N-Complexes and Higher Spin Gauge Fields

$N$-complexes have been argued recently to be algebraic structures relevant to the description of higher spin gauge fields. $N$-complexes involve a linear operator $d$ that fulfills $d^N = 0$ and that defines a generalized cohomology. Some elementary properties of $N$-complexes and the evidence for their relevance to the description of higher spin gauge fields are briefly reviewed.Comment: Presented at the International Workshop "Differential Geometry, Noncommutative Geometry, Homology and Fundamental Interactions" in honour of Michel Dubois-Violette, Orsay, April 8-10, 200

Temporal patterns in Ixodes ricinus microbial communities: an insight into tick-borne microbe interactions

Background: Ticks transmit pathogens of medical and veterinary importance and are an increasing threat to human and animal health. Assessing disease risk and developing new control strategies requires identifying members of the tick-borne microbiota as well as their temporal dynamics and interactions. Methods: Using high-throughput sequencing, we studied the Ixodes ricinus microbiota and its temporal dynamics. 371 nymphs were monthly collected during three consecutive years in a peri-urban forest. After a Poisson lognormal model was adjusted to our data set, a principal component analysis, sparse network reconstruction, and differential analysis allowed us to assess seasonal and monthly variability of I. ricinus microbiota and interactions within this community. Results: Around 75% of the detected sequences belonged to five genera known to be maternally inherited bacteria in arthropods and to potentially circulate in ticks: Candidatus Midichloria, Rickettsia, Spiroplasma, Arsenophonus and Wolbachia. The structure of the I. ricinus microbiota varied over time with interannual recurrence and seemed to be mainly driven by OTUs commonly found in the environment. Total network analysis revealed a majority of positive partial correlations. We identified strong relationships between OTUs belonging to Wolbachia and Arsenophonus, evidence for the presence of the parasitoid wasp Ixodiphagus hookeri in ticks. Other associations were observed between the tick symbiont Candidatus Midichloria and pathogens belonging to Rickettsia. Finally, more specific network analyses were performed on TBP-infected samples and suggested that the presence of pathogens belonging to the genera Borrelia, Anaplasma and Rickettsia may disrupt microbial interactions in I. ricinus. Conclusions: We identified the I. ricinus microbiota and documented marked shifts in tick microbiota dynamics over time. Statistically, we showed strong relationships between the presence of specific pathogens and the structure of the I. ricinus microbiota. We detected close links between some tick symbionts and the potential presence of either pathogenic Rickettsia or a parasitoid in ticks. These new findings pave the way for the development of new strategies for the control of ticks and tick-borne diseases. [MediaObject not available: see fulltext.] © 2021, The Author(s)

Bayesian estimation of abundance based on removal sampling under weak assumption of closed population with catchability depending on environmental conditions. Application to tick abundance

International audienceThe estimation of animal abundance is essential to understand population dynamics, species interactions and disease patterns in populations. Estimations of relative abundance classically are based on a single observation of several sites. In this case, the mapping of abundance assumes that the probability of detecting an individual, hence the sampling rate, remains constant across the observed sites. In practice, however, this assumption is often not satisfied as the sampling rate may fluctuate between sites due to random fluctuations and/or fluctuations associated with the sampling process, notably associated with the characteristics of the site. It is therefore important to account for variations in detection probability. Using a removal sampling design, we studied the performance of a Bayesian approach to estimate both sampling rates and abundance under the assumption of a closed population. The assumption of a closed population often is weakened when the number of successive samplings is large. The number of samplings has to be limited and optimal. We therefore examined the minimal number of successive samplings needed to achieve sufficient statistical accuracy while respecting underlying model assumptions. Using the same simulations, we also compared the performance of the Bayesian approach to the performance of the frequentist Hayne method based on linear regression. We show that the Bayesian approach proposed gives generally better estimations of population size than the Hayne method. The two methods give approximately the same results for the estimation of sampling rate. We then studied the variability of detection probability of Ixodes ricinus ticks sampled under several environmental conditions by using a hierarchical Bayesian model with a random effect. The estimated sampling rate varied between 33.9% and 47.4% for shrubs and 53.6% and 66.7% for dead leaves. The variability of the sampling rate due to the site decreased when the number of successive samplings considered in the model increased. The variability was lower in dead leaves than shrubs. This approach could be used routinely for ecological or epidemiological studies of ticks and species with comparable life histories

Analyse des processus techniques et organisationnels qui mènent à des situations d'équilibre sanitaire dans les élevages bio

