The most dazzling example of the power of negative space comes from the efforts of analysts during World War II to reduce the enormous losses of aircraft and lives of flight crews that were routine during missions from British airfields over the German industrial heartland.

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The only emerging market nations to see downgrades or credit outlook changes to negative were in the junk bond space, and some corporates.

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Proposed by Mexican theoretical physicist Miguel Alcubierre in 1994, the drive would propel a ship at superluminal speeds by creating a bubble of negative energy around it, expanding space (and time) behind the ship while compressing space in front of it.

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"A host of negative results have come together in a short space of time, " Madrid sporting director Jorge Valdano told Canal Plus television after his side's first home league defeat in 11 months.

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The many moon landings are just the most obvious on the plus side of the ledger, the twin space shuttle disasters the most grievous on the negative side.

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