Interpolation and Extrapolation of Toeplitz Matrices via Optimal Mass Transport

In this work, we propose a novel method for quantifying distances between Toeplitz structured covariance matrices. By exploiting the spectral representation of Toeplitz matrices, the proposed distance measure is defined based on an optimal mass transport problem in the spectral domain. This may then be interpreted in the covariance domain, suggesting a natural way of interpolating and extrapolating Toeplitz matrices, such that the positive semi-definiteness and the Toeplitz structure of these matrices are preserved. The proposed distance measure is also shown to be contractive with respect to both additive and multiplicative noise, and thereby allows for a quantification of the decreased distance between signals when these are corrupted by noise. Finally, we illustrate how this approach can be used for several applications in signal processing. In particular, we consider interpolation and extrapolation of Toeplitz matrices, as well as clustering problems and tracking of slowly varying stochastic processes

A Parametric Method for Multi-Pitch Estimation

This thesis proposes a novel method for multi-pitch estimation. The method operates by posing pitch estimation as a sparse recovery problem which is solved using convex optimization techniques. In that respect, it is an extension of an earlier presented estimation method based on the group-LASSO. However, by introducing an adaptive total variation penalty, the proposed method requires fewer user supplied parameters, thereby simplifying the estimation procedure. The method is shown to have comparable to superior performance in low noise environments when compared to three standard multi-pitch estimation methods as well as the predecessor method. Also presented is a scheme for automatic selection of the regularization parameters, thereby making the method more user friendly. Used together with this scheme, the proposed method is shown to yield accurate, although not statistically efficent, pitch Estimates when evaluated on synthetic speech data

Two labour market regimes in Sweden: a comparison between the Saltsjöbaden Agreement of 1938 and the Industrial Agreement of 1997

"Für mehr als 30 Jahre wurden die Arbeitsbeziehungen Schwedens durch das grundlegende Abkommen von Saltsjöbaden aus dem Jahr 1938 geregelt. Das zwischen LO und SAF zentral vereinbarte Abkommen schuf die Grundlage für sozialen Frieden, Kooperation und den Vorrang des Tarifvertrags gegenüber der Gesetzgebung. Mit Beginn der 70er Jahre wurde dieses Regime bedingt durch wachsende Konfrontation zwischen den Arbeitsmarktparteien und radikale Gesetzesinitiativen zunehmend obsolet. Erst in den 90er Jahren kam es zu einer Renaissance der Kooperation. Die Basis dafür schuf das 'Industrieabkommen' von 1997. Dieser Aufsatz ist ein systematischer Vergleich der beiden Abkommen in Bezug auf; (1) die Rolle des Staates bei deren Zustandekommen; (2) die Reichweite der Abkommen und ihrer Konsequenzen für die Spitzenverbände LO und SAF; (3) ihren Inhalt; (4) die Folgewirkungen auf andere Arbeitsmarktsegmente; (5) vertrauensvolle Kooperation der Tarifparteien und (6) deren symbolische Bedeutung für die Integration der Gesellschaft. Die Schlussfolgerung dieser Analyse ist, dass die Gemeinsamkeiten der Abkommen gegenüber Unterschieden überwiegen. Insofern ist davon auszugehen, dass das Industrieabkommen ein neues Arbeitsmarktregime in Schweden begründet hat." (Autorenreferat)"The Saltsjöbaden Agreement of 1938 between the Swedish Employers' Confederation (SAF) and the Swedish Trade Union Confederation (LO) initiated a new, epoch in the history of Swedish industrial relations. It was characterized by labour peace, constructive co-operation, and a strong emphasis on collective bargaining. Around 1970, however, the Saltsjöbaden Regime was superseded by a confrontational regime through a wave of farreaching labour legislation, inspired by a radicalized political climate. Not until the beginning of the 1990s did a new climate of co-operation emerge on the Swedish labour market. The most important manifestation of this change was the so-called Industrial Agreement of l997. The aim of this article is to make a systematic comparison between the two great agreements in terms of (1) the role of the state in the origin of the agreements; (2) The scope of the agreements and their effects LO and SAF; (3) the content of the agreements, (4) effects on other parts of the labour market; (5) institutionalized co-operation and mutual trust; (6) their symbolic relevance for a general spirit of mutual understanding in politics and society. Overall, the similarities between the Saltsjöbaden Agreement and the Industrial Agreement far outweigh the differences. This is why we can talk about a new labour market regime in Sweden, beginning in 1997." (author's abstract

