Research regarding the effect of rhythm on cognition has shown that isochronous rhythms can enhance maintenance in working memory. However, it is important to consider that much contemporary music includes both isochronous and non-isochronous rhythms simultaneously. To determine the practical benefits of this finding, it is necessary to explore rhythms thatclosely simulate contemporary music. The present study investigated how the maintenance-boosting effect of isochronous rhythm is affected by the simultaneous presence of a non-isochronous rhythm. Participants were tasked with remembering sequences of six letters for serial recall. In the rhythm condition, a woodblock sound was presented six times at regular intervals and a kick drum sound was presented eight times at irregular intervals during the delay between encoding and recall. In the silent condition, no sound was presented. The simultaneous presence of regular and irregular rhythms led to decreased memory performance compared to silence, suggesting that listening to complex rhythmic music can cause cognitive overload and disrupt attentional refreshing. These findings are discussed in relation to relevant theoretical frameworks and the limitations of this study.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper examines two rules for data acquisition that have advantages for today's Flight Test Instrumentation (FTI) systems where: • Data is acquired from physically separate test equipment • Deterministic (IRIG-106 (Ch. 4)) and non-deterministic networks co-exist • Data Acquisition Units (DAUs) from multiple vendors are required • Signal lists and sampling rates change rapidly • A time-coherent sampling strategy (even for smart sensors) is required These rules may aid not only in the selection of the data acquisition equipment but also the definition of the sampling, transmission, storage and analysis strategies.

This thesis discloses my exploration of non-isochronous meters through composition and practice. During my two-year studies at the Royal College of Music in Stockholm, I explored different unevenly divided time signatures by practicing them in various ways, producing transcriptions, compositions and arrangements.The main purpose of this project was to further my knowledge and skills within these time signatures and thereby expand my horizon on perceiving, conceptualizing, composing and playing them. My endeavors culminated in seven original compositions, arranged for a jazz sextet, which I rehearsed and performed with an ensemble. During the process of composing, arranging, practicing and rehearsing, I gained a lot of articulated knowledge as well as embodied knowledge of the idiosyncrasies of various non-isochronous meters and different ways to perceive and play them.

No description available.

Although music of the twentieth and twenty-first centuries makes frequent use of non-isochronous meter (meters involving beats of different length, such as 5/4 and 7/8), most studies on meter and metric dissonance focus on isochronous meters (meters involving beats of the same length, such as 4/4 and 9/8). This dissertation bridges this gap by developing two methodologies to account for metric dissonance involving non-isochronous pulses: modified ski-hill graphs and the composite beat attack point system. Modified ski-hill graphs, adapted from Richard Cohn's ski-hill graphs, illustrate metric states involving non-isochronous pulses and reveal degrees of dissonance in musical passages that share time spans, as in 5/4 grouped 3+2 vs. 5/4 grouped 2+3. The composite beat attack point system uses rhythmic notation to illustrate metric states involving any pulse duration or time span, revealing specific points of dissonance and consonance, relative strength of dissonance and consonance, and patterns of dissonance and consonance. The methodology is used to closely examine the treatment of metric dissonance in Holst's "Mars," from The Planets, Ligeti's Hungarian Rock (Chaconne), and Ligeti's Désordre. The analyses focus on passages where the metric dissonance becomes ever more pronounced and ends up obliterating any sense of meter.

