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Acute exercise is a promising non‐pharmacological therapy for alleviating anxiety. However, the effects of different types of acute exercise on anxiety in adolescents and young adults remain unclear. Therefore, our study aims to conduct a network meta‐analysis to compare the effectiveness of various exercise interventions in improving anxiety in adolescents and young adults. We conducted an online literature search in five databases: PubMed, Web of Science, Embase, Cochrane Central Register of Controlled Trials, and PsycINFO. The search was conducted from inception to March 1, 2023, and was limited to English‐language publications. Pairwise and network meta‐analyses were performed using random‐effects models. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework was applied to rate the certainty of evidence. A total of 33 studies involving 1121 participants were included. The network meta‐analysis results revealed that mind–body exercise was the most effective intervention for reducing anxiety in adolescents and young adults (SMD = −0.36, 95% CI: −0.70, −0.03, moderate certainty). Additionally, aerobic exercise (SMD = −0.16, 95% CI: −0.28, −0.03, high certainty) showed significant reduction in anxiety, while resistance exercise (SMD = −0.09, 95% CI: −0.33, 0.14, moderate certainty) and multicomponent exercise (SMD = −0.01, 95% CI: −0.59, 0.57, moderate certainty) did not show significant reduction in anxiety. Moderate certainty evidence suggests that acute mind–body exercise may be the most effective type of exercise for reducing anxiety in adolescents and young adults. Future research should focus on conducting more multi‐arm randomized controlled trials to provide more direct evidence on the relative effectiveness of different exercise interventions. [ABSTRACT FROM AUTHOR]

Background: There is a paucity of knowledge concerning the psychological variables that serve to facilitate the connection between physical activity and self-efficacy, and the factors capable of moderating these pathways. This study aimed to examine the relationship between physical activity and self-efficacy among college students, with a focus on the mediating effect of grit and the moderating effect of gender. Methods: This study recruited 3,228 undergraduate students from a university in Shanghai, China. They completed the General Self-Efficacy Scale, the Short Grit Scale, and the International Physical Activity Questionnaire. Statistical analysis was conducted using SPSS 26.0 and the Process v4.0 plugin. Results: Physical activity had both a direct effect on self-efficacy (β = 0.07, 95% CI [0.04–0.11]) and an indirect effect through the two dimensions of grit: perseverance of effort (β = 0.06, 95% CI [0.04–0.07]) and consistency of interest (β = 0.03, 95% CI [0.02–0.04]). The mediating effect explained 53.27% of the total effect. Furthermore, gender moderated the relationship between perseverance of effort and self-efficacy, with a stronger effect observed in males (β = 0.08, t = 3.27, p < 0.01). Conclusion: The results revealed that grit is an underlying psychological mechanism that links physical activity and self-efficacy. Moreover, gender moderates the effect of perseverance of effort on self-efficacy, with a stronger effect observed in males. These findings have practical implications for educators to design tailored physical activity interventions that foster grit and self-efficacy among college students. [ABSTRACT FROM AUTHOR]

The extinguishment of the candle flame in the well-known candle-and-cylinder experiment has been erroneously viewed as caused by the complete consumption of oxygen, for many reasons. To address this misconception scientifically, a series of experiments are carried out to illustrate the phenomenon from a new point of view. Limewater [Ca(OH)[subscript 2]] placed at different heights in a container was used to qualitatively describe the distribution of CO[subscript 2] in an enclosed cylinder with one or two burning candles. Temperature sensors, CO[subscript 2] sensors, and oxygen (O[subscript 2]) sensors were employed to visually and quantitatively compare the content of CO[subscript 2] at different heights within the container. The resulting temperature curves show that the heat from combustion rose first and then descended soon afterward. Chemical and sensor detection of CO[subscript 2] in the highest two quadrants of the container indicated that the hot CO[subscript 2] gas rose initially and accumulated there in the highest part of the container. Then, the hot CO[subscript 2] gas descended gradually and created a CO[subscript 2] atmosphere surrounding the flame. As a result, the flame was extinguished by the buildup of CO[subscript 2] and depletion of oxygen in the gas in the vicinity of the flame. The change of oxygen concentration showed that there was a mixing process between the remaining air and the hot CO[subscript 2]. These results indicate that the extinguishment of the flame does not mean that the oxygen in the container was completely consumed. Knowing this helps students understand that the density of CO[subscript 2] depends on its temperature.

The design of spacecraft servo mechanism plays an important role in the control of the spacecraft. The research of control algorithm and the construction of simulation platform have important practical value. This paper modelles and simulates the mechanical, electrical, hydraulic parts of the aerospace servo mechanism. The overall model of the whole servo system is established. The mechanical structure of the servo mechanism is built in ADAMS and the hydraulic module is built by AMESim. Based on HM theory, the robust controller is built with Matlab toolbox. Combined with the dynamics model of ADAMS and AMESim, as well as the Matlab controller model, the joint simulation of each module is realized. Through the joint simulation technology, the simulation of physical system is more realistic, and the experimental results are also displayed more intuitively. This simulation has a good guiding significance for the design and construction of actual spacecraft servo mechanism system. [ABSTRACT FROM AUTHOR]