Investigation of the ALICE-MUON forward spectrometer performances for Upsilon measurement

ALICE, présenté par F. Guérin, à paraître dans les proceedings: European physical Journal CALICE (A Large Ion Collider Experiment) is the LHC detector dedicated to the study of nucleus-nucleus collisions, in which the formation of the Quark Gluon Plasma (QGP) is expected. Heavy quarkonia, especially the Upsilon states, are relevant for studying the QGP since they provide an essential probe of the earliest and hottest stages of heavy ion collisions. They will be measured via their dimuon decay channel in ALICE in the muon spectrometer. The muon spectrometer performance has been studied in simulations, the results will be presented with emphasis on the trigger efficiency and rate in Pb-Pb collisions. The expected yields of Upsilon states will be extracted from a simulation based on a global fit of the dimuon mass spectra for different collision centralities

Etude des performances du système de déclenchement du spectromètre à muons de l'expérience ALICE

ALICE (A Large Ion Collider Experiment) est une expérience dédiée à l'étude des collisions d'ions lourds ultra-relativistes qui opèrera au LHC (Large Hadron Collider) en 2007. Le but de cette expérience est de mettre en évidence et d'étudier le plasma de quarks et de gluons (QGP). Une des signatures possibles de ce nouvel état de la matière est la variation du taux de production des quarkonia lorsque l'on passe d'une phase purement hadronique à une phase de déconfinement. Le spectromètre à muons d'ALICE permettra de détecter les quarkonia via le canal de désintégration en dimuons. Un système de déclenchement appelé ``trigger'' associé au spectromètre permet de sélectionner les événements physiquement intéressants (contenant des quarkonia) en effectuant des coupures sur l'impulsion transverse des muons. Cet article présente les performances du système de déclenchement du spectromètre à muons d'ALICE en terme d'efficacité de détection et de taux de trigger

Sources and transfers of particulate organic matter in a tropical reservoir (Petit Saut, French Guiana): a multi-tracers analysis using d¹³C, C/N ratio and pigments

International audienceCarbon cycling and organic matter transfers in the tropical Sinnamary river system (French Guiana), including a mid-stream reservoir (Petit Saut) and its estuary on the Atlantic coast, were studied during the dry season by analyzing the organic carbon isotopic ratios (d13C-OC), C/N ratios and pigments contents of suspended matter, sediments, sediments traps and epiphytic and epilithic biofilms. In the River upstream as well as in surface sediments at the entrance of the reservoir and at the littoral zone of the reservoir, particulate organic matter (POM) was in majority of terrestrial origin, with a d13C-C/N signature close to the one of soil and litter collected in the surrounding forest and with high OC/total pigments ratios. High concentrations of Pheopigments a and b in these surface sediments showed that this terrestrial POM, either carried by the river and eolian transport or present in the soil before flooding, undergoes intense degradation. Deeper in the sediment, the d13C profile showed a decreasing trend with depth typical of what is found in soils, showing that the flooded soil still remains present at the reservoir bottom 10 years after flooding. At the center of the reservoir, POM in the water column, in sediment traps and in surface sediments was in majority of aquatic origin with low C/N and OC/total pigments ratios. In the oxic epilimnion at 3 m depth, Chl a, Chl b and Lutein showed the predominance of Chlorophyceae to the phytoplankton community. At this depth, a C/N ratio of 21 suggests a large contribution of transparent exopolymeric particles to the bulk POM, which, in addition, was 13C-depleted due to a significant contribution of methanotrophic bacteria. At 7 m depth, below the oxicline, high concentrations of BChl d and occasionally BChl c revealed the presence of anoxygenic phototrophic bacteria, namely Chlorobiaceae. In the sediment traps, Chl a, Chl b, Lutein and BChl c and BChl d confirmed the contribution of plankton to the sedimentary POM. This material was undergoing intense degradation as revealed by high concentration of pheopigments and by an increase in C/N ratio and an increase in d13C-OC with trap depth. Scytonemin was found in a biofilm developed on tree trunks at the reservoir surface and in all sediment traps. Other tracers showed however that the contribution of the biofilm to the sedimentary POM was minor compared to the planktonic source. In the Sinnamary downstream of the dam, POM became more 13C-depleted showing a larger contribution of methanotrophic bacteria. Chl b, Lutein and BChl c + BChl d originating from the reservoir progressively decreased downstream as the result of mineralization. At the estuarine mouth, fucoxanthin showed the presence of diatoms and the d13C-C/N signature matched the one of POM carried by the Amazonian coastal mobile mud belt

