One of the smartest health wearables—and that is saying something—to be released in latest years, this ring precisely tracks coronary heart fee, sleep cycles, and activity, then provides insight and steerage primarily based on what it tracks. Considering how discreet it’s, that is quite a feat of engineering. Notwithstanding the outstanding success of solid-state devices in most electronic applications, there are particular specialised functions that solely vacuum tubes can carry out.