Portail "HAL-Francophonie Afrique et Océan Indien"
Not a member yet
43052 research outputs found
Sort by
Assessing the benefits of part-night lighting on a tropical bat species endemic to Reunion Island
No full textInternational audienceArtificial light at night (ALAN) is recognised as an emerging threat to global biodiversity but no technical mitigation strategy can prevent all impacts on ecosystems. Consequently, the most effective measure remains turning-off lights whenever and wherever possible. However, few studies, all carried out in temperate environments, assessed the effectiveness of Part-Night Lighting (PNL) and the benefits that might result from changes in switch-off times. On the tropical Reunion Island, where ALAN is increasing exponentially, we assessed the sensitivity of an endemic bat species (Mormopterus francoismoutoui) to light, and the effectiveness of PNL in reducing the potential impacts on this species, depending on the switch-off times implemented. We took advantage of the modification of an existing PNL during a month-long event, consisting in switching off lights two hours earlier than the rest of the year. By carrying out an acoustic monitoring of bat echolocation calls, using a Before-After Control-Impact Paired protocol, we showed that bats were attracted to lit sites, especially at the beginning and end of the night, when the lights were on. When the lights were switched off earlier in the evening, there was no longer any impact on bat activity and rhythm, although a tendency toward greater activity at the end of the night in lit sites persisted in clear weather. This provides important insights, encouraging extensive use of PNL, ideally with even earlier switch-off times, as a promising measure for mitigating ALAN effects on this endemic species whose overall population vulnerability is still unknown
Palliative and end-of-life care in COVID-19 management in sub-Saharan Africa: a matter of concern.
No full textInternational audienceThe COVID-19 pandemic has strained health care systems beyond capacity resulting in many people not having access to life-sustaining measures even in well-resourced countries. Palliative and end-of-life care are therefore essential to alleviate suffering and ensure a continuum of care for patients unlikely to survive. This is challenging in sub-Saharan Africa where lack of trained teams on basic palliative care and reduced access to opioids limit implementation of palliative and end-of-life care. At the same time, health care providers have to cope with local cultural conceptions of death and absence of advance care directives
Co-speciation and host-switching drives diversity of picornaviruses and sapoviruses in Malagasy fruit bats
No full textInternational audienceBats are reservoir hosts for numerous well-known zoonotic viruses, but their broader virus-hosting capacities remain understudied. Picornavirales are an order of enteric viruses that cause disease across a wide range of mammalian hosts, including Hepatitis A in humans and foot-and-mouth disease in ungulates. Host-switching and recombination drive the diversification of Picornavirales worldwide. Picornaviridae and Caliciviridae (families within Picornavirales) have been described in bats across mainland Africa, but surveillance for these viruses has been rare in the Southwest Indian Ocean Islands. Prior work in Madagascar has described numerous bat viruses, some with zoonotic potential, that demonstrate both high identity to and extreme divergence from viruses found in sister bat species in Africa. Using metagenomic Next Generation Sequencing of urine and fecal samples obtained from three species of endemic Malagasy fruit bats (Eidolon dupreanum, Pteropus rufus, and Rousettus madagascariensis), we identify and describe 13 full-length and 38 partial-length genomic sequences within the Picornaviridae and Caliciviridae families (36 picornavirus and 15 Sapovirus sequences). We find evidence that host-switching between Madagascar and mainland African bat picornaviruses and sapoviruses, followed by host-parasite co-speciation, likely shaped the diversification pattens of these novel sequences, with little evidence for cross-species transmission among Malagasy bat species in close contact
Dynamical analysis and numerical simulation of a reaction-diffusion model for microbial decomposition of organic matter in 3D soil structure
No full textMicrobial decomposition of organic matter in soil is a fundamental process in the global carbon cycle, directly influencing soil health, fertility, and greenhouse gas emissions. This paper presents a dynamic analysis and numerical simulation of a reaction-diffusion model that describes microbial decomposition of organic matter within a three dimensional soil structure. We investigate the interactions between {Microbial Biomass} (MB) and organic substrates, as well as the diffusion of various compounds through the soil matrix, using nonlinear parabolic partial differential equations. Our study provides proofs for the existence and uniqueness of solutions, as well as an analysis of asymptotic behavior. Notably, our investigation reveals the presence of a global attractor, where any solution, regardless of initial conditions, tends to converge. To illustrate the practical implications of our findings, we have developed a numerical tool to simulate the long-term behavior of the system with reasonable computational expense. This tool provides a visual proof of the global attractor for a validated set of biological parameters in a real sandy loam soil sample captured using 3D tomography imagery
