Into an electrolytic bath storing water to be treated, saturated sodium chloride solution identified as an electrolysis accelerator is added from an electrolysis accelerator bath. A management area has a fixed service call capacity to provide maintenance services to a subscriber base of the service enterprise. Methods of identifying differentiation factors capable of promoting the differentiation of endoderm cells, such as PDX1-positive foregut endoderm cells and PDX1-negative definitive endoderm cells, are also disclosed. In some embodiments, the application also allows the users to modify photo books that they select.