Drift effects on electromagnetic geodesic acoustic modes

A two fluid model with parallel viscosity is employed to derive the dispersion relation for electromagnetic geodesic acoustic modes (GAMs) in the presence of drift (diamagnetic) effects. Concerning the influence of the electron dynamics on the high frequency GAM, it is shown that the frequency of the electromagnetic GAM is independent of the equilibrium parallel current but, in contrast with purely electrostatic GAMs, significantly depends on the electron temperature gradient. The electromagnetic GAM may explain the discrepancy between the $f\sim 40$ kHz oscillation observed in TCABR [Yu. K. Kuznetsov $\textit{et al.}$, Nucl. Fusion $\bf{52}$, 063044 (2012)] and the former prediction for the electrostatic GAM frequency. The radial wave length associated with this oscillation, estimated presently from this analytical model, is $\lambda_r\sim 25$ cm, i. e., an order of magnitude higher than the usual value for zonal flows (ZFs).Comment: 20 pages, 1 figur

Driving attitudes, behaviours, risk perception and risk concern among young student car-drivers, motorcyclists and pedestrians in various EU countries

The number of car crashes has gradually reduced in the last decade across all European Countries, but the number of motorcycle crashes has remained nearly the same. In our research we investigate whether there are differences in attitudes towards road safety issues, driving behaviours in specific imagined situations, risk perception and risk concern, among young student drivers and riders. The study involved a large sample taken from across six European countries. The results reveal that although there are no differences between motorcyclists and car drivers in their attitudes toward road safety rules, differences do appear when the road rules compliance is assessed in specific imagined situations, with motorcyclists reporting to be more prone than car-drivers to violations of traffic rules. Moreover, despite the perceived risk during driving is the same for motorcyclists and car-drivers, differences do appear on their concern about this risk, with motorcyclists reporting to be less concerned than car-drivers about the risk of a road crash. This could lead to a high probability of risky driving behaviour in motorcyclists than in car-drivers. Present findings have important practical implications for road safety training courses