Evaluation of a randomized intervention to delay sexual initiation among fifth-graders followed through the sixth grade

US adolescents initiate sex at increasingly younger ages, yet few pregnancy prevention interventions for children as young as 10-12 years old have been evaluated. Sixteen Washington, DC schools were randomly assigned to intervention versus control conditions. Beginning in 2001/02 with fifth-grade students and continuing during the sixth grade, students completed pre-intervention and post-intervention surveys each school year. Each year, the intervention included 10-13 classroom sessions related to delaying sexual initiation. Linear hierarchical models compared outcome changes between intervention and control groups by gender over time. Results show the intervention significantly decreased a rise over time in the anticipation of having sex in the next 12 months among intervention boys versus control boys, but it had no other outcome effects. Among girls, the intervention had no significant outcome effects. One exception is that for both genders, compared with control students, intervention students increased their pubertal knowledge. In conclusion, a school-based curriculum to delay sexual involvement among fifth-grade and sixth-grade high-risk youths had limited impact. Additional research is necessary to outline effective interventions, and more intensive, comprehensive interventions may be required to counteract adverse circumstances in students' lives and pervasive influences toward early sex.ClinicalTrials. gov identifier: NCT00341471.     

Do siblings influence one another? Unpacking processes that occur during sibling conflict

This study examined the extent to which 205 sibling dyads influenced each other during conflict. Data were collected between 2013 to 2015. The sample included 5.9% Black, 15.1% South Asian, 15.1% East Asian, and 63.8% White children. Older siblings were between 7–13 years old (Female = 109) and younger siblings were 5–9 years old (Female = 99). Siblings' conflict resolution was analyzed using dynamic structural equation modeling. Modeling fluctuations in moment-to-moment data (20-s intervals) allowed for a close approximation of causal influence. Older and younger siblings were found to influence one another. Younger sisters were more constructive than younger brothers, especially in sister–sister dyads. Sibling age gap predicted inertia in older siblings. Socialization processes within sibling relationships are discussed.     

Course of depression and anxiety symptoms during the transition to parenthood for female adolescents with histories of victimization

The aim of the current study was to increase understanding of how victimization history impacts the longitudinal course of depression and anxiety in a sample of 55 adolescents emerging into parenthood. Adolescents were interviewed about their victimization experiences during their second trimester of pregnancy, and interviews were subsequently classified according the Maltreatment Classification Scale (Barnett, Manly, & Cicchetti, 1993). Adolescents reported on their symptoms of depression and anxiety prenatally and 6 and 12 months postpartum. Growth curve modeling revealed that, on average, there was a steady linear decline in depression and anxiety symptoms across the transition to parenthood, with a rate of change of 25% and 20%, respectively, from the prenatal assessment to 12 months postpartum. Sexual abuse history attenuated the likelihood of a decrease in depressive symptoms over time. Neglect history was associated with higher prenatal levels of anxiety, as well as a steeper decline in anxiety symptoms over time. Future research is needed to determine the role of poly-victimization in predicting the onset and change of depression and anxiety symptoms. Findings from the current study have the potential to aid in the design of preventative and intervention efforts to reduce risks of mental health difficulties in adolescent parents.     

Validity and reliability of GPS for measuring distance travelled in field-based team sports

Abstract

The aim of the present study was to examine the effects of movement intensity and path linearity on global positioning system (GPS) distance validity and reliability. One participant wore eight 1-Hz GPS receivers while walking, jogging, running, and sprinting over linear and non-linear 200-m courses. Five trials were performed at each intensity of movement on each 200-m course. One receiver was excluded from analysis due to errors during data collection. The results from seven GPS receivers showed the mean (±s) and percent bias of the GPS distance values on the 200-m linear course were 205.8 ± 2.4 m (2.8%), 201.8 ± 2.8 m (0.8%), 203.1 ± 2.2 m (1.5%), and 205.2 ± 4 m (2.5%) for the walk, jog, run, and sprint trial respectively. Walk and sprint distances were significantly different from jogging and running distances (P < 0.05). The GPS distance values on the 200-m non-linear course were 198.9 ± 3.5 m (?0.5%), 188.3 ± 2 m (?5.8%), 184.6 ± 2.9 m (?7.7%), and 180.4 ± 5.7 m (?9.8%) for the walk, jog, run, and sprint trial respectively; these were significantly lower than those for the corresponding values on the linear course (P < 0.05). Differences between all non-linear movement intensities were significant (P < 0.05). The overall coefficient of variation within and between receivers was 2.6% and 2.8% respectively. Path linearity and movement intensity appear to affect GPS distance accuracy via inherent positioning errors, update rate, and conditions of use; reliability decreases with movement intensity.     

