This is easy to detect, and once detected, human intervention becomes possible.

ECONOMIST: A new way of thwarting viral epidemics on computers

Once a vein is detected at a suitable depth, the device alerts the operator, who pushes the syringe needle into the patient's flesh and injects the medicine.

ECONOMIST: Medical technology

Once the issue was detected, the sensing equipment operated as designed and opened a breaker, causing power to be partially cut to the Superdome in order to isolate the issue.

FORBES: The Super Bowl Blackout: "An Abnormality In The System"

"Once the issue was detected, the sensing equipment operated as designed and opened a breaker, causing power to be partially cut to the Superdome in order to isolate the issue, " the statement said.

CNN: Jokesters, advertisers pounce on Super Bowl power outage

The great teacher thought this would make it plain that the real problem with international arms treaties was not a lack of verification but a total lack of penalties once violations have been detected.

CENTERFORSECURITYPOLICY: Saddam's Lessons In Arms Control

Once the department had Tamerlan under surveillance, the NYPD's cyberunit might have detected his suspicious online viewing choices and social-media postings.

WSJ: Judith Miller: How to Stop Terrorists Before They Kill