Evidence of West Nile virus (WNV) circulation in wild birds and WNV RNA negativity in mosquitoes of the Danube Delta Biosphere Reserve, Romania, 2016

West Nile virus (WNV) is a zoonotic flavivirus whose transmission cycle in nature includes wild birds as amplifying hosts and ornithophilic mosquito vectors. Bridge vectors can transmit WNV to mammal species potentially causing West Nile Fever. Wild bird migration is a mode of WNV introduction into new areas. The Danube Delta Biosphere Reserve (DDBR) is a major stopover of wild birds migrating between Europe and Africa. The aim of this study was to investigate the presence of WNV in the DDBR during the 2016 transmission season in wild birds and mosquitoes. Blood from 68 wild birds (nine different species) trapped at four different locations was analyzed by competitive ELISA and Virus Neutralization Test (VNT), revealing positive results in 8/68 (11.8%) of the wild birds by ELISA of which six samples (three from juvenile birds) were confirmed seropositive by VNT. Mosquitoes (n = 6523, 5 genera) were trapped with CDC Mini Light traps at two locations and in one location resting mosquitoes were caught. The presence of WNV RNA was tested in 134 pools by reverse transcription quantitative PCR (RT-qPCR). None of the pools was positive for WNV-specific RNA. Based on the obtained results, WNV was circulating in the DDBR during 2016

Absolute and convective superradiance: Dynamics and macroscopic quantum fluctuations

Classical and quantum dynamics of superradiance in macroscopic samples of active media is discussed. Along with the usual convective instability, the absolute instability is analyzed as the basis of the superradiance phenomenon. Various regimes of superradiance in a conducting inverted two-level medium immersed in the plasma under and out of the condition of plasma-dipole resonance are described and compared. It is shown that the absolute instability of long-wavelength high-frequency polarization waves results in the pulsed generation of strong nonradiating electric fields. The remarkable phenomenon of macroscopic manifestation of quantum fluctuations in the observable parameters of superradiance is described. A general method of the quantization of unstable normal modes in the systems of coupled partial modes with opposite-sign energies is developed. Delay-time statistics of the superradiance pulse is examined in detail. New experiments for the observation of the outlined effects in the nonequilibrium activated semi-conductors and partially ionized gases, e.g. in impulsive discharge, in the infrared range are proposed and appropriate estimates are provided.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

An electrically driven polariton laser

Polariton lasing under electrical pumping is observed in a GaAs multi-quantum-well microcavity diode. Lasing in the strong-coupling regime is unambiguously evidenced by detection of Zeeman-split emission in an external magnetic field as a result of the polaritons' excitonic content