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Optimal ANOVA-Based Emulators of Models With(out) Derivatives
No full textInternational audienceThis paper proposes new ANOVA-based approximations of functions and emulators of high-dimensional models using either available derivatives or local stochastic evaluations of such models. Our approach makes use of sensitivity indices to design adequate structures of emulators. For high-dimensional models with available derivatives, our derivative-based emulators reach dimension-free mean squared errors (MSEs) and a parametric rate of convergence (i.e., O(N−1)). This approach is extended to cope with every model (without available derivatives) by deriving global emulators that account for the local properties of models or simulators. Such generic emulators enjoy dimension-free biases, parametric rates of convergence, and MSEs that depend on the dimensionality. Dimension-free MSEs are obtained for high-dimensional models with particular distributions from the input. Our emulators are also competitive in dealing with different distributions of the input variables and selecting inputs and interactions. Simulations show the efficiency of our approach
Monitoring individual rice field flooding dynamics over a large scale to improve mosquito surveillance and control
No full textInternational audienceBackground Progress in malaria elimination has been hindered by recent changes in mosquito behaviour and increased insecticide resistance in response to traditional vector control measures, such as indoor residual spraying and long-lasting insecticidal nets. There is, therefore, increasing interest in the use of larval source management (LSM) to supplement current insecticide-based interventions. However, LSM implementation requires the characterization of larval habitats at fine spatial and temporal scales to ensure interventions are well-placed and well-timed. Remotely sensed optical imagery captured via drones or satellites offers one way to monitor larval habitats remotely, but its use at large spatio-temporal scales has important limitations. Methods A method using radar imagery is proposed to monitor flooding dynamics in individual rice fields, a primary larval habitat, over very large geographic areas relevant to national malaria control programmes aiming to implement LSM at scale. This is demonstrated for a 3971 km 2 malaria-endemic district in Madagascar with over 17,000 rice fields. Rice field mapping on OpenStreetMap was combined with Sentinel-1 satellite imagery (radar, 10 m) from 2016 to 2022 to train a classification model of radar backscatter to identify rice fields with vegetated and open water, resulting in a time-series of weekly flooding dynamics for thousands of rice fields. ResultsFrom these time-series, over a dozen indicators useful for LSM implementation, such as the timing and frequency of flooding seasons, were obtained for each rice field. These monitoring tools were integrated into an interactive GIS dashboard for operational use by vector control programmes, with results available at multiple scales (district, sub-district, rice field) relevant for different phases of LSM intervention (e.g. prioritization of sites, implementation, follow-up).Conclusions Scale-up of these methods could enable wider implementation of evidence-based LSM interventions and reduce malaria burdens in contexts where irrigated agriculture is a major transmission driver.</div
Incidence and 1‐Year Prognostic of Unstable Angina After High‐Sensitivity Troponin Assessment
No full textInternational audienceBackground: Incidence and prognostic of unstable angina after high-sensitivity troponin assesment is controversial.Aims: This study evaluated prognostic of a contemporary population of patients with UA defined using high sensitive T troponin (T hs-cTn) measurements and with significant coronary artery disease (CAD).Methods: Consecutive patients admitted in 2 French university centres with UA defined as clinical ischemic symptoms and T hs-cTn dosages undetectable (< 5 ng/L), non-elevated (> 14 ng/L) or mildly elevated (14−50 ng/L) were included. The primary end-point included major events at 1-year follow-up.Results: Among 1752 patients admitted for ACS between December 2021 and February 2023, 210 (12.0%) have UA and significant CAD. Mean age was 66 ± 12 years, with predominantly men (n = 143; 68.1%). Patients had undetectable (n = 4), non-elevated (n = 80) or mildly elevated and stable T hs-cTn (n = 126). History of CAD was found in 98 patients (46.6%). Percutaneous intervention was required in main patients (n = 186; 88.6%). Adverse non-fatal in-hospital event occurred in one