Then, apparently not realizing the stock market collapse was an advance warning of a coming recession, the Fed continued raising interest rates until May, 2000, and did not begin cutting interest rates to prevent a recession until January, 2001.

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These schemes offer consolation, but any effort to deflect an asteroid requires plenty of advance warning, and that may not always be available.

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According to Kate Cummings, an Ushahidi consultant in Monrovia, Liberia, Humanity United is funding an effort to set up an early warning system in advance of the late-2011 Liberian elections, that would spread the word about potential political violence before it erupts.

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Not for the first time on this three-month-long mission, the Northumberland has found itself in the same region as an act of piracy but without the advance warning to stop it.

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"If you have an earthquake, or if you have a flood, you don't have much in the way of advance warning -- a little with a flood, none with an earthquake -- so you have to respond as quickly as you can, " he said.

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News organizations are supposed to get advance warning so that they can fight the subpoena in court, unless the notification could compromise an investigation.

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