Staphylococcus argenteus transmission among healthy Royal Marines: A molecular epidemiology case-study.

Objectives During a prospective study of S. aureus carriage in Royal Marines recruits, six S. argenteus strains were identified in four recruits. As S. argenteus sepsis leads to mortality similar to S. aureus, we determined the potential for within same troop transmission, to evaluate future outbreak risk. Methods We used whole-genome sequencing to characterise S. argenteus and investigate phylogenetic relationships between isolates. Results S. argenteus strains (t5078, ST2250) were detected in 4/40 recruits in the same troop (training cohort) in weeks 1, 6 or 15 of training. No mec, tsst or LukPV genes were detected. We identified differences of 1-17 core SNPs between S. argenteus from different recruits. In two recruits, two S. argenteus strains were isolated; these could be distinguished by 2 and 15 core SNPs. Conclusions The identification of S. argenteus within a single troop from the total recruit population suggests a common source for transmission, though high number of SNPs were identified, both within-host and within-cluster. The high number of SNPs between some isolates may indicate a common source of diverse isolates or a high level of S. argenteus mutation in carriage. S. argenteus is newly recognized species; and understanding of the frequency of genetic changes during transmission and transition from asymptomatic carriage to disease is required.

Exploring regional differences in cyclist safety at roundabouts: A comparative study between the UK (based on Northumbria data) and Belgium.

The level of safety for cyclists at roundabouts may vary according to national differences not only in the design itself but also sociodemographic, cyclist and driver behaviour as well as environmental factors. This paper investigates the national influence on cyclist casualty severity at roundabouts by comparing the United Kingdom (using Northumbria as a representative sample) and Belgium. The data included speed limits, socio-demographic characteristics, environmental conditions and driver/cyclist behaviour-related contributory factors. First, a logistic regression analysis for the UK data, including 864 cyclist casualties, was carried out. Increasing the speed limit by ten units (for example 30mph to 40mph) increased the probability of a cyclist being killed or seriously injured by 10%. A cyclist casualty was more than three times more likely to be killed or seriously injured (the odds ratio is 3.02) where sudden braking was recorded as a contributory factor. Second, a separate logistic regression analysis for Belgium was conducted. Cyclists ignoring the priority at roundabouts increased the probability of a fatal or seriously injured collisions (the odds ratio is 2.71). Comparing the individual analysis for both countries, the influence of cyclist age was consistent. Each one-year increase in cyclist age increases chance of being killed or seriously injured as opposed to not being killed or seriously injured by 2 % (odds ratio is 1.02) in both UK and Belgium. A final comparative analysis was applied considering proxy variables for both countries. Three-way chi-square tests of independence showed that all non-behavioural variables (i.e. sociodemographic characteristics, speed limit, and environmental conditions) were found to be statistically different between UK and Belgium for both slight and killed and seriously injured casualties. This suggests that driver/cyclist interaction and behaviour in the two countries is generally similar whilst speed limits, the sociodemographic characteristics of cyclists and environmental conditions are specific for each country. The third part of the logistic regression analysis suggested that the country residual was highly statistically significant. This indicates that there are some statistically significant differences with respect to the characteristics of the two regional datasets used in the analysis.

Cyclist casualty severity at roundabouts - To what extent do the geometric characteristics of roundabouts play a part?

