Cognitive Phonetics: The Transduction of Distinctive Features at the Phonology-Phonetics Interface

We propose that the interface between phonology and phonetics is mediated by a transduction process that converts elementary units of phonological computation, features, into temporally coordinated neuromuscular patterns, called ‘True Phonetic Representations’, which are directly interpretable by the motor system of speech production. Our view of the interface is constrained by substance-free generative phonological assumptions and by insights gained from psycholinguistic and phonetic models of speech production. To distinguish transduction of abstract phonological units into planned neuromuscular patterns from the biomechanics of speech production usually associated with physiological phonetics, we have termed this interface theory ‘Cognitive Phonetics’ (CP). The inner workings of CP are described in terms of Marr’s (1982/2010) tri-level approach, which we used to construct a linking hypothesis relating formal phonology to neurobiological activity. Potential neurobiological correlates supporting various parts of CP are presented. We also argue that CP augments the study of certain phonetic phenomena, most notably coarticulation, and suggest that some phenomena usually considered phonological (e.g., naturalness and gradience) receive better explanations within CP

Cryptography and Its Applications in Information Security

Nowadays, mankind is living in a cyber world. Modern technologies involve fast communication links between potentially billions of devices through complex networks (satellite, mobile phone, Internet, Internet of Things (IoT), etc.). The main concern posed by these entangled complex networks is their protection against passive and active attacks that could compromise public security (sabotage, espionage, cyber-terrorism) and privacy. This Special Issue “Cryptography and Its Applications in Information Security” addresses the range of problems related to the security of information in networks and multimedia communications and to bring together researchers, practitioners, and industrials interested by such questions. It consists of eight peer-reviewed papers, however easily understandable, that cover a range of subjects and applications related security of information

Non-equilibrium states of disordered systems: from low-frequency properties of glasses to distribution function of active Ornstein-Uhlenbeck particles

2022 Spring.Includes bibliographical references.This dissertation focuses on stationary and dynamical properties of non-equilibrium systems of disordered matter. In particular, we discuss the correlation between the stability of ultra-stable to moderately stable amorphous solids and the structural fluctuations of the elastic field at low frequencies. We report a strong correlation between the stability and the structural homogeneity which we demonstrate numerically through the calculation of local elastic moduli of the solid. Notably, we do not identify any significant length scale associated with elastic correlations which bears specific implications for the wave attenuation in amorphous solids. In the second part of the dissertation, we shift our focus to the disordered systems of active matter. We derive a formal expression for the stationary probability density function of a tagged active particle in an interacting system of active Ornstein-Uhlenbeck particles. We further identify an effective temperature in the probability density function which allows for the subsequent numerical validation of our theoretical results beyond the linear response regime. We show that the effective temperature defined through the violation of the Einstein relation (or equivalently the fluctuation-dissipation theorem), can predict the tagged active particle's density distribution. Lastly, we derive theoretical expressions for the stationary probability density distribution and the current of a non-interacting active Ornstein-Uhlenbeck particle in a tilted periodic potential. We demonstrate the quantitative agreement of these expressions with our numerical results for small to moderate correlation times of the colored-noise. We further explore the dependence of the diffusive motion on the strength of tilting force. We observe a giant enhancement in the diffusion of the particle which becomes more pronounced with increasing the persistence time

Load Estimation, Structural Identification and Human Comfort Assessment of Flexible Structures

Stadiums, pedestrian bridges, dance floors, and concert halls are distinct from other civil engineering structures due to several challenges in their design and dynamic behavior. These challenges originate from the flexible inherent nature of these structures coupled with human interactions in the form of loading. The investigations in past literature on this topic clearly state that the design of flexible structures can be improved with better load modeling strategies acquired with reliable load quantification, a deeper understanding of structural response, generation of simple and efficient human-structure interaction models and new measurement and assessment criteria for acceptable vibration levels. In contribution to these possible improvements, this dissertation taps into three specific areas: the load quantification of lively individuals or crowds, the structural identification under non-stationary and narrowband disturbances and the measurement of excessive vibration levels for human comfort. For load quantification, a computer vision based approach capable of tracking both individual and crowd motion is used. For structural identification, a noise-assisted Multivariate Empirical Mode Decomposition (MEMD) algorithm is incorporated into the operational modal analysis. The measurement of excessive vibration levels and the assessment of human comfort are accomplished through computer vision based human and object tracking, which provides a more convenient means for measurement and computation. All the proposed methods are tested in the laboratory environment utilizing a grandstand simulator and in the field on a pedestrian bridge and on a football stadium. Findings and interpretations from the experimental results are presented. The dissertation is concluded by highlighting the critical findings and the possible future work that may be conducted

