KDA

KDA or similar may refer to:

Combat Groups of the Working Class

The Combat Groups of the Working Class (German: Kampfgruppen der Arbeiterklasse, KdA) was a paramilitary organization in East Germany, founded in 1953 and abolished in 1990.

History

The Kampfgruppen were formed on September 29, 1953 after the workers' uprising of June 1953. The KdA made its first public appearance at the annual May Day demonstration on May 1, 1954. It was intended to be the East German equivalent to the People's Militias of Czechoslovakia which played a very important part in the Communist consolidation of power in Czechoslovakia in 1948. Their formation also fit the East German ethos of the worker being the centre of power in the new Communist state.

A central school for KdA leaders was set up in Schmerwitz in 1957. Der Kämpfer was the monthly newspaper and voice of the KdA; it was printed by the SED's Neues Deutschland publishing house.

The largest use of the KdA was during the construction of the Berlin Wall, in the summer and fall of 1961. The best-trained and most-politically reliable KdA units and members from Saxony, Thuringia and East Berlin participated in the construction and guarding of the Wall. Over 8,000 KdA, about 20% of all military units, were involved in this effort. During the six-week deployment of the KdA to the East-West Berlin sector boundary, only eight members escaped to the West, indicating a high state of morale and political reliability.

Atomic mass unit

The unified atomic mass unit (symbol: u) or dalton (symbol: Da) is the standard unit that is used for indicating mass on an atomic or molecular scale (atomic mass). One unified atomic mass unit is approximately the mass of one nucleon (either a single proton or neutron) and is numerically equivalent to 1 g/mol. It is defined as one twelfth of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of 6973166053904000000♠1.660539040(20)×10⁻²⁷ kg. The CIPM has categorised it as a non-SI unit accepted for use with the SI, and whose value in SI units must be obtained experimentally.

The amu without the "unified" prefix is technically an obsolete unit based on oxygen, which was replaced in 1961. However, some sources may still use the term "amu" but now define it in the same way as u (i.e., based on carbon-12). In this sense, most uses of the terms "atomic mass units" and "amu" today actually refer to unified atomic mass unit. For standardization a specific atomic nucleus (carbon-12 vs. oxygen-16) had to be chosen because the average mass of a nucleon depends on the count of the nucleons in the atomic nucleus due to mass defect. This is also why the mass of a proton (or neutron) by itself is more than (and not equal to) 1 u.