Ultrasound may show gallstones, thickening of the gallbladder wall, extra fluid, and other signs of cholecystitis. This test also allows doctors to check the size and shape of your gallbladder. You could also have a gallbladder scan, a nuclear scanning test that checks how well your gallbladder is working.
For high speed algorithmic trading, see high-frequency trading. HF's position in the electromagnetic spectrum. High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 MHz.It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred metres).Frequencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band.requencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band.
The frequency of a wave is measured as the number of complete back-and-forth vibrations of a particle of the medium per unit of time. If a particle of air undergoes 1000 longitudinal vibrations in 2 seconds, then the frequency of the wave would be 500 vibrations per second. high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave. Amazingly, many people, especially those who have been musically trained, are capable of detecting a difference in frequency between two separate sounds that is as little as 2 Hz.