INTRODUCTION: In general, priority junctions are converted into roundabouts to increase capacity and reduce vehicle accidents. However, previous research has indicated that roundabouts are dangerous for vulnerable users, especially cyclists. METHOD: This paper investigates which design factors influence cyclist casualty severity at give way (non-signalized) roundabouts with mixed traffic, using the UK STATS19 National dataset of cyclist casualties. First, the correlation matrix was generated to observe the relationship between variables. Second, dimension reduction was applied to geometric design variables in order to reduce the number of variables and generate the factors. Finally, the binary logistic regression method, with serious and slight casualties as dependent variables, was applied in three steps. The first Binary Logistic Regression Model (BLRM) included speed limit, sociodemographic, and meteorological conditions. The variables in the second BLRM consisted of geometric design variables. The third BLRM included the factors that were generated by dimension reduction. RESULTS: The correlation matrix revealed that the number of lanes on approach and half width on approach were statistically significantly correlated, while the variables, such as geometric design (entry path radius, number of arms, number of flare lanes on approach, type of roundabout and number of circulating lanes), sociodemographic (casualty gender and age), speed limit and meteorologically related factors (daylight, weather and road surface condition), did not show any statistical significance. From the dimension reduction process, two main factors were identified, including Approach Capacity (Factor 1) and Size of Roundabout (Factor 2), and they were subsequently used as independent variables in the logistic regression analysis. The subsequent BLRMs showed that a higher speed limit reduces the safety for cyclists at roundabouts. The probability of a serious casualty increases by approximately five times (odds ratio 4.97) for each additional number of lanes on approach and by 4% (odds ratio 1.04) with a higher entry path radius. It was also found that Factor 2 (Approach Capacity) increases the casualty severity (odds ratio 1.86) for cyclists at roundabouts. Practical applications: While this research studied roundabouts in the UK, the methodological approach and statistical analysis techniques are applicable to other countries and the findings are likely to be of value to decision makers worldwide.

A novel Bayesian hierarchical model for road safety hotspot prediction.

In this paper, we propose a Bayesian hierarchical model for predicting accident counts in future years at sites within a pool of potential road safety hotspots. The aim is to inform road safety practitioners of the location of likely future hotspots to enable a proactive, rather than reactive, approach to road safety scheme implementation. A feature of our model is the ability to rank sites according to their potential to exceed, in some future time period, a threshold accident count which may be used as a criterion for scheme implementation. Our model specification enables the classical empirical Bayes formulation - commonly used in before-and-after studies, wherein accident counts from a single before period are used to estimate counterfactual counts in the after period - to be extended to incorporate counts from multiple time periods. This allows site-specific variations in historical accident counts (e.g. locally-observed trends) to offset estimates of safety generated by a global accident prediction model (APM), which itself is used to help account for the effects of global trend and regression-to-mean (RTM). The Bayesian posterior predictive distribution is exploited to formulate predictions and to properly quantify our uncertainty in these predictions. The main contributions of our model include (i) the ability to allow accident counts from multiple time-points to inform predictions, with counts in more recent years lending more weight to predictions than counts from time-points further in the past; (ii) where appropriate, the ability to offset global estimates of trend by variations in accident counts observed locally, at a site-specific level; and (iii) the ability to account for unknown/unobserved site-specific factors which may affect accident counts. We illustrate our model with an application to accident counts at 734 potential hotspots in the German city of Halle; we also propose some simple diagnostics to validate the predictive capability of our model. We conclude that our model accurately predicts future accident counts, with point estimates from the predictive distribution matching observed counts extremely well.

Investigating the traffic-related environmental impacts of hydraulic-fracturing (fracking) operations.

