The mid-infrared (MIR) system presented in the thesis is based on a sub-100-fs erbium-doped fiber laser operating at 1.55 µm. The output of the laser is split in two, each arm seeding an erbium-doped fiber amplifier. The output of the first amplifier is sent to a grating-based stretcher to be stretched to 50 ps before seeding the optical parametric chirped-pulse amplifier (OPCPA). The output of the second amplifier is coupled to a highly nonlinear fiber to generate the 1 µm needed to seed the a neodymium-doped yttrium lithium fluoride (Nd:YLF) system. This work represents the first time this synchronization scheme is used, and the timing jitter between the two arms at the OPCPA is reduced to 333 fs. The pump laser for the OPCPA is a regenerative amplifier producing 1.6 W followed by a double-pass amplifier, for a final output power of 2.5 W at 1 kHz. Etalons were inserted into the cavity of the regenerative amplifier to stretch the pulses to 50 ps The OPCPA consists of two potassium titanyl arsenate crystals in a noncollinear configuration. With three passes, the gain is 3.8 · 10 6 . Using a grating compressor, the pulse duration is reduced to 140 fs, with a power of 300 mW. Because of the reduction of the timing jitter, the amplitude stability is 1 %, which is a great improvement compare to existing systems. To generate ultrafast light in the MIR, an optical parametric amplifier is used, pumped ii by the output of the OPCPA and seeded with its 3-µm idler. Two crystals were tested, both in a single-pass configuration. For the first crystal, a 4-mm thick silver thiogallate, an efficiency of 7.4 % was reached, with 8.76 mW in the signal and 7.2 mW in the idler. For the second crystal, a 2-mm thick lithium gallium selenide, the efficiency was higher, reaching 10.8 %. The power for the signal was 11.5 mW, and for the idler, 11.11 mW. Using this new scheme, energies on par with current systems are achieved with much higher efficiencies.

This research explores the changing nature of social organization associated with the growth and breakup of large nucleated hunter-gatherer winter settlements in the Mid-Fraser region of south-central British Columbia, ca. 2000-300 cal. B.P. It uses hierarchy and heterarchy as overarching conceptual frameworks for theorizing and evaluating structures of social and political organization. Regional radiocarbon data were used to examine issues of demography and to evaluate the role of scalar stress in producing social change in these burgeoning communities. In order to explore aspects of economic practice and wealth distribution over time artifacts, fauna, and features from sixteen different housepits from five different village sites near the present-day town of Lillooet, British Columbia were analyzed. Results suggest that the villages formed around 1800 cal. B.P. and attained peak population ca. 1200 cal. B.P. The onset of the Medieval Climatic Anomaly at that time altered resource conditions, resulting in greater reliance on mammalian rather than riverine resources. Increased pressure on these resources led to the incorporation of greater amounts of small bodied mammals after 1000 cal. B.P. Apparent declining numbers of houses within large villages after 1200 cal. B.P. suggest that village abandonment began at this time, with individual families likely settling in dispersed villages. The large villages were totally abandoned by 900-800 cal. B.P. Lack of evidence for wealth differentiation in these contexts suggest that social hierarchy based on control over access to resources never emerged in the large villages and that more egalitarian conditions prevailed. Heterarchical structures that allow for shifting balance of power between bands and individual families is argued to have characterized the shift between population aggregation and dispersal.

The mid-infrared (MIR) system presented in the thesis is based on a sub-100-fs erbium-doped fiber laser operating at 1.55 µm. The output of the laser is split in two, each arm seeding an erbium-doped fiber amplifier. The output of the first amplifier is sent to a grating-based stretcher to be stretched to 50 ps before seeding the optical parametric chirped-pulse amplifier (OPCPA). The output of the second amplifier is coupled to a highly nonlinear fiber to generate the 1 µm needed to seed the a neodymium-doped yttrium lithium fluoride (Nd:YLF) system. This work represents the first time this synchronization scheme is used, and the timing jitter between the two arms at the OPCPA is reduced to 333 fs. The pump laser for the OPCPA is a regenerative amplifier producing 1.6 W followed by a double-pass amplifier, for a final output power of 2.5 W at 1 kHz. Etalons were inserted into the cavity of the regenerative amplifier to stretch the pulses to 50 ps The OPCPA consists of two potassium titanyl arsenate crystals in a noncollinear configuration. With three passes, the gain is 3.8 · 10 6 . Using a grating compressor, the pulse duration is reduced to 140 fs, with a power of 300 mW. Because of the reduction of the timing jitter, the amplitude stability is 1 %, which is a great improvement compare to existing systems. To generate ultrafast light in the MIR, an optical parametric amplifier is used, pumped ii by the output of the OPCPA and seeded with its 3-µm idler. Two crystals were tested, both in a single-pass configuration. For the first crystal, a 4-mm thick silver thiogallate, an efficiency of 7.4 % was reached, with 8.76 mW in the signal and 7.2 mW in the idler. For the second crystal, a 2-mm thick lithium gallium selenide, the efficiency was higher, reaching 10.8 %. The power for the signal was 11.5 mW, and for the idler, 11.11 mW. Using this new scheme, energies on par with current systems are achieved with much higher efficiencies.

Graduation date: 1997 / Best scan available for figures. Original figures are black and white photocopies.

