The effect of individual radiographers on rates of attendance to breast screening: A 7-year retrospective study

AIM: To establish whether individual radiographers had significantly different rescreening rates whilst controlling for other known confounding factors. MATERIALS AND METHODS: Women aged 50e69 years were identified from a state-wide screening database at their first screening attendance during the study period (2007e2013). The radiographer performing this index screen and potential confounding factors were recorded and subsequent screening behaviour was assessed. Clients with abnormal screens and those known to have died during the time period were excluded. A univariate analysis of the data from 160,028 women was assessed using the chi-square test to compare those women who attended their next mammography with non-re-attenders. Logistic regression was used to calculate the likelihood of “re-attendance success” across a range of variables. The probability of re-attendance for 11 randomly selected radiographers was determined from the logistic regression model, whilst controlling for other variables. RESULTS: Comparison of non-re-attenders (n¼49,698) with 110,330 (69%) women attending the next round of screening revealed significant differences, including radiographer (Wald statistics¼1188, p\u3c0.000) even when all other known factors were controlled. CONCLUSION: This large, population-level study demonstrates that individual radiographer factors appear to influence a women’s decision to return for their next screening round. Further research is required to identify reasons for differing rescre

Time-resolved measurements of black carbon light absorption enhancement in urban and near-urban locations of southern Ontario, Canada

In this study a photoacoustic spectrometer (PA), a laser-induced incandescence instrument system (LII) and an Aerosol Mass Spectrometer were operated in parallel for in-situ measurements of black carbon (BC) light absorption enhancement. Results of a thermodenuder experiment using ambient particles in Toronto are presented first to show that LII measurements of BC are not influenced by the presence of non-refractory material thus providing true atmospheric BC mass concentrations. In contrast, the PA response is enhanced when the non-refractory material is internally mixed with the BC particles. Through concurrent measurements using the LII and PA the specific absorption cross-section (SAC) can be quantified with high time resolution (1 min). Comparisons of ambient PA and LII measurements from four different locations (suburban Toronto; a street canyon with diesel bus traffic in Ottawa; adjacent to a commuter highway in Ottawa and; regional background air in and around Windsor, Ontario), show that different impacts from emission sources and/or atmospheric processes result in different particle light absorption enhancements and hence variations in the SAC. The diversity of measurements obtained, including those with the thermodenuder, demonstrated that it is possible to identify measurements where the presence of externally-mixed non-refractory particles obscures direct observation of the effect of coating material on the SAC, thus allowing this effect to be measured with more confidence. Depending upon the time and location of measurement (urban, rural, close to and within a lake breeze frontal zone), 30 min average SAC varies between 9 ± 2 and 43 ± 4 m<sup>2</sup> g<sup>−1</sup>. Causes of this variation, which were determined through the use of meteorological and gaseous measurements (CO, SO<sub>2</sub>, O<sub>3</sub>), include the particle emission source, airmass source region, the degree of atmospheric processing. Observations from this study also show that the active surface area of the BC aggregate, which is measured by the LII as the PPS, is an important parameter for inferring the degree of particle collapse of a BC particle. In addition, PPS could be a useful measurement for indicating the importance of recently emitted BC (e.g. from gasoline or diesel engines) relative to the total measured BC in the atmosphere

Predicting the Timing and Magnitude of Tropical Mosquito Population Peaks for Maximizing Control Efficiency

The transmission of mosquito-borne diseases is strongly linked to the abundance of the host vector. Identifying the environmental and biological precursors which herald the onset of peaks in mosquito abundance would give health and land-use managers the capacity to predict the timing and distribution of the most efficient and cost-effective mosquito control. We analysed a 15-year time series of monthly abundance of Aedes vigilax, a tropical mosquito species from northern Australia, to determine periodicity and drivers of population peaks (high-density outbreaks). Two sets of density-dependent models were used to examine the correlation between mosquito abundance peaks and the environmental drivers of peaks or troughs (low-density periods). The seasonal peaks of reproduction (r) and abundance () occur at the beginning of September and early November, respectively. The combination of low mosquito abundance and a low frequency of a high tide exceeding 7 m in the previous low-abundance (trough) period were the most parsimonious predictors of a peak's magnitude, with this model explaining over 50% of the deviance in . Model weights, estimated using AICc, were also relatively high for those including monthly maximum tide height, monthly accumulated tide height or total rainfall per month in the trough, with high values in the trough correlating negatively with the onset of a high-abundance peak. These findings illustrate that basic environmental monitoring data can be coupled with relatively simple density feedback models to predict the timing and magnitude of mosquito abundance peaks. Decision-makers can use these methods to determine optimal levels of control (i.e., least-cost measures yielding the largest decline in mosquito abundance) and so reduce the risk of disease outbreaks in human populations

