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Mechanically controlled variable capacitors allow the plate spacing to be adjusted, for example by rotating or sliding a set of movable plates into alignment with a set of stationary plates. Low cost variable capacitors squeeze together alternating layers of aluminum and plastic with a screw. Electrical control of capacitance is achievable with varactors (or varicaps), which are reverse-biased semiconductor diodes whose depletion region width varies with applied voltage. They are used in phase-locked loops, amongst other applications.
What is an application of varactors?
A: phase-locked loops

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In Latin America and English-speaking countries, most wrestlers (and other on-stage performers) portray character roles, sometimes with personalities wildly different from their own. These personalities are a gimmick intended to heighten interest in a wrestler without regard to athletic ability. Some can be unrealistic and cartoon-like (such as Doink the Clown), while others carry more verisimilitude and can be seen as exaggerated versions of the performer's real life personality (such as Chris Jericho, The Rock, John Cena, Stone Cold Steve Austin, and CM Punk). In lucha libre, many characters wear masks, adopting a secret identity akin to a superhero, a near-sacred tradition.
The Rock's persona is seen as what? 
A: exaggerated versions of the performer's real life personality

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Possibly the first house erected within the site was that of a Sir William Blake, around 1624. The next owner was Lord Goring, who from 1633 extended Blake's house and developed much of today's garden, then known as Goring Great Garden. He did not, however, obtain the freehold interest in the mulberry garden. Unbeknown to Goring, in 1640 the document "failed to pass the Great Seal before King Charles I fled London, which it needed to do for legal execution". It was this critical omission that helped the British royal family regain the freehold under King George III.
Who built the first house on the site?
A: Sir William Blake

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The Houston–The Woodlands–Sugar Land metropolitan area is served by one public television station and two public radio stations. KUHT (HoustonPBS) is a PBS member station and is the first public television station in the United States. Houston Public Radio is listener-funded and comprises two NPR member stations: KUHF (KUHF News) and KUHA (Classical 91.7). KUHF is news/talk radio and KUHA is a classical music station. The University of Houston System owns and holds broadcasting licenses to KUHT, KUHF, and KUHA. The stations broadcast from the Melcher Center for Public Broadcasting, located on the campus of the University of Houston.
Houston Public Radio us comprised of how many stations?
A:
two NPR member stations