Beta-plus (Î² +) radiation is the emission of positrons, which are the antimatter form of electrons. When a positron slows to speeds similar to those of electrons in the material, the positron will annihilate an electron, releasing two gamma photons of 511 keV in the process.
The Congressional Budget Office puts the cut-off lower, at $347,000 in 2007, or $252,000 after subtracting federal taxes and adding back transfers. Measured by net worth, rather than income, the top 1% started at $6.9m in 2009, according to the Federal Reserve, down 23% from 2007.
1 The yearly earnings of 90% of registered nurses were less than $93,140; while remaining 10% were reported to earn more than $93,140. 2  75% received an annual income less than $78,220; while 25% got more than $78,220.  50% were offered less than $64,890; whereas the rest of 50% grossed more than $64,890.