Impact de la chasse sur la dynamique d'une population migratrice : le cas de la Grande Oie des neiges

En gestion des populations animales, le contrôle d’une population peut être atteint par la modification d’un ou plusieurs paramètres démographiques (survie, reproduction ou mouvements). La population de Grandes oies des neiges (Chen caerulescens atlantica), une espèce qui niche en Arctique, est aujourd’hui considérée surabondante suite à la croissance exponentielle de sa population à la fin du 20ème siècle. En 1999, des mesures spéciales de conservation visant à stabiliser la population via une augmentation du taux de récolte à la chasse ont été instaurées, la plus spectaculaire étant une saison de chasse durant la migration printanière au Québec. Cette thèse a pour objectif d’évaluer les effets de ces mesures sur les processus démographiques sous-jacents suivants : la survie, la reproduction et le recrutement des jeunes en tant que reproducteurs. Nous présentons d’abord un nouveau modèle statistique de survie qui permet de produire des estimés de survie non biaisés en présence d’incertitude sur la perte des marques auxiliaires utilisées pour la détection des individus. Ce modèle utilise toutes les informations provenant des recaptures vivantes, des observations et des reprises à la chasse d’individus marqués de 1993 à 2005. En contrastant deux périodes, avant et à partir de 1999, nous avons montré que la diminution de survie a été la plus marquée chez les adultes durant les migrations automnale et printanière au Québec relativement à la baisse observée l’hiver aux États-Unis. Basé sur des données de la principale colonie, Île Bylot, Nunavut (1995-2007), nous n’avons pas trouvé d’évidence d’un effet reporté de la pression de chasse au Québec durant le printemps sur différents paramètres de reproduction l’été suivant (densité de nid, date et taille de ponte), une fois pris en compte l’effet des conditions climatiques rencontrées durant la migration et à l’arrivée sur le site de nidification. Cependant, le taux de récolte des adultes au printemps après 1998 est apparu comme un facteur important affectant à la baisse le recrutement des jeunes dans la population au cours de la période 1992-2005. En lien avec la stratégie mixte de reproduction des oies qui utilisent à la fois des réserves exogènes et endogènes pour la reproduction, le mécanisme sous-jacent suggéré est un effet reporté du dérangement par la chasse sur l’alimentation au printemps via une diminution des réserves endogènes. Nous démontrons ainsi de façon empirique que si la chasse diminue la survie, elle peut aussi diminuer l’accès à la reproduction. Nous suggérons que la diminution de la productivité de la population qui avait déjà été documentée se ferait principalement via la décision de se reproduire ou non (recrutement et propension à se reproduire) plutôt que par une baisse du succès reproducteur (indépendamment de la décision de se reproduire). Cette population semble aujourd’hui stabilisée, mettant en évidence que ces mesures de conservation ont vraisemblablement porté leurs fruits

Carry-over effects of spring hunt and climate on recruitment to the natal colony in a migratory species

International audienc

Iterative Algorithms Applied to Treated Intracranial Aneurysms

Purpose To investigate the impact of iterative metal artifact reduction (iMAR) on artifacts related to neurosurgical clips or endovascular coils when combined to filtered back projection (FBP) or advanced modelled iterative reconstruction (ADMIRE). Material and Methods In this study 21 unenhanced brain computed tomography (CT) examinations were reconstructed with FBP and level 2 of ADMIRE, both techniques with and without iMAR algorithm, resulting in 4 series per acquisition. Subjective assessment of artifact reduction was performed as a double-blinded evaluation with a 5-point-scale. Objective analysis was performed by comparing central tendencies and distributions of voxel densities. The central tendency was assessed as the mean voxel density in Hounsfield units. The distribution was assessed by evaluating the shape and asymmetry of the histograms of voxels densities with measures of kurtosis and skewness, respectively. Results Inter-reader agreement was excellent (>0.8). FBP and ADMIRE without iMAR were scored 4 and with iMAR 5. Unusual artifacts were noted in all of the series reconstructed with iMAR, especially when combined with ADMIRE. Kurtosis revealed statistical differences for all reconstruction techniques (p ≤ 0.0007) except for the association of FBP with iMAR (p = 0.2211) for the coiling population and skewness demonstrated no statistical difference in any population (p ≥ 0.0558), confirming the subjective analysis results, except for the ADMIRE algorithm with or without iMAR (p ≤ 0.0342) in the coiling population. Conclusion iMAR led to the reduction in artifacts due to intracranial metallic devices. However, it created a new artifact in the form of a halo of photon-starvation, especially when combined with ADMIRE. The combination of FBP and iMAR seems more suitable, combining the beneficial metal artifact reduction without the emergence of a halo of photon starvation just around the point of interest

