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.
If the signal vibrates very slowly, it has a low frequency. If the signal vibrates very quickly, it has a high frequency. Frequency is measured in Hertz, which is the count of how quickly a signal changes every second. As an example, FM radio signals vibrate around 100 million times every second! Since communications signals are often very high in frequency, we abbreviate the measurements for the frequencies - millions of vibrations a second is Megahertz (MHz), and billions of vibrations a second is Gigahertz (GHz).