Portail HAL Um (Université de Montpellier)
Not a member yet
163190 research outputs found
Sort by
Positionnement d'un robot parallèle à câbles avec une précision supérieure à 250 μm à l'aide de systèmes de mesure par multilatération et photogrammétrie
No full textInternational audienceImproving the positioning accuracy of cable-driven parallel robots (CDPRs) is crucial for industrial applications. These robots, operating in large volumes and handling heavy loads, have an accuracy limited by several factors, such as variations in ambient temperature or changes of the load being transported, which affect the mechanical structure of the robot or the tensions in the cables. For instance, CoGiRo is a CDPR of dimensions of 11 m × 15 m × 6 m able to move a platform weighing up to 500 kg. Its resolution is a few tens of micrometres, but its positioning, estimated from the winch encoders, lacks accuracy. To accurately place the CoGiRo mobile platform in the desired position and orientation, this paper proposes to use multilateration and photogrammetric measurement systems in a collaborative way. Photogrammetry continuously measured the poses of the mobile platform with worst-case coordinate uncertainties in the depth direction moving away from the cameras, with 0.2 mm being typical for all lines of sight, dropping to 0.5 mm where lines of sight were blocked by occlusion. The photogrammetric system reported poses at 2 Hz to the multilateration system, enabling it to align its stations on the distant targets and measure static poses of the platform with an estimated uncertainty typically less than 70 µm for the position coordinates and less than 110 µrad for the orientation angles. Multilateration measurements were then used by CoGiRo to reduce its positioning errors to less than 250 µm. The technique was validated using a practical assembly of two square-shaped metallic parts equipped with 10 independent capacitive distance sensors that allowed us to demonstrate part alignment to better than 250 µm
The black-chinned tilapia Sarotherodon melanotheron, a model for environmental genomics and aquaculture resilience in the Western African's context of climate change
No full textInternational audienceThe euryhaline black-chinned tilapia (Sarotherodon melanotheron, Rüppell, 1852) has long been recognised as a valuable local resource in West African aquaculture and artisanal fisheries. Its production contributes to food security, the local economy and farmer’s incomes. Initial research on this species focused on understanding its biology and ecology in the field and in controlled conditions, and then on evaluating and improving practices to increase local production. More recently, the scope of this research has expanded to include investigations integrating molecular approaches in wild populations, such as population genetics and genomics studies, as well as ecophysiological and functional transcriptomics. Additionally, issues related to climate change have been incorporated. In the range of the black-chinned tilapia, the increase in salinity observed in so-called ‘inverse estuaries’ in Senegal, where hypersaline conditions of up to 130 psu may prevail throughout the year, has attracted significant attention. Even for a euryhaline species such as S. melanotheron, such conditions impose substantial energetic costs, resulting in observed phenotypic and adaptive changes to the fish’s biological and life-history traits. Salinity is a major issue in tilapia aquaculture. Improved production could be achieved by selecting strains from populations that are tolerant to salinity, or by hybridising with less tolerant tilapia species that demonstrate better growth performance. This study reviews and summarises knowledge acquired on S. melanotheron over several decades, paying particular attention to the northern subspecies, S. m. heudelotii. Current research limitations consist of: (i) the status of the species itself, comprising subspecies that are still too poorly characterized; (ii) the interaction between salinity and other parameters, particularly hypoxia; (iii) the impact of climate change on the entire species range, involving multiple environmental parameters in Western Africa; and (iv) limited access to resources in Africa, hindering local and regional development
Functional characterization of NRT1 / PTR FAMILY transporters: looking for a needle in a haystack
