Beat frequency

Nonciliated cells separate fields of ciliated epithelial cells from each other. Synchronized ciliary movement, with a beat frequency in human proximal airways under normal conditions of 8-15 EIz, propels mucus along the mucociliary escalator at a rate of up to 25 mm/min. Beat frequencies appear to slow to roughly 7 Hz in more distal airways. Cilia move in the same direction and in phase within each field but cilia in adjacent fields move in slightly different directions and are phase shifted. These beat patterns result in metachronal waves that steadily move mucus at higher velocities ( -12-18 mm/min) than would be achievable by summing the motion of individual cilia. 

Luk, C. K., and Dulfano, M. J. (1983). Effect of pH, viscosity and ionic-.srrengtb changes on ciliary beating frequency of human bronchial explants. Clin. Sc. 64, 449-451. 

Ciliary beat frequency Rate at which cilia travel through both the power... 

Second volume and choke-tube resonance frequency and beat frequencies... 

A beat frequency exists as the sum or difference of two frequencies. For a base of 10 cycles/sec and a resonant frequency of 3.48 cycles/sec, beat frequency = 10 — 3.48 = 6.52 cycles/sec, which is below the compressor base frequency of 10 cycles/sec and is acceptable. Beat frequencies of the harmonics of the base frequency will be filtered. 

It is important to investigate possible situations of harmful resonance. Although all pipes and pipe-volume combinations will resonate, it is necessary to investigate only the cases that might cause mechanical problems. This refers to a frequency that will given a objectionable beat frequency or to a length of pipe that is tuned to a stimulating frequency. 

The capillary wave frequency is detected by an optical heterodyne technique. The laser beam, quasi-elastically scattered by the capillary wave at the liquid-liquid interface, is accompanied by a Doppler shift. The scattered beam is optically mixed with the diffracted beam from the diffraction grating to generate an optical beat in the mixed light. The beat frequency obtained here is the same as the Doppler shift, i.e., the capillary wave frequency. By selecting the order of the mixed diffracted beam, we can change the wavelength of the observed capillary wave according to Eq. (11). 

The molecular collective behavior of surfactant molecules has been analyzed using the time courses of capillary wave frequency after injection of surfactant aqueous solution onto the liquid-liquid interface [5,8]. Typical power spectra for capillary waves excited at the water-nitrobenzene interface are shown in Fig. 3 (a) without CTAB (cetyltrimethy-lammonium bromide) molecules, and (b) 10 s after the injection of CTAB solution to the water phase [5]. The peak appearing around 10-13 kHz represents the beat frequency, i.e., the capillary wave frequency. The peak of the capillary wave frequency shifts from 12.5 to 10.0kHz on the injection of CTAB solution. This is due to the decrease in interfacial tension caused by the increased number density of surfactant molecules at the interface. Time courses of capillary wave frequency after the injection of different CTAB concentrations into the aqueous phase are reproduced in Fig. 4. An anomalous temporary decrease in capillary wave frequency is observed when the CTAB solution beyond the CMC (critical micelle concentration) was injected. The capillary wave frequency decreases rapidly on injection, and after attaining its minimum value, it increases... 

As a result of the FMCW waveform with four individual chirp signals, a proper detection process results in four detected beat frequencies /c,s per point target and sensor. In total a single target, detected by the... 

Range-Velocity Estimation. Each measured beat frequency con-... 

Each sensor of the radar network has an individual position behind the front bumper. Therefore, each sensor will calculate individual values for target range and velocity based on the four measured beat frequencies, equation 8, inside the FMCW waveform. The measurement result is described by an eight-element parameter vector. 

A set of linear equations can now be derived which describes the relation between 16 measured beat frequencies and sensor specific target range and velocity parameters. 

In multi-target situations the association of the detected beat frequencies at the FFT output to different targets is not trivial. Therefore, a... 

Even a small subset of the maximum possible sixteen beat frequencies is sufficient for track update processing based on the frequency-to-track association scheme. Almost all association errors could be avoided in multiple and extended target situations applying this procedure. This... 

Ugwoke MI, Agu RU, Jorissen M, Augustijns P, Sciot R, Verbeke N, Kinget R 2000 Toxicological investigations of the effects carboxymethylcellulose on ciliary beat frequency of human nasal epithelial cells in primary suspension culture and in vivo on rabbit nasal mucosa. Int J Pharm 205 43-51. 

Mucociliary Clearance Mucociliary clearance operates by the coordinated movements of cilia, which sweep mucus out of the lungs towards the pharynx where it is swallowed. There is an inverse relationship between mucus velocity and airway generation, which relates to the lower percentage of ciliated cells, shorter cilia, lower ciliary beat frequency and lower number of secretory cells in the peripheral airways [121]. The reported tracheal mucociliary clearance... 

Delmotte P, Sanderson MJ (2006) Ciliary beat frequency is maintained at a maximal rate in the small airways of mouse lung slices. Am J Respir Cell Mol Biol 35 110-117. 

M. Jorissen and A. Bessems. Influence of culture duration and ciliogenesis on the relationship between ciliary beat frequency and temperature in nasal epithelial cells. Eur Arch Otorhinolaryngol 252 451-454 (1995). 

Sanderson MJ, Dirksen ER (1989) Mechanosensitive and beta-adrenergic control of the ciliary beat frequency of mammalian respiratory tract cells in culture. Am Rev Respir Dis 139(2) 432 140. 

Khan AR, Bengtsson B, Lindberg S (1986) Influence of substance P on ciliary beat frequency in airway isolated preparations. Eur J Pharmacol 130(1-2) 91-96. 

Chilvers, M. A. and O Callaghan, C., Analysis of ciliary beat pattern and beat frequency using digital high speed imaging comparison with the photomultiplier and photodiode methods, Thorax, 55, 314-317, 2000. 

Thanou, M.M., Verhoef, J.C., Romeijn, S.G., Merkus, F.W.H.M., Nagelkerke, J.F., and Junginger, H.E., Effects of N-trimethylchitosan chloride, a novel absorption enhancer, on Caco-2 intestinal epithelia and the ciliary beat frequency of chicken embryo trachea, Int. J. Pharm., 185 73-82 (1999). 

The results of the analysis are shown in Table 3.4. It is seen that, although some of the periodicities are extracted, some which appear are difference or beat frequencies and do not correspond to a single layer. The conclusion is that Fourier analysis, with the above procedure, is a powerful aid to a skilled researcher, but it is not yet appropriate for automated analysis. 

For very accurate line profile measurements, a heterodyne technique has been developed 240) which can be briefly explained as follows the light, scattered into a cone within the angle 0 b9 (50< 1 °). is focused onto the cathode of a photomultiplier. The photocurrent is proportional to the square of the incoming light amplitude but cannot follow the rapid light frequency. Any beat frequencies, however, resulting from interference between the... 

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