Rosacea - Symptoms. Rosacea causes a range of symptoms, although not everyone will experience them all. Most people with rosacea have periods when their symptoms are particularly troublesome, followed by periods when their symptoms are less so.
Most motion detectors have a built-in override: 1  Normally the switch is kept on all the time. 2  If you turn the switch off and on within a second or so, the light will stay on, and this overrides motion detection. 3  To go back to normal operation, turn the switch off and wait ~10 seconds, then turn back on.
Police RADAR. RADAR speed detectors bounce microwave radiation off of moving vehicles and detect the reflected waves. These waves are shifted in frequency by the Doppler effect, and the beat frequency between the directed and reflected waves provides a measure of the vehicle speed.