The existence of cosmic strings was proposed in the mid-seventies as a by-product of the various phase transitions that occured in the early Universe. Cosmic strings are one-dimensional topological defects; structures of extremely high energy density with infinitesimal widths and lengths of cosmological size. After they were proposed, cosmic strings with GUT energy scales became very popular as a potential source for galaxy formation, but after CMB observations ruled out this possibility, they stopped attracting much scientific attention. The whole field was revived as part of superstring theory, where the formation of cosmic (super)string networks is a very common characteristic of brane inflation models, allowing them to acquire energies over a much more extended range. Attempts to detect cosmic strings centers on the three most basic observational signatures they create: CMB anisotropies, gravitational lensing events and the stochastic gravitational wave background they are expected to have created. So far, no detection of cosmic strings has been achieved. Their non-detection has inevitably led to setting constraints on their most important characteristic; their lineal energy density (or tension) which describes their energy scale. The topic of this thesis is how to use pulsar timing arrays (PTAs) in order to set constraints on the string tension. The limits PTAs can set on the amplitude of the stochastic gravitational wave background at ~nHz frequencies can be used to set constraints on the string tension. Such an effort is much more complicated than CMB or gravitational lensing investigations due to the large number of unknown cosmic string model parameters which are involved and for which, not only we do not have any observational evidence for their value, but moreover, they can acquire values over very wide ranges. So far, previous investigations were based on assumptions about these parameters and on the specific gravitational wave emission mechanism from cosmic string loops. In this work we have constructed a new code to reproduce the gravitational wave background from a cosmic string network, based on the widely accepted one scale model. Using this, we have performed numerous simulations to study the effects on the gravitational wave spectrum for each cosmic string model parameter, covering the whole parameter space of interest for each of them. Moreover, we have also extended the application of our code in order to describe cosmic string networks which create loops on more than one scale, models of which have recently appeared in the literature. In particular, we have investigated cosmic string networks which create loops at two distinct scales and loops with scales described by a log-normal distribution After studying the properties of the gravitational wave spectrum from cosmic strings, we combined our simulations with the most stringent limit so far on the stochastic gravitational wave background imposed by the EPTA. This limit is provided as a function of the slope of the gravitational wave background and we have also used this information for the first time to acquire even more accurate results. In our approach, we did not make any assumption about the values of the cosmic string model parameters, investigating all possibilities and we managed to compute a conservative and completely general constraint on the cosmic string tension, G mu<5.3x10 -7, which is slightly weaker than the current constraints set by CMB and gravitational lensing. We concluded our work by estimating the projected constraints that are expected to be achieved by near future experiments like LEAP, and ultimately by the SKA, to find an improvement of at least two orders of magnitude, significantly outperforming the expected constraints by future CMB investigations.

This study describes the integration of harmonic idiom and tonal design in Schoenberg's First Quartet, op. 7. Two general questions are answered: whether the composition should be judged by common-practice-period norms, and whether a coherent tonal structure is truly discernible. Chapter 1 first surveys the existing literature. It then describes a prime motivator of foreground chromaticism in the quartet—the chromatic surrounding of tonic and dominant pitches—and discusses two features of large-scale pitch organization applicable to Schoenberg's first-period music that contravene common-practice-period norms: tonal structure consisting of a pattern of keys, and systematic use of dual or even multiple tonics in place of monotonality. Examples illustrate three types of graphic representation of tonal duality to be used in the study. The next four chapters describe tonal process within and across the four "movements" of the quartet (Schoenberg's Parts I through IV). Chapter 2, which studies Part I, reveals systematic avoidance of V-I function in the opening key, D, tonal rivalries between D and each of its two semitone-related keys, and the beginning of a large-scale chromatic surrounding of the key of D. Chapter 3, on Part II of the quartet, demonstrates continuation of the rivalry between tonics D and Dt> by their use as competing secondary tonics within the Scherzo, and the harmonic progression VII-I replacing V-I at a crucial structural point. Chapter 4, on Part III of the quartet, describes tonal duality as it occurs in the Adagio, the furthering of the tonal plot in a section that engages in a "plagal" system of tonality, and the beginning of a large chromatic surrounding of A. Chapter 5 shows that Part IV eschews a simple relationship between the A-major tonic of the Rondo and the D-major tonic of the Coda by allowing the infiltration of elements of the Db-major collection. Chapter 6 summarizes the evidence contradicting a monotonal understanding of the composition and reviews evidence that the demonstrated multi-tonal coherence is part of the musical reality of the work. / Arts, Faculty of / Music, School of / Graduate