DORAVIR: a French national survey of people with HIV-1 treated with an antiretroviral regimen including doravirine

International audienceAbstract Background Doravirine is the latest NNRTI to be approved for the treatment of HIV-1 and has a different resistance profile from first-generation NNRTIs. Our aim was to investigate the virological efficacy of antiretroviral treatment including doravirine in people living with HIV-1 (PLWHIV), the factors associated with virological failure (VF) and those associated with the emergence of reverse transcriptase (RT) mutations in the case of VF. Methods A retrospective national survey of PLWHIV who were either naive or experienced on antiretroviral treatment including doravirine was conducted. VF was defined as two consecutive plasma viral loads (VLs) of ≥50 copies/mL or one VL of ≥200 copies/mL. Genotypic resistance tests were interpreted using the Stanford (v9.4.1) and ANRS (v33) algorithms. Results Of the 589 PLWHIV treated with a doravirine-containing regimen, 8.5% were naive and 91.5% had prior antiretroviral experience; 56.9% were infected with HIV-1 B subtype. Overall, 88.3% and 85.1% of participants were virologically controlled at Month (M)3 and M6 of doravirine treatment, respectively. In multivariable analysis, CRF02_AG subtype, higher zenith plasma HIV-1 RNA VL, doravirine initiation in the context of failure and baseline V179D mutation presence were associated with VF. Among 88 PLWHIV who experienced virological failure at M6, 15.9% had a median of 2 (IQR 1–3) HIV RT mutations. In multivariable analysis, the only factor associated with the occurrence of mutations was a genotypic sensitivity score that was not fully sensitive. Conclusions This study is one of the largest to characterize the virological efficacy of doravirine-containing regimens in clinical practice and to identify factors associated with VF or emergence of resistance mutations that should be considered in clinical management

Séminaire de Probabilités XLVIII

International audienc

Annales de droit civil des obligations 2017

National audienc

Apparent annual survival of staging ruffs during a period of population decline: Insights from sex and site-use related differences

The ruff Philomachus pugnax, a lekking shorebird wintering in Africa and breeding across northern Eurasia, declined severely in its western range. Based on a capture-mark-resighting programme (2004–2011) in the westernmost staging area in Friesland (the Netherlands), we investigated changes in apparent annual survival in relation to age and sex to explore potential causes of decline. We also related temporal variation in apparent survival to environmental factors. We used the Capture- Mark-Recapture multievent statistical framework to overcome biases in survival estimates after testing for hidden heterogeneity of detection. This enabled the estimation of the probability to belong to high or low detectability classes. Apparent survival varied between years but was not related to weather patterns along the flyway, or to flood levels in the Sahel. Over time, a decline in apparent survival is suggested. Due to a short data series and flag loss in the last period this cannot be verified. Nevertheless, the patterns in sex-specific detectability and survival lead to new biological insights. Among highly detectable birds, supposedly most reliant on Friesland, males survived better than females (ΦHDmales = 0.74, range 0.51–0.93; ΦHDfemales = 0.51, range 0.24–0.81). Among low detectable birds, the pattern is reversed (ΦLDmales = 0.64, range 0.37–0.89; ΦLDfemales = 0.73, range 0.48–0.93). Probably the staging population contains a mixture of sexspecific migration strategies. A loss of staging females could greatly affect the dynamics of the western ruff population. Further unravelling of these population processes requires geographically extended demographic monitoring and the use of tracking devices

Correction to: Characteristics and prognosis of bloodstream infection in patients with COVID‑19 admitted in the ICU: an ancillary study of the COVID‑ICU study

International audienc