In essence, duration is a much better measure of sensitivity to changes in interest rates than simple maturity, because it takes into account when investors get their money.

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So while the typical effective duration -- a measure of sensitivity to interest rates -- for global bond mutual funds run by peers is five or six years, his is less than two years.

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Duration is a measure of interest rate sensitivity.

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Reducing the number of beryllium ions in the trap will boost the sensitivity further, the researchers say, and, with a single beryllium ion, it should be possible to measure a single yoctonewton.

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