La conduite d’élevage en agriculture biologique constitue un lieu privilégié pour la mise en œuvre d’une approche globale en santé animale, où l’utilisation d’intrants de synthèse (antibiotiques, antiparasitaires) doit rester une solution de dernier recours. Son cahier des charges recommande une gestion de la santé animale axée sur la prévention des maladies. Au niveau du troupeau, la notion d’équilibre sanitaire est appréhendée par certains éleveurs biologiques et/ou leurs conseillers comme un troupeau avec peu d’animaux malades, recevant peu d’intrants médicamenteux (antibiotiques et antiparasitaires). Cet équilibre est plus ou moins stable dans le temps. Une perte de l’équilibre à l’échelle du troupeau secaractérise par différents troubles, l’expression de plusieurs maladies, des problèmes de reproduction et de bien-être animal. Dans le projet « OTOVEIL : Développer des Outils Techniques et organisationnels de conseil pour la surveillance et la prévention sanitaire dans les élevages biologiques », les déterminants qui qualifient l’équilibre sanitaire ont été identifiés par l’analyse des pratiques et des perceptions des éleveurs, ainsi que par des traitements statistiques issus d’enquêtes en fermes. Le projet OTOVEIL a produit un outil d’aide à la décision pour renforcer la prévention et surveillance à travers des grilles « Panse-Bêtes » pour chacune des 5 filières de ruminants sous formes de « livrets-papier » ou sousforme numérique WebAppli. Cet outil permet de de mieux intégrer une approche multi-factorielle de la gestion de la santé animale, en invitant l’éleveur à rechercher les causes d’un déséquilibre sanitaire (bâtiment, abreuvement, alimentation, santé, prairie, génétique, climat et saison…). Il est utilisable par un éleveur seul, par un binôme éleveur/vétérinaire lors de visites de suivi, ou lors de réunions collectives, le conseiller-animateur pouvant se reposer sur la checklist pour poser les bonnes questions, et créer un plan d’actions pour remédier aux difficultés

Algèbre matricielle

* INRA - Unité de Biométrie Centre de Toulouse (FRA) Diffusion du document : INRA - Unité de Biométrie Centre de Toulouse (FRA)National audienc

Algèbre matricielle

* INRA - Unité de Biométrie Centre de Toulouse (FRA) Diffusion du document : INRA - Unité de Biométrie Centre de Toulouse (FRA)National audienc

Temporal patterns in Ixodes ricinus microbial communities: an insight into tick-borne microbe interactions

International audienceBackground Ticks transmit pathogens of medical and veterinary importance and are an increasing threat to human and animal health. Assessing disease risk and developing new control strategies requires identifying members of the tick-borne microbiota as well as their temporal dynamics and interactions. Methods Using high-throughput sequencing, we studied the Ixodes ricinus microbiota and its temporal dynamics. 371 nymphs were monthly collected during three consecutive years in a peri-urban forest. After a Poisson lognormal model was adjusted to our data set, a principal component analysis, sparse network reconstruction, and differential analysis allowed us to assess seasonal and monthly variability of I. ricinus microbiota and interactions within this community. Results Around 75% of the detected sequences belonged to five genera known to be maternally inherited bacteria in arthropods and to potentially circulate in ticks: Candidatus Midichloria, Rickettsia , Spiroplasma , Arsenophonus and Wolbachia . The structure of the I. ricinus microbiota varied over time with interannual recurrence and seemed to be mainly driven by OTUs commonly found in the environment. Total network analysis revealed a majority of positive partial correlations. We identified strong relationships between OTUs belonging to Wolbachia and Arsenophonus , evidence for the presence of the parasitoid wasp Ixodiphagus hookeri in ticks. Other associations were observed between the tick symbiont Candidatus Midichloria and pathogens belonging to Rickettsia . Finally, more specific network analyses were performed on TBP-infected samples and suggested that the presence of pathogens belonging to the genera Borrelia , Anaplasma and Rickettsia may disrupt microbial interactions in I. ricinus . Conclusions We identified the I. ricinus microbiota and documented marked shifts in tick microbiota dynamics over time. Statistically, we showed strong relationships between the presence of specific pathogens and the structure of the I. ricinus microbiota. We detected close links between some tick symbionts and the potential presence of either pathogenic Rickettsia or a parasitoid in ticks. These new findings pave the way for the development of new strategies for the control of ticks and tick-borne diseases

Knowledge and opinions of French dental students in caries management

International audienc