Six-year trends and intersectional correlates of meeting 24-Hour Movement Guidelines among South Korean adolescents:Korea Youth Risk Behavior Surveys,2013-2018

Background:Grounded in intersectionality theory,this study examined the 6-year prevalence trend and correlates in meeting Canada’s 24-Hour Movement Guidelines(Guidelines hereafter)in a nationally representative adolescent samples of South Korea(officially the Republic of Korea).Methods:Self-reported,annually repeated cross-sectional data collected between 2013 and 2018 were used(n=372,433,12-17 years old,47.9%females).Adolescents were categorized as meeting or not meeting different sets of physical activity,screen time(ST),and sleep recommendations within the Guidelines,separately for weekdays and weekend days.Intersectional correlates included sex and social class(i.e.,family economic status,parental education level,and academic performance).Multiple logistic regression analyses were performed.Results:Overall,the proportion of adolescents meeting physical activity,ST,and sleep recommendations were 5.3%,60.3%,and 10.2%on weekdays and 5.3%,28.2%,and 46.4%on weekend days,respectively.Between 2013 and 2018,no substantial changes were observed for meeting the physical activity or sleep recommendation,while meeting the ST recommendation was markedly lower in 2018.The proportion of meeting all 3 recommendations were 0.5%for weekdays and 0.8%for weekend days.Overall,compared to female adolescents,male adolescents were consistently associated with more favorable patterns of meeting different sets of recommendations,regardless of social class.Among females only,social class appeared to be not important or even detrimental in meeting different sets of recommendations.Being male,compounded with social class,was associated with meeting the ST recommendation.Conclusion:Less than 1%of Korean adolescents met the overall Guidelines.Intersectionality-based analysis and intervention may be important in promoting healthy active lifestyles among South Korean adolescents.

The Convex-Set Algebra and Intersection Theory on the Toric Riemann–Zariski Space

In previous work of the author,a top intersection product of toric b-divisors on a smooth complete toric variety is defined.It is shown that a nef toric b-divisor corresponds to a convex set and that its top inetersection number equals the volume of this convex set.The goal of this article is to extend this result and define an intersection product of sufficiently positive toric b-classes of arbitrary codimension.For this,we extend the polytope algebra of McMullen to the so called convex-set algebra and we show that it embeds in the toric b-Chow group.In this way,the convex-set algebra can be viewed as a ring for an intersection theory for sufficiently positive toric b-classes.As an application,we show that some Hodge type inequalities are satisfied for the convex set algebra.