Albian (late Early Cretaceous) pollen and spores were used to reconstruct the floral history of Allison Guyot in the Albian period, to better understand pollen and spore distributions on mid-oceanic islands, to investigate whether Allison Guyot supported land plants in the Albian, and to test previous hypotheses about the development of the guyot. Albian spores found in Allison Guyot sediments from ODP Leg 143 Site 865 include: Laevigatosporites ovatus, Cyathidites minor, Cicatricosisporites sp., Baculatisporites comaumensis, Ceratosporites equalis, Gleicheniidites senonicus, Leptolepidites verrucatus, Retitriletes circolumenus, Lycopodiacidites dettmannae, Osmundacidites wellmanii, Cicatricosisporites hughesii, Impardecispora excavate, and others. Albian pollen from these samples include Callialasporites dampieri, Ephedra, and others occur in Albian samples. The high abundance of terrestrial palynomorphs in these samples suggests that Allison Guyot was exposed in the Albian and supported land plants. The high frequency of spores (more than 90 percent) reflects a flora dominated by ferns.

Master of Music (Music Education) / This thesis documents an investigation of the selection procedures relating to Australian vocal repertoire for mid-adolescent and Higher School Certificate (New South Wales) performers, as used by private singing teachers, school music teachers and singing students. It explores the similarities and differences in the criteria employed in these selections. Semi-structured interviews were the source of data and were conducted with participants from these three categories as well as two composers. The participants evinced highly disparate views. The private singing teachers believed that repertoire should be dictated by the technical ability and physiological constraints of mid-adolescent students and that their role in selecting repertoire was related to the long term vocal growth of each individual. They felt that the school music teachers vetted their repertoire choices with no useful explanation of their reasoning, while the school music teachers noted that students frequently presented repertoire that was too difficult or that was not readily communicated with the audience. The ability of mid-adolescent singers to communicate with and engage an audience was the prime concern of the school music teachers. The students wanted to impress their examiners and believed that infrequently heard repertoire was the best choice, though this was not endorsed by the teachers. There was a perception that the students would perform at their best when they chose repertoire to which they could relate emotionally. Many private singing teachers and school music teachers are not aware of the very broad range of contemporary Australian music and its divergent characteristics. However, there is a shortage of appropriate Australian repertoire that addresses the physiological and emotional needs of mid-adolescent singers.

Doctor of Philosophy(PhD) / Mid-ocean ridges are a fundamental but insufficiently understood component of the global plate tectonic system. Mid-ocean ridges control the landscape of the Earth's ocean basins through seafloor spreading and influence the evolution of overriding plate margins during midocean ridge subduction. The majority of new crust created at the surface of the Earth is formed at mid-ocean ridges and the accretion process strongly influences the morphology of the seafloor, which interacts with ocean currents and mixing to influence ocean circulation and regional and global climate. Seafloor spreading rates are well known to influence oceanic basement topography. However, I show that parameters such as mantle conditions and spreading obliquity also play significant roles in modulating seafloor topography. I find that high mantle temperatures are associated with smooth oceanic basement, while cold and/or depleted mantle is associated with rough basement topography. In addition spreading obliquities greater than > 45° lead to extreme seafloor roughness. These results provide a predictive framework for reconstructing the seafloor of ancient oceans, a fundamental input required for modelling ocean-mixing in palaeoclimate studies. The importance of being able to accurately predict the morphology of vanished ocean floor is demonstrated by a regional analysis of the Adare Trough, which shows through an analysis of seismic stratigraphy how a relatively rough bathymetric feature can strongly influence the flow of ocean bottom currents. As well as seafloor, mid-ocean ridges influence the composition and morphology of overriding plate margins as they are consumed by subduction, with implications for landscape and natural resources development. Mid-ocean ridge subduction also effects the morphology and composition of the overriding plate margin by influencing the tectonic regime experienced by the overriding plate margin and impacting on the volume, composition and timing of arc-volcanism. Investigation of the Wharton Ridge slab window that formed beneath Sundaland between 70 Ma and 43 Ma reveals that although the relative motion of an overriding plate margin is the dominant force effecting tectonic regime on the overriding plate margin, this can be overridden by extension caused by the underlying slab window. Mid-ocean ridge subduction can also affect the balance of global plate motions. A longstanding controversy in global tectonics concerns the ultimate driving forces that cause periodic plate reorganisations. I find strong evidence supporting the hypothesis that the plates themselves drive instabilities in the plate-mantle system rather than major mantle overturns being the driving mechanism. I find that rapid sub-parallel subduction of the Izanagi mid-ocean ridge and subsequent catastrophic slab break o_ likely precipitated a global plate reorganisation event that formed the Emperor-Hawaii bend, and the change in relative plate motion between Australia and Antarctica at approximately 50 Ma

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007. / "Joint Program in Oceanography/Applied Ocean Science and Engineering"--Cover. Title from Web page (viewed on Mar. 24, 2008). "September 2007". Includes bibliographical references.

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Germanovich, Leonid; Committee Co-Chair: Lowell, Robert; Committee Member: Di Iorio, Daniela; Committee Member: Huang, Haiying; Committee Member: Rix, Glenn; Committee Member: Xu, Wenyue.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 65-68).