Censored data considerations and analytical approaches for salivary bioscience data

Left censoring in salivary bioscience data occurs when salivary analyte determinations fall below the lower limit of an assay’s measurement range. Conventional statistical approaches for addressing censored values (i.e., recoding as missing, substituting or extrapolating values) may introduce systematic bias. While specialized censored data statistical approaches (i.e., Maximum Likelihood Estimation, Regression on Ordered Statistics, Kaplan-Meier, and general Tobit regression) are available, these methods are rarely implemented in biobehavioral studies that examine salivary biomeasures, and their application to salivary data analysis may be hindered by their sensitivity to skewed data distributions, outliers, and sample size. This study compares descriptive statistics, correlation coefficients, and regression parameter estimates generated via conventional and specialized censored data approaches using salivary C-reactive protein data. We assess differences in statistical estimates across approach and across two levels of censoring (9% and 15%) and examine the sensitivity of our results to sample size. Overall, findings were similar across conventional and censored data approaches, but the implementation of specialized censored data approaches was more efficient (i.e., required little manipulations to the raw analyte data) and appropriate. Based on our review of the findings, we outline preliminary recommendations to enable investigators to more efficiently and effectively reduce statistical bias when working with left-censored salivary biomeasure data

Revisiting Static and Dynamic Spin Ice Correlations in Ho2Ti2O7

Elastic and inelastic neutron scattering studies have been carried out on the pyrochlore magnet Ho2Ti2O7. Measurements in zero applied magnetic field show that the disordered spin ice ground state of Ho2Ti2O7 is characterized by a pattern of rectangular diffuse elastic scattering within the [HHL] plane of reciprocal space, which closely resembles the zone boundary scattering seen in its sister compound Dy2Ti2O7. Well-defined peaks in the zone boundary scattering develop only within the spin ice ground state below ~ 2 K. In contrast, the overall diffuse scattering pattern evolves on a much higher temperature scale of ~ 17 K. The diffuse scattering at small wavevectors below [001] is found to vanish on going to Q=0, an explicit signature of expectations for dipolar spin ice. Very high energy-resolution inelastic measurements reveal that the spin ice ground state below ~ 2 K is also characterized by a transition from dynamic to static spin correlations on the time scale of 10^{-9} seconds. Measurements in a magnetic field applied along the [1${\bar1}$0] direction in zero-field cooled conditions show that the system can be broken up into orthogonal sets of polarized alpha chains along [1${\bar1}$0] and quasi-one-dimensional beta chains along [110]. Three dimensional correlations between beta chains are shown to be very sensitive to the precise alignment of the [1${\bar1}$0] externally applied magnetic field.Comment: 11 pages, 10 figures. Submitted for publicatio

Uptake of smoking cessation aids by smokers with a mental illness

Psychiatric inpatient settings represent an opportunity to initiate the provision of tobacco cessation care to smokers with a mental illness. This study describes the use of evidence-based smoking cessation aids proactively and universally offered to a population of psychiatric inpatients upon discharge, and explores factors associated with their uptake. Data derived from the conduct of a randomised controlled trial were analysed in terms of the proportion of participants (N = 378) that utilised cessation aids including project delivered telephone smoking cessation counselling and nicotine replacement therapy (NRT), and Quitline support. Factors associated with uptake of cessation aids were explored using multivariable logistic regression analyses. A large proportion of smokers utilised project delivered cessation counselling calls (89 %) and NRT (79 %), while 11 % used the Quitline. The majority accepted more than seven project delivered telephone cessation counselling calls (52 %), and reported NRT use during more than half of their accepted calls (70 %). Older age, higher nicotine dependence, irregular smoking and seeing oneself as a non-smoker were associated with uptake of behavioural cessation aids. Higher nicotine dependence was similarly associated with use of pharmacological aids, as was NRT use whilst an inpatient. Most smokers with a mental illness took up a proactive offer of aids to support their stopping smoking. Consideration by service providers of factors associated with uptake may increase further the proportion of such smokers who use evidence-based cessation aids and consequently quit smoking successfully

Oral microbial communities in children, caregivers, and associations with salivary biomeasures and environmental tobacco smoke exposure

