Problem: Madonna (entertainer):

To allow for greater movement while dancing and singing, Madonna was one of the earliest adopters of hands-free radio-frequency headset microphones, with the headset fastened over the ears or the top of the head, and the microphone capsule on a boom arm that extended to the mouth. Because of her prominent usage, the microphone design came to be known as the "Madonna mic". Metz noted that Madonna represents a paradox as she is often perceived as living her whole life as a performance. While her big-screen performances are panned, her live performances are critical successes. Madonna was the first artist to have her concert tours as reenactment of her music videos. Author Elin Diamond explained that reciprocally, the fact that images from Madonna's videos can be recreated in a live setting enhances the realism of the original videos. Thus her live performances have become the means by which mediatized representations are naturalized. Taraborrelli said that encompassing multimedia, latest technology and sound systems, Madonna's concerts and live performances are deemed as "extravagant show piece, a walking art show."

What was the microphone coined as?
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A: "Madonna mic"


Problem: Railway electrification system:

In comparison to the principal alternative, the diesel engine, electric railways offer substantially better energy efficiency, lower emissions and lower operating costs. Electric locomotives are usually quieter, more powerful, and more responsive and reliable than diesels. They have no local emissions, an important advantage in tunnels and urban areas. Some electric traction systems provide regenerative braking that turns the train's kinetic energy back into electricity and returns it to the supply system to be used by other trains or the general utility grid. While diesel locomotives burn petroleum, electricity is generated from diverse sources including many that do not produce carbon dioxide such as nuclear power and renewable forms including hydroelectric, geothermal, wind and solar.

Electricity is generated from many sources that do produce carbon what?
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A: unanswerable


Problem: Zinc:

Although not yet tested as a therapy in humans, a growing body of evidence indicates that zinc may preferentially kill prostate cancer cells. Because zinc naturally homes to the prostate and because the prostate is accessible with relatively non-invasive procedures, its potential as a chemotherapeutic agent in this type of cancer has shown promise. However, other studies have demonstrated that chronic use of zinc supplements in excess of the recommended dosage may actually increase the chance of developing prostate cancer, also likely due to the natural buildup of this heavy metal in the prostate.

What could normal use of zinc possibly cause?
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A: unanswerable


Problem: Slavs:

In the 7th century, the Frankish merchant Samo, who supported the Slavs fighting their Avar rulers, became the ruler of the first known Slav state in Central Europe, which, however, most probably did not outlive its founder and ruler. This provided the foundation for subsequent Slavic states to arise on the former territory of this realm with Carantania being the oldest of them. Very old also are the Principality of Nitra and the Moravian principality (see under Great Moravia). In this period, there existed central Slavic groups and states such as the Balaton Principality, but the subsequent expansion of the Magyars, as well as the Germanisation of Austria, separated the northern and southern Slavs. The First Bulgarian Empire was founded in 681, the Slavic language Old Bulgarian became the main and official of the empire in 864. Bulgaria was instrumental in the spread of Slavic literacy and Christianity to the rest of the Slavic world.

What outlived the first Slav ruler?
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A:
unanswerable