patient. The primary outcome was achieved in 55 patients (26.2%; CI 95% [20.2−32.1]) mainly related to new ACS (n = 34, 16.2%). The level of troponin at admission (p = 0.639) was not associated with the primary outcome. In multivariate analysis, multiple risk factors (OR 1.93, [1.01−3.69], p = 0.0194), history of CAD (3.09; CI [1.63; 5.87], p = 0.0005), and tritroncular disease (OR 2.66; CI [1.24; 5.69], p = 0.0118) were significantly associated with major events at 1-year.Conclusion: Contemporary incidence of UA with significant CAD is low with few in-hospital events, but with a 1-year incidence of cardiac events high (26%), mainly related to new ACS. Improving secondary prevention may be crucial for these patients. (ID: NCT06378333)
Newly Designed Fluorescence In Situ Hybridization Probes Reveal Previously Unknown Endophytic Abilities of Tuber magnatum in Herbaceous Plants
No full textInternational audienceTuber magnatum Picco (the Italian white truffle) is the most valuable and widely appreciated truffle. It is an ectomycorrhizal fungus known to associate with many broadleaf tree species. However, its mycorrhizae are rarely observed in the field, suggesting possible alternative symbiotic strategies, such as endophytism with non-ectomycorrhizal plants. In order to test potential endophytic interactions of T. magnatum with wild plants, a combination of polymerase chain reaction (PCR) and Fluorescence In Situ Hybridization (FISH) approaches were used. Specific FISH probes for T. magnatum were designed, tested in vitro on hyphae and/or ectomycorrhizae, and selected for their specificity. These probes were then used on a wide variety root samples of wild plants collected from three T. magnatum production areas in Italy and previously tested for the presence of T. magnatum mycelium using PCR-specific primers. Molecular analyses detected the presence of T. magnatum in 21 of 100 plant samples analyzed. FISH analysis confirmed the extracellular presence of active T. magnatum hyphae inside the root system of Carex pendula Huds plant. This study provides the first evidence of T. magnatum acting as an endophyte in an herbaceous plant. The newly designed, highly specific T. magnatum FISH probes can be used for further investigations to confirm the endophytic tendencies of T. magnatum and to understand their influence on the life cycle and biology of this fungus
Do ecological groups show different hydraulic and thermal sensitivities within the buffering understory environment in tropical forest?
No full textInternational audienceWe aim to identify which ecological groups (canopy trees, juvenile trees, understory specialists, or juvenile lianas) are more vulnerable to droughts events, using the thermal (T50) and hydraulic (P50) leaf sensitivity in tropical forest. Safety margins are reliable indicators of tree vulnerability to drought and can be estimated for thermal and hydraulic processes, as the difference between T50 or P50 and maximum leaf temperature or minimum leaf water potential during dry season (TSM and HSM, respectively).We show that in the understory, all ecological groups had significantly higher TSM (15.01°C to 23.51°C) compared to adult canopy trees (5.27°C to 10.17°C), due to the lower temperatures in this buffer habitat (offset ~5°C). However, we show a quite high P50 and large HSM (-3.82 +/- 1.12; 2.24 +/- 1.46 MPa, respectively), suggesting that hydraulic traits are more conserved across ecological types, despite contrasting environments.These findings demonstrate a strong adaptation of trees and lianas to the understory. Moreover, we found no strong correlation between thermal and hydraulic sensitivity, although these traits are linked to stomatal water flow and heat dissipation. Further research is needed to explore additional traits, such as stomatal conductance and leaf anatomy, for a deeper understanding of these interactions
The Thermal Tolerance of Springtails in a Tropical Cave, with the Description of a New Coecobrya Species (Collembola: Entomobryidae) from Thailand