Defining Fundamental Frequency for Almost Harmonic Signals

In this work, we consider the modeling of signals that are almost, but not quite, harmonic, i.e., composed of sinusoids whose frequencies are close to being integer multiples of a common frequency. Typically, in applications, such signals are treated as perfectly harmonic, allowing for the estimation of their fundamental frequency, despite the signals not actually being periodic. Herein, we provide three different definitions of a concept of fundamental frequency for such inharmonic signals and study the implications of the different choices for modeling and estimation. We show that one of the definitions corresponds to a misspecified modeling scenario, and provides a theoretical benchmark for analyzing the behavior of estimators derived under a perfectly harmonic assumption. The second definition stems from optimal mass transport theory and yields a robust and easily interpretable concept of fundamental frequency based on the signals' spectral properties. The third definition interprets the inharmonic signal as an observation of a randomly perturbed harmonic signal. This allows for computing a hybrid information theoretical bound on estimation performance, as well as for finding an estimator attaining the bound. The theoretical findings are illustrated using numerical examples.Comment: Accepted for publication in IEEE Transactions on Signal Processin

Zero-Shot Blind Audio Bandwidth Extension

Audio bandwidth extension involves the realistic reconstruction of high-frequency spectra from bandlimited observations. In cases where the lowpass degradation is unknown, such as in restoring historical audio recordings, this becomes a blind problem. This paper introduces a novel method called BABE (Blind Audio Bandwidth Extension) that addresses the blind problem in a zero-shot setting, leveraging the generative priors of a pre-trained unconditional diffusion model. During the inference process, BABE utilizes a generalized version of diffusion posterior sampling, where the degradation operator is unknown but parametrized and inferred iteratively. The performance of the proposed method is evaluated using objective and subjective metrics, and the results show that BABE surpasses state-of-the-art blind bandwidth extension baselines and achieves competitive performance compared to non-blind filter-informed methods when tested with synthetic data. Moreover, BABE exhibits robust generalization capabilities when enhancing real historical recordings, effectively reconstructing the missing high-frequency content while maintaining coherence with the original recording. Subjective preference tests confirm that BABE significantly improves the audio quality of historical music recordings. Examples of historical recordings restored with the proposed method are available on the companion webpage: (http://research.spa.aalto.fi/publications/papers/ieee-taslp-babe/)Comment: Submitted to IEEE/ACM Transactions on Audio, Speech and Language Processin

Causes of Stillbirth and Time of Death in Swedish Holstein Calves Examined Post Mortem

This study was initiated due to the observation of increasing and rather high levels of stillbirths, especially in first-calving Swedish Holstein cows (10.3%, 2002). Seventy-six Swedish Holstein calves born to heifers at 41 different farms were post mortem examined in order to investigate possible reasons for stillbirth and at what time in relation to full-term gestation they had occurred. The definition of a stillborn calf was dead at birth or within 24 h after birth after at least 260 days of gestation. Eight calves were considered as having died already in uterus. Slightly less than half of the examined calves (46.1%) were classified as having died due to a difficult calving. Four calves (5.3%) had different kinds of malformations (heart defects, enlarged thymus, urine bladder defect). Approximately one third of the calves (31.6%) were clinically normal at full-term with no signs of malformation and born with no indication of difficulties at parturition or any other reason that could explain the stillbirth. The numbers of male and female calves were rather equally distributed within the groups. A wide variation in post mortem weights was seen in all groups, although a number of the calves in the group of clinically normal calves with unexplained reason of death were rather small and, compared with e.g. those calves categorised as having died due to a difficult calving, their average birth weight was 6 kg lower (39.9 ± 1.7 kg vs. 45.9 ± 1.5 kg, p ≤ 0.01). It was concluded that the cause of stillbirth with a non-infectious aetiology is likely to be multifactorial and difficult calving may explain only about half of the stillbirths. As much as one third of the calves seemed clinically normal with no obvious reason for death. This is a target group of calves that warrants a more thorough investigation in further studies

