Calciphylaxis. Calciphylaxis is a condition characterised by necrosis (cellular death) of the skin and fatty tissue. It is seen mainly in patients with end stage kidney disease. It is also sometimes called calcific uraemic arteriolopathy.
Besides a data link, USB provides 5 +/- 0.25 volts to power an otherwise unpowered device or charge a battery in a self powered device. A USB controller or hub is required to power one unit load (100 mA, a low power load). It can optionally power up to 5 unit loads (500 mA, a high power load).
Yes, USB 3 devices can use up to 900mA of power (compared to 500mA used by USB 2 devices). You'll need to use a USB 3 cable to use the 900mA of power available. USB 2 cables don't support 900mA.