No full textInternational audienceNRT1/PTR FAMILY (NPF) transporters play crucial roles in plant physiology and development due to their involvement in nitrogen nutrition and their ability to transport multiple signaling molecules and metabolites. Whereas most eukaryotic and prokaryotic NPF orthologs are peptide transporters, most flowering plant NPF transport other substrates such as nitrate as well as a wide range of structurally unrelated molecules like amino acids, potassium, chloride, glucosinolates, alkaloids, nicotianamine, sugars, or glycerate. Some NPF have also been reported to transport hormones, such as auxin, abscisic acid, gibberellins, or jasmonate. Strikingly, several NPF were shown to transport more than one of these molecules. This multispecificity places NPF in a central position in the integration of plant signals. In addition, different plant NPF were reported to have a signaling activity that is independent of their transport activity, indicating a direct role in molecule sensing. Identification of NPF substrates is not trivial and requires specific heterologous expression systems such as Xenopus oocytes or yeast to be functionally characterized. The aim of this review is to highlight the techniques used for NPF characterization, provide a comprehensive overview of their different substrates, and to speculate on the role of NPF during plant evolution
Plant conservation in a changing Mediterranean world
No full textInternational audienceSocietal Impact Statement The Mediterranean is one of five climatic regions on the planet characterised by a prolonged summer drought, exceptional plant diversity and high rates of endemism. We provide a framework to link the ecology of plant species conservation in the context of rapid and extreme climate deregulation to a philosophical typology of temporal attitudes (i.e., past, present and future). We argue that we must go beyond the historical heritage approach to embrace conservation action in a changing world. We review pragmatic and original ways to deepen social awareness for plant conservation, aligned with the three temporal themes. It is time to bring plants to the forefront of conservation action. Summary In this Thomas Review, we provide a structure that links ecological science of plant species conservation to a philosophical typology of temporal attitudes of scientists, i.e. ways of considering the inscription of one's action in time, with a preference for a temporal dimension in the past, the present or the future. We developed this framework to illustrate original ways of deepening social awareness for plant conservation. In section 1, we widen ecological and evolutionary foundations for plant conservation based on the historical floristic heritage to embrace the need to protect species at their range limits and the need to monitor the effects of extreme climate events. The processes that shape diversity and adaptation are central to this approach. Section 2 describes three temporal attitudes associated with the above three conservation themes. The remembrance attitude is characterised by its interest in the long‐term history of plant diversity. The anticipation attitude relies on climate scenarios and expected species distribution changes. Finally, a prudent attitude consists of making regular observations of ongoing change that relies on an iterative temporality of a continually renewed present. In section 3, we illustrate pragmatic and original ways to deepen social awareness for plant conservation in line with the three temporal themes. We conclude with a comment on the uncertainties surrounding conservation science and the need for confidence to act locally.El Mediterráneo es una de las cinco regiones climáticas del planeta caracterizadas por una prolongada sequía estival, una diversidad vegetal excepcional y altos índices de endemismo. En un contexto de desregulación climática acelerada y extrema, proponemos un marco para vincular la ecología de la conservación de especies vegetales con una tipología filosófica de actitudes temporales (pasado, presente y futuro). Sostenemos que es necesario superar un enfoque rígido centrado en el patrimonio natural y estructurar acciones de conservación adecuadas a un mundo en transformación. Examinamos medios pragmáticos y originales para fortalecer la concientización social sobre la conservación de las plantas en relación con estas tres dimensiones temporales. Ha llegado el momento de situar a las plantas en el centro de las estrategias de conservación.La Méditerranée est l'une des cinq régions climatiques de la planète caractérisées par une sécheresse estivale prolongée, une diversité végétale exceptionnelle et des taux élevés d'endémisme. Dans un contexte de dérégulation climatique accélérée et extrême, nous proposons un cadre pour relier l'écologie de la conservation des espèces végétales, à une typologie philosophique