RESUMO
The demand for high-speed wireless communication systems has led to the development of ultrawide-band (UWB) antennas with a compact size and high performance. In this paper, we propose a novel four-port multiple-input multiple-output (MIMO) antenna with an asymptote-shaped structure that overcomes the limitations of existing designs for UWB applications. The antenna elements are placed orthogonally to each other for polarization diversity, and each element features a stepped rectangular patch with a tapered microstrip feedline. The unique structure of the antenna significantly reduces its dimensions to 42 × 42 mm2 (0.43λ×0.43λ@ 3.09GHz), making it highly desirable for use in small wireless devices. To further enhance the antenna's performance, we use two parasitic tapes on the ground plane at the back as decoupling structures between adjacent elements. The tapes are designed in a windmill shape and a rotating extended cross shape, respectively, to further improve the isolation. We fabricated and measured the proposed antenna design on a single-layer substrate (FR4) with a dielectric constant of 4.4 and a thickness of 1 mm. The measured results show that the impedance bandwidth of the antenna is 3.09-12 GHz, with an isolation of -16.4 dB, an envelope correlation coefficient (ECC) of 0.02, a diversity gain (DG) of 9.991 dB, an average total effective reflection coefficient (TARC) of -20 dB, an overall group delay value less than 1.4 ns, and a peak gain of 5.1 dBi. Although there may be some antennas that have better performance in one or two specific aspects, our proposed antenna has an excellent trade-off among all the antenna characteristics including bandwidth, size, and isolation. The proposed antenna also exhibits good quasi-omnidirectional radiation properties, making it well-suited for a range of emerging UWB-MIMO communication systems, particularly in small wireless devices. In summary, the compact size and ultrawide-band capabilities of the proposed MIMO antenna design, coupled with its improved performance compared to other recent UWB-MIMO designs, make it a promising candidate for 5G and next-generation wireless communication systems.
RESUMO
Introduction: Without parental support, left-behind adolescents are more likely than their peers to experience negative emotions and demonstrate aggressive behavior in the same frustrating situation. However, research on this subject has been sparse. To fill this gap and identify potential targets for intervention, this study sought to examine the relationships among factors influencing left-behind adolescents' aggressive behavior. Methods: A total of 751 left-behind adolescents were enrolled in a cross-sectional survey, with data collected using the Adolescent Self-Rating Life Events Checklist, Resilience Scale for Chinese Adolescents, Rosenberg Self-Esteem Scale, Coping Style Questionnaire, and Buss-Warren Aggression Questionnaire. The structural equation model was used for data analysis. Results: The results showed that left-behind adolescents reported higher levels of aggression. Further, the factors found to have a direct or indirect effect on aggressive behavior included life events, resilience, self-esteem, positive coping, negative coping, and household income. The results of confirmatory factor analysis indicated goodness of fit. In the face of negative life events, left-behind adolescents with high resilience, self-esteem, and positive coping were less likely to exhibit aggressive behavior (P < 0.05). Discussion: Left-behind adolescents can reduce their aggressive behavior by assuaging the adverse effects of life events via increased resilience and self-esteem as well as the adoption of positive coping strategies.
RESUMO
The objective of this study was to investigate and analyze the status and influential factors of gender equality awareness, self-esteem, and subjective well-being in school-age boys and girls. The results can help schools and teachers provide more effective gender equality and mental health education. In the study, 284 valid questionnaires were collected from a total of 323 school-age boys and girls in the Hunan Province, China (effective response rate of 87.93%). The questionnaire covered gender equality awareness, self-esteem, and subjective well-being, with the influencing factors analyzed through multiple linear regression. There was a significant correlation among children's gender equality awareness in all areas examined (family, occupation, and school), with both boys and girls having the lowest awareness of gender equality in occupational fields. The children's self-esteem and subjective well-being were significantly correlated as well. Gender equality awareness, self-esteem, and subjective well-being among boys and girls reflected different influential factors. Androgynous traits (neither feminine nor masculine) were conducive to the development of gender equality awareness and self-esteem among the children. Therefore, schools and teachers need to provide gender equality and mental health education according to the specific psychological characteristics of each boy and girl.
RESUMO
Objective: This study aims to explore the association between life events and coping styles, and how resilience and self-esteem mediate the association. Methods: A cross-sectional study was conducted among 981 left-behind adolescents (LBAs) in five junior high schools in Hunan Province, China, from April 13 to April 20, 2020. We utilized self-designed sociodemographic questionnaire, Adolescent Self-Rating Life Events Checklist, Resilience Scale Chinese Adolescent, Rosenberg Self-Esteem Scale, and Simplified Coping Style Questionnaire to assess the mental health of LBAs. Statistic description, Pearson correlation analysis, and structural equation model were adopted to analyze the data. Results: Results revealed that life events could negatively predict resilience (ß = -0.29, P < 0.001) and self-esteem (ß = -0.39, P < 0.001) and positively predict LBAs' positive coping style (ß = 0.28, P < 0.001) and negative coping style (ß = 0.21, P < 0.001). Self-esteem could also positively predict the resilience of LBAs (ß = 0.62, P < 0.001); resilience could negatively predict the negative coping style (ß = -0.21, P < 0.001) and positively predict the positive coping style (ß = 0.79, P < 0.001). Life events not only have direct effects on negative coping style (ß = 0.21) and positive coping style (ß = 0.28) but also have indirect effects on coping styles by affecting resilience (ß = -0.29) and self-esteem (ß = -0.39). The total effect of life events on coping styles was 0.32, where 34.37% was mediated by resilience and self-esteem. Conclusion: We proved that resilience and self-esteem mediated most of the effects of life events on coping styles. The findings had important implications for interventions to promote mental health of LBAs, particularly the enhancement of resilience and self-esteem.