No full textInternational audienceA new species of Collembola in the genus Coecobrya, C. microphthalma sp. nov., is described from a cave environment in Saraburi province, central Thailand. The new species is the second described species of the boneti-group found in the country. It is most similar to C. chompon Nilsai, Lima & Jantarit, 2022, which is also described from a Thai cave. However, the new species is morphologically different from C. chompon in having orange dot pigmentation on its body and a combination of other morphological characteristics such as the number of sublobal hairs on the maxillary outer lobe and the number of medio-sublateral mac on Th. II, Abd. I, Abd. III and Abd. IV and the anterior face of the ventral tube. The morphological comparison of all known boneti species and a key to the world species of Coecobrya of the boneti-group are given. Coecobrya microphthalma sp. nov. was successfully cultured in the laboratory. The thermal tolerance of the new species was studied and tested with seven different temperature experiments (27 °C as a control, 30, 32, 33, 34, 35 and 36 °C). The results showed that C. microphthalma sp. nov. cannot survive at a temperature higher than 32 °C after exposure to the experimental heat for 7 and 14 consecutive days. At 27, 30 and 32 °C, C. microphthalma sp. nov. remained alive and produced eggs, but the duration of egg production and number of egg-laying days significantly declined when the temperature increased (p < 0.001). An interesting aspect of their reproduction concerns temperature. At 32 °C (5 °C above the control temperature), the F1 generation survived, was active and was able to molt to the adult stage. However, specimens were unable to produce the next generation of offspring. For postembryonic development, C. microphthalma sp. nov. required six molts to reach the adult stage. The development rate (from egg to adult) varied and differed significantly between the tested temperatures (p < 0.001). An increase in temperature from the control temperature significantly accelerated the developmental rate from egg to juvenile instars to adult with a statistical significance (p < 0.01). This study is the first attempt that provide information on the impact of increasing temperature on the population dynamics, reproductive capacity and life history of a subterranean tropical Collembola
Iron-rich microband formation in marine sediments by hydrothermal iron cycling bacteria at Lucky Strike
No full textInternational audienceModels describing banded iron formation deposition beneath oxygenated Paleoproterozoic marine shelf waters assume that microaerophilic iron-oxidizing microorganisms were significant contributors. However, direct evidence for this mechanism is lacking, and it remains unclear how associated primary organic biomass and biogenic iron oxyhydroxides transformed into organic carbon-poor iron oxide/ carbonate-rich bands in banded iron formations. Here we explore in situ modern Zetaproteobacterial iron-oxidizing mats thriving in the Lucky Strike hydrothermal vent field to develop an empirical model that explains the potential contribution of iron-based metabolisms to deposition of rocks resembling banded iron formations. Petrographic, mineralogical, and geochemical data suggest that abundant production of Zetaproteobacterial stalks nucleates and drives spontaneous biotic/abiotic ferrihydrite precipitation in the mats. Subsequent early diagenetic anaerobic microbial oxidation of dead biomass as the mats aged, coupled to microbial reduction of iron oxyhydroxides/oxides, generates ferrous carbonates and mixed valence magnetite. Collectively, this forms crystalline iron-rich organic carbonlean 13C-depleted layers reminiscent of Precambrian banded iron formation microbands
Aborder les interactions entre les élasmobranches et les parcs éoliens offshore : Une approche spatiale multi-échelle
No full textElasmobranchs play an important role in marine food webs, but their populations are globally declining and often overlooked in the face of anthropogenic disturbances. The rapid development of offshore wind farms (OWFs) raises questions about their impacts on these species. To this end, the beginning of this work consisted in reviewing the current state of knowledge on the potential effects of these structures on the biology and ecology of these species and identifying key research gaps. Despite important lack of baseline data on these species, the synthesis demonstrated that several pressures could potentially cause effects at different spatial scales for these species. For example, on a large scale, the installation of an OWF may affect connectivity during species movements, while electromagnetic field emissions generated by submarine cables may cause behavioural changes within a few metres around the source. Acoustic telemetry appears as a relevant tool to address knowledge gaps on space use, occupation patterns and movements of free-swimming individuals within their natural environment and how those behaviours are influenced by anthropogenic activities.Fine-scale positioning of acoustically tracked individuals is a promising approach, increasingly used to study the natural behaviour of target species and the impact of anthropogenic activities. However, the accuracy of current positioning