Electric current certain materials when cooled below a characteristic critical temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of "perfect conductivity" in classical physics. In a semiconductor it is sometimes useful to think of the current as due to the flow
Heike Kemmer breeding stable for Hanoverian horses now run by Heike. In the 1990s, Heike became the farm manager, and moved the focus of the stables from show jumping to dressage. Kemmer attended her first Olympics in 2000, as an alternate to the German team, but did not participate in the Games. In 2004, she rode in the Olympics for the first time, placing 26th individually. She also rode as part of the gold-medal winning German team, but as the lowest-scoring member, her score was not used to determine the team's standing. At the 2008 Summer Olympics, her performance improved significantly, and