To provide a brake cylinder unit wherein both the normal brake and the spring brake that is used as a parking brake, etc. The semiconductor layer includes an GaN layer and a AlGaN layer provided on the GaN layer. The logic controller is operable to close the valve upon sensing a pressure above a predetermined limit. These limitations are occasionally exasperated by problems in either power or cooling systems. The substituted instructions result in strength reduction in the computer program. A method for obtaining an endothelial cell culture from a blood sample involved: obtaining a sample for mononuclear cells from a blood sample; and culturing the sample of mononuclear cells, without further cell separation, on a cell adhesive polymer-coated solid support in the presence of endothelial growth factors.