Safety effects of mobile speed cameras in Norfolk: no more than regression to the mean?

This letter is a comment on the paper by Jones, Sauerzapf and Haynes, "The effects of mobile speed camera introduction on road traffic crashes and casualties in a rural county of England", published in this journal (vol. 39, issue 1, pp. 101-110, 2008). These authors analyse the effects of a camera enforcement programme on injury crashes in the county of Norfolk. The investigation reported is a sound observational before-after accident study. The paper is clear and well documented. It seems, however, that a slight error was made in the calculation of the regression-to-the-mean (RTM) effect, leading to an underestimation of RTM bias. A correction of this error would partly change the conclusions of the paper: based on the corrected results, there is no clear evidence of an overall safety benefit due to the mobile speed camera introduction at the treated sites

Excess accident risk among residents of deprived areas

This study examines road risks among residents of deprived neighbourhoods targeted by social policy compared with residents of other contiguous neighbourhoods that are socially more privileged. The data used are from accident reports filled in by the police. When these data are brought to the level of the population in the areas studied, the adjusted relative risk for those living in sensitive urban areas compared with those living in other areas is assessed at 1.366 (with a 95% confidence interval from 1.240 to 1.502). Distributions by age and gender are then studied. In the discussion, several hypotheses concerning behaviour, mobility and socio-spatial factors are discussed. Deprived areas, socioeconomic differences, accident risk, age, gender

Stopping power and nano-particles: Collisions of ions in low charge states with metallic clusters

In an experimental study, the multi-ionisation of metallic clusters (Nan) has been analysed in collisions with light ions in low charge states (H+, He+, He2+, O3+) at collision velocities below 1 a.u. Cluster ions are produced in charge states up to 5+. The average charge of the nano-particles is found to increase linearly with the variation of projectile velocity and the square of the effective projectile charge, well in agreement with the electronic stopping power of the bulk material. A fraction of 50% to 30% of the total projectile energy loss (decreasing with velocity) is transferred into vibrational modes in good agreement with recent theoretical predictions

Human Cytomegalovirus Carries a Cell-Derived Phospholipase A2 Required for Infectivity

Human cytomegalovirus (HCMV) is known to carry host cell-derived proteins and mRNAs whose role in cell infection is not understood. We have identified a phospholipase A2 (PLA2) activity borne by HCMV by using an assay based on the hydrolysis of fluorescent phosphatidylcholine. This activity was found in all virus strains analyzed and in purified strains. It was calcium dependent and was sensitive to inhibitors of cytosolic PLA2 (cPLA2) but not to inhibitors of soluble PLA2 or calcium-independent PLA2. No other phospholipase activity was detected in the virus. Purified virus was found to contain human cellular cPLA2α, as detected by monoclonal antibody. No homology with PLA2 was found in the genome of HCMV, indicating that HCMV does not code for a PLA2. Decreased de novo expression of immediate-early proteins 1 and 2 (IE1 and IE2), tegument phosphoprotein pp65, and virus production was observed when HCMV was treated with inhibitors of cPLA2. Cell entry of HCMV was not altered by those inhibitors, suggesting the action of cPLA2 was postentry. Together, our results indicate a selective sorting of a cell-derived cPLA2 during HCMV maturation, which is further required for infectivity