ECOLOGICAL-ECONOMIC MODELS OF SUSTAINABLE HARVEST FOR AN ENDANGERED BUT EXOTIC MEGAHERBIVORE IN NORTHERN AUSTRALIA

ABSTRACT. How can one manage wildlife under a suite of competing values? In isolation, the ecological economics of native wildlife harvest, threatened species conservation and control of exotic species are all well established sub-disciplines of wildlife management. However, the wild banteng (Bos javanicus) population of northern Australia represents an interesting combination of these aspirations. A native bovid of Southeast Asia now 'endangered' in its native range, banteng were introduced into northern Australia in 1849. Today, a population of 8,000 10,000 resides on one small, isolated peninsula in western Arnhem Land, Northern Territory and is harvested by both recreational (trophy) and aboriginal subsistence hunters. Indigenous, industry and conservationist stakeholders differ in their requirements for population management. Here we analyze the ecological and economic costs/benefits of a series of potential harvest management options for Australia's banteng population, with the aim being either to: (1) maximize sustainable yield (MSY); (2) maximize harvest of trophy males; (3) maximize indigenous off-take; (4) suppress density or completely eradicate the population; (5) minimize risk of extinction whilst limiting range expansion; (6) scenarios incorporating two or more of options 1 5. The modeling framework employed stochastic, density-regulated matrix population models with life-history parameters derived from (i) allometric relationships (for estimating r max , generation length, fecundity and densities for a banteng-sized mammal) and (ii) measured For each management option, we present a simple economic analysis that incorporates estimated costs of management implementation and associated profits projected. Results demonstrate that revenue of >AU$200,000 is possible from meat production and safari hunting without compromising long-term population stability or the conservation status of this endangered bovid

Continuity of cannabis use and violent offending over the life course

Although the association between cannabis use and violence has been reported in the literature, the precise nature of this relationship, especially the directionality of the association, is unclear. Young males from the Cambridge Study of Delinquent Development (n = 411) were followed up between the ages of 8 and 56 years to prospectively investigate the association between cannabis use and violence. A multi-wave (eight assessments, T1–T8) follow-up design was employed that allowed temporal sequencing of the variables of interest and the analysis of violent outcome measures obtained from two sources: (i) criminal records (violent conviction); and (ii) self-reports. A combination of analytic approaches allowing inferences as to the directionality of associations was employed, including multivariate logistic regression analysis, fixed-effects analysis and cross-lagged modelling. Multivariable logistic regression revealed that compared with never-users, continued exposure to cannabis (use at age 18, 32 and 48 years) was associated with a higher risk of subsequent violent behaviour, as indexed by convictions [odds ratio (OR) 7.1, 95% confidence interval (CI) 2.19–23.59] or self-reports (OR 8.9, 95% CI 2.37–46.21). This effect persisted after controlling for other putative risk factors for violence. In predicting violence, fixed-effects analysis and cross-lagged modelling further indicated that this effect could not be explained by other unobserved time-invariant factors. Furthermore, these analyses uncovered a bi-directional relationship between cannabis use and violence. Together, these results provide strong indication that cannabis use predicts subsequent violent offending, suggesting a possible causal effect, and provide empirical evidence that may have implications for public policy

Local and global pyrogeographic evidence that indigenous fire management creates pyrodiversity

Despite the challenges wildland fire poses to contemporary resource management, many fire-prone ecosystems have adapted over centuries to millennia to intentional landscape burning by people to maintain resources. We combine fieldwork, modeling, and a literature survey to examine the extent and mechanism by which anthropogenic burning alters the spatial grain of habitat mosaics in fire-prone ecosystems. We survey the distribution of Callitris intratropica, a conifer requiring long fire-free intervals for establishment, as an indicator of long-unburned habitat availability under Aboriginal burning in the savannas of Arnhem Land. We then use cellular automata to simulate the effects of burning identical proportions of the landscape under different fire sizes on the emergent patterns of habitat heterogeneity. Finally, we examine the global extent of intentional burning and diversity of objectives using the scientific literature. The current distribution of Callitris across multiple field sites suggested long-unburnt patches are common and occur at fine scales (<0.5 ha), while modeling revealed smaller, patchy disturbances maximize patch age diversity, creating a favorable habitat matrix for Callitris. The literature search provided evidence for intentional landscape burning across multiple ecosystems on six continents, with the number of identified objectives ranging from two to thirteen per study. The fieldwork and modeling results imply that the occurrence of long-unburnt habitat in fire-prone ecosystems may be an emergent property of patch scaling under fire regimes dominated by smaller fires. These findings provide a model for understanding how anthropogenic burning alters spatial and temporal aspects of habitat heterogeneity, which, as the literature survey strongly suggests, warrant consideration across a diversity of geographies and cultures. Our results clarify how traditional fire management shapes fire-prone ecosystems, which despite diverse objectives, has allowed human societies to cope with fire as a recurrent disturbance