des attitudes temporelles (passé, présent et futur). Nous défendons l'idée qu'il faut dépasser une approche figée du patrimoine naturel et structurer des actions de conservation dans un monde en mutation. Nous passons en revue des moyens pragmatiques et originaux de renforcer la sensibilisation sociale à la conservation des plantes, en lien avec ces trois dimensions temporelles. Le moment est venu de mettre les plantes au cœur des stratégies de conservation.Il Mediterraneo è una delle cinque regioni climatiche del pianeta caratterizzate da una siccità estiva prolungata, un'eccezionale diversità vegetale e alti tassi di endemismo. In un contesto di sregolamento climatico, rapido ed estremo, proponiamo un quadro per collegare l'ecologia della conservazione delle specie vegetali a una tipologia filosofica delle attitudini temporali (passato, presente e futuro). Sosteniamo che occorre superare un approccio statico al patrimonio naturale e strutturare azioni di conservazione in un mondo in trasformazione. Esaminiamo modalità pragmatiche e originali per rafforzare la consapevolezza sociale sulla conservazione delle piante, in relazione a queste tre dimensioni temporali. È giunto il momento di mettere le piante al centro delle strategie di conservazione
Efficient Control Allocation and 3D Trajectory Tracking of a Highly Manoeuvrable Underactuated Bio-inspired AUV
No full textInternational audienceFin actuators can be used for both thrust generation and vectoring. Therefore, fin-driven autonomous underwater vehicles (AUVs) can achieve high maneuverability with a smaller number of actuators, but their control is challenging. This study proposes an analytic control allocation method for underactuated AUVs. By integrating an adaptive hybrid feedback controller, we enable an AUV with 4 actuators to move in 6 degrees of freedom (DOF) in simulation and up to 5 DOFs in real-world experiments. The proposed method outperformed state-of-the-art control allocation techniques in 6-DOF trajectory tracking simulations, exhibiting centimeter-scale accuracy along with energy and computational efficiency. Real-world pool experiments confirmed the method's robustness and efficacy in tracking complex 3D trajectories, with significant computational efficiency gains (0.007 ms vs. 22.28 ms). Our method offers a balance between performance, energy efficiency, and computational efficiency, showcasing a potential avenue for more effective tracking across multiple DOF for underactuated underwater robots
Engineering Synthetic Apomixis in Hybrid Rice
No full textEG, IK, RM, and VS are co-inventors of patent WO2024074888 (PCT/IB2023/000562).International audienceThe transfer of apomixis, a clonal mode of reproduction by seeds, to crops has the potential to revolutionize agriculture by enabling the generation of one-line F1 hybrids that propagate clonally by seeds from one generation to the next. However, despite nearly four decades of intensive research, all the attempts to transfer the identified genetic determinants of apomixis from naturally apomictic wild plants to their crop relatives have failed to produce apomictic crops. Engineering of apomixis, mimicking the key features of a natural form of apomixis known as gametophytic diplosporous apomixis, has recently been achieved in rice and further improvements by the introduction of a single “all-in-one” T-DNA construct into calli derived from F1 hybrid seed embryos resulted in high frequency of clonal seeds. The T-DNA encodes a constitutively expressed Cas9 protein guided by sgRNAs designed to knock-out the functions of three genes essential for regulating crucial steps involved in meiosis, thereby eliminating meiosis and creating the Mitosis instead of Meiosis (MiMe) triple mutant. Additionally, the T-DNA contains another gene expression cassette consisting of a parthenogenetic trigger, the BABY BOOM1 (BBM1) transcription factor driven by an egg cell-specific (ECS) promoter. Inactivation of the three MiMe genes converts meiosis into mitosis—apomeiosis—yielding unrecombined and unreduced male and female spores developing into gametophytes. The BBM1 expression triggers parthenogenetic development of an embryo from the diploid egg cell of the female gametophyte. The endosperm develops sexually by the fusion of a diploid sperm cell and the central cell of the female gametophyte, which contains two diploid polar nuclei, resulting in an initially hexaploid endosperm. To date, the “all-in-one” T-DNA method has proved to be the most efficient for achieving high frequency (95–100% clonal seeds) synthetic apomixis in rice. Since the original publication, we have successfully generated synthetic apomictic events in three additional F1 hybrids. Here, we describe the methods for designing T-DNA constructs, analyzing mutations in first-generation (T0) MiMe mutant plants of F1 hybrids, and ascertaining the apomictic nature of the progenies from confirmed MiMe F1 hybrids, which relies on the egg cell-specific accumulation of BBM1
