High Throughput, Multiplexed Pathogen Detection Authenticates Plague Waves in Medieval Venice, Italy

Background: Historical records suggest that multiple burial sites from the 14th-16(th) centuries in Venice, Italy, were used during the Black Death and subsequent plague epidemics.Methodology/Principal Findings: High throughput, multiplexed real-time PCR detected DNA of seven highly transmissible pathogens in 173 dental pulp specimens collected from 46 graves. Bartonella quintana DNA was identified in five (2.9%) samples, including three from the 16th century and two from the 15th century, and Yersinia pestis DNA was detected in three (1.7%) samples, including two from the 14th century and one from the 16th century. Partial glpD gene sequencing indicated that the detected Y. pestis was the Orientalis biotype.Conclusions: These data document for the first time successive plague epidemics in the medieval European city where quarantine was first instituted in the 14th century

Toward an improved representation of middle atmospheric dynamics thanks to the ARISE project

This paper reviews recent progress toward understanding the dynamics of the middle atmosphere in the framework of the Atmospheric Dynamics Research InfraStructure in Europe (ARISE) initiative. The middle atmosphere, integrating the stratosphere and mesosphere, is a crucial region which influences tropospheric weather and climate. Enhancing the understanding of middle atmosphere dynamics requires improved measurement of the propagation and breaking of planetary and gravity waves originating in the lowest levels of the atmosphere. Inter-comparison studies have shown large discrepancies between observations and models, especially during unresolved disturbances such as sudden stratospheric warmings for which model accuracy is poorer due to a lack of observational constraints. Correctly predicting the variability of the middle atmosphere can lead to improvements in tropospheric weather forecasts on timescales of weeks to season. The ARISE project integrates different station networks providing observations from ground to the lower thermosphere, including the infrasound system developed for the Comprehensive Nuclear-Test-Ban Treaty verification, the Lidar Network for the Detection of Atmospheric Composition Change, complementary meteor radars, wind radiometers, ionospheric sounders and satellites. This paper presents several examples which show how multi-instrument observations can provide a better description of the vertical dynamics structure of the middle atmosphere, especially during large disturbances such as gravity waves activity and stratospheric warming events. The paper then demonstrates the interest of ARISE data in data assimilation for weather forecasting and re-analyzes the determination of dynamics evolution with climate change and the monitoring of atmospheric extreme events which have an atmospheric signature, such as thunderstorms or volcanic eruptions

Evolution des contraintes internes generees au sein d'un alliage de Zr oxyde a haute temperature puis refroidi

National audienceLors de situations accidentelles hypothetiques dans les reacteurs nucleaires a eau pressurisee, comme par exemple lors d'un Accident de Perte de Refrigerant Primaire (APRP), la gaine en alliage de zirconium des crayons combustibles peut etre exposee durant quelques minutes a de la vapeur d'eau a haute temperature (jusqu'a 1200DC) avant d'etre refroidie puis trempee a l'eau. Lors d'un transitoire de type APRP, cette gaine subit de nombreuses evolutions metallurgiques (formation d'une couche d'oxyde, diffusion d'oxygene dans le metal sous-jacent, changements de phases, ) et est soumise a des contraintes internes dont l'etat evolue au cours de l'oxydation a Haute Temperature (HT) mais aussi lors du refroidissement et de la trempe. Ces contraintes internes sont non seulement susceptibles d'avoir un effet sur la structure de l'oxyde et sur la cinetique d'oxydation du materiau, mais elles peuvent aussi nuire a la tenue mecanique de la gaine, fragilisee par son oxydation, lors du refroidissement et de la trempe apres l'oxydation a HT, ou encore avoir des consequences sur l'integrite du materiau a plus long terme. Or ces gaines constituent la premiere barriere de confinement des produits radioactifs.Des lors, il est necessaire de pouvoir estimer les contraintes internes generees au cours de l'oxydation a HT et du refroidissement au sein de ces alliages a base de zirconium (1). Ces contraintes, tres difficiles a evaluer experimentalement du fait des conditions extremes (haute temperature, atmosphere oxydante, trempe), sont a ce jour inconnues. Dans le but de progresser sur la connaissance de ces contraintes internes, des experiences in-situ de diffraction des rayons X sous rayonnement synchrotron ont ete realisees a SOLEIL, pendant l'oxydation a HT (a 700, 800 et 900DC) sous O2-He (en substitution a la vapeur d'eau) et le refroidissement ulterieur, sur des plaquettes en Zircaloy-4 (2-3). Grace au detecteur bidimensionnel XPAD S140, il a ete possible de faire des acquisitions lors du palier d'oxydation puis au cours du refroidissement, simultanement pour les phases monoclinique et quadratique de la zircone. Apres traitement des donnees 2D acquises, l'evolution des contraintes internes moyennes a alors pu etre suivie en fonction du temps pour les differentes conditions investiguees, pour les phases monoclinique et quadratique de la zircone, dont les proportions evoluent au cours du cycle thermique, pendant le palier d'oxydation a 700, 800 et 900DC et le refroidissement ulterieur (Figure 1). On observe une diminution des contraintes moyennes de compression au cours de l'oxydation et du refroidissement pour les deux phases de zircone. Les resultats mettent egalement en lumiere le fait que l'oxyde forme de structure quadratique est en moyenne toujours moins contraint que celui de structure monoclinique, et que l'oxyde (quadratique ou monoclinique) forme a 700DC reste toujours plus contraint a la fin du cycle thermique que celui formes a 800 et 900DC

In-situ time-resolved study of structural evolutions in a zirconium alloy during high temperature oxidation and cooling

International audienceIn-situ time-resolved Synchrotron X-ray diffraction analyses were performed on zirconium alloy (Zircaloy-4) sheet samples, during their heating, isothermal oxidation at 700, 800 and 900 degrees C under a flowing mixture of He and O-2 and cooling. The oxide growth and the evolution of the oxide structure as a function of time and temperature were studied with suitable time resolution. Oxide layer thicknesses of approximately 10 mu m were formed during the experiments. The incident X-rays penetrated the whole oxide thickness. The samples were examined after the experiments by field emission gun scanning electron microscopy, electron backscatter diffraction and electron-probe microanalysis. The results showed that the oxide contains a mixture of monoclinic and tetragonal zirconia evolving during heating, oxidation and cooling. The average volume fraction of tetragonal zirconia decreases during oxidation. This fraction is larger at 900 degrees C than at 700 and 800 degrees C. For oxide layers thinner than approximately 5 mu m, this fraction is larger at 800 degrees C than at 700 degrees C, but it is rather equivalent for both temperatures when the oxide thickness ranges between 5 and 8 mu m. Some of the tetragonal zirconia crystals transforms into the monoclinic phase during cooling after oxidation. This fraction of transformed tetragonal zirconia is larger after oxidation at 900 degrees C than after oxidation at 700 and 800 degrees C. It is suggested that these evolutions of the oxide crystallographic structure are related to micro-stresses and to temperature dependences of the critical size of zirconia crystals below which tetragonal zirconia is stabilized