989Relationship between housing tenure and cigarette smoking among adolescents – A population-based study

Background Cigarette smoking leads to significant morbidity and pre-mature mortality. We examined the relationship between housing tenure at ages 15, 16, 17 and 18 and smoking five years later using data from a well-established cohort study. Methods We analysed the data on 15-18-year-old adolescents (n = 2305) from the Household Income and Labour Dynamics in Australia (HILDA) survey. We applied augmented inverse probability treatment weights to maximise exchangeability between those in social housing and homeowners, and private renters. By estimating potential outcomes for the exposed and unexposed, we compared risk of smoking five years later on both absolute and relative scale. Baseline covariates included household income, age at study entry, sex, family type, smoking at baseline and highest household education. Results Adolescents in social housing had an increased risk of current smoking five years later (average treatment effect (ATE): 0.24, 95% CI: 0.02, 0.47) than homeowners. On the relative scale those in social housing had 2.23 times (95% CI: 1.08, 3.39) higher risk of being a smoker than homeowners. Those in social housing also had an increased risk of being a smoker (ATE: 0.14, 95%CI: 0.04, 0.25) than private renters. On the relative scale we estimated that those in social housing had 1.46 times (95% CI: 1.09, 1.83) higher risk of smoking than private renters. Conclusions Adolescents in social housing have a higher risk of smoking than those living in owned or private rented homes. Key messages Tobacco control efforts must target adolescent in social housing for reducing inequalities in cigarette smoking.

Estimation of the molecular weight of nanoparticles using a single small-angle X-ray scattering measurement on a relative scale

Both small-angle scattering methods, X-rays (SAXS) and neutrons (SANS) rank among the methods that facilitate the determination of the molar mass of nanoparticles. Using this measure, aggregation or degradation processes are easy to follow. Mono- and multichain assemblies of nanoparticles in solution could be resolved, swelling ratio can also be obtained. In this work, we present a method that allows extraction of additional information, including molecular weight, from a single scattering curve, even on a relative scale. The underlying theory and step-by-step procedure are described.

Maximal Time Spent at VO2max from Sprint to the Marathon

Until recently, it was thought that maximal oxygen uptake (VO2max) was elicited only in middle-distance events and not the sprint or marathon distances. We tested the hypothesis that VO2max can be elicited in both the sprint and marathon distances and that the fraction of time spent at VO2max is not significantly different between distances. Methods: Seventy-eight well-trained males (mean [SD] age: 32 [13]; weight: 73 [9] kg; height: 1.80 [0.8] m) performed the University of Montreal Track Test using a portable respiratory gas sampling system to measure a baseline VO2max. Each participant ran one or two different distances (100 m, 200 m, 800 m, 1500 m, 3000 m, 10 km or marathon) in which they are specialists. Results: VO2max was elicited and sustained in all distances tested. The time limit (Tlim) at VO2max on a relative scale of the total time (Tlim at VO2max%Ttot) during the sprint, middle-distance, and 1500 m was not significantly different (p > 0.05). The relevant time spent at VO2max was only a factor for performance in the 3000 m group, where the Tlim at VO2max%Ttot was the highest (51.4 [18.3], r = 0.86, p = 0.003). Conclusions: By focusing on the solicitation of VO2max, we demonstrated that the maintenance of VO2max is possible in the sprint, middle, and marathon distances.

