Some context: Bucks Fizz are a British pop group that achieved success in the 1980s, most notably for winning the 1981 Eurovision Song Contest with the song "Making Your Mind Up". The group was formed in January 1981 specifically for the contest and comprised four vocalists: Bobby G, Cheryl Baker, Mike Nolan and Jay Aston. They achieved instant attention with the dance routine which accompanied the song, involving a skirt-rip. The group went on to have a successful career around the world (albeit ignored in the United States), while the UK remained their biggest market, where they had three No.1 singles with "Making Your Mind Up" (1981), "The Land of Make Believe" (1981) and "My Camera Never Lies" (1982) and became one of the top-selling groups of the 1980s.
During rehearsals, a dance routine was devised for the song which went on to become famous for the moment where the girls' skirts are ripped off halfway through - only to reveal shorter skirts underneath. The routine itself was choreographed by Chrissie Wickham, a former member of dance troupe Hot Gossip, although Martin, Baker and Aston have all since laid claim to the skirt-rip idea.  On 11 March, A Song for Europe took place with the then unknown Bucks Fizz competing against well-known act Liquid Gold, as well as Hill and Martin's own group, Gem. "Making Your Mind Up" became an easy winner and the group recorded the song with Hill as producer. Later in the month it was released as a single and entered the charts at No.24. By the time the contest was staged, the single had risen to No.2.  On 4 April, Bucks Fizz represented United Kingdom in the 1981 Eurovision Song Contest, which was held in Dublin. Although they were favourites to win, the song faced stiff competition and after a vocally unsound rendition, the early votes were poor. Halfway through the voting process, Bucks Fizz took the lead, although they remained close throughout. Ultimately, Bucks Fizz won the contest by a margin of four points, beating Germany into second place. "Making Your Mind Up" became a major hit around the continent, reaching No.1 in the UK as well as eight other countries. It charted highly in other countries such as Australia, eventually selling four million copies worldwide.
What happened at Eurovision?
A: On 4 April, Bucks Fizz represented United Kingdom in the 1981 Eurovision Song Contest, which was held in Dublin.

Question: Murray Newton Rothbard (; March 2, 1926 - January 7, 1995) was an American heterodox economist of the Austrian School, a historian, and a political theorist whose writings and personal influence played a seminal role in the development of modern right-libertarianism. Rothbard was the founder and leading theoretician of anarcho-capitalism, a staunch advocate of historical revisionism, and a central figure in the twentieth-century American libertarian movement.

Murray Rothbard's parents were David and Rae Rothbard, Jewish immigrants to the U.S. from Poland and Russia, respectively. David Rothbard was a chemist. Murray attended Birch Wathen, a private school in New York City. Rothbard later stated that he much preferred Birch Wathen to the "debasing and egalitarian public school system" he had previously attended in the Bronx.  Rothbard wrote of having grown up as a "right-winger" (adherent of the "Old Right") among friends and neighbors who were "communists or fellow-travelers." Rothbard characterized his immigrant father as an individualist who embraced the American values of minimal government, free enterprise, private property, and "a determination to rise by one's own merits". "[A]ll socialism seemed to me monstrously coercive and abhorrent."  He attended Columbia University, where he received a Bachelor of Arts degree in mathematics in 1945 and, eleven years later, his PhD in economics in 1956. The delay in receiving his PhD was due in part to conflict with his advisor, Joseph Dorfman, and in part to Arthur Burns rejecting his doctoral dissertation. Burns was a longtime friend of the Rothbard family and their neighbor at their Manhattan apartment building. It was only after Burns went on leave from the Columbia faculty to head President Eisenhower's Council of Economic Advisors that Rothbard's thesis was accepted and he received his doctorate. Rothbard later stated that all of his fellow students there were extreme leftists and that he was one of only two Republicans on the Columbia campus at the time.  During the 1940s Rothbard became acquainted with Frank Chodorov and read widely in libertarian-oriented works by Albert Jay Nock, Garet Garrett, Isabel Paterson, H. L. Mencken and others, as well as Austrian economist Ludwig von Mises. In the early 1950s, when Mises was teaching at the Wall Street division of New York University Business School, Rothbard attended Mises' unofficial seminar. Rothbard was greatly influenced by Mises' book, Human Action. Rothbard attracted the attention of the William Volker Fund, a group that provided financial backing to promote various "right-wing" ideologies in the 1950s and early 1960s. The Volker Fund paid Rothbard to write a textbook to explain Human Action in a form which could be used to introduce college undergraduates to Mises' views; a sample chapter he wrote on money and credit won Mises's approval. For ten years, Rothbard was paid a retainer by the Volker Fund, which designated him a "senior analyst." As Rothbard continued his work, he enlarged the project. The result was Rothbard's book Man, Economy, and State, published in 1962. Upon its publication, Mises praised Rothbard's work effusively.

Using a quote from the above article, answer the following question: What was the subject of his doctoral dissertation?
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Answer: 

Some context: Madikizela-Mandela's Xhosa name was Nomzamo ("She who tries"). She was born in the village of Mbongweni, Bizana, Pondoland, in what is now the Eastern Cape province. She was the fourth of eight children, seven sisters and a brother. Her parents, Columbus and Gertrude, who had a white father, and Xhosa mother, were both teachers.
Due to her political activities, Winnie was regularly detained by the National Party government. She was tortured, subjected to house arrest, kept under surveillance, held in solitary confinement for over a year and even banished to a remote town. She emerged as a leading opponent of apartheid during the later years of her husband's imprisonment (August 1963 - February 1990). For many of those years, she was banished to the town of Brandfort in the Orange Free State and confined to the area, except for when she was allowed to visit her husband at Robben Island. Beginning in 1969, she spent eighteen months in solitary confinement at Pretoria Central Prison. It was at this time that Winnie Mandela became well known in the Western world. She organised local clinics, campaigned actively for equal rights and was promoted by the ANC as a symbol of their struggle against apartheid.  In a leaked letter to Jacob Zuma in October 2008, outgoing President of South Africa Thabo Mbeki alluded to the role the ANC had created for her in their anti-apartheid activism:  In the context of the global struggle for the release of political prisoners in our country, our movement took a deliberate decision to profile Nelson Mandela as the representative personality of these prisoners, and therefore to use his personal political biography, including the persecution of his then wife, Winnie Mandela, dramatically to present to the world and the South African community the brutality of the apartheid system.  Beaten by the apartheid police, she developed an addiction to painkillers and alcohol as a result of a back injury caused by the assault.
Why did she go to prison?
A:
Due to her political activities, Winnie was regularly detained by the National Party government.