sentinel

“The workers, the cats, and the bulk milk samples are the best sentinels for early dairy herd diagnoses,” he said.

The rate at which flu tests returned positive results at the state’s clinical sentinel labs surged to 27.8% for the week ending Feb. 1, the most recent for which complete data are available.

The Hollywood sign stands sentinel above Los Angeles, watching as embers dance through the January night like wayward stars.

The delta smelt has been called a “sentinel species,” meaning that its health signals the condition of its ecosystem — and the signal it has flashed is alarming.

Trucks equipped with cannons and 50-caliber machine guns sit as bereft sentinels on street corners.