conclusion and applicability of results: This work promotes ethnoveterinary medicine in asituation where knowledge is disappearing and more thought needs to be given tophytochemical and pharmacological aspects, as well as to the management of plant resources,by identifying locally interesting species to be incorporated into initiatives to reconstitute theecosystem in a context of desertification.Objectif : L’objectif de cette étude est de recenser les pathologies animales virales et de déterminer la diversité végétale impliquée dans leur traitement au Ferlo Nord, une région du Sénégal considérée comme zone d’élevage par excellence foisonnant de pratiques ethno vétérinaires jusque-là non documentées Méthodes et résultats : Une enquête ethnobotanique, réalisée au moyen d’un guide d’entretien ouvert semi- structuré, a ciblé prioritairement des bergers d’un âge avancé. Les données collectées ont permis d’évaluer particulièrement un paramètre ethnobotanique : le niveau de fidélité. Deux pathologies virales (fièvre aphteuse et clavelée) nécessitant l’usage d’organes (feuille, racine, écorce, sève, fruit) de six végétaux suivant des préparations diverses (pilage, emploi direct, macération et séchage) et deux modes d’administration (locale et orale) ont été répertoriées. La fièvre aphteuse implique majoritairement des végétaux particulièrement Acacia nilotica subsp. adstringens (Schum. & Thonn.) Roberty et la clavelée, sollicite faiblement le recours aux végétaux avec des espèces comme Combretum glutinosum Hochst. ex A. Rich. également utilisée contre la fièvre aphteuse. Conclusion et applicabilité des résultats : Ce travail promeut la médecine ethno vétérinaire dans une situation de disparition des connaissances qui nécessiteraient plus de réflexion aux plans phytochimique et pharmacologique mais aussi dans la gestion des ressources végétales, en distinguant des espèces intéressantes localement à incorporer dans les initiatives de reconstitution de l’écosystème dans un contexte de désertification. Mots clé : Ethnobotanique, pathologies animales virales, guide d’entretien, Ferlo Nord, Senegal. Pathologies animales virales (fièvre aphteuse, clavelée) et traitements végétaux impliqués à Widou Thiengoly (Ferlo Nord). Viral animal pathologies (foot-and-mouth disease, sheep pox) and their plant treatments in Widou Thiengoly (North Ferlo) ABSTRACT Objective: The aim of this study was to determine the plant diversity involved in the treatment foot-and-mouth disease and sheep pox in Ferlo Nord, a region of Senegal considered to be a livestock production area par excellence, with a wealth of hitherto undocumented ethnoveterinary practices. Methods and results: An ethnobotanical survey was carried out using a semi-structured open interview guide, targeting mainly older herders. The data collected made it possible to assess one ethnobotanical parameter in particular: the level of fidelity. Two viral pathologies (foot and-mouth disease and sheep pox) requiring the use of organs (leaf, root, bark, sap, fruit) from six plants following various preparations (crushing, direct use, maceration and drying) and two modes of administration (local and oral) were listed. Foot-and-mouth disease mainly involves plants, particularly Acacia nilotica subsp. adstringens (Schum. & Thonn.) Roberty and sheep pox, with little recourse to plants, with species such as Combretum glutinosum Hochst. ex A.Rich. also used against foot-and-mouth disease. Conclusion and applicability of results: This work promotes ethnoveterinary medicine in a situation where knowledge is disappearing and more thought needs to be given to phytochemical and pharmacological aspects, as well as to the management of plant resources, by identifying locally interesting species to be incorporated into initiatives to reconstitute the ecosystem in a context of desertification. Keywords: Ethnobotany, viral animal pathologies, interview guide, North Ferlo, Senegal
Development of a polyhedral DEM method for simulating the relocation of nuclear fuel during a LOCA
No full textInternational audienceDuring a Loss of Coolant Accident (LOCA), fuel rods are heated by the residual power. The resulting increase of internal pressure leads to a ballooning of the cladding which allows the fuel to relocate and, if there is a rupture, to disperse into the primary circuit.Here, we propose to assimilate the fragmented fuel to a granular medium and implement a Discrete Element Method (DEM) to model the behavior of fragments within the rod. The aim is to describe their relocation through the analysis of packing fraction along the rod. This model echoes previous DEM-focused numerical simulation works on fragment relocation. Some of these models have limitations in terms of representation which we aim to overcome by creating a realistic 3D model to describe the main features of the fuel rod during a LOCA: • The complex shape of the fragments; • The deformation of the cladding and the interaction of fragments with the inner wall; • The interaction of fuel fragments with fission gases and the confinement gas;The initial developments aimed to adapt the discrete element method and extend it to arbitrary polyhedral geometries, adopting a method based on sphero-polyhedra. This method allows to facilitate the contact detection stage, which is challenging to implement for complex geometries.Verification and validation test cases of the polyhedral DEM method have been conducted. They serve as benchmarks for applied simulations aimed at studying the effect of size and shape distribution of fragments on relocation in the case of a dry granular medium.Further developments are in progress to address the effects of fragment interaction with cladding walls and fission gases. Various coupling methods with DEM are being explored, and their selection is the subject of current research efforts
Experimental study of secondary hydriding during a LOCA transient
No full textInternational audienceDuring the oxidation phase of a Loss of Coolant Accident (LOCA), significant hydrogen absorption can occur at the inner side of the fuel rod, between the pellet and the cladding. This phenomenon, known as secondary hydriding, has been investigated through semi -integral tests. To better understand this phenomenon, a new protocol was developed to simulate and conduct separate effects tests (SETs). The results of these separate effects tests are valuable for supporting codes aimed at simulating secondary hydriding. In this study, separate effects tests were carried out to characterize the influence of pellet positioning inside the cladding on the azimuthal distribution of hydrogen within the cladding after the transient. Hydrogen measurements have revealed a correlation between the azimuthal hydrogen distribution and the non -coaxial positioning of pellets during the transient
Reduced order modelling of fully coupled electro-mechanical systems through invariant manifolds with applications to microstructures
No full textInternational audienceThis article presents the first application of the direct parametrisation method for invariant manifolds to a fully coupled multiphysics problem involving the nonlinear vibrations of deformable structures subjected to an electrostatic field. The formulation proposed is intended for model order reduction of electrostatically actuated resonating Micro‐Electro‐Mechanical Systems (MEMS). The continuous problem is first rewritten in a manner that can be directly handled by the parametrisation method, which relies upon automated asymptotic expansions. A new mixed fully Lagrangian formulation is thus proposed, which contains only explicit polynomial nonlinearities, which is then discretised in the framework of finite element procedures. Validation is performed on the classical parallel plate configuration, where different formulations using either the general framework or an approximation of the electrostatic field due to the geometric configuration selected are compared. Reduced‐order models along these formulations are also compared to full‐order simulations operated with a time integration approach. Numerical results show a remarkable performance both in terms of accuracy and the wealth of nonlinear effects that can be accounted for. In particular, the transition from hardening to softening behaviour of the primary resonance while increasing the constant voltage component of the electric actuation is recovered. Secondary resonances leading to superharmonic and parametric resonances are also investigated with the reduced‐order model
