Portail HAL de l'Université du Littoral Côte d'Opale
Not a member yet
11255 research outputs found
Sort by
Achieving inclusive digital development : A frugal strategy based on lessons from three West African smallholder agriculture value chains
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/614560/)International audienceThis article has two objectives. One is to examine mechanisms of inclusion and exclusion that arise despite the widespread diffusion of digital devices and supporting infrastructure. The second is to propose expanding the perspective on digital inclusion to consider users of digital technologies within their environment. Recognizing that innovation diffusion processes can exacerbate existing inequalities and/or create new ones, this study aims to assist researchers and practitioners in preventing potential negative impacts of digitalization. Using digital divides and digital inclusion frameworks, we examine three value chains in three West African countries using mixed methods. The findings reveal that communication networks and phones are increasingly available, yet traditional digital divides persist in all three value chains. Although the value chains share similarities in their challenges and opportunities, the needs of the actors involved vary. The discussion underscores two key points: first, the efficacy of digital solutions hinges upon their alignment with collective habits and capacities; and second, solutions should prioritize frugality, particularly when designing digital technologies for producers who have limited yet valuable digital skills. These insights highlight the importance of tailoring digital interventions to local contexts and use habits
Interaction Graphs of Phytoplankton Species Interactions using Logical Learning
No full textInternational audienceThe functioning of marine ecosystems depends on key processes such as climate regulation and water quality. Phytoplankton, unicellular microalgae at the base of marine food webs, play a central role in these dynamics that are threatened by global change. Although abiotic factors (e.g., temperature) are well studied, biotic interactions (i.e., between species) are poorly understood. Classical machine learning models, while effective at prediction, often operate as black boxes and provide limited biological interpretability. Meanwhile, symbolic and qualitative modeling approaches, which could offer greater explanatory power, remain largely underused in marine ecology. To address this gap, we investigate phytoplankton interactions using an explainable machine learning method, LFIT (Learning From Interpretation Transitions), which infers logical rules from observational time series data. Adapting this framework required methodological contributions, notably a species-specific discretization strategy informed by ecological theory. The extracted rules enable the construction of an interaction graph, where edges represent probable interspecies interactions. This graph offers an interpretable representation of the dynamics of the community and helps identify key drivers of the development of phytoplankton
Influence of the phytoplankton community structure on the southern elephant seals' foraging activity within the Southern Ocean
No full textInternational audienceThe intricate relationship between trophic levels in marine ecosystems remains largely unexplored, particularly in the Southern Ocean. To investigate the complex composition of water constituents, notably the phytoplankton community, we used machine learning techniques to classify six bio-optical classes from a comprehensive ocean-color data time-series. In situ data from the Southern Ocean further characterized these classes by predominant phytoplankton types. Bio-logging data from southern elephant seals revealed that 60% of prey-catch attempts were concentrated within the diatom-dominated class, despite its lower regional frequency. Seals exhibited enhanced foraging activity and prolonged residency periods, up to 42 consecutive days, in diatom-rich waters compared to 5-10 days in other classes. These findings suggest a preference among southern elephant seals for diatom-rich waters, indicating a selective foraging activity influenced by the phytoplankton community’s structural composition rather than total biomass alone. This preference underscores the intricate interplay between marine top predators and ecosystem dynamics, hinting at mechanisms through which phytoplankton structure shapes seal activity
Critical factors influencing PM 10 and PM 2.5 pollution episodes and their associated particle chemical composition and mixing state in a coastal multisources area
No full textInternational audienc
Le paradoxe des traileurs face aux enjeux environnementaux des mobilités : entre engagement dans les trajets quotidiens et « désengagement » dans les déplacements pour la pratique
No full textInternational audienc
Engaging Students in Spectroscopic Analysis of Organic Compounds: A Collaborative Tournament Approach for Third-Year Chemistry Students in Northern France
No full textInternational audienceThe ability to elucidate the structure of organic compounds from their nuclear magnetic resonance (NMR), infrared (IR), and mass spectrometry (MS) spectra is an essential skill, particularly for those engaged in the fields of synthetic and analytical organic chemistry. Spectral analysis constitutes a fundamental component of the curriculum for all chemistry students, as it requires the development of critical thinking skills. To engage and motivate students in the structure’s elucidation course, a gamified learning activity was designed in the form of a tournament involving third-year chemistry students from three universities in Northern France. In this tournament, the students are divided into teams comprising of four to five individuals. They are tasked with elucidating the structures of organic compounds based on their NMR, IR, and MS spectra in the shortest possible time with the fewest possible incorrect answers. The tournament was conducted in two distinct phases, each with a duration of 1.5 h and 1 h, respectively. The initial phase is competitive and involves teams of students from the same university, while the subsequent phase is designed to facilitate interaction and comparison between students from different universities, allowing them to discuss and evaluate their respective knowledge and methodology. The students were invited to evaluate the tournament approach by a questionnaire. The students expressed appreciation for the tournament and recommended its repetition in future years, citing its value in advancing their spectroscopy skills. Additionally, the students found the opportunity to interact with students from other universities and engage in discussions about their training programs and methodologies to be a valuable experience
