That breakout above the downtrend line is a distant early warning signal that the psychology of the markets is changing.

FORBES: The Dollar Peeks Above Its 13-Month Downtrend Line

Still his father said nothing, his eyes fixed on the view like a soldier on guard duty, determined not to miss the signal flare sent up by a savage tribe on a distant hill.

NEWYORKER: Town of Cats

Had it been situated in a much more distant galaxy -- as many gamma-ray bursts are -- its signal would have been relatively feeble.

CNN: Why gamma-ray burst shocked scientists