Runtime Monitoring for Safety-Critical Vision-based Runway Detection
No full textInternational audienc
Stellar Interpretation of Meteoritic Data and PLotting for Everyone (SIMPLE): Isotope Mixing Lines for Six Sets of Core-Collapse Supernova Models
No full textInternational audienceBulk meteorites and their inclusions exhibit, for many chemical elements, isotopic variability produced by nucleosynthetic events in stars and supernovae before the formation of the Sun. While the exact astrophysical origins of these variations are still a matter of debate, their identification provides insights on the environment of the Sun's birth and the formation of the Solar System. Here we present a new Python tool called SIMPLE (Stellar Interpretation of Meteoritic Data and Plotting for Everyone) designed to compare the isotopic composition of the ejecta from core-collapse supernovae (CCSNe) with meteoritic data. In the present version, the SIMPLE toolkit includes a dataset of 18 CCSN models, from 6 different published sets, with initial masses of 15, 20, and 25 M and solar metallicity. SIMPLE is designed to easily extract the isotopic abundances predicted by each CCSN model for any elements and post-process them into the format needed to compare to the meteoritic data, therefore, facilitating their interpretation. As an example of how to use SIMPLE, we analyze the composition of the Ni isotopes in the 18 models and confirm that bulk meteorite Ni anomalies are compatible with material from the innermost Si-rich region of CCSN ejecta. Designed as a collaborative platform, SIMPLE is open-source and welcomes community contributions to enhance its development and dissemination for stellar nucleosynthesis and meteoritic studies. Future enhancements include addition of more model predictions and inclusion of mixing between different layers of supernova ejecta
Fine-scale fishery patterns reveal challenges and opportunities for coastal management and conservation in Madagascar
No full textInternational audienceThe blue economy agenda has generated tensions over marine space use, often marginalising small-scale fisheries in development policies. Boat tracking technology has only recently begun to be applied in these fisheries, but it offers a promising approach to accurately map fishing distribution. In this study, we explored how environmental, technological, and social factors influenced fishers’ spatial behaviour and catches at sea in one of the Madagascar's most heavily exploited coral reef fisheries. We recorded boat movements at 30 s intervals and reef fish catches simultaneously during a 12-month participatory survey. The spatial distribution of annual fishing effort (h·ha −1 ) and fish catch rates (kg·ha −1 ) was characterised by fishing community and gear type (beach seine, mosquito net trawl, gillnet, handline, and speargun) at 250−m resolution. A total of 75 reef fish families were recorded in catches (1,466 t·yr −1 ) across approximately 218 km 2 . Annual catch rates of the seven dominant families (comprising 62% of total catches) were highly variable and heterogeneous (mostly 1–391 kg·ha −1 ) across marine habitats. A total of 7,359 tracks by 521 boats were recorded. Fishing pressure was highly variable spatially (mostly 1−150 h·ha −1 ) among communities and gear types. The results revealed preferential target areas, informal marine tenure, limited travel distance to fishing grounds, and overexploitation patterns within the fishery, offering critical insights for fishery management and inclusive marine spatial planning. This study showed the usefulness and opportunities of deploying combined boat tracking and catch surveys in small-scale fisheries through participatory research
Use of non‐destructive methods to differentiate cocoa beans based on variety and fermentation level
No full textInternational audienceAbstract Background Theobroma cocoa is a cash crop found in all cocoa‐producing countries. In the Republic of Congo, there are three main varieties: Criollo, Forastero, and Trinitario. Determining cocoa bean quality (i.e. fermentation level) is an important production and trade issue. This study aimed to (i) determine whether the variety and geographical origin of whole fermented dried cocoa beans could be distinguished using Raman spectrometry, hyperspectral imaging (HSI), and near‐infrared spectrometry (NIRS) and (ii) assess whether these non‐destructive methods could characterize bean fermentation level. The latter was determined using the cut test and the fermentation index. Results The main peaks of the Raman, HSI, and NIR spectra were associated with chemical compounds and groups when possible. Bean variety could be distinguished (accuracy = 98.2%, 91.4%, and 80.2% for Raman, HSI, and NIRS, respectively) as could bean geographical origin (accuracy = 99.4%, 97.3%, and 97.1% for Raman, HSI, and NIRS, respectively). All three methods yielded very good predictions of actual fermentation levels, determined using the cut test (accuracy: 97%); the most effective methods were HSI followed by Raman spectroscopy. All three methods could also yield very good predictions of fermentation index values using models containing a selection of 9–12 spectral bands (Raman: R 2 = 0.92, HSI: R 2 = 0.99, and NIRS: R 2 = 0.997; model errors < 0.04). Conclusion These non‐destructive methods are thus demonstrably effective and versatile and could be used by industry to assess cocoa bean quality, and even authenticate beans, if a wider database is built. © 2026 Society of Chemical Industry