Atrial fibrillation (AF) is a troublesome disease often overlooked by more serious myocardial infarctions. Up until now, there has been very little or no use of high order spectral techniques in order to evaluate the organization of the atrium during AF. Cross-bicoherence algorithm can be used alongside a surrogate data threshold in order to determine significant phase coupling interactions, giving rise to an organizational metric. This proposed algorithm is used to show rotigaptide, a gap junction coupling drug, significantly increases the organization of the atria during episodes of AF due to improvement of cell-to-cell coupling.

Electrical Bioimpedance measurement has been used in clinical practice for several years for non-invasive monitoring. In recent years new applications of electrical bioimpedance measurements based in the spectral analysis has been validated.This fact have encouraged the use of spectral analysis on Electrical Bioimpedance measurements and it is a wide spread idea that spectral analysis of electrical bioimpedance data is going to open the door for new indicators for health assessment.The intended goal of this project is to develop a software tool, based in Matlab, that allows researchers to perform, both spectral and time signal analysis on the measurements performed Electrical Bioimpedance Spectrometers. This tool must incorporate the necessary display capabilities to allow quick visual inspection and visualization of the analysis results.Once this tool has been implemented, spectral analysis and validation of classification features will be possible in an easy way accelerating the process of test and analysis of experimental data analysis. This task is always critical in any research or clinical study.To facilitate the spectral analysis of electrical bioimpedance data will contribute to the developing of novel methods of non-invasive diagnosis and monitoring. / Uppsatsnivå: D

Neste texto são revisados métodos de reamostragem de séries temporais discretas baseados em wavelets, como alternativas as abordagens clássicas, feitas nos domínios do tempo e da frequência. Tais métodos, conhecidos na literatura como wavestrap e wavestrapping fazem uso, respectivamente, das transformadas wavelet discreta (DWT) e wavelet packet discreta (DWPT). Existem poucos resultados sobre a aplicação da DWPT, de forma que este texto pode ser considerado uma contribuição. Aqui mostra-se também, a superioridade do wavestrapping sobre o wavestrap quando aplicados na estimação da densidade espectral de potência de séries temporais sintéticas geradas a partir de modelos autoregressivos. Tais séries possuem uma particularidade interessante que são picos, geralmente acentuados, em sua reapresentação espectral, de tal forma que grande parte dos métodos clássicos de reamostragem apresentam resultados viesados quando aplicados a estes casos. / This paper reviews resampling methods based on wavelets as an alternative to the classic approaches which are, made in the time and frequency domains. These methods, known in the literature as wavestrap and wavestrapping, make use, respectively, of the discrete wavelet transform (DWT) and of the discrete wavelet packet transform (DWPT). Since only few results are avaliable when the DWPT is applied, this text can be considered a contribution to the subject. Here we, also show the superiority of wavestrapping over wavestrap when they are applied to the estimation of power spectral densities of the synthetic time series generated from autoregressive models. These series have an interesting feature that are sharp peaks in their spectral representation, so that most of the traditional methods of resampling lead to biased results.

abstract: In the past half century, low-power wireless signals from portable radar sensors, initially continuous-wave (CW) radars and more recently ultra-wideband (UWB) radar systems, have been successfully used to detect physiological movements of stationary human beings. The thesis starts with a careful review of existing signal processing techniques and state of the art methods possible for vital signs monitoring using UWB impulse systems. Then an in-depth analysis of various approaches is presented. Robust heart-rate monitoring methods are proposed based on a novel result: spectrally the fundamental heartbeat frequency is respiration-interference-limited while its higher-order harmonics are noise-limited. The higher-order statistics related to heartbeat can be a robust indication when the fundamental heartbeat is masked by the strong lower-order harmonics of respiration or when phase calibration is not accurate if phase-based method is used. Analytical spectral analysis is performed to validate that the higher-order harmonics of heartbeat is almost respiration-interference free. Extensive experiments have been conducted to justify an adaptive heart-rate monitoring algorithm. The scenarios of interest are, 1) single subject, 2) multiple subjects at different ranges, 3) multiple subjects at same range, and 4) through wall monitoring. A remote sensing radar system implemented using the proposed adaptive heart-rate estimation algorithm is compared to the competing remote sensing technology, a remote imaging photoplethysmography system, showing promising results. State of the art methods for vital signs monitoring are fundamentally related to process the phase variation due to vital signs motions. Their performance are determined by a phase calibration procedure. Existing methods fail to consider the time-varying nature of phase noise. There is no prior knowledge about which of the corrupted complex signals, in-phase component (I) and quadrature component (Q), need to be corrected. A precise phase calibration routine is proposed based on the respiration pattern. The I/Q samples from every breath are more likely to experience similar motion noise and therefore they should be corrected independently. High slow-time sampling rate is used to ensure phase calibration accuracy. Occasionally, a 180-degree phase shift error occurs after the initial calibration step and should be corrected as well. All phase trajectories in the I/Q plot are only allowed in certain angular spaces. This precise phase calibration routine is validated through computer simulations incorporating a time-varying phase noise model, controlled mechanic system, and human subject experiment. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018