A Diffusion-Based Generative Equalizer for Music Restoration

This paper presents a novel approach to audio restoration, focusing on the enhancement of low-quality music recordings, and in particular historical ones. Building upon a previous algorithm called BABE, or Blind Audio Bandwidth Extension, we introduce BABE-2, which presents a series of significant improvements. This research broadens the concept of bandwidth extension to \emph{generative equalization}, a novel task that, to the best of our knowledge, has not been explicitly addressed in previous studies. BABE-2 is built around an optimization algorithm utilizing priors from diffusion models, which are trained or fine-tuned using a curated set of high-quality music tracks. The algorithm simultaneously performs two critical tasks: estimation of the filter degradation magnitude response and hallucination of the restored audio. The proposed method is objectively evaluated on historical piano recordings, showing a marked enhancement over the prior version. The method yields similarly impressive results in rejuvenating the works of renowned vocalists Enrico Caruso and Nellie Melba. This research represents an advancement in the practical restoration of historical music.Comment: Submitted to DAFx24. Historical music restoration examples are available at: http://research.spa.aalto.fi/publications/papers/dafx-babe2

Epidemiological studies of vacuum extraction delivery : incidence, risk factors and subsequent childbearing

The aim of this thesis was to bring focus on factors and outcomes associated with vacuum extraction delivery (VE). Delivery by VE is associated with both maternal risks (such as obstetric anal sphincter ruptures, postpartum hemorrhage and a negative birth experience) and infant risks (such as scalp lacerations, cephalohematoma, intracranial hemorrhage and brachial plexus injury). In Sweden, every seventh first time mother is delivered by VE, yet little is known about risk factors, incidence over time, birth experience and subsequent childbearing. In study I we used the Medical Birth Register (MBR) to investigate factors related to VE and use over time among 589 108 primiparous women with singleton, term births in 1992-2010. We found that rates of VE increased from 11.5% in 1992 to 14.8% in 2010. The risk of VE increased with maternal age and gestational length, but decreased with increasing maternal height. Logistic regression analyses showed that the increased use of VE over time was partly explained by increasing maternal age and increased use of epidural anesthesia (EDA). Among women with and without EDA, the increase in VE over time was confined to VE due to the indication non-reassuring fetal status. In study II we included a total of 265 456 singleton neonates born to nulliparous women at term between 1999 and 2008. Compared with women giving birth to a neonate with average size head circumference (35 cm), women giving birth to an infant with a very large head circumference (39–41 cm) had significantly higher odds of being diagnosed with prolonged labor (OR 1.49, 95% CI 1.33–1.67), signs of fetal distress (OR 1.73, 95% CI 1.49– 2.03) and maternal distress (OR 2.40, 95% CI 1.96–2.95). The odds ratios for VE and cesarean section were thereby elevated to 3.47 (95% CI 3.10–3.88) and 1.22 (95% CI 1.04– 1.42), respectively. In study III, 3006 women were interviewed in their third trimester and one month after first childbirth to assess fear of birth and birth experience. Logistic regression was performed to examine the interactions and associations between fear of birth, mode of delivery and birth experience. Compared to women with low levels of fear of birth, women with higher levels of fear had a more negative birth experience and were more affected by an EmCS or VE. Compared to women with low levels of fears with a SVD, women with high levels of fear who were delivered by VE had a 10-fold increased risk of reporting a negative birth experience (OR 10.35, 95% CI 5.25-20.39). A SVD was associated with the most positive birth experience among the women in this study. In study IV we used a cohort of 771 690 women who delivered their first singleton infant in Sweden between 1992 and 2010 to investigate the relationship between mode of first delivery and probability of subsequent childbearing. Using Cox’s proportional-hazards regression models, risks of subsequent childbearing were compared across four modes of delivery. Compared with women who had a SVD, women who delivered by VE were less likely to have a second pregnancy (HR 0.96, 95% CI 0.95–0.97), and the probabilities of a second childbirth were substantially lower among women with a previous EmCS (HR 0.85, 95% CI 0.84–0.86) or an elective caesarean section (HR 0.82, 95% CI 0.80–0.83). There were no clinically important differences in the median time between first and second pregnancy by mode of first delivery