Hydraulic fracturing (fracking) has been used extensively in the US and Canada since the 1950s and offers the potential for significant new sources of oil and gas supply. Numerous other countries around the world (including the UK, Germany, China, South Africa, Australia and Argentina) are now giving serious consideration to sanctioning the technique to provide additional security over the future supply of domestic energy. However, relatively high population densities in many countries and the potential negative environmental impacts that may be associated with fracking operations has stimulated controversy and significant public debate regarding if and where fracking should be permitted. Road traffic generated by fracking operations is one possible source of environmental impact whose significance has, until now, been largely neglected in the available literature. This paper therefore presents a scoping-level environmental assessment for individual and groups of fracking sites using a newly-created Traffic Impacts Model (TIM). The model produces estimates of the traffic-related impacts of fracking on greenhouse gas emissions, local air quality emissions, noise and road pavement wear, using a range of hypothetical fracking scenarios to quantify changes in impacts against baseline levels. Results suggest that the local impacts of a single well pad may be short duration but large magnitude. That is, whilst single digit percentile increases in emissions of CO2, NOx and PM are estimated for the period from start of construction to pad completion (potentially several months or years), excess emissions of NOx on individual days of peak activity can reach 30% over baseline. Likewise, excess noise emissions appear negligible (<1dBA) when normalised over the completion period, but may be considerable (+3.4dBA) in particular hours, especially in night-time periods. Larger, regional scale modelling of pad development scenarios over a multi-decade time horizon give modest CO2 emissions that vary between 2.5 and 160.4kT, dependent on the number of wells, and individual well fracking water and flowback waste requirements. The TIM model is designed to be adaptable to any geographic area where the required input data are available (such as fleet characteristics, road type and quality), and we suggest could be deployed as a tool to help reach more informed decisions regarding where and how fracking might take place taking into account the likely scale of traffic-related environmental impacts.

Attitudes towards and perceptions of eco-driving and the role of feedback systems.

This paper addresses whether eco-driving may be encouraged by providing drivers with feedback, and how eco-driving attitudes fit with other environmental attitudes. Eight focus groups, including fleet drivers, discussed how feedback and other motives might affect driving behaviour. A survey of 350 respondents investigated attitudes towards saving fuel, the role of incentives and use of eco-friendly products. The focus groups' findings show that the environment is a lower priority than comfort and convenience, that feedback might provide a stimulus to eco-driving and that saving money was less important than saving time. The attitude survey showed that price, convenience, attitudes and eco-driving are not conceptually linked together, that convenience is rated as more important than saving money from fuel efficiency and that although the environment is of concern, it is not a high enough priority to increase fuel efficiency. The findings are discussed in relation to the low level of priority given to environmental concerns and the inability of financial incentives presenting significant challenges in terms of changing the subjective norms of the majority of drivers. PRACTITIONER SUMMARY: This paper, using focus groups and a questionnaire, aims to understand how feedback devices, attitudes and motivation can improve eco-driving behaviours. The incentive to save money by better fuel economy was found to be insufficient, and roles for feedback devices and how information is presented are identified.

Linking road casualty and clinical data to assess the effectiveness of mobile safety enforcement cameras: a before and after study.

OBJECTIVES: To use police STATS19 road casualty data and accident and emergency and in-patient information to estimate the impact of mobile safety cameras on the cost of treating individuals injured in road traffic collisions. DESIGN: A data-matching and costing exercise to link casualty and clinical information in a 'before' and 'after' study of 56 mobile safety cameras. SETTING: The Northumbria Police Force area of the UK covering six local authority districts. PARTICIPANTS: Slight, serious and fatal casualties involved in road traffic collisions at mobile camera sites in the case-study area between April 2001-March 2003 and April 2004-March 2006. PRIMARY AND SECONDARY OUTCOME MEASURES: Changes in the number and severity of casualties at the mobile camera sites between the 'before' and 'after' period that can be attributed to mobile safety camera activity, and any impacts these changes had on the 'cost of treatment saved' by the secondary healthcare service in the case-study area. RESULTS: Using tariff values for accident and emergency and In-patient Health Resource Groups, the impacts of the cameras in terms of the 'cost of treatment saved' are in the range £12 500-£15 000 per annum. However, inconsistencies between databases resulted in approximately one-third of the casualties not being matched successfully in the clinical databases. The number of closed fractures requiring investigations, treatment and follow-up care reduced considerably, although this was offset by an increase in head injury contusions and open fractures that require high-cost investigations and extensive in-patient care. CONCLUSIONS: Road safety cameras could have a significant impact in terms of 'cost of treatment saved'. However, it is argued that investigating the impacts of road safety measures in the future should be based on Fully Bayesian techniques as they can produce more reliable estimates of the effects of regression to mean and general trends in casualty statistics.