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Sensitivity of fish stock trajectories to climate forcing and human exploitation at a global scale
No full textInternational audienceGlobal fisheries are under increasing pressure from overfishing and climate change, threatening marine biodiversity and food security. Disentangling the impacts of these two drivers is essential for sustainable management, yet it remains a major challenge due to the complex nature of marine ecosystems. Here, we utilize a data-driven Empirical Dynamic Modeling (EDM) framework to assess causal relationships between harvest rate, sea surface temperature (SST), and the productivity of fish stocks worldwide. Our analysis identifies fishing pressure as the most prevalent driver of stock productivity, with a causal link detected in stocks. SST was also identified as a significant driver of productivity in stocks. While the impact of harvest rate was stock-specific, being either positive or negative, the influence of SST was predominantly negative and, in many cases, intensifying over time. These results provide empirical evidence that direct exploitation and climate warming are systematically impacting fish stock productivity.</div
Efficient Succinct Zero-Knowledge Arguments in the CL Framework
No full textInternational audienceThe CL cryptosystem, introduced by Castagnos and Laguillaumie in 2015, is a linearly homomorphic encryption scheme that has seen numerous developments and applications in recent years, particularly in the field of secure multiparty computation. Designing efficient zero-knowledge proofs for the CL framework is critical, especially for achieving adaptive security for such multiparty protocols. This is a challenging task due to the particularities of class groups of quadratic fields used to instantiate the groups of unknown order required in the CL framework.In this work, we provide efficient proofs and arguments for statements involving a large number of ciphertexts. We propose a new batched proof for correctness of CL ciphertexts and new succinct arguments for correctness of a shuffle of these ciphertexts. Previous efficient proofs of shuffle for linearly homomorphic encryption were designed for Elgamal "in the exponent" which has only a limited homomorphic property. In the line of a recent work by Braun, Damgård and Orlandi (CRYPTO 2023), all the new proofs and arguments provide partial extractability, a property that we formally introduce here. Thanks to this notion, we show that bulletproof techniques, which are in general implemented with groups of known prime order, can be applied in the CL framework despite the use of unknown order groups, giving non interactive arguments of logarithmic sizes. To prove the practicability of our approach we have implemented these protocols with the BICYCL library, showing that computation and communication costs are competitive. We also illustrate that the partial extractability of our proofs provide enough guarantees for complex applications by presenting a bipartite private set intersection sum protocol which achieves security against malicious adversaries using CL encryption, removing limitations of a solution proposed by Miao et al. (CRYPTO 2020).</p
Artificial intelligence in dentistry: From general to custom GPTs: Part 1
No full textInternational audienceArtificial intelligence (AI) has become a transformative force in healthcare, with profound implications for dentistry. Dental professionals, faced with the ongoing challenge of keeping pace with scientific advances, can now leverage AI-powered virtual assistants to improve clinical decision-making and patient care. Today, virtual assistants have been developed to meet the unique needs of dental professionals, offering more targeted support than general-purpose AI tools such as ChatGPT. After a brief overview of the technology used, this two-part series will explore a range of platforms where virtual dental assistants can be created or utilised.[…
On n'a pas de terres rares, mais on a des idées: Partitionnement en classe d'équivalence pour le test d'algorithmes du texte.
No full textNational audienceThe consumption of resources, such as electricity and materials used in the manufacture of computers, is increasing sharply with the development of the digital economy and human activities. The question is how to limit this consumption without reducing activities that may be socially useful or necessary.In bioinformatics, we develop a lot of software, and sometimes many software for the same task, the same computational question. Think, for instance, about genome assembly or read mapping.When it comes to software development, it's advisable to develop the most comprehensive series of tests to ensure the validity of a piece of software. In the development cycle, we iterate, frequently or automatically, the execution of tests in order to verify the software's correctness at each step. Tests may also be run to evaluate computational speed. This raises scientific questions about the usefulness or redundancy of certain test instances.Let's take the case of a program that searches for a word in a text, such as your favorite genome. To test the program in all situations, we can run tests on all words of length k, for k equals 2, then 3, then 4, . . . , up to, say 31 (The value k=31 is common for some DNA sequence analyses). But clearly the number of instances increases exponentially with length k, and quickly becomes prohibitive. From the point of view of computer science, we can rephrase our initial question as follows: Can we identify redundant test instances? Can we generate only useful test instances? I will address these questions during this talk, illustrating them with two complex sequence processing algorithms and showing the impact of instance selection. This principle of test organization is called Equivalence Class Partitioning (ECP) in the domain of software development. The study of these equivalence classes for a given algorithm can be complex. Given the frequency with which tests are run during software development, and the number of software in bioinformatics, this type of approach can help reducing the ecological impact of our developments.In addition to