1 Department of Human Ecology, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan, tsudatos@md.okayama-u.ac.jpDepartment of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, JapanDepartment of Information Science, Faculty of Informatics, Okayama University of Science, Okayama, JapanDepartment of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.