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• Development trend of collaborative security in middle reaches is considerable. • Collaborative security levels of Sichuan, Hunan and Jiangxi are lowest in 2020. • Bellman optimal equation is used to calculate expected benefits of measures. • Quantitative assessment is conducive to the collaborative security of the nexus. • Optimal implementation sequences of indictors with poor performance are proposed. Water, energy, and food are essential for human survival, and the production and consumption of these three resources are closely related. In the backdrop of limited resources and constantly expanding demand, the collaborative security of the water-energy-food nexus (WEF-nexus) is under serious threat. It is of great practical significance to study the adaptive management countermeasures of the collaborative security of the WEF-nexus in the Yangtze River Economic Belt (YREB) and to quantitatively evaluate the implementation sequence of relevant management countermeasures to improve the collaborative security and promote the sustainable development of the WEF-nexus. This study first establishes an evaluation indicator system for the collaborative security of the WEF-nexus in the YREB by utilizing the pressure-state-response (PSR) model. Then, the CRITIC and TOPSIS methods are used to determine the weight of indicators and the collaborative security level of the WEF-nexus in each province and city. The state transition matrix is determined based on the transition at the collaborative security level. Finally, based on the barrel theory to make up for shortcomings, the adaptive management countermeasures of provinces and cities with low collaborative safety levels are studied by combining the Bellman optimal equation. By comparing the expected returns of the same countermeasure in different implementation sequences and conducting quantitative research on the implementation sequence of adaptive management countermeasures, targeted policy suggestions are proposed based on regional characteristics, providing a reference for strategic decision-making of relevant resources in the YREB and improving regional WEF-nexus collaborative security. The results show that: (1) For Jiangxi, improving the water conservancy engineering regulation and storage capacity and other ways in a particular order can effectively improve the collaborative security level of nexus. (2) For Hunan, increasing the investment proportion of agriculture, forestry and water conservancy and resource exploration intensity and other means in a particular order can effectively improve the collaborative security level of the nexus. (3)For Sichuan, increasing the water-saving irrigation rate according to a particular order and other ways can effectively improve the collaborative security level of nexus. [ABSTRACT FROM AUTHOR]

It is unclear about the mutual impact of COVID-19 related psychological stress and infection on mental health of adolescent and youth students. This study aimed to explore the mutual impact of COVID-19 related psychological stress and infection on mental health problems among students. This study was conducted from December 14, 2022 to February 28, 2023 in Sichuan, China. Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, PTSD Checklist for DSM-5, Insomnia Severity Index, and Internet Addiction Test were used. Participants were grouped by COVID-19 infection and psychological stress level. The differences among groups were compared, and logistic regression analysis was used to investigate risk factors for depression, anxiety, PTSD and insomnia among groups. Of 90,118 participants, 82,873 (92.0 %) finished the questionnaires and were included in the study. Of 82,873 participants, 33,314 (40.2 %) reported to be infected with COVID-19. Participants had depression symptoms (38.1 %), anxiety symptoms (31.8 %), PTSD (33.9 %), insomnia (34.0 %), and internet addiction (60.3 %). Compared with participants uninfected with low psychological stress level, the risk for symptoms of depression, anxiety, PTSD and insomnia increased by 9.6 %, 12.3 %, 6.6 %, and 12.0 % in participants infected with low psychological stress level (p < 0.001), 106.8 %, 125.9 %, 125.2 %, and 95.7 % in participants uninfected with high psychological stress level (p < 0.001), and 147.3 %, 161.1 %, 158.7 %, and 141.0 % in participants infected with high psychological stress level (p < 0.001). This study is a cross-sectional design, and no causal associations should be inferred. Infection status was based on self-report of participants with infectious symptoms. COVID-19 related psychological stress and infection per se have mutually overlapping impacts on mental health problems among students. Further health policies and psychosocial interventions should be developed to reduce mutually overlapping impact and improve the long-term mental health among students. • It is unclear about the mutual impact of COVID-19 infection and psychological stress on individuals' mental health • This study supports the mutual overlapping theory (MOT) of COVID-19 infection and psychological stress • The overlap of COVID-19 infection and psychological stress may cause more severe mental health problems • Health policies and interventions should be developed for reducing the impact of infection and psychological stress [ABSTRACT FROM AUTHOR]