the advantage in terms of resource usage, the partitioning approach can also inform us about the average program execution time on a class of instances of a given size. This generic approach points to avenues of research for many core algorithms, avenues that may foster interactions with other areas of computer science.La consommation de ressources, telles que l'électricité ou les matériaux de fabrication des ordinateurs, s'accroît fortement avec le développement de l'économie et des activités humaines numériques. La question se pose de limiter cette consommation sans pour autant réduire des activités qui peuvent s'avérer socialement utiles ou nécessaires.En bioinformatique, nous développons beaucoup de logiciels, et parfois de nombreux logiciels pour la même tâche, la même question computationnelle. Prenez par exemple le cas de l'assemblage de génome ou celui de la localisation des lectures de séquençage (ou "read mapping" en anglais; plusieurs dizaines d'outils de mapping ont été développés et maintenus).En matière de développement logiciel, il est recommandé de développer des tests les plus complets possibles afin de s'assurer de la validité d'un logiciel. Dans le cycle de développement, nous itérons, fréquemment ou automatiquement, l'exécution des tests afin de vérifier la correction du logiciel ou d'en évaluer la rapidité. Dès lors, on peut se questionner scientifiquement sur l'utilité ou la redondance de certaines instances de tests.Considérons le cas d'un programme de recherche d'un mot dans un texte, par exemple votre génome préféré (ou bien dans la séquence de De Bruijn d'ordre /k/). Pour tester le logiciel dans toutes les situations, on peut lancer des tests sur tous les mots de longueur k, pour k égale 2, puis 3, puis 4, ..., jusqu'à par ex. disons 31 (La valeur k=31 est commune pour certaines analyses de séquences). Mais clairement le nombre d'instances augmente exponentiellement avec la longueur k, et devient vite rédhibitoire. Du point de vue de la science informatique, nous pouvons reformuler notre question initiale ainsi: Peut-on identifier des instances de test redondantes ? Peut-on générer seulement des instances de test utiles ?J'aborderai ces questions durant cet exposé en les illustrant avec deux algorithmes complexes de traitement des séquences et en montrant l'impact du choix des instances. Ce principe d'organisation des tests se nomme Partitionnement par Classes d'Équivalence. L'étude de ces classes d'équivalence pour un algorithme donné peut s'avérer complexe.Étant donnée la fréquence d'exécution des tests durant le développement logiciel, ce type d'approche peut aider à diminuer l'impact écologique de nos développements. Outre l'avantage en termes d'utilisation de ressources, l'approche par Partitionnement peut aussi nous informer sur le temps moyen d'exécution du programme sur une classe d'instances d'une taille donnée. Cette réflexion générique ouvre des pistes de recherches pour de nombreux algorithmes, pistes à même de favoriser des interactions avec d'autres domaines de la recherche en informatique
Simulating light quantity and quality over plant organs using a ray-tracing method to investigate plant responses in growth chambers
No full textInternational audienceRay-tracing models enable the assessment of light quantity and quality intercepted by plant organs, supporting biological studies in growth chambers with varying light conditions. However, their validation within canopies and clear usage methods remain limited. This work establishes a reliable method for using these models. The method includes i) accounting for the intensity and spectrum of light sources in the calibration procedure; ii) a generic calibration strategy using a few well-placed light measurement points based on chamber geometry. It evaluates the method to simulate light phylloclimate at the organ scale across biologically relevant wavebands of contrasted widths and properties. Using the SEC2 light simulation framework, three virtual experiments were conducted in a growth chamber, with and without rose plants. Inputs included chamber geometry, material optical properties, lamp emissions, and digitised plant mock-ups. Simulations were compared with spectral measurements at various chamber positions and sensor orientations, both without plants and inside a canopy. Results showed high accuracy in replicating spatial light variability, with RMSE ranging 0.011 to 0.021 and 0.014–0.038 μmol m−2s−1nm−1 across different wavebands and sensor orientations, for vertical and horizontal transects, respectively. Applying this approach to a case study demonstrated its effectiveness in formulating new biological hypotheses regarding the role of local light in regulating bud outgrowth. This was achieved by highlighting differences in phylloclimate induced by variations in plant architecture. This work thus provides a comprehensive framework for facilitating the application of ray-tracing models in growth chamber studies
A revisited adaptive super-twisting control of underactuated mechanical systems: Design and experiments
No full textInternational audienceThis paper presents a real-time implementation of an adaptive super-twisting (ASTW) controller. This work deals with the stabilization challenging problems of underactuated mechanical system subject to parametric variations and state- and time-dependent disturbances. Due to the low number of control inputs compared to the number of DOFs, the proposed approach has been designed based on an explicit global change of coordinates. The stability analysis of the resulting closed-loop system was performed based on Lyapunov’s theory. Extensive experimental investigations were conducted on the inertia wheel inverted pendulum (IWIP) to demonstrate the robustness of the proposed solution. These experiments include a real-time comparison with existing control solutions from the literature, providing a detailed analysis of performance, effectiveness, and robustness under various conditions. Quantitative evaluations were carried out based on different performance criteria, highlighting the practical applicability and superiority of the proposed control strategy in real-time scenarios. The results from both numerical simulations and physical experiments demonstrate the controller’s capability to maintain stability and performance despite the presence of disturbances and parametric variations
