Practice Essentials. The term âpernicious anemiaâ is an anachronismâit dates from the era when treatment had not yet been discovered, and the disease was fatalâbut it remains in use for megaloblastic anemia resulting from vitamin B12 deficiency due to lack of intrinsic factor (IF).
The definition of a fan is  a person who is very enthusiastic about someone or something, or a device that moves and cools the air. An example of a fan is a person who only wears gold and red in support of the San Francisco 49ers. An example of a fan is an electrical device with moving blades that cools air.
A computer fan is any fan inside, or attached to, a computer case used for active cooling, and may refer to fans that draw cooler air into the case from the outside, expel warm air from inside, or move air across a heat sink to cool a particular component.Contents.n the IBM compatible PC market, the computer's power supply unit (PSU) almost always uses an exhaust fan to expel warm air from the PSU. Active cooling on CPUs started to appear on the Intel 80486, and by 1997 was standard on all desktop processors.