1. Department of Radiobiology/Molecular EpidemiologyRadiation Effects Research FoundationHiroshimaJapan
2. Department of StatisticsRadiation Effects Research FoundationHiroshimaJapan
3. Department of Mathematics and StatisticsOakland UniversityRochesterMichiganUSA
4. Central Research LaboratoryHiroshima UniversityFaculty of DentistryHiroshimaJapan