They estimate that for every 2m five-year-old girls who travel one round-trip a week, one additional breast cancer would occur from the scans.

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Also keep in mind that with charter, one must pay to return the aircraft to its point of origin, so one-way trips must be priced on a round-trip basis.

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One of the few good things about a San Francisco-to-New York 36-hour round-trip is the time it affords one to read.

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Umar Farouk AbdulMutallab, the man accused of trying to blow up a U.S. airliner bound for Detroit, Michigan, had a one-way ticket from Accra, Ghana, to Lagos, Nigeria, and a round-trip ticket for his trip from Lagos to the Netherlands and then to Detroit, according to the Nigerian Aviation Authority.

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Air Canada now breaks down round-trip flights as separate one-way tickets on its Web site, showing you exactly what you pay for each leg.

CNN: Pros and cons of a la carte airfare pricing

For its part, Eos appears to be overhauling its sales effort. (The company denies this.) One quirky promotion promises a free Apple video iPod for purchasing a round-trip flight by August 31.

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Two round-trip flights during the promotion will get you a free one-way flight, originating from Atlanta.

WSJ: Card Issuers Reward Purchases

Look for somebody who's bought a one-way ticket, or look for somebody who's bought a round trip ticket.

NPR: Airport Security Marked by Hassles

However, if you needed to transport yourself and seven other people to a concert, it would take seven round trips in the 2-passenger Insight to accomplish this, versus one trip in the 8-passenger Navigator.

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One, completing a round trip, and the other, it's off on a one-way ticket.

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