Ninth Graders’ Energy Balance Knowledge and Physical Activity Behavior: An Expectancy-Value Perspective

Expectancy beliefs and task values are two essential motivators in physical education. This study was designed to identify the relation between the expectancy-value constructs (Eccles & Wigfield, 1995) and high school students’ physical activity behavior as associated with their energy balance knowledge. High school students (N = 195) in two healthful-living programs (i.e., combination of physical and health education) responded to measures of expectancy-value motivation, energy balance knowledge, in-class physical activity, and after-school physical activity. The structural equation modeling confirmed positive impact from expectancy beliefs and interest value to in-class physical activity (Path coefficient range from .19 to .26, ps \u3c .01). Cost perception was found exerting a negative impact on after-school physical activity but a positive one on lower level of understanding of energy balance (Path coefficient range from -.33 to -.39, ps \u3c .01). The findings painted a complex but meaningful picture about the motivational impact of expectancy-value constructs on physical activity and energy balance knowledge. School healthful-living programs should create motivational environments that strengthen students’ expectancy beliefs and interest value and alleviate their negative perceptions and experiences

The contributing role of physical education in youth’s daily physical activity and sedentary behavior

Background: School physical education (PE) is considered as an effective channel for youth to accumulate moderate-to-vigorous physical activity (MVPA) and reduce sedentary time. The purpose of this study was to determine the contributing role of PE in daily MVPA and sedentary time among youth. Methods: The study recruited 67 sixth grade children (29 boys; Mean age = 11.75) from two suburban schools at a U.S. Midwest state, 48 of whom contributed ≥10 hours of physical activity (PA) data per day were included for analysis. An objective monitoring tool (i.e., Sensewear armband monitor) was used to capture the participants’ MVPA and sedentary time for 7–14 days. Pearson product–moment correlation analysis (r), multi-level regression analyses, and analysis of variance were conducted for data analysis. Results: MVPA and sedentary time in PE showed significant positive associations with daily MVPA and sedentary time, respectively (r = 0.35, p \u3c 0.01; r = 0.55, p \u3c 0.01). Regression analyses revealed that one minute increase in MVPA and sedentary behavior in PE was associated with 2.04 minutes and 5.30 minutes increases in daily MVPA and sedentary behavior, respectively, after controlling for sex and BMI. The participants demonstrated a significantly higher level of MVPA (p = .05) but similar sedentary time (p = 0.61) on PE days than on non-PE days. Boys had significantly more daily MVPA (p \u3c .01) and less sedentary time (p \u3c .01) than girls; while higher BMI was associated with more sedentary time (p \u3c .01). Conclusions: PE displayed a positive contribution to increasing daily MVPA and decreasing daily sedentary time among youth. Active participation in PE classes increases the chance to be more active and less sedentary beyond PE among youth

Drive laser system for the DC-SRF photoinjector at Peking University

Photoinjectors are widely used for linear accelerators as electron sources to generate high-brightness electron beam. Drive laser, which determines the timing structure and quality of the electron beam, is a crucial device of photoinjector. A new drive laser system has been designed and constructed for the upgraded 3.5-cell DC-SRF photoinjector at Peking University. The drive laser system consists of a 1064 nm laser oscillator, a four- stage amplifier, the second and fourth harmonic generators, the optical system to transfer the UV pulses to the photocathode, and the synchronization system. The drive laser system has been successfully applied in the stable operation of DC-SRF photoinjector and its performance meets the requirements. 266 nm laser with an average power close to 1W can be delivered to illuminate the Cs2Te photocathode and the instability is less than 5% for long time operation. The design consideration for improving the UV laser quality, a detailed description of laser system, and its performance are presented in this paper.Comment: 6 pages, 8 figures, submit to CP

Gender and Grade Differences in Knowledge and Behaviors Related to Active Living for Adolescents

