Mental health difficulties and related factors in Chinese children and adolescents during the COVID-19 pandemic: a cross-sectional study Tongtong Li; Chunhao Li; Guoquan Zhang; Naijian Zhang; Jing Li; Qinghan Ren; Wen Li; Zhenshu Li; Guowei Huang; Jing Yan;

Physical activity and quality of life of children and adolescents with juvenile idiopathic arthritis, juvenile systemic lupus erythematosus and juvenile dermatomyositis during the COVID-19 pandemic Renata Soares; Fabiana de Carvalho Silva; Jade Dib Fernandez; Melissa Fraga; Maria Teresa Terreri; Claudio Arnaldo Len;

Effect of sleep duration on child development in Fortaleza, Northeastern Brazil Shamyr Sulyvan Castro; Marcia Maria Tavares Machado; Luciano Lima Correia; Simone Farias-Antúnez; Pedro Lucas Grangeiro de Sá Barreto Lima; Sophia Costa Vasconcelos; Elisa Rachel Pisani Altafim; Marcia C. Castro;