Atomic clock. An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element. Atomic clocks are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, to control the wave frequency of television broadcasts, and in global navigation satellite systems such as GPS. The principle of
From Wikipedia, the free encyclopedia. Wound healing is the process by which skin or other body tissue repairs itself after trauma. In undamaged skin, the epidermis (surface layer) and dermis (deeper layer) form a protective barrier against the external environment.
The proliferative phase of wound healing restores skin integrity by filling in the wound with new tissue. New blood vessels form within the wound by extending from the woundâs edges; this is called angiogenesis.