Bituplaning a low dry friction phenomenon of new bituminous road surfaces

The potential for binder rich bituminous road surfaces to deliver low levels of dry friction was first noted in 1944. Using established test methods exploiting basic principles of physics first tested in criminal court in the 1940s (and still in use today) it has been possible to show statistically that modern negative textured road surfaces (NTS) deliver levels of dry friction significantly below those considered typical by collision investigators for the more traditional positive textured surfaces (PTS). NTS surfaces are shown to perform relatively worse in the absence of ABS (Anti-Blockier System, Anti-lock braking) than PTS equivalents such as Hot Rolled Asphalt (HRA). Skid tests undertaken on DRY NTS surfaces with ABS braking have been shown to manifest momentary low levels of deceleration similar to those experienced during NOABS tests on the same surfaces and to generate dash like skid marks atypical of ABS tests on DRY PTS surfaces. The ratio of peak to sliding friction also appears lower for dry NTS surfaces than for Dry PTS surfaces documented in the literature.Using high-speed video and false colour infrared imaging it has been possible to see the low friction phenomenon termed “bituplaning”. Vehicles equipped with ABS have also been shown to suffer momentary “bituplanes” resulting in less than optimum performance. Tyre deformation during dry skidding on NTS appears reduced in relation to a PTS equivalent.<br/

Comprehensive Identification of Salmonella enterica Serovar Typhimurium Genes Required for Infection of BALB/c Mice

Genes required for infection of mice by Salmonella Typhimurium can be identified by the interrogation of random transposon mutant libraries for mutants that cannot survive in vivo. Inactivation of such genes produces attenuated S. Typhimurium strains that have potential for use as live attenuated vaccines. A quantitative screen, Transposon Mediated Differential Hybridisation (TMDH), has been developed that identifies those members of a large library of transposon mutants that are attenuated. TMDH employs custom transposons with outward-facing T7 and SP6 promoters. Fluorescently-labelled transcripts from the promoters are hybridised to whole-genome tiling microarrays, to allow the position of the transposon insertions to be determined. Comparison of microarray data from the mutant library grown in vitro (input) with equivalent data produced after passage of the library through mice (output) enables an attenuation score to be determined for each transposon mutant. These scores are significantly correlated with bacterial counts obtained during infection of mice using mutants with individual defined deletions of the same genes. Defined deletion mutants of several novel targets identified in the TMDH screen are effective live vaccines