The thesis presents a network model, where financial institutions form linkages at various investment horizons through their interdependence measured by volatility connectedness. Applying the novel framework of frequency connectedness mea- sures Baruník & Křehlík (2018), based on spectral representation of variance de- composition, we show fundamental properties of connectedness that originate in heterogeneous frequency responses to shocks. The newly proposed network mod- els characterize financial connections and systemic risk at the short-, medium- and long-term frequency. The empirical focus of this thesis is on the interde- pendence structure of US financial system, specifically, major U.S. banks in the period 2000 - 2016. In the light of frequency volatility connectedness measures, we argue that stocks with high levels of long-term connectedness represent greater systemic risk, because they are subject to persistent shocks transmitted for longer periods. When we assess institutions' risk premiums in asset pricing model, the model confirms the significance of volatility connectedness factor for asset prices. JEL Classification C18, C58, C58, G10, G15, Keywords connectedness, frequency, spectral analysis, sys- temic risk, financial network Author's e-mail 93539385@fsv.cuni.cz Supervisor's e-mail...

The primary goal of this paper is to demonstrate the application of a relatively esoteric and interdisciplinary technique, called spectral analysis, to dyadic social sciences data. Spectral analysis is an analytical and statistical technique, commonly used in engineering, that allows times series data to be analyzed for the presence of significant regular/periodic fluctuations/oscillations. These periodic fluctuations are reflected in the frequency domain as amplitude or energy peaks at certain frequencies. Furthermore, a Magnitude Squared Coherence analysis may be used to interrogate more than one time series concurrently in order to establish the degree of frequency domain correlation between the two series, as well to establish the phase (lead/lag) relationship between the coherent frequency components. In order to demonstrate the application of spectral analysis, the current study utilizes a secondary dyadic dataset comprising 30 daily reports of perceived sexual desire for 65 couples. The secondary goal of this paper is to establish a) whether there is significant periodic fluctuation in perceived levels of sexual desire for men and/or women, and at which specific frequencies, and b) how much correlation or `cross-spectral coherence' there is between partners' sexual desire within the dyads, and c) what the phase lead-lag relationship is between the partners at any of the identified frequency components. Sexual desire was found to have significant periodic components for both men and women, with a fluctuation of once per month being the most common frequency component across the groups of individuals under analysis. Mathematical models are presented in order to describe and illustrate these principal fluctuations. Partners in couples, on average, were found to fluctuate together at a number of identified frequencies, and the phase lead/lag relationships of these frequencies are presented.

This composition proposes and implements a way in which to incorporate the pipe organ into a contemporary instrumental setting. Considering the instrument's wide use in concert halls and its popularity with contemporary music, much of the timbre-based music has evaded incorporating it into its settings; for one reason or another, there are currently no timbre-based works composed for organ and chamber orchestra. By using the process of spectral analysis, this timbre-based composition demonstrates one possible way of doing so by investigating timbre similarities and differences between selected ranks of the organ and selected orchestral instruments and mapping them into pitch structures.