Socializing A* Algorithm for Crowd- and Socially Aware Navigation
No full textInternational audienceToday, an undeniable interest is given to the development of socially intelligentrobotic systems and efficient crowd- and socially-aware navigation strategies. Inthis paper, we introduce a novel crowd-aware navigation algorithm that combinesthe A* path planner with the Double Deep Q-Network (DDQN) method.The algorithm, named Social A*, aims to allow safe navigation for mobile robotsin social dynamics and crowded environments. In order to facilitate future realworldimplementation, a new learning environment compatible with the RobotOperating System (ROS) is developed. This allows expert teleoperation to helptrain the DDQN agent and refine the reward function. We conducted extensivesimulations to compare the performance of Social A* with Socially-attentiveReinforcement Learning (SARL*) and Intention Aware Robot Crowd Navigationwith Attention-Based Interaction Graph (IARL). The obtained simulation resultsdemonstrate that Social A* not only surpasses SARL* and IARL but also showsenhanced performance in handling static obstacles. These results showcase theexcellent crowd-aware navigation performance, the efficiency, and the significantpotential of the algorithm
Brooks-type colourings of digraphs in linear time
No full text26 pages, 5 figuresInternational audienceBrooks' Theorem is a fundamental result on graph colouring, stating that the chromatic number of a graph is almost always upper bounded by its maximal degree. Lov\'asz showed that such a colouring may then be computed in linear time when it exists. Many analogues are known for variants of (di)graph colouring, notably for list-colouring and partitions into subgraphs with prescribed degeneracy. One of the most general results of this kind is due to Borodin, Kostochka, and Toft, when asking for classes of colours to satisfy "variable degeneracy" constraints. An extension of this result to digraphs has recently been proposed by Bang-Jensen, Schweser, and Stiebitz, by considering colourings as partitions into "variable weakly degenerate" subdigraphs. Unlike earlier variants, there exists no linear-time algorithm to produce colourings for these generalisations. We introduce the notion of (variable) bidegeneracy for digraphs, capturing multiple (di)graph degeneracy variants. We define the corresponding concept of -dicolouring, where is a vector of functions, and an -dicolouring requires vertices coloured to induce a "strictly--bidegenerate" subdigraph. We prove an analogue of Brooks' theorem for -dicolouring, generalising the result of Bang-Jensen et al., and earlier analogues in turn. Our new approach provides a linear-time algorithm that, given a digraph , either produces an -dicolouring of , or correctly certifies that none exist. This yields the first linear-time algorithms to compute (di)colourings corresponding to the aforementioned generalisations of Brooks' theorem. In turn, it gives an unified framework to compute such colourings for various intermediate generalisations of Brooks' theorem such as list-(di)colouring and partitioning into (variable) degenerate sub(di)graphs
A novel protocol for rapid deployment of heart rate data storage tags in Atlantic bluefin tuna Thunnus thynnus reveals cardiac responses to temperature and feeding
No full textInternational audienceThe Atlantic bluefin tuna (ABFT) is a highly prized species of large pelagic fish. Studies of their environmental physiology may improve understanding and management of their populations, but this is difficult for mature adults because of their large size. Biologging of heart rate holds promise in investigating physiological responses to environmental conditions in free-swimming fishes but it is very challenging to anesthetize large ABFT for invasive surgery to place a tag in the body cavity near to the heart. We describe a novel method for rapid deployment of a commercially available heart-rate tag on ABFT, using an atraumatic trocar to implant it in the musculature associated with the cleithrum. We performed three sequential experiments to show that the tagging method (1) is consistently repeatable and reliable, (2) can be used successfully on commercial fishing boats and does not seem to affect fish survival, and (3) is effective for long-term deployments. In experiment 3, a tag logged heart rate over 80 days on a 60-kg ABFT held in a farm cage. The logged data showed that heart rate was sensitive to prevailing seasonal temperature and feeding events. At low temperatures, there were clear responses to feeding but these all disappeared above a threshold temperature of 25.5°C. Overall, the results show that our method is simple, rapid, and repeatable, and can be used for long-term experiments to investigate physiological responses by large ABFT to environmental conditions
Travaux Pratiques de commande de robots sous-marins basée modèle et capteurs
No full textNational audienceAu cours de l'année universitaire 2021-2022, l'Université de Toulon a accueilli la première promotion du Master Erasmus Mundus MIR (Master Sciences en robotique marine et maritime intelligente). Parmi les enseignements proposés en première année, le module Marine Mechatronics vise à enseigner la modélisation, la commande et le guidage des robots sous-marins. Dans ce domaine, l'expérimentation joue un rôle clé, permettant aux étudiants d'acquérir des compétences pratiques spécifiques tout en appréhendant la complexité de la commande des véhicules sous-marins, notamment en navigation assistée par sonar (pour l'évitement d'obstacles) ou par asservissement visuel. Cet article présente les travaux pratiques durant desquels les étudiants manipulent pour la première fois des robots sous-marins. Ces séances leur permettent d'identifier certains paramètres du modèle, de réaliser la commande selon deux degrés de liberté (profondeur et cap), d'expérimenter l'évitement d'obstacles et de pratiquer l'asservissement visuel. Enfin, l'article se termine par une évaluation de cet enseignement réalisée par les étudiants