Every year Guinness produces a new variation on his black-and-white theme.

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The latest variation on the theme is Limitless, the Hollywood film starring Bradley Cooper and Robert De Niro.

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Three professors (from Stanford, INSEAD and MIT, respectively) have come up with a variation on this theme: that the price paid can also influence behaviour.

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But the problem with these innovative expensive sets is that the director wants to get all he can out of it, and the whole opera turns out to be something like a variation on a theme of The Machine.

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