Suppose that the officers in the present case had followed respondent by surreptitiously activating a stolen vehicle detection system that came with the car when it was purchased.

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An important note: Although many cars come with detection devices like backup cameras or radars that emit sounds when they sense an obstruction behind the car, they cannot compensate for the act of circling the vehicle to make sure everything and every one is out of the way.

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These, he says, are 1, 500 times better than existing sensors at detecting hydrogen. (The gas combines with the tubes, changing their electrical properties.) Hydrogen detection is used to help control certain processes in industrial food production, for tweaking fuel combustion in car engines, and in monitoring certain bacterial infections.

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