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From the viewpoint of operator theory, we discuss spectral properties for infinite directed graphs that have bounded valences. Graphs may have selfloops, but they are assumed not to have multiedges. Note that we use the transpose adjacency operator throughout this chapter by reason of this viewpoint. As a subsidiary effect, one may read this as a visual introduction to operator theory. [ABSTRACT FROM AUTHOR]

By using quasi-derivatives, we develop a Fourier method for studying the spectral properties of one-dimensional Schrödinger operators with periodic singular potentials. [ABSTRACT FROM AUTHOR]

In this paper, we propose an audio steganalysis method called reference based Fourier Spectrum Steganalysis. The mean values and the standard deviations of the high frequency spectrum of the second and high order derivatives are extracted from the testing signals and the reference versions. A Support Vector Machine (SVM) is employed to discriminate the unadulterated carrier signals and the steganograms wherein covert messages were embedded. Experimental results show that our method delivers very good performance and holds great promise for effective detection of steganograms produced by Hide4PGP, Invisible Secrets, S-tools4 and Steghide. [ABSTRACT FROM AUTHOR]

An algebraic field extension of ℚ or ℤ/(p) may be regarded either as a structure in its own right, or as a subfield of its algebraic closure ]> (either ]> or ]> ). We consider the Turing degree spectrum of F in both cases, as a structure and as a relation on ]> , and characterize the sets of Turing degrees that are realized as such spectra. The results show a connection between enumerability in the structure F and computability when F is seen as a subfield of ]> . [ABSTRACT FROM AUTHOR]

One important goal of many intelligent interactive systems is dynamic personalization and adaptivity to users. `Motion΄ and intention that are involved in the individual perception of musical structure combined with mirror neuron (MN) system activation are studied in this article. The mechanism of MN involved in the perception of musical structures is seen as a means for cueing the learner on `known΄ factors that can be used for his/her knowledge scaffolding. To explore such relationships, EEG recordings, and especially the Mu-rhythm in the premotor cortex that relates to the activation of MN, were acquired and explored. Three experiments were designed to provide the auditory and visual stimuli to a group of subjects, including both musicians and non-musicians. The acquired signals, after appropriate averaging in the time domain, were analysed in frequency and bifrequency domains, using spectral and bispectral analysis, respectively. Experimental results have shown that an intention-related activity shown in musicians could be associated with Mu-rhythm suppression. Moreover, an underlying ongoing function appearing in the transition from heard sound to imagined sound could be revealed in the bispectrum domain and a Mu-rhythm modulation provoked by the MNs could cause bispectral fluctuations, especially when visual stimulation is combined with an auditory one for the case of musicians. These results pave the way for transferring the research in the area of blind or visually impaired people, where hearing is the main information sensing tool. [ABSTRACT FROM AUTHOR]

As we saw in the last chapter, there was no generally agreed upon theory of muon decay processes in the early 1950s, although the decays were consistent with an STP combination. It was known that the coupling constants for those processes were approximately equal to those for nuclear β decay. This suggested the idea of a Universal Fermi Interaction that would apply to all weak interactions. The situation was quite different in the area of β-decay theory, where a consensus existed. In his 1943 review of the theory, Konopinski had noted the general support for Fermi's theory with a preference for the Gamow-Teller interaction involving the tensor (T) or axial vector (A) forms of the interaction. By the time of a 1953 review article by Konopinski and Langer, they stated, “As we shall interpret the evidence here, the correct law must be what is known as an STP combination” (1953, p. 261, emphasis added). In this section I will examine the evidence and arguments for this definite conclusion, which, as the subsequent history will show, was wrong, but not unreasonable. There were several attempts, based on general theoretical principles, to reduce the arbitrariness of the forms of the interactions involved in β decay. Recall that Critchfield and Wigner (1941) and Critchfield (1943) had, on the basis of symmetry considerations, found that the antisymmetric sum of the S, A, and P forms would fit the data. [ABSTRACT FROM AUTHOR]