Some effects of short-term immediate prior exposure to light change on responding for light change

The present experiment was designed to test the prediction that short-term immediate prior exposure to one light change will reduce not only the reward value of that light change but also a light change in the opposite direction. The prediction arises from explanations of sensory reinforcement in terms of a single general need for stimulus change. Each 20-min LCBP (light-contingent barpressing) session was divided into halves (exposure and test periods, respectively). Rats received either light onset or light offset as the reinforcer in the two halves according to a 2 by 2 design. The prediction was confirmed for the first 10 of 15 LCBP sessions, but thereafter exposure to one direction of light change had little or no effect on responding for light change in the other direction. The results were interpreted in terms of (a) an increase across sessions in the level of novelty and change the animals were capable of accommodating and (b) separate reinforcing effects for different sensory changes.     

Factorial validity and invariance of a self-report measure of physical activity among adolescent girls

We examined the factorial validity and factorial invariance of the 3-day physical activity recall (3DPAR) using confirmatory factor analysis. Adolescent girls from two cohorts (N = 955, N = 1,797) completed the 3DPAR in the eighth grade; participants in Cohort 2 (N = 1,658) completed the 3DPAR again 1 year later in the ninth grade. The 3DPAR was best represented by two uncorrelated factors in Cohort 1. The two-factor, uncorrelated measurement model exhibited evidence of cross-validity between Cohorts 1 and 2. This model also exhibited configural and partial metric invariance between race and across time. Hence, the 3DPAR consisted of two uncorrelated factors underlying three indicators of both moderate and vigorous physical activity in this sample of Black and White girls across a 1-year period. The 3DPAR can be used in cross-sectional, prospective cohort and intervention studies that examine mediators and moderators of physical activity among Black and White adolescent girls.     

Physical activities and sedentary pursuits in African American and Caucasian girls

The purposes of this study were to describe and compare the specific physical activity choices and sedentary pursuits of African American and Caucasian American girls. Participants were 1,124 African American and 1,068 Caucasian American eighth-grade students from 31 middle schools. The 3-Day Physical Activity Recall (3DPAR) was used to measure participation in physical activities and sedentary pursuits. The most frequently reported physical activities were walking, basketball, jogging or running, bicycling, and social dancing. Differences between groups were found in 11 physical activities and 3 sedentary pursuits. Participation rates were higher in African American girls (p < or = .001) for social dancing, basketball, watching television, and church attendance but lower in calisthenics, ballet and other dance, jogging or running, rollerblading, soccer, softball or baseball, using an exercise machine, swimming, and homework. Cultural differences of groups should be considered when planning interventions to promote physical activity.     

Perceived parental social support and psychological control predict depressive symptoms for lesbian,gay, bisexual,transgender, queer,or questioning youth in the United States

Salient practices in the parenting literature—support and control—have seldom been applied to understanding lesbian, gay, bisexual, transgender, queer, or questioning (LGBTQ) youth mental health. We examine associations among perceived parental social support, psychological control, and depressive symptoms for LGBTQ youth in the United States (n = 536; M_age = 18.98; 48.1% women; 25.2% Black or African American; 37.1% Hispanic or Latino/a/x). Data were collected in 2011–2012. Results indicated joint effects of social support and psychological control predicting youth depressive symptoms. Multiple group analysis yielded a significant interaction of parenting practices for youth whose parent(s) did not know their LGBTQ identity. Findings support further consideration of parental support and control in relation to LGBTQ youth well-being.     

A comparative study of baseball bat performance

The results of a comparative study of five aluminum and one wood baseball bats are presented. The study includes an analysis of field data, high-speed laboratory testing, and modal analysis. It is found that field performance is strongly correlated with the ball–bat coefficient of restitution (BBCOR) and only weakly correlated with other parameters of the bat, suggesting that the BBCOR is the primary feature of a bat that determines its field performance. It is further found that the instantaneous rotation axis of the bat at the moment of impact is very close to the knob of the bat and that the rotational velocity varies inversely with the moment of inertia of the bat about the knob. A swing speed formula is derived from the field data and the limits of its validity are discussed. The field and laboratory measurements of the collision efficiency are generally in good agreement, as expected on theoretical grounds. Finally, the BBCOR is strongly correlated with the frequency of the lowest hoop mode of the hollow bats, as predicted by models of the trampoline effect.     

Don't Forget Us!Messages from the Mental Health Foundation Committee's Report on Services for Children with Learning Disabilities and Severe Challenging Behaviour

Philippa Russell (Director of the Council for Disabled Children) who chaired the Mental Health Foundation Committee on Services for Children with Learning Disabilities and Severe Challenging Behaviour, provides an overview of the evidence received and summarises its report's recommendations.