Prussian blue functionalized MIL-101(Cr)-SO3H for Cs+ ion capture for the management of contaminated water
No full textInternational audienceThis study investigates the property of Metal-Organic Frameworks (MOFs) grafted with Prussian blue analogs (PBA) for the efficient removal of Cs+ ions from aqueous solutions. MIL-101(Cr)-SO3H-PBA material was synthesized using a two-step process: hydrothermal reaction between monosodium 2-sulfoterephthalic acid (BDC-SO3Na) and chromium oxide (CrO3) to produce MIL-101(Cr)-SO3H, followed by grafting with CuK2[Fe(CN)6] (PBA). Both materials were characterized using XRD, IR, N2 sorption and Raman spectroscopy. The results confirmed the conservation of MOF porosity after functionalization and the successful incorporation of PBA. Batch adsorption experiments were conducted to evaluate Cs+ removal performance of the adsorbents. The study examined contact time (up to 1440 min), pH (2, 7 and 11), initial Cs+ concentration (from 9 ppb to 1800 ppm) and competing ions. The resistance of the porous solids under drastic conditions involving gamma radiation (from 0.5 MGy up to10 MGy) was also investigated.MIL-101(Cr)-SO3H-PBA exhibited a maximum Cs⁺ adsorption capacity of 242 mg.gMOF-1, compared to 161 mg.gMOF-1 for pristine MIL-101(Cr)-SO3H and showed high selectivity toward Cs+ in the presence of competing ions (Na+, K+, Mg2+, Ca2+, Sr2+). MI-101(Cr)-SO3H-PBA also demonstrates remarkable stability under radiation and alkaline conditions, maintaining 95% efficiency, whereas the performance of pristine MIL-101(Cr)-SO3H material decreased significantly (7.5-fold decrease).Cette étude examine les propriétés des structures métal-organiques (MOF) greffées avec des analogues du bleu de Prusse (PBA) pour l'élimination efficace des ions Cs+ des solutions aqueuses. Le matériau MIL-101(Cr)-SO3H-PBA a été synthétisé selon un procédé en deux étapes : réaction hydrothermale entre l'acide 2-sulfotéréphtalique monosodique (BDC-SO3Na) et l'oxyde de chrome (CrO3) pour produire du MIL-101(Cr)-SO3H, suivie d'un greffage avec du CuK2[Fe(CN)6] (PBA). Les deux matériaux ont été caractérisés par DRX, IR, sorption de N2 et spectroscopie Raman. Les résultats ont confirmé la conservation de la porosité des MOF après fonctionnalisation et l'incorporation réussie du PBA. Des expériences d'adsorption par lots ont été menées pour évaluer les performances d'élimination du Cs+ des adsorbants. L'étude a examiné le temps de contact (jusqu'à 1 440 min), le pH (2, 7 et 11), la concentration initiale en Cs+ (de 9 ppb à 1 800 ppm) et les ions concurrents. La résistance des solides poreux à des conditions extrêmes impliquant un rayonnement gamma (de 0,5 MGy à 10 MGy) a également été étudiée.Le MIL-101(Cr)-SO3H-PBA a montré une capacité d'adsorption maximale de Cs+ de 242 mg.gMOF-1, contre 161 mg.gMOF-1 pour le MIL-101(Cr)-SO3H, et a montré une forte sélectivité pour le Cs+ en présence d'ions concurrents (Na+, K+, Mg2+, Ca2+, Sr2+). Le MI-101(Cr)-SO3H-PBA présente également une stabilité remarquable dans des conditions de rayonnement et alcalines, maintenant une efficacité de 95 %, tandis que les performances du matériau MIL-101(Cr)-SO3H ont diminué de manière significative (diminution de 7,5 fois)
Death by Neurologic Criteria in Neonates Undergoing Extracorporeal Membrane Oxygenation: Extracorporeal Life Support Organization Registry Study, 2010–2023
No full textInternational audienceObjectives: To identify factors associated with the development of death by neurologic criteria (DNC) in neonates treated with extracorporeal membrane oxygenation (ECMO). Design: Retrospective registry study. Setting: Data reported to the Extracorporeal Life Support Organization registry from 2010 to 2023. Patients: Neonates (≤ 28 d old) who were supported with ECMO, excluding those born before 37 weeks’ gestation or with missing gestational age data. The final cohort comprised 14,970 neonates. Interventions: None. Measurements and Main Results: DNC occurred in 70 neonates in the cohort (0.5%), accounting for 2% of overall mortality rate. Pre-ECMO factors associated with greater relative risk ratio (RRR) of DNC included pre-ECMO cardiac arrest (RRR, 2.64), pH less than 7.08 (25th percentile: RRR, 2.06), and cardiac support type (RRR, 2.04). On-ECMO, factors independently associated