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In the 1970s, the United States began developing a new generation of reusable orbital spacecraft known as the Space Shuttle, and launched a range of unmanned probes. The USSR continued to develop space station technology with the Salyut program and Mir ('Peace' or 'World', depending on the context) space station, supported by Soyuz spacecraft. They developed their own large space shuttle under the Buran program. However, the USSR dissolved in 1991 and the remains of its space program were distributed to various Eastern European countries. The United States and Russia would work together in space with the Shuttle–Mir Program, and again with the International Space Station.

What year did the USSR disband?
Answer: 1991
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Areas such as South Street and Old City have a vibrant night life. The Avenue of the Arts in Center City contains many restaurants and theaters, such as the Kimmel Center for the Performing Arts, which is home to the Philadelphia Orchestra, generally considered one of the top five orchestras in the United States, and the Academy of Music, the nation's oldest continually operating opera house, home to the Opera Company of Philadelphia and the Pennsylvania Ballet. The Wilma Theatre and Philadelphia Theatre Company have new buildings constructed in the last decade on the avenue. They produce a variety of new works. Several blocks to the east are the Walnut Street Theatre, America's oldest theatre and the largest subscription theater in the world; as well as the Lantern Theatre at St. Stephens Church, one of a number of smaller venues.

What is the home of the orchestra?
Answer: Kimmel Center for the Performing Arts
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DC commutating electric motors, if fitted with laminated pole pieces, become universal motors because they can also operate on AC; reversing the current in both stator and rotor does not reverse the motor. But the now-standard AC distribution frequencies of 50 and 60 Hz caused difficulties with inductive reactance and eddy current losses. Many railways chose low AC frequencies to overcome these problems. They must be converted from utility power by motor-generators or static inverters at the feeding substations or generated at dedicated traction powerstations.

What problems did AC distribution cause?
Answer:
inductive reactance and eddy current losses