Increasing feed production using legume and cereal mixtures as a second crop (DiverIMPACTS Practice Abstract)

Improved feed diversity and more resilient feed production, less dependent on soybean imports. This strategy helps to mitigate droughts effects, through an “avoidance strategy”, with production of forage during seasons less likely to be affected by such phenomenon. Other benefits include improved soil biodiversity and soil health, reduced leaching during winter (as mixtures are used as cover crops) and benefits associated with incorporating residues from roots and crops (nitrogen availability for maize, carbon input to the soil, etc.)

An amplicon-based nanopore sequencing workflow for rapid tracking of avian influenza outbreaks, France, 2020-2022

During the recent avian influenza epizootics that occurred in France in 2020/21 and 2021/22, the virus was so contagiousness that it was impossible to control its spread between farms. The preventive slaughter of millions of birds consequently was the only solution available. In an effort to better understand the spread of avian influenza viruses (AIVs) in a rapid and innovative manner, we established an amplicon-based MinION sequencing workflow for the rapid genetic typing of circulating AIV strains. An amplicon-based MinION sequencing workflow based on a set of PCR primers targeting primarily the hemagglutinin gene but also the entire influenza virus genome was developed. Thirty field samples from H5 HPAIV outbreaks in France, including environmental samples, were sequenced using the MinION MK1C. A real-time alignment of the sequences with MinKNOW software allowed the sequencing run to be stopped as soon as enough data were generated. The consensus sequences were then generated and a phylogenetic analysis was conducted to establish links between the outbreaks. The whole sequence of the hemagglutinin gene was obtained for the 30 clinical samples of H5Nx HPAIV belonging to clade 2.3.4.4b. The consensus sequences comparison and the phylogenetic analysis demonstrated links between some outbreaks. While several studies have shown the advantages of MinION for avian influenza virus sequencing, this workflow has been applied exclusively to clinical field samples, without any amplification step on cell cultures or embryonated eggs. As this type of testing pipeline requires only a short amount of time to link outbreaks or demonstrate a new introduction, it could be applied to the real-time management of viral epizootics

The feather epithelium contributes to the dissemination and ecology of clade 2.3.4.4b H5 high pathogenicity avian influenza viruses in ducks

Immature feathers are known replication sites for high pathogenicity avian influenza viruses (HPAIVs) in poultry. However, it is unclear whether feathers play an active role in viral transmission. This study aims to investigate the contribution of the feather epithelium to the dissemination of clade 2.3.4.4b goose/Guangdong/1996 lineage H5 HPAIVs in the environment, based on natural and experimental infections of domestic mule and Muscovy ducks. During the 2016–2022 outbreaks, H5 HPAIVs exhibited persistent and marked feather epitheliotropism in naturally infected commercial ducks. Infection of the feather epithelium resulted in epithelial necrosis and disruption, as well as the production and environmental shedding of infectious virions. Viral and feather antigens colocalized in dust samples obtained from poultry barns housing naturally infected birds. In summary, the feather epithelium contributes to viral replication, and it is a likely source of environmental infectious material. This underestimated excretion route could greatly impact the ecology of HPAIVs, facilitating airborne and preening-related infections within a flock, and promoting prolonged viral infectivity and long-distance viral transmission between poultry farms.This study was performed in the framework of the “Chaire de Biosécurité et Santé Aviaires”, hosted by the National Veterinary College of Toulouse (ENVT) and funded by the Direction Generale de l’Alimentation, Ministère de l’Agriculture et de la Souveraineté Alimentaire, France. The animal experiment was partially funded by the Veterinary Biocontained facility Network (VetBioNet) [EU Grant Agreement INFRA-2016-1 N°731014].info:eu-repo/semantics/publishedVersio