with DNC included pH less than 7.35 (25th percentile: RRR, 2.76), Pa o 2 greater than 162 mm Hg (75th percentile: RRR, 2.75), and central cannulation (RRR, 2.36). We failed to identify an association between relative change in Pa co 2 greater than 50% and DNC, but it correlated with other causes of death. Most DNC diagnoses (84%) occurred after 24 hours of ECMO. Conclusions: DNC is rarely diagnosed in neonatal ECMO cases. Both pre-ECMO and on-ECMO factors associated with DNC included pre-ECMO cardiac arrest, severe metabolic acidosis, and cannulation type. These findings underscore the importance of optimizing pre-ECMO and on-ECMO management and may indicate certain modifiable risk factors such as optimization of cardiopulmonary resuscitation and hyperoxia. Future research should explore preventive strategies and interventions to mitigate the risk of DNC in neonates receiving ECMO
Sex-specific aggressive and emotional behavior in myostatin-deficient mice: Ratio of acylated versus unacylated ghrelin is reduced, but not correlated with butyrylcholinesterase activity level, however parvalbumin expression is lost in the habenular complex
No full textMyostatin plays crucial roles in negative regulation of muscle growth. Inactivation of the myostatin gene results in gross muscle hypertrophy. We observed that myostatin knock-out (myostatin-KO) mice are more aggressive than wild-type (WT) mice. Ghrelin is a hormone produced by cells of the gastrointestinal tract that activates cells in the brain and increases the drive to eat. The level of circulating ghrelin affects anxiety, stress, and aggression. Ghrelin controls expression of myostatin in disease-associated cachexia. Butyrylcholinesterase (BChE) is responsible for the deacylation of ghrelin. BChE knock-out mice show higher level of acylated ghrelin and are more aggressive than WT mice. De-acylation of ghrelin by BChE reduces aggression in mice. We hypothesizedthat the levels of expression of BChE, ghrelin and myostatin could explain the aggressive behavior of myostatin-myostatin-KO mice. Resident/intruder tests shows that male myostatin-KO mice are more aggressive than WT littermates. Female myostatin-KO mice show much higher spontaneous exercise than female WT and males of both genotypes. Behavioral tests (elevated plus maze and light/dark box) show that myostatin-KO mice present anxious behavior without any change in circulating corticosterone. Myostatin-KO mice have a lower acylated/unacylated ghrelin ratio. Female myostatin-KO mice show lower level of BChE activity compared with WT lit-termates. Comparison of staining for various neurotransmitter systems involved in behavior showed that the onlyregion where there was a difference between WT and myostatin-KO mice was in the habenular complex which involved in regulation of behavior. Reduced ghrelin levels and loss of parvalbumin neurons of the habenular complex could partly explain the behavior of our model
Analysis of oil palm cultivation practices of smallholders in Thailand: environmental sustainability implications
No full textInternational audienceThe rapid expansion of oil palm cultivation in the humid tropics has raised major sustainability concerns. Certification systems, notably the Roundtable on Sustainable Palm Oil (RSPO), aim to promote transparency and accountability in supply chains, yet smallholder participation remains limited, and certification is often driven more by market pressures than environmental objectives. This study evaluates the environmental sustainability of RSPO-certified and non-certified smallholders in Surat Thani Province, Thailand. Results show that certified farmers achieve marginally higher overall sustainability scores, with significant improvement only in soil fertility management through mandatory soil and leaf analyses and frond mulching. These practices are supported by better training access and stronger social networks. No significant differences were observed in water management or agro-biodiversity conservation, which depend mainly on agroecological conditions. The findings suggest that RSPO certification alone does not ensure environmental sustainability. Broader sustainability transitions are driven by market dynamics, government extension, and farmer learning networks. Policies should promote sector-wide sustainability by scaling successful RSPO soil fertility initiatives – public – private partnerships linking mills, universities, and local authorities – and supporting integrated management of soil, water, and biodiversity alongside improved planting material and irrigation access to advance Thailand’s sustainable oil palm transition