La mise en place d'un dispositif de partage de la valeur : la sempiternelle ritournelle de la négociation collective
No full textInternational audienc
Genetic diversity and virulence gene profiling of Vibrio harveyi in a vibriosis-affected European seabass (Dicentrarchus labrax) aquaculture tank
No full textInternational audienceAquaculture is crucial in meeting global seafood demand; however, intensification often leads to bacterial diseases that threaten productivity. Dicentrarchus labrax, a key species in European aquaculture, is highly vulnerable to vibriosis, primarily caused by Vibrio harveyi. This study investigates genetic profiles associated with vibriosis by analyzing V. harveyi strains from a seabass farm during 2022 vibriosis outbreaks. Sampling from biofilm and water environments yielded 946 bacterial isolates, of which 56 were identified as V. harveyi using MALDI-TOF MS. ERIC-PCR genotyping revealed four distinct profiles. Despite observing variability in the presence of the 80 tested virulence genes, the overall genetic variation among these profiles was not pronounced. Notably, no single genotypic profile was linked to vibriosis. These findings suggest that the presence of virulence genes alone may not predict disease outbreaks, thus highlighting the need for future research on environmental and transcriptional factors to improve disease control in aquaculture systems.</div
Spectroscopie THz à Haute Résolution Basée sur des Peignes de Fréquences et des Lasers Moléculaires Pompes Optiquement
No full textThe objective of this thesis is to study the use of frequency combs for high-resolution molecular spectroscopy in the terahertz (THz) region of the electromagnetic spectrum. This approach is based on the conversion of an optical frequency comb into the THz domain. Nevertheless, the state of the art of these sources requires a highly sensitive THz heterodyne receiver to measure the amplitude of each comb tooth separately. We demonstrate the effectiveness of this approach at frequencies below 1 THz using Schottky diode-based heterodyne receivers. For higher frequencies, commercial mixers exist, but the challenge lies with the local oscillator (LO). We explored the use of optically pumped molecular lasers (OPML). Several active media were considered: ammonia (NH3), hydrogen cyanide (HCN), water vapor (H2O), and heavy water vapor (D2O). The experimental results show significant gains, though limited by the power of the available quantum cascade lasers (QCL) used to pump the gas. Sufficient THz power for pumping a mixer is nevertheless achieved, paving the way for more advanced OPML designs. Finally, the OPML is used as an LO in a molecular spectroscopy experiment involving synchrotron radiation. The experimental setup and techniques used for signal acquisition allow for high-precision measurements in the 1 – 4 THz range, where few solutions exist. This work ultimately envisions a compact and high-performance spectrometer for this entire range.L'objectif de cette thèse est d'étudier l'utilisation Peignes de fréquence pour la spectroscopie moléculaire à haute résolution dans la région du spectre électromagnétique Térahertz (THz). Cette approche est basée sur la conversion d'un peigne dans le domaine optique vers le domaine THz. Néanmoins l'état de l'art de ces sources nécessite un récepteur THz très sensible de type hétérodyne afin de mesurer séparément l'amplitude de chaque dent du peigne. Nous démontrons l'efficacité de cette approche à des fréquences inferieures à 1 THz à l'aide de récepteurs à base de diodes Schottky. Pour les fréquences supérieures des mélangeurs commerciaux existent mais il se pose le problème de l'oscillateur local (OL). Nous avons exploré l'utilisation de lasers moléculaires pompés optiquement (OPML). Plusieurs milieux actifs ont été considérés : l'ammoniac (NH3), le cyanure d'hydrogène (HCN), la vapeur d’eau (H2O), et la vapeur d'eau lourde (D2O). Les résultats expérimentaux mettent en evidence des gains significatifs toutefois limités par la puissance des lasers à cascade quantiques (quantum cascade lasers ou QCL) disponibles. Des puissances suffisantes pour le pompage d'un mélangeur sont néanmoins obtenues et ouvrent la voie à des conceptions plus avancées d'OPML. Enfin l’OPML est utilisé comme OL dans une expérience de spectroscopie moléculaire mettant en jeu le rayonnement synchrotron. Le montage expérimental et les techniques utilisées pour l'acquisition des signaux permettent des mesures de grande précision dans une gamme (1 – 4 THz) où il existe peu de solutions. Ce travail permet d'envisager à terme un spectromètre compact et performant dans toute cette gamme
Pas de devoir de mise en garde au profit des sous-cautions: note ss. Cass. com., 2 avr. 2025, no 23-22311, in « Droit bancaire – Chronique de jurisprudence »
No full textInternational audienceLa caution, qui n’est pas le dispensateur de crédit, n’est tenue d’aucun devoir de mise en garde à l’égard de la sous-caution sur le risque de l’endettement né de l’octroi du prêt garanti, lequel résulte de l’inadaptation du prêt aux capacités financières de l’emprunteur