Wheels work well on flat surfaces, but are much less efficient on uneven terrain.

ECONOMIST: REPORTS

Ports vary widely too: Montevideo in Uruguay, Panama and the main Colombian and Chilean ports are efficient, others much less so.

ECONOMIST: Efficiency drive

In the United States, I think we are learning how to develop buildings that use much less energy, that are much more energy-efficient.

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Although they are more expensive, bigger, heavier and in theory less efficient than mechanical drives, they use much less fuel.

ECONOMIST: Electric ships

CCDs are much more efficient at imaging very faint objects and are far less likely to be foiled by Earth-based light.

FORBES: A Star Is Born

It seems like it could be a very efficient way to perform this type of operation, and much less risky for rescuers, as well.

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Project Frog, the San Francisco startup behind the 7-Eleven store, is dragging a 19th-century industry into the future with stylish, energy-efficient buildings that can be built in less time and as much as 50% cheaper.

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At 184 horsepower, the base, four-cylinder engine is slightly less powerful than the 2001 Cherokee's base V6, but it's much more efficient.

WSJ: Jeep takes a radical new turn with Cherokee

In contrast, supply-side practices have become more efficient in wealthy industrialized nations, according to Sonesson, but consumers have become much less diligent: "We throw away more food than ever before, " he said.

CNN: June 27, 2012 -- Updated 1104 GMT (1904 HKT)