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).
As stated in Wikipedia The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire to power connected USB devices. A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0. As power is equal to current times voltage, all you have to do is multiply 5V with the current the device is drawing from the port. Note there also exists a convention for charging devices. These kinds of ports allow for currents up to 1.5 A (also using 5V).