BackgroundThe coronavirus disease (COVID-19) pandemic has been spreading and brought unprecedented psychological pressure on people across the entire globe since December 2019.ObjectivesTo synthesize the existing evidence of the prevalence of mental health status during the epidemic and provide the basis for mental health education.Materials and methodsThe literature search was conducted in nine databases from December 2019 to October 2020. The risk of bias for each study was assessed, and the random-effects meta-analysis was used to estimate the prevalence of specific mental health problems. The review protocol was registered in PROSPERO with the registration number CRD42020208619.ResultsAbout 27 studies were included in the analysis with a total of 706,415 participants combined, and 14 mental health problems were gathered. Meta-analysis showed that the prevalence of depression was 39% (95% CI: 27–51%) and that of anxiety was 36% (95% CI: 26–46%). Subgroup analysis indicated that the prevalence of depression and anxiety varied among nations and due to the survey date. The prevalence of depression (60%, 95% CI: 46–74%) and anxiety (60%, 95% CI: 46–74%) in non-Chinese college students was higher than those in Chinese college students (26%, 95% CI: 21–30% and 20%, 95% CI: 14–26%). The proportion of depression (54%, 95% CI: 40–67%) and anxiety (37%, 95% CI: 26–48%) was higher after March 1 than before it (21%, 95% CI: 16–25% and 19%, 95% CI: 13–25%).ConclusionsThe meta-analysis results presented that the prevalence of depression (39%) or anxiety (36%) among college students greatly increased during the COVID-19 pandemic. In addition, the mental health of college students is affected by the nations and the survey date. It was necessary to take measures to reduce mental health risks during the pandemic.
Freeze–thaw processes in soils, including changes in frost and thaw fronts (FTFs), are very sensitive to warming. However, the latest climate models do not predict changes in FTFs directly. In this study, a new frozen soil parameterization including changes in FTFs was incorporated into the Community Land Model version 4.5 for climate modeling, which we denote CLM4.5_FTF. A set of numerical experiments including single points, regions in China, and a global scale were conducted using the model to validate its performance. The simulated FTF depths compare well with observed data from both the D66 station (permafrost) and Hulugou station (seasonally frozen ground). The simulated active layer thickness, defined as the maximum thaw front depth in permafrost, is in general agreement but slightly greater than observations from the Circumpolar Active Layer Monitoring program. The simulated distributions of different types of frozen soil in China and permafrost in the northern hemisphere are in agreement with the frozen soil map of China and the International Permafrost Association map, respectively. The results confirm that the model performs well for FTF simulations. The model was also used for year‐long simulations of soil temperature and freeze–thaw processes to check its applicability in continuous simulation. The results show that CLM4.5_FTF performed better than the original model, and the improvement was better for lower levels than for the upper level. Finally, we give simulated latent heat flux, sensible heat flux, and 10‐cm soil temperature deviations determined via the couple model with and without the new scheme.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.