Artpop was Gaga's second consecutive number-two record in the United States.
The Kaup -- Kupershmidt equation -LRB- named after David J. Kaup and Boris Abram Kupershmidt -RRB- is the nonlinear fifth-order partial differential equation. nonlinear. nonlinear. partial differential equation. partial differential equation. It is the first equation in a hierarchy of integrable equations with Lax operator. integrable equations. integrable system. Lax operator. Lax pair. It has properties similar -LRB- but not identical -RRB- to those of the better-known KdV hierarchy in which the Lax operator has order 2 .. Lax operator. Lax pair. KdV hierarchy. Korteweg–de Vries equation