The purpose of this study was to examine differences by gender and grade in middle school students’ physical activity and fitness (PAF) knowledge, physical activity, and sedentary behavior (SB). The study took place at one middle school located in the Southeastern region of the United States. Boys (n = 136) and girls (n = 166) in 6th (n =129), 7th (n = 96) and 8th (n = 77) completed a PE Metrics written test to assess PAF knowledge. They (N = 312) also completed the validated Youth Activity Profile to report physical activity at school (PAS), physical activity at home (PAH), and SB. Two-way (gender by grade) multivariate analysis of variances (MANOVA) followed by Bonferroni post-hoc multiple comparison analysis were conducted. Box’s M test of covariance matrices showed no statistical violation (M = 37.78, F = .73, p \u3e .05). The two-way MANOVA showed significant gender (Wilks’s λ = .94, F = 4.40, p \u3c .01, N(2/p) \u3c .06) and grade main effects (Wilks’s λ = .89, F = 4.20, p \u3c .01, N(2/p) \u3c .05). No significant gender by grade interaction effect was detected (p \u3e .05). Subsequent tests of between subjects effect located the significant gender difference in PAS favoring boys (F = 9.3, p \u3c .01, N(2/p) = .03). Boys and girls showed no significant difference on PAF knowledge, PAH, and SB. Significant grade differences were observed for PAS (F = 8.57, p \u3c .01, N(2/p) =.06), PAH (F = 8.18, p \u3c .01, N(2/p) =.05), and SB (F = 4.61, p = .01, N(2/p) \u3e = .03). Sixth grade students showed significantly higher levels of PAS and PAH than 7th and 8th grade students (p \u3c .05 or \u3c .01). Sixth grade students further showed significantly lower SB than 7th grade students (p \u3c .05). This study found boys to be more physically active during school hours than girls, and students in lower grades to be more active than higher grade students. Future school-based interventions should take into account gender and grade-based differences

Sparse least squares support vector regression for nonstationary systems

A new adaptive sparse least squares support vector regression algorithm, referred to as SLSSVR has been introduced for the adaptive modeling of nonstationary systems. Using a sliding window of recent data set of size N to track t he non-stationary characteristics of the incoming data, our adaptive model is initially formulated based on least squares support vector regression with forgetting factor (without bias term). In order to obtain a sparse model in which some parameters are exactly zeros, a l 1 penalty was applied in parameter estimation in the dual problem. Furthermore we exploit the fact that since the associated system/kernel matrix in positive definite, the dual solution of least squares support vector machine without bias term, can be solved iteratively with guaranteed convergence. Furthermore since the models between two consecutive time steps there are (N-1) shared kernels/parameters, the online solution can be obtained efficiently using coordinate descent algorithm in the form of Gauss-Seidel algorithm with minimal number of iterations. This allows a very sparse model per time step to be obtained very efficiently, avoiding expensive matrix inversion. The real stock market dataset and simulated examples have shown that the proposed approaches can lead to superior performances in comparison with the linear recursive least algorithm and a number of online non-linear approaches in terms of modelling performance and model size

Tracking Energy Balance in Adolescents: Levels of Compliance, Energy Flux, and Learning

Background/Objective: Advancing knowledge about energy balance (EB) is important for helping to reverse the obesity epidemic in many modern societies. This study examined adolescents\u27 experience and perception of using an objective self-monitoring tool (SenseWear armband; SWA) and a portable diet journal to track EB for 7 days. Methods: Forty-five 6th grade students in a midwestern state of the United States [Caucasian: n = 34, 76%; age: 11.7 ± 1.8 years; body mass index (BMI): 20.84 ± 3.94] participated in the study. The SWA, diet journal, and semistructured individual interview were used to measure energy expenditure (EE) and physical activity (PA), energy intake (EI), and perception of the experience, respectively. Mixed methods were used to analyze quantitative and qualitative data. Results: It was found that the participants were physically active over the week (moderate-to-vigorous PA: 218.06 ± 26.50 minutes per day). Both SWA (% of wearing time: 85 ± 5%) and diet journal (days of using: 5.58 ± 2.15 days), especially the latter, were found to be under-used. A conceptual model depicting the adolescents\u27 experience and perception was established based on the results. Conclusion: The study indicates that the majority of adolescents were able to effectively use the SWA and the diet journal to track EB over time. Qualitative observations revealed that tracking EI and EE with these tools provided a valuable, experiential way for youth to learn about EB. The findings support the continued exploration of self-monitoring EB for promoting knowledge and awareness about EB among adolescents

Evaluation of a Concept-Based Physical Education Unit for Energy Balance Education