Nesta tese é analisada a dinâmica de uma partícula relativística se movendo sob a influência de um campo magnético uniforme e uma onda eletrostática e estacionária dada na forma de pulsos periódicos. O mapa que descreve a evolução temporal do sistema é explícito e pode ser considerado como uma versão relativística e magnetizada do mapa padrão clássico. A posição aproximada dos pontos periódicos é calculada analiticamente e com essa informação é possível estudar as ressonâncias primárias. Para o sistema em estudo, observa-se que a maior parte das ressonâncias possui mais de uma cadeia de ilhas. Isso ocorre pois o sistema apresenta um número infinito de termos ressonantes com o mesmo número de rotação e que podem gerar ilhas na mesma posição do espaço de fases. Verifica-se que essa superposição de termos ressonantes faz com que o número de cadeias varie em função dos parâmetros da onda. Para valores de período ou número de onda suficientemente elevados, todas as ressonâncias primárias apresentam duas ou mais cadeias de ilhas no espaço de fases. As ilhas de ressonância primária são utilizadas nesta tese para acelerar partículas de forma regular. Em particular, considera-se a ressonância principal do sistema, para a qual a energia inicial da partícula pode estar muito próxima de sua energia de repouso se os parâmetros da onda forem adequados. Além disso, aplica-se um método de controle do caos para Hamiltonianas quase integráveis que consiste na adição de um termo de controle simples e com baixa amplitude ao sistema. Esse termo de controle cria toros invariantes em todo o espaço de fases que confinam as trajetórias caóticas em pequenas regiões, tornando a dinâmica controlada mais regular. Verifica-se numericamente que o termo de controle reduz drasticamente as regiões caóticas. Além disso, observa-se que o controle do caos e a consequente recuperação de trajetórias periódicas e quase periódicas no espaço de fases podem ser utilizados para melhorar o processo de aceleração regular de partículas. / In this thesis, we analyze the dynamics of a relativistic particle moving under the influence of a uniform magnetic field and a stationary electrostatic wave given as a series of periodic pulses. The map that describes the time evolution of the system is explicit, and it can be considered as a magnetized relativistic version of the classical standard map. We calculate analytically the approximate position of the periodic points and we use this information to study the primary resonances. For the system under study, we observe that most of its resonances exhibit more than one island chain. It occurs because the system presents an infinite number of resonant terms with the same winding number that may generate islands in the same position of phase space. We verify that this superposition of resonant terms makes the number of chains vary as a function of the parameters of the wave. For sufficiently large values of the wave period or wave number, all the primary resonances present two or more island chains in phase space. We use the islands of primary resonances in this thesis to regularly accelerate particles. In particular, we consider the main resonance of the system, for which the initial energy of the particle can be very close to its rest energy if the parameters of the wave are adequate. Furthermore, we apply a method of control of chaos for near-integrable Hamiltonians that consists in the addition of a simple control term with low amplitude to the system. This control term creates invariant tori in the whole phase space that confine the chaotic trajectories to small regions, making the controlled dynamics more regular. We verify numerically that the control term drastically reduces the chaotic regions. Moreover, we observe that the control of chaos and the consequent recovery of periodic and quasiperiodic trajectories in phase space can be used to improve the process of regular particle acceleration.

The center-focus and isochronicity problems are two classic problem in the qualitative theory of ordinary differential equations (ODEs). Although such problems have been studied during more than hundred years a complete understanding of them is far from be reached. Recently the computational algebra tools have been contributing significantly with the development of such problems. The aim of this thesis is to contribute with the studies of the center-focus and isochronicity problem. Using computational algebra tools we find conditions for the existence of two simultaneous centers for a family of quintic systems possessing symmetry. The studies of the simultaneous existence of two centers in differential systems is known as the bi-center problem. We investigate conditions for the isochronicity of centers for families of cubic and quintic systems and we study its global behaviour in the Poincaré disk. Finally, we study the existence of invariant surfaces and first integrals in a family of 3-dimensional systems. Such family is known as the May-Leonard asymmetric system and it appears in modelling, for instance it is a model for the competition of three species. / Os problemas do foco-centro e da isocronicidade são dois problemas clássicos da teoria qualitativa das equações diferenciais ordinárias (EDOs). Apesar de tais problemas serem investigados a mais de cem anos ainda pouco se sabe sobre eles. Recentemente o uso e desenvolvimento de ferramentas algebro-computacionais tem contribuído significativamente em seu avanço. O objetivo desta tese é colaborar com o estudo do problema do foco-centro e da isocronicidade. Utilizando ferramentas algebro-computacionais encontramos condições para a existência simultânea de dois centros em famílias de sistemas diferenciais quínticos com simetria. O estudo sobre a existência simultânea de dois centros é também conhecido como problema do bi-centro. Investigamos condições para a isocronicidade de centros para famílias de sistemas cubicos e quínticos e estudamos o comportamento global de suas órbitas no disco de Poincaré. Finalmente, tratamos da existência de superfícies invariantes e integrais primeiras para uma familia de sistemas 3-dimensionais encontrado entre outras situações na modelagem da competição entre três espécies e conhecido como sistema de May-Leonard.

Chaotic dynamics produced by optical delay systems have interesting applications in telecommunications. Optical chaos can be used to transmit secretly, in real-time, a message between an emitter and a receiver. The noise-like appearance of chaos is used to conceal the message, and the synchronization of the receiver with the chaotic emitter is used to decode the message. This work focuses on the study of two crucial topics in the field of chaotic optical communications. The first topic is the synchronization of chaotic external-cavity laser diodes, which are among the most promising chaotic emitters for secure communications. It is shown that, for edge-emitting lasers, two drastically different synchronization regimes are possible. The regimes differ in terms of the delay time in the synchronization and in terms of the robustness of the synchronization with respect to parameter mismatches between the emitter and the receiver. In vertical-cavity surface-emitting lasers, the two linearly-polarized components of the electric field also exhibit isochronous and anticipating synchronization when the coupling between the lasers is isotropic. When the coupling is polarized, the linearly-polarized component that is parallel to the injected polarization tends to synchronize isochronously with the injected optical field, while the other component tends to be suppressed, but it can also be antisynchronized. The second topic is the analysis of time series produced by optical chaotic emitters subjected to a delayed feedback. First, we verify with experimental data that chaos produced by optical delay systems is highly complex. This high complexity is demonstrated by estimating chaos dimension and entropy from experimental time series and from models of optical delay systems. Second, by analyzing chaotic time series, it is shown that the value of the delay of a single-delay system can always be identified, independently of the type of system used and of its complexity. Unfortunately, an eavesdropper can use this information on the delay value to break the cryptosystem. We propose a new cryptosystem with two delayed feedback loops that increases the difficulty of the delay identification problem.

We describe some classical results on global injectivity of local dieomorphism on Euclidian spaces. This is not exhaustive, and it does not purport to be a complete history, it simply describes some useful results in injectivity. The first part describes some results related to the Qualitative Theory of Diferential Equations, and presents a characterization of global injectivity on planar applications by using the existence of an isochronous global center. The Global Asymptotic Stability Problem is also described. The second part describes the so called Palais-Smale condition. / Se dan algunos teoremas que garantizan la inyectividad global de los difeomorsmos locales en espacios euclidanos. De momento el trabajo no es aun exaustivo, ni pretende serlo, simplemente se describe algunos resultados utiles en la teoría del estudio de las aplicaciones inyectivas. La primera parte describe algunos resultados relacionados con la teoría cualitativa de las ecuaciones diferenciales, y presenta una caracterización de la inyectividad global de aplicaciones en el plano por medio de la existencia de un centro global isócrono. También se presenta el problema de la estabilidada sintóotica global. La segunda parte describe la "condicion de Palais Smale".

Nesta tese é analisada a dinâmica de uma partícula relativística se movendo sob a influência de um campo magnético uniforme e uma onda eletrostática e estacionária dada na forma de pulsos periódicos. O mapa que descreve a evolução temporal do sistema é explícito e pode ser considerado como uma versão relativística e magnetizada do mapa padrão clássico. A posição aproximada dos pontos periódicos é calculada analiticamente e com essa informação é possível estudar as ressonâncias primárias. Para o sistema em estudo, observa-se que a maior parte das ressonâncias possui mais de uma cadeia de ilhas. Isso ocorre pois o sistema apresenta um número infinito de termos ressonantes com o mesmo número de rotação e que podem gerar ilhas na mesma posição do espaço de fases. Verifica-se que essa superposição de termos ressonantes faz com que o número de cadeias varie em função dos parâmetros da onda. Para valores de período ou número de onda suficientemente elevados, todas as ressonâncias primárias apresentam duas ou mais cadeias de ilhas no espaço de fases. As ilhas de ressonância primária são utilizadas nesta tese para acelerar partículas de forma regular. Em particular, considera-se a ressonância principal do sistema, para a qual a energia inicial da partícula pode estar muito próxima de sua energia de repouso se os parâmetros da onda forem adequados. Além disso, aplica-se um método de controle do caos para Hamiltonianas quase integráveis que consiste na adição de um termo de controle simples e com baixa amplitude ao sistema. Esse termo de controle cria toros invariantes em todo o espaço de fases que confinam as trajetórias caóticas em pequenas regiões, tornando a dinâmica controlada mais regular. Verifica-se numericamente que o termo de controle reduz drasticamente as regiões caóticas. Além disso, observa-se que o controle do caos e a consequente recuperação de trajetórias periódicas e quase periódicas no espaço de fases podem ser utilizados para melhorar o processo de aceleração regular de partículas. / In this thesis, we analyze the dynamics of a relativistic particle moving under the influence of a uniform magnetic field and a stationary electrostatic wave given as a series of periodic pulses. The map that describes the time evolution of the system is explicit, and it can be considered as a magnetized relativistic version of the classical standard map. We calculate analytically the approximate position of the periodic points and we use this information to study the primary resonances. For the system under study, we observe that most of its resonances exhibit more than one island chain. It occurs because the system presents an infinite number of resonant terms with the same winding number that may generate islands in the same position of phase space. We verify that this superposition of resonant terms makes the number of chains vary as a function of the parameters of the wave. For sufficiently large values of the wave period or wave number, all the primary resonances present two or more island chains in phase space. We use the islands of primary resonances in this thesis to regularly accelerate particles. In particular, we consider the main resonance of the system, for which the initial energy of the particle can be very close to its rest energy if the parameters of the wave are adequate. Furthermore, we apply a method of control of chaos for near-integrable Hamiltonians that consists in the addition of a simple control term with low amplitude to the system. This control term creates invariant tori in the whole phase space that confine the chaotic trajectories to small regions, making the controlled dynamics more regular. We verify numerically that the control term drastically reduces the chaotic regions. Moreover, we observe that the control of chaos and the consequent recovery of periodic and quasiperiodic trajectories in phase space can be used to improve the process of regular particle acceleration.