Polonium initiator was classified until the 1960s. The Atomic Energy Commission and the Manhattan Project funded human experiments using polonium on five people at the University of Rochester between 1943 and 1947. The people were administered between of polonium to study its excretion. Polonium is a very rare element in nature because of the short half-life of all its isotopes. Po, Po, and Po appear in the decay chain of U; thus polonium can be found in uranium ores at about 0.1 mg per metric ton (1 part in 10), which is approximately 0.2% of the abundance of radium. The amounts
Field with one element objects. While there is still no field with a single element in these theories, there is a field-like object whose characteristic is one. F cannot be a field because all fields must contain two distinct elements, the additive identity zero and the multiplicative identity one. Even if this restriction is dropped, a ring with one element must be the zero ring, which does not behave like a finite field. Instead, most proposed theories of F replace abstract algebra entirely. Mathematical objects such as vector spaces and polynomial rings can be carried over into these new theories by mimicking their abstract