Most of these rides have a dead mans operators chair to detect absence of operator, as not to move if handle was bumped.

Dead mans operator chair that detects absence of operator.

To get past that appearance, you would have to detect presence or absence of chemical equilibrium, accurately.

These simple on/off electric switches detect the presence or absence of fluid pressure in a particular hydraulic line.

This model has the advantage that it requires the bird only to detect the presence or absence of a range of odours.

The CD laser stylus is designed to detect only the presence or absence of a pit.

More expensive Teletype systems used photo readers that used light sensors to detect the presence or absence of punched holes in the tape.

This opened the door to the current minimally intrusive drug sniffs of the home which can only detect the presence or absence of drugs.

Man is fallen; nature is erect, and serves as a differential thermometer, detecting the presence or absence of the divine sentiment in man.

In this processes, antibodies are used to detect the presence or absence of the alpha3, alpha4, and alpha5 chains of collagen type 4.