As described previously, cervical cancers are caused by infection with one of the high-risk HPV types. However, since not all people who are infected with HPV will develop cancer, it is likely that other factors also play a role in the development of cervical cancer.
ballast factor (BF) - The ratio of the light output of a fluorescent lamp or lamps operated on a ballast to the light output of the lamp(s) operated on a standard (reference) ballast. Ballast factor depends on both the ballast and the lamp type; a single ballast can have several ballast factors depending on lamp type. compact fluorescent lamp (CFL) - A family of single-ended fluorescent-discharge light sources with small-diameter [16-millimeter (5/8-inch) or less] tubes.
Definition of ballast. 1  1 : a heavy substance (as rocks or water) placed in such a way as to improve stability and control (as of the draft of a ship or the buoyancy of a balloon or submarine) tossed several tons of ballast overboard. 2 : something that gives stability (as in character or conduct) She provided the ballast we needed during stressful times.