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Exact targeting of Gibbs distributions using velocity-jump processes
No full textInternational audienceThis work introduces and studies a new family of velocity jump Markov processes directly amenable to exact simulation with the following two properties: i) trajectories converge in law when a time-step parameter vanishes towards a given Langevin or Hamil-tonian dynamics; ii) the stationary distribution of the process is always exactly given by the product of a Gaussian (for velocities) by any target log-density whose gradient is pointwise computabe together with some additional explicit appropriate upper bound. The process does not exhibit any velocity reflections (jump sizes can be controlled) and is suitable for the 'factorization method'. We provide a rigorous mathematical proof of: i) the small time-step convergence towards Hamiltonian/Langevin dynamics, as well as ii) the exponentially fast convergence towards the target distribution when suitable noise on velocity is present. Numerical implementation is detailed and illustrated
The invasive land flatworm Obama nungara in La Réunion, a French island in the Indian Ocean, the first report of the species for Africa
No full textInternational audienceThe land flatworm Obama nungara, a species originating from South America and already invasive in many European countries, is recorded from La Réunion, a French island in the Indian Ocean. This is the first record of O. nungara from this locality and also the first record of the species for Africa. Three specimens were collected in 2021 and 2022, in the communes of Saint Paul, Saint Joseph and Le Tampon, respectively; the three localities are widely separated, with two in the Western part and one in the Southeastern part of the island. This suggests that the species is already present in several locations in La Réunion, and it is likely that the species is already present since 2020. The specimen from Saint Paul had the same cox1 haplotype as specimens previously recorded from several countries of Europe; it is hypothesized that the species was imported from Europe, probably from France. We mapped climatic suitability of the species in La Réunion and found that O. nungara could potentially invade a large part of the island. One record was apparently associated with the transport of plates of travertine, a construction material which has numerous cavities thus suitable for the transport and survival of adult or cocoons of land flatworms.Le Plathelminthe terrestre Obama nungara, une espèce originaire d'Amérique du Sud et déjà envahissante dans de nombreux pays européens, est signalé à La Réunion, une île française de l'Océan Indien. Ceci est le premier signalement d’O. nungara dans cette localité et aussi le premier signalement de l'espèce pour l'Afrique. Trois spécimens ont été collectés en 2021 et 2022, respectivement dans les communes de Saint Paul, Saint Joseph et Le Tampon ; les trois localités sont largement séparées, avec deux dans la partie occidentale et une dans la partie sud-est de l'île. Ceci suggère que l'espèce est déjà présente dans plusieurs localités de La Réunion, et il est probable que l'espèce soit déjà présente depuis 2020. Le spécimen de Saint Paul avait le même haplotype du cox1 que les spécimens précédemment récoltés dans plusieurs pays d'Europe ; nous faisons l’hypothèse que l'espèce a été importée d'Europe, probablement de France. Nous avons cartographié l'adéquation climatique de l'espèce à La Réunion et constaté qu’O. nungara pourrait potentiellement envahir une grande partie de l'île. Un signalement était apparemment associé au transport de plaques de travertin, un matériau de construction qui possède de nombreuses cavités, donc adapté au transport et à la survie des adultes ou des cocons de vers plats terrestres
Blood mercury concentrations in four sympatric gull species from South Western France: Insights from stable isotopes and biologging
No full textInternational audienceMercury (Hg) is a toxic trace element widely distributed in the environment, which particularly accumulates in top predators, including seabirds. Among seabirds, large gulls (Larus sp) are generalist feeders, foraging in both terrestrial and marine habitats, making them relevant bioindicators of local coastal Hg contamination. In the present study, we reported blood Hg concentrations in adults and chicks of four different gull species breeding on the French Atlantic coast: the European herring gull (Larus argentatus), the Lesser black-backed gull (L. fuscus), the Great black-backed gull (L. marinus) and the Yellow-legged gull (L. michahellis). We also investigated the potential role of foraging ecology in shaping Hg contamination across species, using the unique combination of three dietary tracers (carbon, nitrogen and sulfur stable isotopes) and biologging (GPS tracking). A high concentration of Hg was associated with high trophic position and a marine diet in gulls, which was corroborated by birds’ space use strategy during foraging trips. Adults of all four species reached Hg concentrations above reported toxicity thresholds. Specifically, adults of Great black-backed gulls had a high trophic marine specialized diet and significantly higher Hg concentrations than the three other species. Blood Hg was 4–7 times higher in adults than in chicks, although chicks of all species received mainly marine and high trophic position prey, which is expected to be the cause of blood Hg concentrations of toxic concern. By using both stable isotopes and GPS tracking, the present study provides compelling insights on the main feeding habits driving Hg contamination in a seabird assemblage feeding in complex coastal environments
Factors associated with perceived stress in patients with vitiligo in the ComPaRe e-cohort
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La ludopédagogie : le cas des sciences de gestion - Résultats de recherches
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Severe relapse of SARS‐CoV‐2 infection in a kidney transplant recipient with negative nasopharyngeal SARS‐CoV‐2 RT‐PCR after rituximab
No full textInternational audienceImmunocompromised patients may experience prolonged viral shedding after their initial SARS-CoV-2 infection, however, symptomatic relapses after remission currently remain rare. We herein describe a severe COVID-19 relapse case of a kidney transplant recipient (KTR) following rituximab therapy, 3 months after a moderate COVID-19 infection, despite viral clearance after recovery of the first episode. During the clinical relapse, the diagnosis was established on a broncho-alveolar lavage specimen (BAL) by RT-PCR. The infectivity of the BAL sample was confirmed on a cell culture assay. Whole genome sequencing confirmed the presence of an identical stain (Clade 20A). However, it had an acquired G142D mutation and a larger deletion of 3-amino-acids at position 143-145. These mutations located within the N-terminal domain are suggested to play a role in viral entry. The diagnosis of a COVID-19 relapse should be considered in the setting of unexplained persistent fever and/or respiratory symptoms in KTRs (especially for those after rituximab therapy), even in patients with previous negative naso-pharyngeal SARS-CoV-2 PCR
Exploring digital twin adaptation to the urban environment: comparison with CIM to avoid silo-based approaches
No full textInternational audienceThe use of digital models and tools to support a more sober, sustainable and human-centred spatial planning is constantly expanding. Among those, digital models of buildings and territories are considered useful by scientists and practitioners and used for a wide range of purposes. Several labels are currently used to characterise those digital tools and models, partly reflecting on technological developments: 3D city models, Planning support systems, Smart Cities, urbanism 3.0., City Information Model (CIM), Digital Twins (DT), etc. First used in industry, the label DT is now both used by practitioners and researchers, in relation to the development of innovative city models. Nevertheless, this label remains fuzzily defined and designates heterogeneous models from a technical standpoint. In this paper, we propose an exploration of the definitions and technical contents of DT at the city scale and a comparison with CIM approaches, as CIM is also used to label similar city models. Our analysis is based on a literature review of both DT and CIM definitions and applications to the urban context, an exploratory survey conducted with 13 practitioners about their views on DT and its potential regarding urban planning and management and a comparison of a few real-world projects either labelled CIM or DT by practitioners. Our analysis leads us to pinpoint several of the remaining challenges for a DT approach to be developed at the city scale. We also shed light on potential shortcomings of future research, if based on too narrow DT definitions
