Phase Lags and Coherence of X-Ray Variability in Black Hole Candidates

The ``low'' (hard or ``non-thermal'') state of black hole candidates is sometimes modelled via an optically thick, hot Compton cloud that obscures a softer input source such as an accretion disk. In these models the observed output spectra consist entirely of photons reprocessed by the cloud, making it difficult to extract information about the input spectra. Recently Miller (1995) has argued that the Fourier phase (or time) lag between hard and soft X-ray photons in actuality represents the phase lags intrinsic to the input source, modulo a multiplicative factor. The phase lags thus would be a probe of the input photon source. In this paper we examine this claim and find that, although true for the limited parameter space considered by Miller, the intrinsic phase lag disappears whenever the output photon energy is much greater than the input photon energy. The remaining time lags represent a ``shelf'' due to differences between mean diffusion times across the cloud. As pointed out by Miller, the amplitude of this shelf -- which is present even when the intrinsic time lags remain -- is indicative of the size and temperature of the Compton cloud and is a function of the two energies being compared. However, we find that with previous instruments such as Ginga the shelf, if present, was likely obscured by counting noise. A more sensitive measure of Compton cloud parameters may be obtainable from the coherence function, which is derived from the amplitude of the Fourier cross power spectral density. This function has been seen to exponentially decrease at high Fourier frequencies in Cygnus X-1. Coherence loss is characteristic of Compton clouds that undergo large variations of size and/or temperature on time scales longer than about 10 seconds. We argue that observing phase lags and coherenceComment: 14 pages, uuencoded postscript, accepted for publication in Monthly Notice

Universal Design in Curriculum Development to Address Issues of Socio-Cultural Capital in Third-level Education

Universal Design for Instruction (UDI) is primarily focused on ensuring that curricula are as accessible to students with a range of disabilities and difficulties. However, UDI can also be leveraged as a means of addressing issues of socio-cultural capital in third-level education. The assumption that all students belong to the dominant habitus can have a detrimental effect on those seen as being external to it. This paper examines the use of UDI as part of a wider approach to curriculum development as a means of addressing these issue. This is especially pertinent in light of the amalgamation of a number of technical institutes (Dublin Institute of Technology (DIT), Institute of Technology Tallaght (ITT) Institute of Technology Blanchardstown (ITB)) as part of the development of a Technical University in Dublin (colloquially referred to as TU4Dublin), as the student population across these institutes encapsulates a wide-range of socio-cultural, and educational backgrounds

Universal Design in Curriculum Development to Address Issues of Socio-Cultural Capital in Third-Level Education

Universal Design for Instruction (UDI) is primarily focused on ensuring that curricula are as accessible to students with a range of disabilities and difficulties. However, UDI can also be leveraged as a means of addressing issues of socio-cultural capital in third-level education. The assumption that all students belong to the dominant habitus can have a detrimental effect on those seen as being external to it. This paper examines the use of UDI as part of a wider approach to curriculum development as a means of addressing these issue. This is especially pertinent in light of the amalgamation of a number of technical Institutes (DIT, ITT, and ITB) as part of the development of a Technical University in Dublin (colloquially referred to as TU4Dublin), as the student population across these institutes encapsulates a wide-range of socio-cultural, and educational backgrounds

Naturalistic Emotional Speech Corpora with Large Scale Emotional Dimension Ratings

The investigation of the emotional dimensions of speech is dependent on large sets of reliable data. Existing work has been carried out on the creation of emotional speech corpora and the acoustic analysis of emotional speech and this research seeks to buildupon this work while suggesting new methods and areas of potential. A review of the literature determined that a two dimensional emotional model of activation and evaluation was the ideal method for representing the emotional states expressed inspeech. Two case studies were carried out to investigate methods of obtaining naturalunderlying emotional speech in a high quality audio environment, the results of which were used to design a final experimental procedure to elicit natural underlying emotional speech. The speech obtained in this experiment was used in the creation ofa speech corpus that was underpinned by a persistent backend database that incorporated a three-tiered annotation methodology. This methodology was used to comprehensively annotate the metadata, acoustic data and emotional data of the recorded speech. Structuring the three levels of annotation and the assets in a persistent backend database allowed interactive web-based tools to be developed; aweb-based listening tool was developed to obtain a large amount of ratings for the assets that were then written back to the database for analysis. Once a large amount of ratings had been obtained, statistical analysis was used to determine the dimensionalrating for each asset. Acoustic analysis of the underlying emotional speech was then carried out and determined that certain acoustic parameters were correlated with the activation dimension of the dimensional model. This substantiated some of thefindings in the literature review and further determined that spectral energy was strongly correlated with the activation dimension in relation to underlying emotional speech. The lack of a correlation for certain acoustic parameters in relation to the evaluation dimension was also determined, again substantiating some of the findings in the literature.The work contained in this thesis makes a number of contributions to the field: the development of an experimental design to elicit natural underlying emotional speech in a high quality audio environment; the development and implementation of acomprehensive three-tiered corpus annotation methodology; the development and implementation of large scale web based listening tests to rate the emotional dimensions of emotional speech; the determination that certain acoustic parameters are correlated with the activation dimension of a dimensional emotional model inrelation to natural underlying emotional speech and the determination that certain acoustic parameters are not correlated with the evaluation dimension of a twodimensional emotional model in relation to natural underlying emotional speech

Emotional Speech Corpus Creation, Structure, Distribution and Re-Use

Abstract This paper details the on-going creation of a natural emotional speech corpus, its structure, distribution, and re-use. Using Mood Induction Procedures (MIPs), high quality emotional speech assets are obtained, analysed, tagged (for acoustic features), annotated and uploaded to an online speech corpus. This method structures the corpus in a logical and coherent manner, allowing it to be utilized for more than one purpose, ensuring distribution via a URL and ease of access through a web browser

Measuring Variations of Mimicry by Means of Prosodic Cues in Task-Based Scenarios and Conversational Speech

Here, we address the measurement of mimicry, that is when speakers’ speech variations look like parallel patterns. As a definition of mimicry, we often read in the literature description such as mimicry is “The situation where the observed behaviours of two inter-actants although dissimilar at the start of the interaction are moving towards behavioral matching”. These types of descriptions imply that mimicry is a linear phenomenon and that speakers tend to imitate over time. However, it can be assumed, especially when studying spontaneous speech, that there are rather phases of mimicry and non-mimicry and that mimicry should be rather investigated as a dynamic phenomenon. As mimicry has been considered so far as a linear phenomenon, metrics developed to measure this phenomenon failed to capture its temporal dynamics. In this work then, we propose to measure mimicry on the whole interaction but also at certain points of the conversation