models remains a significant challenge, especially in open marine environments, and is an evolving field of study using passive acoustic telemetry. This thesis developed and improved the accuracy of a fine-scale positioning method to analyse individual behaviour at a metric scale in offshore open environments. The work also illustrates the importance of precision in measured field parameters to ensure high performance of positioning models.Multilateral passive acoustic telemetry was used in this thesis to monitor in situ the occupancy patterns of two benthic elasmobranch species, the small spotted dogfish Scyliorhinus canicula and the undulate ray Raja undulata, within an area with a dense array of receivers around an OWF export cable. Using a fine-scale positioning model, results suggested a higher presence during cable tensioning. The application of Hidden-Markov Chain movement models allowed the identification of two to three behavioural states within the study area, with a predominantly dominant behaviour that could be associated with foraging. The results have identified various metrics to qualify the behaviour of these two species, including vertical movements in the water column observed in S. canicula. The overall results provide valuable information as the first in situ study on the interactions of these species with the submarine cables of an OWF, which can serve as a reference.Last, the current study also examined the occurrence and occupancy patterns of the small spotted dogfish at a larger spatial scale, across different habitat types within the first operational French OWFs. A field study was conducted to acoustically track over 30 individuals for over 10 months at the Saint Nazaire OWF. The results showed that the OWF did not appear to repulse tagged individuals, that displayed habitat fidelity with seasonal residency of individuals. Although individuals were present throughout the OWF, monopiles installed on sandy substrates and equipped with scour protection showed a significantly higher occurrence.The current study has provided new insights into key aspects of the ecology of benthic elasmobranchs and how they interact with OWF structures. This thesis underscores the relevance of using acoustic telemetry at multiple spatial scales and brings new perspectives to the study of effects of OWFs in natura on free-swimming elasmobranch.Les élasmobranches jouent un rôle important dans les réseaux trophiques marins, mais leurs populations sont en déclin à l'échelle mondiale et souvent négligées face aux perturbations anthropiques. Le développement rapide des parcs éoliens offshores interroge sur l'impact de ces structures sur les espèces marines. À cette fin, le début de cette thèse a consisté à faire le point sur l'état actuel des connaissances des effets potentiels des parcs éoliens offshores sur la biologie et l'écologie des élasmobranches et d'identifier les principales lacunes. Malgré un manque important de données de référence sur ces espèces, la synthèse a démontré que plusieurs pressions pourraient potentiellement avoir des effets à différentes échelles spatiales. Par exemple, à large échelle, l'installation d'un parc éolien peut affecter la connectivité de ces espèces, tandis qu'à plus fine échelle, les émissions de champs électromagnétiques des câbles sous-marins peuvent provoquer des changements comportementaux à quelques mètres autour de la source. La télémétrie acoustique apparaît comme un outil pertinent pour combler les lacunes dans les connaissances sur l'utilisation spatio-temporelle et les déplacements des individus dans leur environnement et sur la façon dont ces comportements sont influencés par les activités anthropiques.Le positionnement à fine échelle d'individus à l'aide de la télémétrie acoustique est une approche prometteuse pour étudier le comportement des espèces marines. Cependant, la précision des modèles de positionnement actuels reste un défi important, en particulier dans les environnements marins avec une bathymétrie importante. Cette thèse a développé et amélioré la précision d'une méthode de positionnement à fine échelle pour analyser le comportement individuel à une échelle métrique dans des environnements offshores. Les travaux illustrent également l'importance de la précision des paramètres de terrain mesurés pour assurer des performances élevées des modèles de positionnement.La télémétrie acoustique passive multilatérale a été utilisée pour suivre in situ les patrons comportementaux de deux espèces d'élasmobranches benthiques, la petite roussette Scyliorhinus canicula et la raie brunette Raja undulata autour d'un câble d'exportation d'un parc éolien offshore. Les