Maximum length sequence

Rife and Vanderkooy, 1987] Rife, D. D. and Vanderkooy, J. (1987). Transfer-Function Measurement using Maximum-Length Sequences . In Proc. Audio Eng. Soc. Conv. Preprint 2502. 

An alternative method for excitation of nuclei over a range of chemical shifts is by irradiation with a weak, noise-modulated radio-frequency, instead of with strong r.f. pulses. In one realization of this method, protons were irradiated with repetitive sequences of noise that was truly random,162 and, in another,163 fluorine nuclei were excited by pseudo-random noise generated by amplitude modulation of the r.f. with maximum-length sequences of pulses from a computer or shift register (a series of flip-flop devices connected by feedback loops). With the carrier wave suppressed, the latter process is equivalent to phase modulation of the r.f. by+7r/2 radians when the pulse is turned on, and by —ir/2 radians when it is turned off. This method is identical with that used in most broadband, heteronuclear, noise decouplers, except that greater power is required for decoupling. 

S. Gawad, T. Stm, N. G. Green and H. Morgan, Impedance spectroscopy using maximum length sequences Application to single cell analysis. Rev. Sci. Instr., 78, 054301 (2007). 

R. Mazurek and H. Lasota, Application of Maximum-Length Sequences to Impulse Response Measurement of Hydroacoustic Communications Systems, Hydroacoustics, vol. 10, pp. 123-130, 2007. 

N. Xiang and K. Gemiit, Characteristic Maximum-Length Sequences for the Interleaved Sampling Method, Acustica, vol. 82, pp. 905-907, 1996. 

Fig. 27a). The shift register is feedbacked through an exclusive OR (XOR) logic element. The number of produced random pulses is N = 2 — 1. This pattern is a period of the maximum length sequence (MLS) with duration Tmls = N//cik (Fig. 27b). The MLS has a continuous RMS spectral density expressed via the sinus cardinalis function (lsin(pf)/(pf)l) see Fig. 27c. It has enough power up to the frequency, at which the power spectral density PSD still retains its 50 % level ( 3 dB RMS level). 

Such a solution similar to Fig. 33c has been in use in the Southampton University, UK [7]. Excitation signal used in [7] is a pseudorandom sequence of binary pulses - the maximum length sequence MLS, see Fig. 27, enabling to perform fast and wide band impedance spectroscopy. The response signal is processed using a... 

In the formal measurements, the speed of sound in air and the air absorption at different measuranent times need to be taken into consideration. The diameter of the flat turntable is about 3.6 m, so it might be difficult to have a perfectly flat and circular turntable with a low-noise driving motor. The imperfections in the turntable also need to be compensated for by additional measurements. The measurements must use a deterministic source signal such as the maximum length sequences (MLS) signal to... 

The extended chain is another conformation which has been discussed often and proved to exist—e.g., in linear polyethylene crystallized at high pressures. It has also been assumed for amorphous polymers in the form of strands of parallel molecules [kink model (57)]. The maximum length L (x-ray) of a sequence of vinyl monomers of basic molecular weight M0 is 2.52 A. Straight strands of molecules can be... 

Maximum length binary sequences (MLBSs) of length N = 2l-l, where I is a positive integer, have a perfectly flat power spectrum [77]. The deconvolution in Eq. (61) can be computed very efficiently by means of a fast Hadamard transform, and they have, for example, been employed for Hadamard NMR spectroscopy [78]. 

Fig. 27.3-bit shift register to generate a maximum length binary sequence of length 23-1=7. The summation is modulo 2... 

Limitations of the TR-FRET approach in terms of peptide sequence flexibility must be considered as well. The prerequisites and limitations for successful peptide labeling, for example, for the LANCE Ultra approach include (1) need for a cysteine in position zero, i.e., the peptide s N terminus, (2) no other free cysteine allowed in the peptide sequence, (3) overall charge different from zero, (4) no disulfide bonds in the peptide, (5) no tryptophan or histidine at the C terminal position, and (6) maximum length of 30 amino acids (personal communication). 

An interesting application of the Hadamard transformation is its use for determination of the linear impulse-response function with maximum length binary sequences or m... 

The sequence of amino acids dictates certain geometric constraints for the polypeptide. These constraints include maximum lengths between covalent bonds, limiting angles in which bonds can be bent, and van der Waals radii, which limit how tightly structures can be packed. These factors, mixed with forces that help preferentially stabilize structures, such as hydrogen bonds, ionic attractions/ repulsions, hydrophobic interactions, and others, ultimately determine the shape that a peptide has over a short distance. The structure resulting from all these interactions is called the secondary structure of the protein. 

The TMpred Web interface is very simple. The sequence, in one-letter code, is pasted into the query sequence box, and the user can specify the minimum and maximum lengths of the hydrophobic part of the transmembrane helix to be used in the analysis. The output has four sections a list of possible transmembrane helices, a table of correspondences, suggested models for transmembrane topology, and a graphic representation of the same results. When the sequence of the G-protein-coupled receptor (P51684) served as the query, the following models were generated ... 

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