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Abstract: The archaeocyath-bearing reefs that first appeared in South China in the Atdabanian were last seen in the lower Toyonian (e.g., in the Tianheban and Jindingshan formations). The upper Toyonian–lower Amgan Qingxudong Formation of Hunan Province examined in this study includes large-sized reefs formed solely by calcimicrobes of Epiphyton, Kordephyton, Girvanella, Hedstroemia, and Renalcis. During the middle and upper Cambrian, small-scale stromatolite reefs were formed. The Qingxudong reefs are therefore interpreted to be the most well-developed microbial reefs of the post archaeocyath-bearing reefs in the late early Cambrian. The transition from archaeocyath-bearing to purely microbial reefs was caused by a decline in the diversity of metazoans, and was accompanied by a reduction in the abundance of reefs, possibly related in part to late early Cambrian regression. The late early Cambrian reefs of South China contain a well-preserved record of reef succession, and provide important insights into the factors that led to the demise of archaeocyath-bearing reefs and the subsequent long-lasting hindrances to the development of skeletal-dominated reefs during the middle and late Cambrian. [Copyright &y& Elsevier]

Introduction: Prior studies have explored the prevalence of social anxiety disorders and found that childhood major adverse experiences increased the risk of social anxiety. However, few studies analyzed features of social anxiety and explored the mediation mechanism of the relationship between childhood major adverse experiences and social anxiety in early adulthood.Methods: Two thousand seven hundred and fifty-nine college students from Hunan, China participated in the survey-based study. They completed questionnaires on major adverse childhood experiences, social anxiety symptoms, and a sense of security during a study conducted from 2017 to 2018.Results: 1) 33.38% of the students reported experiencing at least one social anxiety symptom; the highest detection rate (20.22%) was social anxiety symptoms related to participants' nervousness when in large groups. 2) Females and individuals who consumed alcohol in the past year and individuals with a poor physical condition had a significantly higher risk of having social anxiety symptoms (p<0.05). 3) Childhood major adverse events experience increased the risk of some social anxiety symptoms, especially experiencing 3 or more adverse events (p<0.05). 4) A sense of security mediated the relationship between childhood major adverse events experience and social anxiety symptoms.Conclusions: Extensive detection rate of social anxiety symptoms existed among college students, early adversities increased the risk of social anxiety in early adulthood, and the relationship between childhood major adversity and social anxiety was affected by sense of security. [ABSTRACT FROM AUTHOR]