résultats ont suggéré une présence plus élevée des individus lors de la mise en tension des câbles. L'application de modèles de mouvement de Markov Cachés (HMM) a permis d'identifier deux à trois états comportementaux des individus dans la zone d'étude, avec un comportement principalement dominant qui pourrait être associé à la recherche de nourriture. L'ensemble des résultats fournit des informations précieuses en tant que première étude in situ sur les interactions de ces espèces avec les câbles sous-marins d'un parc éolien offshore, pouvant servir de référence.Enfin, cette thèse a également examiné l'utilisation spatio-temporelle de S. canicula au sein du premier parc éolien offshore français opérationnels. Dans cette étude, plus de 30 individus ont été marqués et suivis sur une période de 10 mois au sein du parc. Les résultats ont montré que le parc éolien ne semblait pas repousser les individus marqués avec une fidélité à l'habitat et une résidence saisonnière des individus. Bien que des individus aient été présents dans l'ensemble du parc éolien, les monopieux installés sur des substrats sablonneux et équipés d'une protection contre l'affouillement ont montré une occurrence significativement plus élevée.Cette thèse a fourni de nouvelles informations sur des aspects clés de l'écologie des élasmobranches benthiques et sur la façon dont ils interagissent avec les structures des parcs éoliens offshores. Elle souligne la pertinence de l'utilisation de la télémétrie acoustique à plusieurs échelles spatiales et apporte de nouvelles perspectives à l'étude des effets des parcs éoliens offshores in situ sur les élasmobranches
Love Thy Neighbour? Tropical Tree Growth and Its Response to Climate Anomalies Is Mediated by Neighbourhood Hierarchy and Dissimilarity in Carbon‐ and Water‐Related Traits
No full textInternational audienceTaxonomic diversity effects on forest productivity and response to climate extremes range from positive to negative, suggesting a key role for complex interactions among neighbouring trees. To elucidate how neutral interactions, hierarchical competition and resource partitioning between neighbours' shape tree growth and climate response in a highly diverse Amazonian forest, we combined 30 years of tree censuses with measurements of water‐ and carbon‐related traits. We modelled individual tree growth response to climate and neighbourhood to disentangle the relative effect of neighbourhood densities, trait hierarchies and dissimilarities. While neighbourhood densities consistently decreased growth, trait dissimilarity increased it, and both had the potential to influence climate response. Greater water conservatism provided a competitive advantage to focal trees in normal years, but water–spender neighbours reduced this effect in dry years. By underlining the importance of density and trait‐mediated neighbourhood interactions, our study offers a way towards improving predictions of forest dynamics
Elasmobranch vulnerability to global warming: insights from bioenergetic modelling of catsharks under climate scenarios
No full textInternational audienceEctotherms are especially vulnerable to global warming due to their temperature-sensitive metabolic processes, impacting survival and reproductive success. Elasmobranchs, with slow life histories and low reproductive rates, may face amplified risks. In this study, we investigated two catshark species with distinct life traits and distributions: the Small-spotted Catshark (Scyliorhinus canicula) and the Nursehound (S. stellaris). Using newly calibrated bioenergetic models, we assessed changes in growth, sexual maturity, offspring production, and population dynamics under two CMIP6 climate scenarios projected for 2100: SSP2-4.5 (Middle of the Road) and SSP5-8.5 (Fossil-fueled Development), comparing these to historical data (1994-2015). Survival rates for early life stages remained similar under historical temperatures (80 %) and SSP2 (83 %) but dropped sharply under SSP5 to 33 % for S. canicula and 23 % for S. stellaris. Under both SSP2 and SSP5, S. canicula showed slight delays in maturation, yet the proportion of mature individuals ultimately exceeded historical levels in SSP2. Conversely, S. stellaris experienced progressively delayed maturation with warming. In SSP5, reduced growth, reproduction, and survival caused a population crash for S. stellaris, suggesting potential extinction. Our results reveal contrasting climate impacts on these species, underscoring the risk for late-maturing, low-fecundity, and narrowly distributed species. This emphasizes the urgency of conservation strategies tailored to mitigate their vulnerability to global warming