Public or private religiosity: which Is protective for adolescent substance use and by what pathways?

While it is well understood that adolescent religiosity is associated with the use and abuse of licit and illicit substances, few studies have revealed the pathways through which religiosity buffers youth against involvement in such behavior. The aim of this study is to examine the complexity of the relationships between religiosity, sensation seeking, injunctive norms, and adolescent substance use. Using a national sample of adolescents (N = 18,614), negative binomial regression and path analysis were used to examine the various components of the relationship between religiosity and the use of cigarettes, alcohol, and marijuana. Results indicate that private religiosity moderates the relationship between key risk factors and substance use. Public and private religiosity were associated with tolerant injunctive substance use norms which, in turn, were associated with substance use. Implications for research and theory related to religiosity and adolescent substance use are discussed

Attacks intended to seriously harm and co-occurring drug use among youth in the United States

BACKGROUND: While it is known that substance use and violence co-occur, less is understood in terms of how this relationship might vary based on the degree of youth involvement in violence. OBJECTIVES: This study sought to examine the prevalence and degree that substance use disorders (SUD) and related intrapersonal and contextual factors were associated with violent attacks. METHOD: Repeated cross-sectional data from a population-based study (National Survey on Drug Use and Health) of youth ages 12–17 (n = 216,852) in the United States between 2002 and 2013 were pooled to increase the analytic sample size. Survey multinomial regression was used to examine psychosocial and substance use differences between youth reporting episodic (1–2 times, n = 13,091; 5.84%) and repeated violent attacks (3+ times, n = 1,819; 0.83%) in contrast with youth reporting no attacks. Additional analyses examined the association of sociodemographic, intrapersonal, and contextual factors with SUD among youth reporting violent attacks. RESULTS: The prevalence of SUD among youth with no attacks was 6% compared to 22% among episodic and 36% among repeatedly violent youth. Violence-involved youth were substantially more likely to experience elevated sensation-seeking, easy drug access, and recent drug offers and less likely to benefit from religiosity and protective substance use beliefs. CONCLUSIONS/IMPORTANCE: Findings highlight the importance of distinguishing between the various gradations of violence among youth in understanding the relationship between substance use and violence, and shed light on the intrapersonal and contextual factors that can help identify violent youth at greatest risk for substance use problems

Changing perspectives on marijuana use during early adolescence and young adulthood: Evidence from a panel of cross-sectional surveys

Introduction. Prior research has often overlooked potential cohort differences in marijuana views and use across adolescence and young adulthood. To begin to address this gap, we conduct an exploratory examination of marijuana views and use among American youth using a panel of cross-sectional surveys. Method. Findings are based on repeated, cross-sectional data collected annually from adolescents (ages 12-17; n = 230,452) and young adults (ages 18-21; n = 120,588) surveyed as part of the National Survey on Drug Use and Health between 2002 and 2014. For each of the birth years between 1986 and 1996, we combined a series of nationally representative cross-sections to provide multi-year data strings designed to approximate nationally representative cohorts. Results. Compared to youth born in the mid-to-late 1980s, youth born in the mid-1990s reported significantly higher levels of marijuana disapproval during the early adolescent years (Age 14: 1988 = 64.7%, 1994 = 70.4%) but lower levels of disapproval during the young adult years (Age 19: 1988 = 32.0%, 1994 = 25.0%; Age 20: 1988 = 27.9%, 1994 = 19.7%). Moreover, the prevalence of marijuana use among youth born in 1994 was significantly lower—compared to youth born in 1988—at age 14 (1988: 11.39%, 1994: 8.19%) and significantly higher at age 18 (1988: 29.67%, 1994: 34.83%). This pattern held even when adjusting for potential confounding by demographic changes in the population across the study period. Conclusions. We see evidence of changes in the perceptions of marijuana use among youth born during the late twentieth century.2018-01-0

Critical Field Strength in an Electroclinic Liquid Crystal Elastomer

We elucidate the polymer dynamics of a liquid crystal elastomer based on the time-dependent response of the pendent liquid crystal mesogens. The molecular tilt and switching time of mesogens are analyzed as a function of temperature and cross-linking density upon application of an electric field. We observe an unexpected maximum in the switching time of the liquid crystal mesogens at intermediate field strength. Analysis of the molecular tilt over multiple time regimes correlates the maximum response time with a transition to entangled polymer dynamics at a critical field strength.Comment: 4 pages, 3 figure

The evolutionary costs of immunological maintenance and deployment

<p>Abstract</p> <p>Background</p> <p>The evolution of disease resistance and immune function may be limited if increased immunocompetence comes at the expense of other fitness-determining traits. Both the maintenance of an immune system and the deployment of an immune response can be costly, and the observed costs may be evaluated as either physiological or evolutionary in origin. Evolutionary costs of immunological maintenance are revealed as negative genetic correlations between immunocompetence and fitness in the absence of infection. Costs of deployment are most often studied as physiological costs associated with immune system induction, however, evolutionary costs of deployment may also be present if genotypes vary in the extent of the physiological cost experienced.</p> <p>Results</p> <p>In this study we analyzed evolutionary and physiological costs of immunity in two environments representing food-limited and food-unlimited conditions. Patterns of genetic variation were estimated in females from 40 'hemiclone families' isolated from a population of <it>D. melanogaster</it>. Phenotypes evaluated included fecundity, weight measures at different time periods and resistance to <it>Providencia rettgeri</it>, a naturally occurring Gram-negative pathogen of <it>D. melanogaster</it>. In the food-limited environment we found a negative genetic correlation between fecundity in the absence of infection and resistance, indicative of an evolutionary cost of maintenance. No such correlation was observed in the food-unlimited environment, and the slopes of these correlations significantly differed, demonstrating a genotype-by-environment interaction for the cost of maintenance. Physiological costs of deployment were also observed, but costs were primarily due to wounding. Deployment costs were slightly exaggerated in the food-limited environment. Evolutionary costs of immunological deployment on fecundity were not observed, and there was only marginally significant genetic variation in the cost expressed by changes in dry weight.</p> <p>Conclusion</p> <p>Our results suggest that the costs of immunity may be an important factor limiting the evolution of resistance in food-limited environments. However, the significant genotype-by-environment interaction for maintenance costs, combined with the observation that deployment costs were partially mitigated in the food-unlimited environment, emphasizes the importance of considering environmental variation when estimating patterns of genetic variance and covariance, and the dubious nature of predicting evolutionary responses to selection from quantitative genetic estimates carried out in a single environment.</p

Subsonic and Transonic Wind Tunnel Testing of Two Inflatable Aerodynamic Decelerators

Two inflatable aerodynamic decelerator designs were tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center: a tension cone and an isotensoid. The tension cone consists of a flexible tension shell attached to a torus and the isotensoid employs a ram-air inflated envelope. Tests were conducted at Mach numbers from 0.3 to 1.08 and Reynolds numbers from 0.59 to 2.46 million. The main objective of these tests was to obtain static aerodynamic coefficients at subsonic and transonic speeds to supplement supersonic aerodynamic data for these same two designs. The axial force coefficients of both designs increased smoothly from subsonic through transonic Mach numbers. Dynamic data show significant oscillation of the tension cone and minimal oscillation of the isotensoid. The transonic and subsonic data will be used to assemble an inflatable decelerator aerodynamic database for use in computational analyses and system studies