Doctor of Philosophy / This dissertation provides an overview of my research over the last five years into the spectral analysis involved in human sound localization. The work involved conducting psychophysical tests of human auditory localization performance and then applying analytical techniques to analyze and explain the data. It is a fundamental thesis of this work that human auditory localization response directions are primarily driven by the auditory localization cues associated with the acoustic filtering properties of the external auditory periphery, i.e., the head, torso, shoulder, neck, and external ears. This work can be considered as composed of three parts. In the first part of this work, I compared the auditory localization performance of a human subject and a time-delay neural network model under three sound conditions: broadband, high-pass, and low-pass. A “black-box” modeling paradigm was applied. The modeling results indicated that training the network to localize sounds of varying center-frequency and bandwidth could degrade localization performance results in a manner demonstrating some similarity to human auditory localization performance. As the data collected during the network modeling showed that humans demonstrate striking localization errors when tested using bandlimited sound stimuli, the second part of this work focused on human sound localization of bandpass filtered noise stimuli. Localization data was collected from 5 subjects and for 7 sound conditions: 300 Hz to 5 kHz, 300 Hz to 7 kHz, 300 Hz to 10 kHz, 300 Hz to 14 kHz, 3 to 8 kHz, 4 to 9 kHz, and 7 to 14 kHz. The localization results were analyzed using the method of cue similarity indices developed by Middlebrooks (1992). The data indicated that the energy level in relatively wide frequency bands could be driving the localization response directions, just as in Butler’s covert peak area model (see Butler and Musicant, 1993). The question was then raised as to whether the energy levels in the various frequency bands, as described above, are most likely analyzed by the human auditory localization system on a monaural or an interaural basis. In the third part of this work, an experiment was conducted using virtual auditory space sound stimuli in which the monaural spectral cues for auditory localization were disrupted, but the interaural spectral difference cue was preserved. The results from this work showed that the human auditory localization system relies primarily on a monaural analysis of spectral shape information for its discrimination of directions on the cone of confusion. The work described in the three parts lead to the suggestion that a spectral contrast model based on overlapping frequency bands of varying bandwidth and perhaps multiple frequency scales can provide a reasonable algorithm for explaining much of the current psychophysical and neurophysiological data related to human auditory localization.

The need for a standard approach for the diagnosis of speech disorders, in particular resonance disorders associated with cleft lip and/or palate, has been recognised. A reliable and valid measure of nasality is important, because it not only affects clinical decision making but is also essential for the evaluation of treatment outcomes. In order to allow cross-linguistic comparisons of the assessment of resonance, language specific stimuli developed according to a common set of guidelines have been recommended. The aim of this thesis was to contribute to the development of an assessment protocol for use in Malay speaking individuals with clefts of the lip and/or palate, specifically focusing on the detection of nasality. A series of four studies were completed which systematically developed and then validated a set of stimuli in the Malay language using both perceptual and instrumental measures. / In the first study, three stimuli were developed for the assessment of nasality based on both the proportion of nasal phonemes in typical conversation samples in Malay and guidelines from the current international literature. The phonetic content of the stimuli were comparable to similar passages used in English and comprised of an Oral Passage, a Nasal Passage and a Set of Sentences. / In the second study, the stimuli constructed were tested in a large number of typically developing (non-cleft) Malay speaking children using both instrumental and perceptual methods of assessment. The results of this study provide the first set of normative data of nasalance scores for the three newly developed stimuli. The mean nasalance score for the Oral Passage was 13.86% (SD = 5.11, 95% CI = 13.04–14.68), 60.28% (SD = 6.99, 95% CI = 59.15–61.41) for the Nasal Passage, and 27.72% (SD = 4.74, 95% CI = 26.96–28.49) for the Set of Sentences. These scores were significantly different from each other suggesting that they can be used to detect the different types of resonance disorder in speech (e.g. hypernasality and/or hyponasality). / In the third study, the stimuli were validated in a sample of Malay speaking children with cleft of the lip and/or palate and compared with a control population. Nasality was measured using perceptual evaluation and nasometry. The results suggested that the Oral Passage and Set of Sentences developed in Malay were valid measures for detecting hypernasality for both perceptual evaluation of nasality, and for nasometry. Due to the small number of participants that were hyponasal, the validity of the Nasal Passage could not be determined. / For nasometry to be clinically relevant threshold values that indicate abnormal nasality are required. The threshold values for each of the stimuli were first ascertained after obtaining typical nasality levels from a group of healthy Malay speaking children and then tested in a sample of cleft and non-cleft Malay speaking children. In contrast to the nasalance cutoffs obtained from typical Malay speaking children, the cutoffs obtained from the cleft children yielded better outcomes for detecting resonance disorders. The cutoffs were: ≥ 22% for the Oral Passage (sensitivity = 0.91, specificity = 0.93, overall efficiency = 0.92), ≥ 30% for the Set of Sentences (sensitivity = 0.96, specificity = 0.85, overall efficiency = 0.88) and ≤ 39 on the Nasal Passage (sensitivity = 1.00, specificity = 0.99, overall efficiency = 0.99). / Finally, the fourth study explored the application of recently developed techniques for assessing nasality using spectral voice analysis and compared these results with nasometry using a sub-sample of Malay speaking children from the third study. The participants were children with cleft lip and/or palate with perceived hypernasality and a group of healthy controls perceived to have normal resonance. The potential of assessing nasality using vowels, which ideally can be an easier option to administer clinically and have minimal impact on language and literacy skills, were investigated. / The findings showed that only the one-third-octave analysis method could be successfully used to detect hypernasality in the cleft population compared to the VLHR method. Using the one-third-octave analysis, the spectral characteristics of nasalised vowel /i/ taken from /pit/ and /tip/ showed an increase in amplitude in F1, between F1 and F2 regions. The amplitude of the formants at F3 region was lower in the cleft group but did not differ from the control group as reported in previous studies. Although, the one-third-octave analysis has some potential in detecting hypernasality, the accuracy of the analysis compared to perceptual ratings of nasality was only moderate. Compared to nasometry, the diagnostic value of the one-third-octave analysis in detecting hypernasality was lower. / The overall findings suggest that, except for the Nasal Passage, the Oral Passage and the Set of Sentences developed in Malay using this systematic approach were culturally appropriate and valid for the assessment of nasality. Furthermore, by comparing two instrumental methods (nasometry and spectral analysis) with perceptual evaluation in a large number of cleft and typically developing children, the present thesis was able to demonstrate the clinical benefits of two recently proposed methods of spectral voice analyses and compare them to existing methods. Compared to spectral analysis, nasometry remains a superior method for assessing nasality. Threshold values that indicate abnormal nasality levels for the newly developed stimuli in Malay have been recommended.

