The formation of Kuiper-belt Binaries through Exchange Reactions

Recent observations have revealed an unexpectedly high binary fraction among the Trans-Neptunian Objects (TNOs) that populate the Kuiper-belt. The discovered binaries have four characteristics they comprise a few percent of the TNOs, the mass ratio of their components is close to unity, their internal orbits are highly eccentric, and the orbits are more than 100 times wider than the primary's radius. In contrast, theories of binary asteroid formation tend to produce close, circular binaries. Therefore, a new approach is required to explain the unique characteristics of the TNO binaries. Two models have been proposed. Both, however, require extreme assumptions on the size distribution of TNOs. Here we show a mechanism which is guaranteed to produces binaries of the required type during the early TNO growth phase, based on only one plausible assumption, namely that initially TNOs were formed through gravitational instabilities of the protoplanetary dust layer.Comment: 12pages, 4 figure

Adult Consequences of Late Adolescent Alcohol Consumption: A Systematic Review of Cohort Studies

In a systematic review of cohort studies of adolescent drinking and later outcomes, Jim McCambridge and colleagues show that although studies suggest links to worse adult physical and mental health and social consequences, existing evidence is of poor quality

Self-reported drunkenness among adolescents in four sub-Saharan African countries: associations with adverse childhood experiences

<p>Abstract</p> <p>Background</p> <p>Consumption of alcohol is associated with acute and chronic adverse health outcomes. There is a paucity of studies that explore the determinants of alcohol use among adolescents in sub-Saharan Africa and, in particular, that examine the effects of adverse childhood experiences on alcohol use.</p> <p>Methods</p> <p>The paper draws on nationally-representative data from 9,819 adolescents aged 12-19 years from Burkina Faso, Ghana, Malawi, and Uganda. Logistic regression models were employed to identify correlates of self-reported past-year drunkenness. Exposure to four adverse childhood experiences comprised the primary independent variables: living in a food-insecure household, living with a problem drinker, having been physically abused, and having been coerced into having sex. We controlled for age, religiosity, current schooling status, the household head's sex, living arrangements, place of residence, marital status, and country of survey. All analyses were conducted separately for males and females.</p> <p>Results</p> <p>At the bivariate level, all independent variables (except for coerced sex among males) were associated with the outcome variable. Overall, 9% of adolescents reported that they had been drunk in the 12 months preceding the survey. In general, respondents who had experienced an adverse event during childhood were more likely to report drunkenness. In the multivariate analysis, only two adverse childhood events emerged as significant predictors of self-reported past-year drunkenness among males: living in a household with a problem drinker before age 10, and being physically abused before age 10. For females, exposure to family-alcoholism, experience of physical abuse, and coerced sex increased the likelihood of reporting drunkenness in the last 12 months. The association between adverse events and reported drunkenness was more pronounced for females. For both males and females there was a graded relationship between the number of adverse events experienced and the proportion reporting drunkenness.</p> <p>Conclusions</p> <p>We find an association between experience of adverse childhood events and drunkenness among adolescents in four sub-Saharan African countries. The complex impacts of adverse childhood experiences on young people's development and behavior may have an important bearing on the effectiveness of interventions geared at reducing alcohol dependence among the youth.</p

Conjoint Developmental Trajectories of Young Adult Substance Use

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65293/1/j.1530-0277.2008.00643.x.pd

Cross-boundary Substance Uses Among Hong Kong Chinese Young Adults

The study documents the characteristics of Hong Kong residents who used substances in mainland China. Characteristics of such users were compared with those using substances elsewhere. A cross-sectional survey was used. Data analyses were stratified by gender, and multivariate analyses were performed. Respondents, Hong Kong adults aged 18–30 (n = 6,528), were interviewed using a mixed interviewer and computerized mobile phone method, at the Hong Kong-mainland China boundary. Cross-border substance users and other types of substance users had characteristics that were quite different (e.g., education level, perceived harmfulness of substance use in general, having friends who frequently used substances in mainland China). Cross-boundary substance users also found it easier to obtain substances in mainland China than in Hong Kong (males: 60.5%, females: 39.6%) and perceived no chance of being arrested in mainland China because of substance use (men: 28.8%, women: 24.5%). They tended to use substances in discos/rave parties together with friends (men: 77%, women: 81%), and substances were often obtained for free (men: 63.2%, women: 78%). Ecstasy and ketamine were often used (men: 86.5% & 79.4%, women: 81% & 70.2%), and multiple uses of different substances were common (men: 81.3%, women: 68.6%). Lower price, peer influence, and better availability were reasons behind cross-boundary substance use behaviors. Cross-boundary substance users have specific characteristics. Prevention policies should take these characteristics into account. Regional collaborations are highly warranted

Do people with intersecting identities report more high-risk alcohol use and lifetime substance use?

© 2018 Swiss School of Public Health (SSPH+) Objectives: We examined protective and non-protective effects of disadvantaged social identities and their intersections on lifetime substance use and risky alcohol consumption. Methods: Data from 90,941 participants of the Global Drug Survey 2015 were analysed. Multivariable logistic regressions were used to calculate adjusted odds ratios for lifetime use of nine psychoactive substances, as well as high-risk/harmful alcohol use. Disadvantaged identities from three categories (ethnicity, sexual identity, gender), and interactions between these were compared. Results: Findings indicate that participants with disadvantaged ethnic and sexual minority identities are more likely to use psychoactive substances compared to their counterparts. The intersecting identity ‘disadvantaged ethnic identity and sexual minority’ appears to be protective compared to those with just one of these identities. While female gender appears to be highly protective in general, it is not protective among females with disadvantaged social identities. Conclusions: Stark disparities in substance use between different social identities and their intersections emphasise the importance of intersectionality theories in public health research intervention design. Future research on health equity, particularly substance use, should target individuals with intersecting identities