The classical example of thermionic emission is the emission of electrons from a hot cathode into a vacuum (also known as thermal electron emission or the Edison effect) in a vacuum tube. The hot cathode can be a metal filament, a coated metal filament, or a separate structure of metal or carbides or borides of transition metals.
Low confidence regions are areas for which there s a small amount of DNA evidence found in your sample. All ethnicities with predicted percentages of less than 4.5% appear as low confidence regions. Inferior complex is low complex .
The other reason has to do with how likely it is that people you are related to have done the Ancestry DNA test. Only a very small percentage of people have done DNA testing. I hope I'm not misquoting, but I believe Jeff has said that it's only about 1%. So it depends on how many people in that 1% are related to you.