Background: Physical education (PE) is a key channel that impacts children’s decisions and behaviors for healthful living. This study evaluated the effects of a concept-based PE (CBPE) instructional unit, featured by energy balance (EB) education, on students’ knowledge learning, situational interest, cognitive, and physical engagements as well as teachers’ perceptions. Methods: Fourth and 5th grade students (n = 468) in a mid-western state of the United States were recruited as the participants. Four elementary schools were randomized to the CBPE or control groups. Students’ EB knowledge, situational interest, cognitive engagement, and physical engagement were measured by a knowledge test, the Situational Interest Scale—Elementary, written task sheets, and accelerometers, respectively, while teachers’ perceptions of the CBPE unit were captured by individual interviews at the end of the experiment. Results: The CBPE group showed a significant increase in EB knowledge, while the control did not. Both groups showed a similar increasing trend for situational interest over time, although the statistical results favored the control group. For physical engagement, the CBPE group demonstrated a statistically different but substantively similar level of in-class physical activity compared to the control group. The CBPE group also showed a moderate level of cognitive engagement throughout the unit. The PE teachers reported overall positive perceptions about teaching the CBPE unit. Conclusion: These results support the utility of the CBPE unit in enhancing EB education along with facilitating positive student interest and engagement as well as positive teaching experiences

Learners\u27 Motivational Response to the Science, PE, & Me! Curriculum: A Situational Interest Perspective

Background: The Science, PE, & Me! (SPEM) curriculum is a concept-based physical education curriculum that offers students coherent educational experiences for constructing health-related fitness knowledge through movement experiences. The purpose of this study was to evaluate students’ motivational response to the SPEM curriculum from the situational interest perspective. Methods: The study used a cluster randomized controlled design in which 30 elementary schools in one of the largest metropolitan areas in the eastern United States were randomly assigned to an experimental or comparison condition. Although all students in the 3rd, 4th, and 5th grades in the targeted schools were eligible to participate in the study, a random sample of students from the experimental (n = 1749; 15 schools) and comparison groups (n = 1985; 15 schools) provided data. Students’ motivational response to the SPEM curriculum or comparison curriculum was measured using the previously validated Situational Interest Scale Elementary. Data were analyzed using structural mean modeling. Results: The results demonstrated that the experimental group (as reference group) showed significantly higher enjoyment (z = 2.01), challenge (z = 6.54), exploration (z = 12.195), novelty (z = 8.80), and attention demand (z = 7.90) than the comparison group. Conclusion: The findings indicate that the SPEM curriculum created a more situationally interesting context for learning than the comparison physical education curriculum

Temporal Changes in Energy-Balance Behaviors and Home Factors in Adolescents with Normal Weight and Those with Overweight or Obesity

This study aimed to examine the temporal changes in energy-balance behaviors and home factors in adolescents with normal weight and those with overweight or obesity (OWOB). Adolescents or parent proxies completed survey assessments two to four years before (T0; n = 82), ≤ six months before (T1; n = 68), and ≤ three months after the COVID-19 pandemic outbreak (T2; n = 82), to capture energy-balance behaviors (i.e., physical activity [PA], screen time, sleep) and home factors (i.e., food environment, food worry, parent support for PA). At T0 and T1 (before pandemic), participants visited our laboratory for anthropometric measurements. At T2, parent proxies also completed a survey to report the COVID-19 pandemic exposure and impact. The participating families experienced moderate levels of pandemic exposure and impact, although exposure was higher in the OWOB group (F1,78= 5.50, p \u3c .05). Repeated-measure multivariate analyses of covariance (RM-MACOVAs) did not show significant time by weight status interaction effects (p \u3e 0.05; adjusted for race and sex). However, the models detected significant time (T0 vs. T2) by race (White vs. non-White) interaction effect (λ7,66=0.81, p \u3c 0.05), with greater increase in food worry (F1,72 = 4.36, p \u3c .05) but less increase in screen time (F1,72= 4.54, p \u3c .05) among the non-White group. Graphical visualization depicted some favorable change patterns in adolescents with normal weight (vs. those with OWOB) for certain behaviors and home factors (e.g., number of days per week ≥ 60 mins PA, food worry). These findings suggest that the COVID-19 pandemic exerted greater adverse effects on adolescents with OWOB and specifically on screen time and food worry among non-White adolescents