Research has rarely considered within-person variability in executive function. Using a web-based program, this study investigated end-of-day executive function for 2 weeks among 178 racially/ethnically diverse adolescents (M age = 14.53). For each core component of executive function (cognitive flexibility, inhibitory control, working memory), short-term practice effects were identified for the first 4 days of assessments, and no fatigue effects emerged for the remaining days. Another 5 days were needed to achieve good reliability for assessing executive function at the between-person level. Considerable daily variation was identified for each component and the overall construct of executive function, with between 40% and 55% of the variation attributed to within-person variability. These daily variations were associated with adolescents' affective and academic experiences during the day. Public Significance StatementThis study identified significant daily variation in adolescents' executive function, which was influenced by their affective and academic experiences during the day. The current findings highlight important ways to improve adolescents' executive function in everyday life.

Social norms around adolescent risky health behaviors have been often studied in separate developmental settings (e.g., family norms, peer norms), and little is known regarding the overall patterns of social norms across contexts and how they influence adolescent risky health behaviors. This study explored profiles of social norms around risky health behaviors across family, peer, and school settings, using data from 11,086 adolescents (50% female; 49% White, 22% Black, 18% Latinx, 8% Asian American, 3% other race/ethnicities) in the National Longitudinal Study of Adolescent to Adult Health. Five profiles of social norms around risky health behaviors emerged. Only a small portion of the sample experienced either congruent-restrictive (6%) or congruentpermissive (10%) social norms across settings. The majority experienced incongruent social norms, including the developmentally normative-low risk (30%), developmentally normative-high risk (40%), and resilient (5%) profiles. Adolescents with the congruent-restrictive profile and developmentally normative-low risk profiles exhibited the least risky health behaviors over time, followed by those with the resilient profile, and adolescents with the developmentally normativehigh risk and the congruent-permissive profile exhibited the greatest risky health behaviors over time. Each profile was associated with unique developmental, socio-demographic, and psychosocial characteristics. The findings highlighted the complexity of social norms across contexts and the developmental versus risky natures of these social norm profiles.

Based on forced vibration tests for high-performance concrete (HPC), the influence of bridge vibration induced by traveling vehicle on compressive strength and durability of HPC has been studied. It is concluded that 1 d and 2 d compressive strength of HPC decreased significantly, and the maximum reduction rate is 9.1%, while 28 d compressive strength of HPC had a slight lower with a 3% maximal drop under the action of two simple harmonic vibrations with 2 Hz, 3 mm amplitude, and 4 Hz, 3 mm amplitude. Moreover, the vibration had a slight effect on the compressive strength of HPC when the simple harmonic vibration had 4 Hz and 1 mm amplitude; it is indicated that the amplitude exerts a more prominent influence on the earlier compressive strength with the comparison of the frequency. In addition, the impact of simple harmonic vibration on durability of HPC can be ignored; this shows the self-healing function of concrete resulting from later hydration reaction. Thus, the research achievements mentioned above can contribute to learning the laws by which bridge vibration affects the properties of concrete and provide technical support for the design and construction of the bridge deck pavement maintenance.

No abstract

In cold orbital forging (COF) processes, large stress, displacement and vertical vibration of the COF machine are bad for the quality of the part and the fatigue life of the COF machine. It is necessary to investigate the static and dynamic performance of the COF machine and provide methods for reducing the stress, displacement and vertical vibration of the COF machine. In this paper, finite element analysis, theoretical analysis, numerical simulation and experimental analysis were applied to study the static and dynamic performance of a 6300 KN COF machine. The static and dynamic analyses were verified effectively by carrying out strain and vertical vibration test experiments. In the static analysis, the large stress and displacement positions of the COF machine were mainly distributed near the working table and the junction between the working table and the column. Large stress and displacement will be bad for the quality of the part and the fatigue life of the COF machine. Structural optimizations of the COF machine include ribbed plates on the working table and beam. This structural optimization method of the COF machine obviously reduced the stress and displacement of the COF machine. When the angular velocities of the eccentric rings were 8π rad/s, the vertical vibration of the swing shaft is a low-frequency vibration. The existence of absorber obviously reduced the vertical vibration of the COF machine.