The purpose of this study was to explore the ways in which high school violin students transform and comprehend a teacher’s model through the framework of Kolb’s (1984) Experiential Learning Theory. Additionally, the Learning Styles Inventory (LSI) results of this study’s participants were compared to extant researchers’ LSI data. Kolb and Kolb’s Learning Styles Inventory 3.1 and a brief survey were administered to participants (N = 100) during Phase I of the study in order to gather data regarding three quantitative independent variables—learning style, gender, and grade level. A subset of participants (n = 15) representing an array of those variables participated in Phase II of the study wherein participants were shown a video recorded lesson. During that lesson, a teacher modeled an eight-measure melodic phrase for each participant whose responses to the lesson were recorded for later analysis. Qualitative student responses (applied strategy, focus during the lesson, type of response to the model, performance intensity, task complexity) and interview responses were coded and distilled into common themes and compared among independent variables from Phase I. The high school violinist participants in this study preferred reflective observation and concrete experience orientations more frequently than was the case in extant research. The only significant interaction between independent variables was found between gender and learning preference. The two most frequently applied strategies were derived from Initiating (AE/CE = 24.46%) and Creating (CE/RO = 20.44%) learning styles. Participants largely focused on musical components (77.55%)—e.g., rhythm, pitch, intonation, articulation—by performing with the bow (48.72%) concurrently with the model (57.95%). When provided with practice time, participants largely utilized low (33. 68%) or silent, reflective (24.47%) intensities. Fundamental, two-phase combinations of strategies were applied the majority of the time (57.72%) by participants. Qualitative descriptions of the variety of participant responses were included and contextualized using LSI data. I concluded, based on a synthesis of the quantitative data and qualitative observations, that participants largely prioritized immediate individual needs—such as pitch identification or previous sections of the lesson—over both teacher instruction and their own learning preferences. I also concluded that a single modeling experience often resulted in a diverse array of participant responses—which may or may not adhere to the immediate content of the lesson. As a result of this study, I suggest that music educators and researchers consider that learners potentially utilize a singular modeling experience in a variety of different ways resulting in an array of potential outcomes. It is important for teachers to be explicit and clear in their instructions surrounding a modeling task in order to better guide students towards desired outcomes. Future researchers might consider learners’ viewpoints in response to a modeled experience as a means of framing achievement, outcome, or other research topics. ELT researchers might consider building on the implications of the comparison among KLSI data and qualitative data among learners under the age of 19 with a focus on variables outside the typical factors of gender, age, educational level, educational specialization, and culture.

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Made available in DSpace on 2015-03-26T13:45:35Z (GMT). No. of bitstreams: 1 texto completo.pdf: 956809 bytes, checksum: ebf2affe7b281f8af02d3a0fdd8101f6 (MD5) Previous issue date: 2012-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Special biserial algebras are a class of algebras that appear in many contexts. Butler and Ringel [6] made a description of indecomposable modules and irreducible morphisms of algebras string, a subclass of special biserial algebras. We show that special biserial algebras which are not string, have only one module projective-injective indecomposable for each binomial relation. We are present the Auslander-Reiten sequence in which these modules appear. Then we verify that the remainder of Auslander-Reiten quiver of special biserial algebras is obtained as done by Butler and Ringel [6] for string algebras. We conclude this work by applying the above results for the representations of the algebras of finite cyclic groups and algebras of the Klein group and diedral groups over algebraically closed field of characteristic 2. / Álgebras bisseriais especiais formam uma classe de álgebras que aparecem em diferentes contextos. A aplicabilidade destas álgebras que estamos interessados é no estudo de representações de algumas álgebras de grupo não semissimples sobre corpos algebricamente fechados. Para isso, descrevemos, a menos de isomorfismos, seus módulos indecomponíveis e seus morfismos irredutíveis. Tal descrição é feita através de uma bela apresentação combinatória, dada por Butler e Ringel [6], dos módulos indecomponíveis e dos morfismos irredutíveis de um caso particular de álgebras bisseriais especiais, as álgebras string. No caso geral, de álgebras bisseriais especiais que não são string, mostramos que são acrescentados apenas um módulo projetivo-injetivo indecomponível para cada relação binomial. Apresentamos a sequência de Auslander-Reiten em que estes módulos aparecem e verificamos que, a menos destas sequências, o restante do quiver de Auslander-Reiten é obtido como feito por Butler e Ringel [6] para álgebras string. Para módulos string, apresentamos ainda uma descrição gráfica de uma base dos espaços de morfismos, de acordo com Crawley-Boevey [7]. Finalizamos o trabalho aplicando os resultados acima para obter as representações das álgebras de grupos cíclicos finitos e para as álgebras do grupo de Klein e dos grupos dihedrais sobre corpos algebricamente fechados de característica 2.

Our research is in the general area of String Algorithms and Combinatorics on Words. Specifically, we study a generalization of square-free strings, shuffle properties of strings, and formalizing the reasoning about finite strings. The existence of infinitely long square-free strings (strings with no adjacent repeating word blocks) over a three (or more) letter finite set (referred to as Alphabet) is a well-established result. A natural generalization of this problem is that only subsets of the alphabet with predefined cardinality are available, while selecting symbols of the square-free string. This problem has been studied by several authors, and the lowest possible bound on the cardinality of the subset given is four. The problem remains open for subset size three and we investigate this question. We show that square-free strings exist in several specialized cases of the problem and propose approaches to solve the problem, ranging from patterns in strings to Proof Complexity. We also study the shuffle property (analogous to shuffling a deck of cards labeled with symbols) of strings, and explore the relationship between string shuffle and graphs, and show that large classes of graphs can be represented with special type of strings. Finally, we propose a theory of strings, that formalizes the reasoning about finite strings. By engaging in this line of research, we hope to bring the richness of the advanced field of Proof Complexity to Stringology. / Thesis / Doctor of Philosophy (PhD)

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Various approaches to rhythmic analysis have been produced by recent research. Many of these are most suitable for tonal musical compositions; when other methods of tonal organization are present, these theories are less useful. This study uses accent based criteria in order to establish a set of analytical procedures which are applicable to a wide range of musical compositions. Four accent types (contour, agogic, dynamic, and motivic) are identified in two string quartet movements. These are Beethoven's Op. 18, No. 1, movement four, and Bartok's String Quartet No. 4, movement five. The study finds great differences in accent placement between the two works. In both works accents affect phrase grouping and meter. Accent patterns and composite accent profiles, which represent all the accent types in a particular passage, are compiled for important themes. Large fluctuations in accent use are evident between the formal sections of each work.

This thesis proposes to determine the construction of the two string quartets and to reveal through the study of the quartets the similarities and contrasts of the creative musical characteristics of Debussy and Ravel.