Circadian Organization of the Neuroendocrine System of an Adult Insect, Rhodnius Prolixus (STÄL) (HEMIPTERA)

Circadian clocks synchronize with external environmental cycles and regulate rhythms throughout the organism, creating an internal temporal organization of cellular and physiological processes. In the model insect Rhodnius prolixus the prothoracicotropic hormone (PTTH)-ecdysteroid axis is a central component of the larval circadian system. However, PTTH is considered a larval hormone and its only known target, the ecdysteroid-producing prothoracic glands, are absent in adults. Here, PTTH is demonstrated to be present in adult female Rhodnius and its synthesis and release during the period of egg development and oviposition were shown to fluctuate with a daily rhythm that is controlled by the circadian clock in the brain. Ecdysteroids are also present during this time and their levels in hemolymph and ovaries undergo synchronous daily variations that are likewise under clock control. Ovaries are the only adult tissue examined that both contained and released ecdysteroids. It is inferred that the ovaries generate the rhythm of ecdysteroids in the hemolymph. The parallel patterns of PTTH and ecdysteroid release suggest these processes are related and it is tempting to speculate that the PTTH-ecdysteroid axis persists in the adult leading to the orchestration of complex adult-specific processes, such as egg development and oviposition

Interpretations of Bicoherence in Space & Lab Plasma Dynamics

The application of bicoherence analysis to plasma research, particularly in non-linear, coupled-wave regimes, has thus far been significantly belied by poor resolution in time, and/or outright destruction of frequency information. Though the typical power spectrum cloaks the phase-coherency between frequencies, Fourier transforms of higher-order convolutions provide an n-dimensional spectrum which is adept at elucidating n-wave phase coherence. As such, this investigation focuses on the utility of the normalized bispectrum for detection of wave-wave coupling in general, with emphasis on distinct implications within the scope of non-linear plasma physics. Interpretations of bicoherent features are given for time series from shots at the DIII-D tokamak facility; the solar wind, as measured by the Cluster-II satellite installation; a van der Pol oscillator; and various audio signals, both recorded and contrived. Evaluations of the bicoherence exhibited by simple harmonic relationships are contrasted with those displaying truly non-linear signatures, and the temporal dynamics of their respective bispectra are assessed. Also considered are the curatives and caveats of cogently condensing these 4-dimensional data

A Statistical Perspective of the Empirical Mode Decomposition

This research focuses on non-stationary basis decompositions methods in time-frequency analysis. Classical methodologies in this field such as Fourier Analysis and Wavelet Transforms rely on strong assumptions of the underlying moment generating process, which, may not be valid in real data scenarios or modern applications of machine learning. The literature on non-stationary methods is still in its infancy, and the research contained in this thesis aims to address challenges arising in this area. Among several alternatives, this work is based on the method known as the Empirical Mode Decomposition (EMD). The EMD is a non-parametric time-series decomposition technique that produces a set of time-series functions denoted as Intrinsic Mode Functions (IMFs), which carry specific statistical properties. The main focus is providing a general and flexible family of basis extraction methods with minimal requirements compared to those within the Fourier or Wavelet techniques. This is highly important for two main reasons: first, more universal applications can be taken into account; secondly, the EMD has very little a priori knowledge of the process required to apply it, and as such, it can have greater generalisation properties in statistical applications across a wide array of applications and data types. The contributions of this work deal with several aspects of the decomposition. The first set regards the construction of an IMF from several perspectives: (1) achieving a semi-parametric representation of each basis; (2) extracting such semi-parametric functional forms in a computationally efficient and statistically robust framework. The EMD belongs to the class of path-based decompositions and, therefore, they are often not treated as a stochastic representation. (3) A major contribution involves the embedding of the deterministic pathwise decomposition framework into a formal stochastic process setting. One of the assumptions proper of the EMD construction is the requirement for a continuous function to apply the decomposition. In general, this may not be the case within many applications. (4) Various multi-kernel Gaussian Process formulations of the EMD will be proposed through the introduced stochastic embedding. Particularly, two different models will be proposed: one modelling the temporal mode of oscillations of the EMD and the other one capturing instantaneous frequencies location in specific frequency regions or bandwidths. (5) The construction of the second stochastic embedding will be achieved with an optimisation method called the cross-entropy method. Two formulations will be provided and explored in this regard. Application on speech time-series are explored to study such methodological extensions given that they are non-stationary