As a promising alternative to laboratory constrained video capture systems in studies of human movement, inertial sensors (accelerometers and gyroscopes) are recently gaining popularity. Secondary quantities such as velocity, displacement and joint angles can be calculated through integration of acceleration and angular velocities. However, it is broadly accepted that this procedure is significantly influenced by cumulative errors due to integration, arising from sensor noise, non-linearities, asymmetries, sensitivity variations and bias drifts. In this study, new methods for improving foot motion from inertial sensors are explored and assessed. / Sensor devices have been developed previously, for example, to detect postural changes that determine potential elderly fallers, and monitor a person’s gait. Recently, a gait variable known as minimum toe clearance (MTC) has been proposed to describe age-related declines in gait with better success as a predictor of falls risk. The MTC is the minimum vertical distance between the lowest point on the shoe and the ground during the mid-swing phase of the gait cycle. It is therefore of our interest to design a cost effective but accurate solution to measure toe clearance data which can then be used to identify the individuals at risk of falling. In this study, hardware, firmware and software features from off-the-shelf inertial sensors and wireless motes are evaluated and their configuration optimized for this application. A strap-down method, which consists of the minimizing of the integration drift due to cumulative errors, is evaluated off-line. Analysis revealed the necessity of band-pass filtering methods to correct systematic sensor errors that dramatically reduce the accuracy in estimating foot motion. / Cumulative errors were studied in the frequency domain, employing content of inertial sensor foot motion evaluated against a ’gold standard’ video-based device, namely the Optotrak Certus NDI. In addition, the effectiveness of applying band-pass filtering to raw inertial sensor data is assessed, under the assumption that sensor drift errors occur in the low frequency spectrum. The normalized correlation coefficient ρ of the Fast Fourier Transform (FFT) spectra corresponding to vertical toe acceleration from inertial sensors and from a video capture system as a function of digital band-pass filter parameters is compared. The Root Mean Square Error (RMSE) of the vertical toe displacement is calculated for 5 healthy subjects over a range of 4 walking speeds. The lowest RMSE and highest cross correlation achieved for the slowest walking speed of 2.5km/h was 3.06cmand 0.871 respectively, and 2.96cm and 0.952 for the fastest speed of 5.5km/h.