A comparison of two methods for the calculation of accumulated oxygen deficit

Abstract

The aim of this study was to compare accumulated oxygen deficit data derived using two different exercise protocols with the aim of producing a less time-consuming test specifically for use with athletes. Six road and four track male endurance cyclists performed two series of cycle ergometer tests. The first series involved five 10 min sub-maximal cycle exercise bouts, a VO_2peak test and a 115% VO_2peak test. Data from these tests were used to estimate the accumulated oxygen deficit according to the calculations of Medbø et al. (1988). In the second series of tests, participants performed a 15 min incremental cycle ergometer test followed, 2 min later, by a 2 min variable resistance test in which they completed as much work as possible while pedalling at a constant rate. Analysis revealed that the accumulated oxygen deficit calculated from the first series of tests was higher (P<0.02) than that calculated from the second series: 52.3±11.7 and 43.9±6.4 ml·kg^?1, respectively (mean±s). Other significant differences between the two protocols were observed for VO_2peak, total work and maximal heart rate; all were higher during the modified protocol (P<0.01 and P<0.02, respectively). Oxygen kinetics were also significantly faster during the modified 2 min maximal test. We conclude that the difference in accumulated oxygen deficit between protocols was probably due to a reduced oxygen uptake, possibly caused by a slower oxygen on-response during the 115% VO_2peak test in the first series, and VO₂—power output regression differences caused by an elevated VO ₂ during the early stages of the second series.     

Temporal Aspects of the VO2 Response at the Power Output Associated with VO2peak in Well Trained Cyclists—Implications for Interval Training Prescription

Abstract

The power output achieved at peak oxygen consumption (VO ₂Peak) and the time this power can be maintained (i. e., Tmax) have been used in prescribing high-intensity interval training. In this context, the present study examined temporal aspects of the VO₂ response to exercise at the cycling power that output well trained cyclists achieve their VO ₂peak (i. e., Pmax). Following a progressive exercise test to determine VO ₂peak, 43 well trained male cyclists (M age = 25 years, SD = 6; M mass = 75 kg, SD = 7; M VO₂ peak = 64.8 ml-kg¹ min^?1, SD = 5.2) performed two Tmax tests 1 week apart. Values expressed for each participant are means and standard deviations of these two tests. Participants achieved a mean VO ₂peak during the Tmax test after 176 s (SD = 40; M = 74% of Tmax, SD = 12) and maintained it for 66 s (SD = 39; M = 26% of Tmax, SD = 12). Additionally, they obtained mean 95% of VO ₂peak after 147 s (SD = 31; M = 62% of Tmax, SD = 8) and maintained it for 95 s (SD = 38; M = 38 % of Tmax, SD = 8). These results suggest that 60–70 % of Tmax is an appropriate exercise duration for a population of well trained cyclists to attain VO ₂peak during exercise at Pmax. However, due to intraparticipant variability in the temporal aspects of the VO₂ response to exercise at Pmax, future research is needed to examine whether individual high-intensity interval training programs for well trained endurance athletes might best be prescribed according to an athlete's individual VO₂ response to exercise at Pmax.     

School-based assessment of practical competence in science: Some issues from English experience

Teacher-conducted assessments of practical skills are a compulsory component of GCSE examinations in science in England and Wales. The paper presents some of the findings of a research project that investigated this aspect of a science teacher's work. The project was concerned principally with the ways in which science teachers interpreted and operationalised the policy decision of central government and examination boards that teachers assume responsibility for the internal assessment of the practical competence of pupils aged 14–16 preparing for GCSE examinations in science. Specializations: the social history and politics of school science education     

Plain language summaries: Enabling increased diversity,equity, inclusion and accessibility in scholarly publishing

• Plain language summaries (PLS) are accessible, short, peer-reviewed summaries of scholarly journal articles written in non-technical language.
• The aim of PLS is to enable a broader audience of experts and non-experts to understand the original article.
• Here, we outline the evidence base for the value and impact of PLS and how they can enable diversity, equity, inclusion and accessibility in scholarly publishing.
• PLS can diversify readership and authorship, address information inequity, include typically under-represented stakeholders and provide an accessible route into scholarly literature.