1 Echocardiography (echo) is a painless test that uses sound waves to create pictures of your heart.  This test gives your doctor information about the size and shape of your heart and how well your heart's chambers and valves are working.
USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power.
USB means Universal Serial Bus. It is and standard and its initial purpose were to replacing the multitude of connectors at the back of PCs. It uses four shielded wires, two of them for power and the other to for data transmission. If you connect two resistor at data+ and data â then you have charging cable.