Comparative performances of new and existing indices of crown asymmetry: an evaluation using tall trees of Eucalyptus pilularis (Smith)

Over the past 50 years, crown asymmetry of forest trees has been evaluated through several indices constructed from the perspective of projected crown shape or displacement but often on an ad hoc basis to address specific objectives related to tree growth and competition, stand dynamics, stem form, crown structure and treefall risks. Although sharing some similarities, these indices are largely incoherent and non-comparable as they differ not only in the scale but also in the direction of their values in indicating the degree of crown asymmetry. As the first attempt at devising normative measures of crown asymmetry, we adopted a relative scale between 0 for perfect symmetry and 1 for extreme asymmetry. Five existing crown asymmetry indices (CAIs) were brought onto this relative scale after necessary modifications. Eight new CAIs were adapted from measures of circularity for digital images in computer graphics, indices of income inequality in economics, and a bilateral symmetry indicator in plant leaf morphology. The performances of the 13 CAIs were compared over different numbers of measured crown radii for 30 projected crowns of mature Eucalyptus pilularis trees through benchmarking statistics and rank order correlation analysis. For each CAI, the index value based on the full measurement of 36 evenly spaced radii of a projected crown was taken as the true value in the benchmarking process. The index (CAI13) adapted from the simple bilateral symmetry measure proved to be the least biased and most precise. Its performance was closely followed by that of three other CAIs. The minimum number of crown radii that is needed to provide at least an indicative measure of crown asymmetry is four. For more accurate and consistent measures, at least 6 or 8 crown radii are needed. The range of variability in crown morphology of the trees under investigation also needs to be taken into consideration. Although the CAIs are from projected crown radii, they can be readily extended to individual tree crown metrics that are now commonly extracted from LiDAR and other remotely sensed data. Adding a normative measure of crown asymmetry to individual tree crown metrics will facilitate the process of big data analytics and artificial intelligence in forestry wherever crown morphology is among the factors to be considered for decision making in forest management.

Many continuous variables should be analyzed using the relative scale: a case study of β2-agonists for preventing exercise-induced bronchoconstriction

Background The relative scale adjusts for baseline variability and therefore may lead to findings that can be generalized more widely. It is routinely used for the analysis of binary outcomes but only rarely for continuous outcomes. Our objective was to compare relative vs absolute scale pooled outcomes using data from a recently published Cochrane systematic review that reported only absolute effects of inhaled β2-agonists on exercise-induced decline in forced-expiratory volumes in 1 s (FEV1). Methods From the Cochrane review, we selected placebo-controlled cross-over studies that reported individual participant data (IPD). Reversal in FEV1 decline after exercise was modeled as a mean uniform percentage point (pp) change (absolute effect) or average percent change (relative effect) using either intercept-only or slope-only, respectively, linear mixed-effect models. We also calculated the pooled relative effect estimates using standard random-effects, inverse-variance-weighting meta-analysis using study-level mean effects. Results Fourteen studies with 187 participants were identified for the IPD analysis. On the absolute scale, β2-agonists decreased the exercise-induced FEV1 decline by 28 pp., and on the relative scale, they decreased the FEV1 decline by 90%. The fit of the statistical model was significantly better with the relative 90% estimate compared with the absolute 28 pp. estimate. Furthermore, the median residuals (5.8 vs. 10.8 pp) were substantially smaller in the relative effect model than in the absolute effect model. Using standard study-level meta-analysis of the same 14 studies, β2-agonists reduced exercise-induced FEV1 decline on the relative scale by a similar amount: 83% or 90%, depending on the method of calculating the relative effect. Conclusions Compared with the absolute scale, the relative scale captures more effectively the variation in the effects of β2-agonists on exercise-induced FEV1-declines. The absolute scale has been used in the analysis of FEV1 changes and may have led to sub-optimal statistical analysis in some cases. The choice between the absolute and relative scale should be determined based on biological reasoning and empirical testing to identify the scale that leads to lower heterogeneity.

Avian survey in tourist sites near Putao in northern Myanmar

We present the results of short ornithological observations conducted in November–December 2014 and December 2015 in the territory near Putao in northern Myanmar at elevations below 1,500m. We recorded 105 species, which were mostly resident birds, and evaluated the species abundance with a relative scale along tourist walking routes in the area. The bird species richness in the Mali Hka River Valley was observed to be less than in the adjacent virgin mountain forests. Our results could be used for future bird monitoring fieldworks.