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This study investigates portfolio optimization within the Mean–Variance framework using alternative estimators for expected returns and risk. Based on daily data of VN30 stocks from March 2021 to December 2025, nine portfolio strategies are constructed by combining three return estimators (historical mean, CAPM, and Exponential Moving Average) with three risk estimators (sample covariance, Ledoit–Wolf shrinkage covariance, and semicovariance). Portfolios are optimized by maximizing the Sharpe ratio under realistic weight constraints and a post-optimization sparsification procedure to improve implementability. Empirical results indicate that portfolios using EMA-based expected returns combined with Ledoit–Wolf or semicovariance estimators deliver more stable and superior out-of-sample performance over 1-, 3-, and 6-month horizons. In contrast, strategies relying on historical mean returns with sample covariance suffer from severe performance degradation, while CAPM-based approaches underperform consistently. These findings underscore the importance of adaptive return estimation and robust risk modeling in emerging equity markets and offer timely implications for portfolio construction in Vietnam as it prepares for a potential upgrade to emerging market status.

Physical activity plays a crucial role in maintaining health and reducing stress, particularly among students in demanding disciplines such as nursing. This study examines how social media and self-efficacy influence exercise behavior and stress relief, drawing on the Social Cognitive Theory and Uses and Gratifications Theory. Data were collected from 295 Vietnamese undergraduate nursing students and analyzed using structural equation modeling (SEM). The results reveal that both social media use and self-efficacy significantly and positively affect stress relief, with exercise behavior acting as a mediating variable. The proposed model explains 69.2% of the variance in exercise behavior and 57.8% in stress relief. These findings suggest that exposure to fitness-related content and higher confidence in one’s ability to exercise contribute to greater engagement in physical activity and improved stress management. The study highlights the importance of integrating digital media and self-efficacy enhancement strategies into university health promotion programs. Universities should consider using social media platforms to share motivational content, facilitate online exercise communities, and organize student-led fitness initiatives. Policy-makers may also support campaigns promoting physical activity as an effective stress management strategy for health-related professions.

Grounded in Conservation of Resources theory, this study examines how psychological capital influences organizational citizenship behavior among Vietnamese IT expatriates in Taiwan, focusing on the mediating role of cross-cultural adjustment and the moderating influence of cultural intelligence. Survey data from 500 participants were analyzed using PROCESS Macro and AMOS. The results show that hope, self-efficacy, and optimism significantly predict cross-cultural adjustment, whereas resilience does not. All psychological capital dimensions positively predict organizational citizenship behavior, and cross-cultural adjustment partially mediates these relationships, indicating that psychological resources promote discretionary behaviors more effectively when expatriates achieve cultural ease. Cultural intelligence significantly strengthens the psychological capital, cross-cultural adjustment link, with the strongest effects observed for self-efficacy and optimism, highlighting the importance of cultural capability in resource deployment. This study advances expatriate research by integrating psychological capital, cross-cultural adjustment, cultural intelligence, and organizational citizenship behavior into a unified model within an East Asian technology context. Practical implications include developing psychological capital-cultural intelligence training, enhancing intercultural onboarding practices, and supporting migrant professional networks to improve expatriate retention and performance.

Partial Least Squares Structural Equation Modeling has gained considerable attention across diverse academic fields, including business, social sciences, marketing, and management. A key challenge in utilizing PLS-SEM is balancing explanatory and predictive power when selecting the most suitable model from competing alternatives. This paper explores the effectiveness of various quality criteria for evaluating causal-predictive models, with a focus on resistance to change in Vietnamese SMEs. The study emphasizes the importance of both in-sample and out-of-sample predictions, using metrics such as R², BIC, AIC, Q², RMSE, MAE, and CVPAT. The findings reveal that traditional criteria like R² may not be sufficient for identifying the best model, while PLSpredict, CVPAT, BIC, and AIC offer superior performance in determining the optimal balance between explanatory and predictive capabilities. These insights provide practical implications for researchers and practitioners, highlighting the need to tailor model selection to specific objectives, such as theory development or real-world forecasting. For practitioners, the study underscores the benefits of leveraging simpler, more generalizable models for robust decision-making in dynamic or resource-constrained environments.

In recent years, increased understanding has led individuals to prioritize exercise for the purposes of sustaining health, achieving weight loss, preventing various diseases, and alleviating stress. This research aims to deepen our understanding of human exercise behavior by examining the factors that influence this trend. The writers utilize the framework of "Social Learning Theory" to elucidate the correlation among influencing factors, exercise behavior, and stress relief. This study details a survey that involved 323 participants, primarily Vietnamese college students with a focus on tourism. The analysis comprised 151 males and 172 females. This research employed structural equation modeling (SEM) for data analysis. The results showed that enabling circumstances and social impact have a positive impact on stress relief, with exercise activity playing a mediating role. The model accounts for 57.3% of the variance in exercise behavior and 57.1% in stress relief. Moreover, social impact has a direct favorable impact on students' stress relief. In conclusion, both enabling factors and social impact are associated with increased exercise activity. These characteristics increase the likelihood of students participating in exercise and reducing their academic stress. The study also that the institution introduces a course that combines academics with yoga and team sports to the general education curriculum. The institution should offer on-campus fitness or partner with local gyms. Finally, joining clubs and organizations might encourage university students to exercise.

This research aims to explore the recognized advantages of Communities of Practice (CoPs) in enhancing knowledge sharing and spurring organizational transformation. Despite their acknowledged importance, CoPs often receive inadequate attention or representation in numerous organizations, likely due to leaders' unfamiliarity or insufficient skills to manage such groups. This study introduces the "Real Option Perspective" as the recommended approach for top executives to understand and leverage CoPs. Initially, it clarifies the concepts of CoPs and the Real Option Perspective, highlighting their significance. These concepts then lay the groundwork for developing a management model for CoPs. The proposed management trajectory for CoPs involves five phases: Investment in CoPs, Recognition of Stagnation, Re-engagement with CoPs, Transition of Value, and finally, Dissolution and Feedback. This research seeks to expand the applicability of the Real Options framework in managing CoPs, providing leaders with strategic insights to fully realize the potential of CoPs in line with organizational objectives.

This research explores how Corporate Accounting Disclosure (CAD) affects the corporate reputation (CR) of publicly traded Taiwan companies, with special emphasis on the moderating influence of social learning (SL). While Corporate Accounting Disclosure and social learning serve as the independent and moderating variables, respectively, corporate reputation is the study's dependent variable. A sample of 125 companies, listed on the Taiwan Stock Exchange Corporation (TWSE), was selected for this study. Our findings suggest that Corporate Accounting Disclosure positively correlates with corporate reputation, as does social learning. Interestingly, the anticipated moderating effect of Social Learning on the association between Corporate Accounting Disclosure and Corporate Reputation was not observed. Future research endeavors may delve deeper into the underlying reasons for this phenomenon by adopting a multifaceted approach of longitudinal studies and cross-cultural analysis. The study also offers in-depth discussions of its findings and clearly outlines its theoretical and practical implications. It concludes by offering recommendations and charting potential avenues for subsequent research.