Human oral microbial communities are diverse, with implications for oral and systemic health. Oral microbial communities change over time; thus, it is important to understand how healthy versus dysbiotic oral microbiomes differ, especially within and between families. There is also a need to understand how the oral microbiome composition is changed within an individual including by factors such as environmental tobacco smoke (ETS) exposure, metabolic regulation, inflammation, and antioxidant potential. Using archived saliva samples collected from caregivers and children during a 90-month follow-up assessment in a longitudinal study of child development in the context of rural poverty, we used 16S rRNA gene sequencing to determine the salivary microbiome. A total of 724 saliva samples were available, 448 of which were from caregiver/child dyads, an additional 70 from children and 206 from adults. We compared children’s and caregivers’ oral microbiomes, performed “stomatotype” analyses, and examined microbial relations with concentrations of salivary markers associated with ETS exposure, metabolic regulation, inflammation, and antioxidant potential (i.e., salivary cotinine, adiponectin, C-reactive protein, and uric acid) assayed from the same biospecimens. Our results indicate that children and caregivers share much of their oral microbiome diversity, but there are distinct differences. Microbiomes from intrafamily individuals are more similar than microbiomes from nonfamily individuals, with child/caregiver dyad explaining 52% of overall microbial variation. Notably, children harbor fewer potential pathogens than caregivers, and participants’ microbiomes clustered into two groups, with major differences being driven by Streptococcus spp. Differences in salivary microbiome composition associated with ETS exposure, and taxa associated with salivary analytes representing potential associations between antioxidant potential, metabolic regulation, and the oral microbiome

The association of adolescents' smoking with the physical activity levels of their friends

Funding Information: This study is part of the SILNE-R project (Enhancing the Effectiveness of Programs and Strategies to Prevent Smoking by Adolescents: A Realist Evaluation Comparing Seven European Countries), which is supported by the European Union‘s Horizon 2020 research and innovation programme, under grant agreement 635,056. The funder was not involved and did not have any input in the design, analysis and reporting of this study. Publisher Copyright: © 2023Background: Smoking is inversely related to people's Physical Activity Level (PAL). As the behavior of friends may affect the choices and behavior of adolescents, having friends with a high PAL may potentially protect against adolescent smoking. This study aims to assess whether adolescents' smoking is associated with the PAL of their friends. Methods: SILNE-R survey data of 11.918 adolescents from 55 different schools in 7 European cities was used to determine weekly smoking, individual PAL, PAL of friends, school PAL, and smoking of friends. Multilevel, multivariable logistic regression analysis were used to assess the association between the PAL of friends and weekly smoking. Several socio-demographic variables were included as covariates in the analysis. Results: Our results indicated that 10.8% of the respondents was smoking weekly. Weekly smoking was most common among adolescents whose friends had a PAL of 0–42.0 min per day (14.5%). Respondents were significantly more likely to be smoking weekly if their friends were on average 0–42 min vs. 80–180 min physically active (OR 1.27 [95% CI 1.04–1.55]). This association existed independently of the individual PAL of respondents. Stratification for smoking of friends yielded equal results, although the association appeared to be somewhat stronger for those with smoking friends (OR 1.38 [95% CI 1.06–1.82]). Conclusion: Adolescents are less likely to smoke weekly if they associate with friends who spend >80 min per day on physical activity. Initiatives aimed at the prevention of smoking among adolescents may benefit from organizing group-based physical activity programs.publishersversionpublishe

Brane-world black holes and the scale of gravity

A particle in four dimensions should behave like a classical black hole if the horizon radius is larger than the Compton wavelength or, equivalently, if its degeneracy (measured by entropy in units of the Planck scale) is large. For spherically symmetric black holes in 4 + d dimensions, both arguments again lead to a mass threshold MC and degeneracy scale Mdeg of the order of the fundamental scale of gravity MG. In the brane-world, deviations from the Schwarzschild metric induced by bulk effects alter the horizon radius and effective four-dimensional Euclidean action in such a way that MC \simeq Mdeg might be either larger or smaller than MG. This opens up the possibility that black holes exist with a mass smaller than MG and might be produced at the LHC even if M>10 TeV, whereas effects due to bulk graviton exchanges remain undetectable because suppressed by inverse powers of MG. Conversely, even if black holes are not found at the LHC, it is still possible that MC>MG and MG \simeq 1TeV.Comment: 4 pages, no figur