Low-frequency climate variability in the Atlantic basin during the 20th century

From joint sea surface temperature/sea level pressure (SST/SLP) EOF analyses, lowfrequency variability modes are compared. The multi-decadal oscillation (MDO) changed phases twice during the 20th century, with its north Atlantic SST patterns resembling the Atlantic multi-decadal oscillation (AMO). The quasi-decadal oscillation (QDO) SST patterns displayed a double tripole configuration over the entire Atlantic basin, leading to tropical inter-hemispheric out-of-phase relationship. From the mid-1960s onward, while ST anomalies were negative to the north (negative phases of MDO/AMO), the Sahelian drought persisted with a weaker hurricane power dissipation index (PDI). During that period, the QDO modulated the intensity of the Sahelian drought

La fièvre de West Nile dans le Bassin méditerranéen

La fièvre West Nile est une maladie virale transmise à l'Homme et au cheval par les moustiques. Les hôtes réservoirs sont des oiseaux sauvages, essentiellement des passereaux. En Europe, l'incidence des cas neurologiques humains et équins a brutalement augmenté dans les années 2000, en particulier à partir de 2010. L'étude présentée ici montre qu'une température excessive en juillet, une anomalie positive de l'indice d'eau à différence normalisée modifié en juin, la présence de zones humides, de couloirs migratoires aviaires, l'occurrence d'une épidémie l'année précédente et la densité de population humaine sont des facteurs de risque d'occurrence de la maladie. Une large part de la variabilité de l'intensité de transmission du virus West Nile en Europe dépend donc des conditions environnementales. Néanmoins, d'autres facteurs entrent en jeu, tels que la densité des oiseaux ou les préférences trophiques des moustiques vecteurs présents. Ces facteurs devront être pris en compte dans l'avenir pour améliorer les performances des modèles prédictifs et ainsi permettre la mise en place d'une surveillance ciblée dans le temps et l'espace, ou de mesures de prévention appropriées

Climate change projections of West Nile virus infections in Europe: implications for blood safety practices

Background: West Nile virus (WNV) is transmitted by mosquitoes in both urban as well as in rural environments and can be pathogenic in birds, horses and humans. Extrinsic factors such as temperature and land use are determinants of WNV outbreaks in Europe, along with intrinsic factors of the vector and virus. Methods: With a multivariate model for WNV transmission we computed the probability of WNV infection in 2014, with July 2014 temperature anomalies. We applied the July temperature anomalies under the balanced A1B climate change scenario (mix of all energy sources, fossil and non-fossil) for 2025 and 2050 to model and project the risk of WNV infection in the future. Since asymptomatic infections are common in humans (which can result in the contamination of the donated blood) we estimated the predictive prevalence of WNV infections in the blood donor population. Results: External validation of the probability model with 2014 cases indicated good prediction, based on an Area Under Curve (AUC) of 0.871 (SD = 0.032), on the Receiver Operating Characteristic Curve (ROC). The climate change projections for 2025 reveal a higher probability of WNV infection particularly at the edges of the current transmission areas (for example in Eastern Croatia, Northeastern and Northwestern Turkey) and an even further expansion in 2050. The prevalence of infection in (blood donor) populations in the outbreak-affected districts is expected to expand in the future. Conclusions Predictive modelling of environmental and climatic drivers of WNV can be a valuable tool for public health practice. It can help delineate districts at risk for future transmission. These areas can be subjected to integrated disease and vector surveillance, outreach to the public and health care providers, implementation of personal protective measures, screening of blood donors, and vector abatement activities. (Résumé d'auteur

Environmental predictors of West Nile fever risk in Europe

BACKGROUND: West Nile virus (WNV) is a mosquito-borne pathogen of global public health importance. Transmission of WNV is determined by abiotic and biotic factors. The objective of this study was to examine environmental variables as predictors of WNV risk in Europe and neighboring countries, considering the anomalies of remotely sensed water and vegetation indices and of temperature at the locations of West Nile fever (WNF) outbreaks reported in humans between 2002 and 2013. METHODS: The status of infection by WNV in relationship to environmental and climatic risk factors was analyzed at the district level using logistic regression models. Temperature, remotely sensed Normalized Difference Vegetation Index (NDVI) and Modified Normalized Difference Water Index (MNDWI) anomalies, as well as population, birds’ migratory routes, and presence of wetlands were considered as explanatory variables. RESULTS: The anomalies of temperature in July, of MNDWI in early June, the presence of wetlands, the location under migratory routes, and the occurrence of a WNF outbreak the previous year were identified as risk factors. The best statistical model according to the Akaike Information Criterion was used to map WNF risk areas in 2012 and 2013. Model validations showed a good level of prediction: area under Receiver Operator Characteristic curve = 0.854 (95% Confidence Interval 0.850-0.856) for internal validation and 0.819 (95% Confidence Interval 0.814-0.823) (2012) and 0.853 (95% Confidence Interval 0.850-0.855) (2013) for external validations, respectively. CONCLUSIONS: WNF incidence is increasing in Europe and WNV is expanding into new areas where it had never been observed before. Our model can be used to direct surveillance activities and public health interventions for the upcoming WNF season

Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements