Doctor of Philosophy / Department of Physics / Charles L. Cocke / The broad objective of ultrafast strong-field studies is to be able to measure and control atomic and molecular dynamics on a femtosecond timescale. This thesis work has two major themes: (1) Study of high-energy photoelectron distributions from atomic targets. (2) Electron localization control in atomic and molecular reactions using shaped laser pulses. The first section focuses on the study of photoelectron diffraction patterns of simple atomic targets to understand the target structure. We measure the full vector momentum spectra of high energy photoelectrons from atomic targets (Xe, Ar and Kr) generated by intense laser pulses. The target dependence of the angular distribution of the highest energy photoelectrons as predicted by Quantitative Rescattering Theory (QRS) is explored. More recent developments show target structure information can be retrieved from photoelectrons over a range of energies, from 4U$_p$ up to 10U$_p$, independent of the peak intensity at which the photoelectron spectra have been measured. Controlling the fragmentation pathways by manipulating the pulse shape is another major theme of ultrafast science today. In the second section we study the asymmetry of electron (and ion) emission from atoms (and molecules) by interaction with asymmetric pulses formed by the superposition of two colors (800 $\&$ 400 nm). Xe electron momentum spectra obtained as a function of the two-color phase exhibit a pronounced asymmetry. Using QRS theory we can analyze this asymmetric yield of the high energy photoelectrons to determine accurately the laser peak intensity and the absolute phase of the two-color electric field. This can be used as a standard pulse calibration method for all two-color studies. Experiments showing strong left-right asymmetry in D$^+$ ion yield from D$_2$ molecules using two-color pulses is also investigated. The asymmetry effect is found to be very ion-energy dependent.

Clastic varves and tree-rings offer unique opportunities to decipher various changing paleoclimatic and environmental conditions through the past. The environmental signals they contain can differ greatly from one proxy to the other, but given their common annual resolution, these signals can be isolated, compared and eventually brought together to obtain a clearer picture of local, regional or global environmental changes. This thesis examines three different approaches by which climatic, paleoclimatic and sedimentary time series from northeastern North America can be used as proxies of changing environmental conditions. Using existing and new paleoclimatic records from the eastern Canadian Boreal biome and the Arctic, we show that common variance shared by different independent proxies appears to correspond to an oscillation in North Atlantic sea surface temperatures commonly referred as the Atlantic Multidecadal Oscillation (AMO) and demonstrate that the AMO can be traced back to 1550 in the Canadian Arctic. By comparing historical climate records with an integrated record of North Atlantic sea surface temperature anomalies, we show, seasonally, the extent of the North Atlantic influence on the eastern and Arctic climate. Our analysis demonstrate the relative importance of the AMO on summer and spring climate in northern Canada as well as its imprint along the St. Lawrence during the winter months. Finally at the local level, using an array of techniques, we investigate the sedimentary history of Temiskaming Lake (Québec/Canada). The recent clastic varve sediments found this lake appear to be the product of three main controls: (1) a significant increase in fluvial input to the lake and accessibility to large supply of fine grained sediments due to historical land use changes; (2) an open, unstable landscape that promotes fluvial erosion and rapid streamflow during snowmelt period; and, (3) highly seasonal river discharge and presence of winter ice cover conditions that ensure the formation of annual structures within the sediments. These conditions have previously not been investigated or reported in the boreal region of North America and these results point to the potential for other recent varve records in areas with suitable lakes and postglacial sediment supplies. / Thesis (Ph.D, Geography) -- Queen's University, 2008-12-18 12:22:27.663

Unusual and challenging ionization processes take place when an atom or molecule is placed in the presence of a super intense, ultra short laser field. One such process is the ionization and subsequent return of an electron to the ionic core. The electron carries with it the energy it has absorbed from the laser field and this energy drives different atomic phenomena such as high harmonic generation or multiple ionization. The mechanism of the electron return is often referred to as the “three-step” model. In this model, an electron is first ionized at the peak amplitude of the laser field. Once ionized, a change in the direction of the laser field forces the electron to return to the parent ion and causes a subsequent recollision. The purpose of this thesis is to examine in great detail the recollision process, its mechanisms, and its dependence on physical parameters (such as laser intensity and ellipticity) for a number of physically interesting scenarios.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este texto é uma fabulação que cumpre papel de revelar um processo de trabalho em arte ao longo de dois anos. Trata-se de um percurso teórico-poético percorrido a partir da descoberta/invenção de um ateliê de criação em meio a minha residência. Um quadrado de 2x2 metros demarcado por sobreposição = fita amarela. Instaurado em divergentes contextos paisagísticos = casa, quarto de hotel, estúdio de dança, galeria de arte, palco, cidade. Trata de habitar os mesmos friccionando esfera de vivência pessoal e sítio específico de acontecimento. No texto, tem lugar reflexões pessoais a partir do trabalho, articulada a outros artistas (como Lygia Clark, Angel e Klauss Vianna, Antonin Artaud, Yves Klein, Min Tanaka, Tadashi Endo) e teóricos (dentre eles Hannah Arendt e Michel Foucault), compondo diferentes tons de fala produzidos ao longo desse período de trabalho / This essay is a fabulation that presents an art work over two years. It is a theoretical-poetic way, coursed from the discovery/invention of a creation studio inside my residence. A square of 2x2m made by superposition = yellow tape, done in different landscape contexts = house, hotel room, dance studio, art gallery, theater stage, city. The intention is to inhabit it rubbing a sphere of personal experiences and a specific site of happening. In the text, personal reflections take place from the art work, articulated with other artists (as Lygia Clark, Angel e Klauss Vianna, Antonin Artaud, Yves Klein, Min Tanaka, Tadashi Endo) and theorists (Hannah Arendt e Michael Foucault), composing different kinds of speech produced along this work period

Made available in DSpace on 2014-12-17T13:54:51Z (GMT). No. of bitstreams: 1 LannaPMN_DISSERT.pdf: 1734744 bytes, checksum: 33b5eb549d744ca596c30e81fd492955 (MD5) Previous issue date: 2012-10-08 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This thesis aims to investigating the cantadores and the toadas in the Boi Bumb?, debating questions which put together around the construction and performance of amo s and cantador s role in the Boi Bumb? Caprichoso of Bel?m-PA city and exploring the extent of toadas its characteristics, functions, the uses that are made of theirs and the relations that establishes between them and the cantadores. The problematic of the research consisted on analysing what the amos, cantadores and toadas represent in the whole context of boi-bumb? plays in Bel?m, nowadays. Considering this perspective, I tried to identify on Boi Caprichoso the most meaningful expressions which were related to toadas and how the roles of amo and cantador were performed. Participative observation, ethnical research, open and semistructured interviews were used as research methods. The role performances on Boi Caprichoso plays an essential part on the playing realization, highlighting themselves as pivotal characters. These performances, characterized by the vocal presence, also highlighted the size that toadas occupy in the whole play, and pointed the way for an emerging model of presentation, in which both toada and cantador appear as central figures / Esta disserta??o tem como objetivo investigar os cantadores e as toadas na brincadeira do boi-bumb?, trazendo para o debate quest?es que se agregam em torno da constru??o e da performatiza??o dos papeis de amo e de cantador no Boi-Bumb? Caprichoso de Bel?m-PA e explorando o ?mbito das toadas no que diz respeito as suas caracter?sticas, fun??es, os usos que delas s?o feitos e as rela??es que se estabelecem entre elas e os cantadores. A problem?tica da pesquisa constituiu-se em analisar o que os amos, os cantadores e as toadas expressam no contexto atual das brincadeiras de boi-bumb? em Bel?m. Nessa perspectiva, busquei identificar no Boi Caprichoso express?es significativas em rela??o ?s toadas e a performatiza??o dos papeis de amo e de cantador. Foram utilizadas como m?todos de pesquisa, a observa??o participante, a pesquisa etnogr?fica e entrevistas abertas e semiestruturadas. A performance em torno desses papeis no Boi Caprichoso se faz primordial ? realiza??o da brincadeira, evidenciando-os como personagens pilares. Tais performances, marcadas pela presen?a da voz, tamb?m evidenciaram a dimens?o do espa?o das toadas na brincadeira e sinalizaram para um emergente modelo de apresenta??o no qual toada e cantador figuram como elementos centrais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este texto é uma fabulação que cumpre papel de revelar um processo de trabalho em arte ao longo de dois anos. Trata-se de um percurso teórico-poético percorrido a partir da descoberta/invenção de um ateliê de criação em meio a minha residência. Um quadrado de 2x2 metros demarcado por sobreposição = fita amarela. Instaurado em divergentes contextos paisagísticos = casa, quarto de hotel, estúdio de dança, galeria de arte, palco, cidade. Trata de habitar os mesmos friccionando esfera de vivência pessoal e sítio específico de acontecimento. No texto, tem lugar reflexões pessoais a partir do trabalho, articulada a outros artistas (como Lygia Clark, Angel e Klauss Vianna, Antonin Artaud, Yves Klein, Min Tanaka, Tadashi Endo) e teóricos (dentre eles Hannah Arendt e Michel Foucault), compondo diferentes tons de fala produzidos ao longo desse período de trabalho / This essay is a fabulation that presents an art work over two years. It is a theoretical-poetic way, coursed from the discovery/invention of a creation studio inside my residence. A square of 2x2m made by superposition = yellow tape, done in different landscape contexts = house, hotel room, dance studio, art gallery, theater stage, city. The intention is to inhabit it rubbing a sphere of personal experiences and a specific site of happening. In the text, personal reflections take place from the art work, articulated with other artists (as Lygia Clark, Angel e Klauss Vianna, Antonin Artaud, Yves Klein, Min Tanaka, Tadashi Endo) and theorists (Hannah Arendt e Michael Foucault), composing different kinds of speech produced along this work period

Quantum measurement is one of the most important features of quantum theory. Although mathematical predictions have been verified in great detail, practical implementation has lagged behind. Only recently have people begun to take advantage of quantum measurement properties to produce new technologies. This research helps fill that technological gap by experimental examination of a continuous, optical measurement for an ensemble of cold atomic spins. The essential physics reduces to the interaction between an atomic ensemble and a weak optical field, which has many well known results. While this work demonstrates many novel applications of the interaction, it also shows that the whole can be more than the sum of the individual parts. Starting with basic characterization of the measurement system using laser-cooled cæsium atoms, the mean value of a spin component is obtained in real time. In essence, the angular momentum of the atomic spins creates a Faraday-like rotation in the polarization of a laser probe beam. With slight modifications, additional spin components are also observed, and are shown to be in good agreement with predictions. In measuring spin dynamics, it is important to account for effects of the probe on the spin states as well. Capitalizing on this as a resource, the probe-induced ac-Stark shift is used to transform a quasi-classical spin-coherent state into a highly quantum Schrödinger cat type of superposition between two spin states. Finally, this work combines all the previous results to demonstrate how a continuous measurement of the spin with a carefully crafted evolution created in part by the probe, allows for nearly real-time determination of the complete spin density matrix. In a single 1.5 millisecond run, a spin density matrix is determined with fidelities ranging from about 85% to 90% across a wide spectrum of test states.

No description available.

No description available.