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Historically, they are also called "Berger's waves" after Hans Berger, who first described them when he invented the EEG in 1924. [ 3 ] Alpha waves are one type of brain waves detected by electrophysiological methods, e.g., electroencephalography (EEG) or magnetoencephalography (MEG), and can be quantified using power spectra and time-frequency ...
The wavelength of a sine wave, λ, can be measured between any two points with the same phase, such as between crests (on top), or troughs (on bottom), or corresponding zero crossings as shown. In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats.
Examples are the generation of rhythmic activity such as a heartbeat and the neural binding of sensory features in perception, such as the shape and color of an object. Neural oscillations also play an important role in many neurological disorders , such as excessive synchronization during seizure activity in epilepsy , or tremor in patients ...
For example, human subjects with high depression scores exhibit differential gamma signaling when performing emotional, spatial, or arithmetic tasks. Increased gamma signaling is also observed in brain regions that participate in the default mode network, which is normally suppressed during tasks requiring significant attention. Rodent models ...
It is used as the starting point for subtractive synthesis, as a sawtooth wave of constant period contains odd and even harmonics that decrease at −6 dB/octave. The Fourier series describes the decomposition of periodic waveforms, such that any periodic waveform can be formed by the sum of a (possibly infinite) set of fundamental and harmonic ...
The frequency of a sound is defined as the number of repetitions of its waveform per second, and is measured in hertz; frequency is inversely proportional to wavelength (in a medium of uniform propagation velocity, such as sound in air). The wavelength of a sound is the distance between any two consecutive matching points on the waveform.
For example, many hydrogen atoms emit a radio wave photon that has a wavelength of 21.12 cm. Also, frequencies of 30 Hz and below can be produced by and are important in the study of certain stellar nebulae [ 4 ] and frequencies as high as 2.9 × 10 27 Hz have been detected from astrophysical sources.
Electromagnetic – infrared light used in thermal imaging, for example for night vision: 31.5 THz: Electromagnetic – peak of black-body radiation emitted by human body: 10 14: 100 THz: 400 THz to 790 THz: Electromagnetic – visible light, from red to violet: 10 15: 1 petahertz (PHz) 2.47 PHz: Electromagnetic – Lyman-alpha line: 10 16: 10 ...