8 resultados para Drilling and boring machinery

em Brock University, Canada


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Dorothy Rungeling was born in 1911 and raised in Fenwick, Ontario, by her adopted mother, Ethelwyn Wetherald. After graduating high school, she attended Fort Erie business College. She worked briefly in Toronto and then Hamilton, but eventually took a job with Brown Brothers’ Nursery in Pelham to be closer to home. Dorothy pursued many interests, learning to play the violin, saxophone and clarinet. She met her husband Charles at a local dance where she was playing. In 1939, they opened an automobile and farm machinery business in Welland. In their spare time, they were active in skeet and trap shooting, for which Dorothy won many trophies. In the early 1940s, Dorothy developed a passion for horses, training and showing them in addition to teaching riding at the Welland Riding Club, as well as judging at horse shows. By the late 1940s her interest in horses was waning, but she soon after discovered and pursued a new interest: flying. She joined the Welland Flying Club, obtained a flying licence, and in 1949 purchased her first plane. She proceeded to obtain a Commercial Pilot Licence in 1951, an Instructor’s Licence in 1953, and a Senior Commercial Licence in 1954. She participated in many air races in the 1950s, including the All Women’s International Air Races, the Women’s Transcontinental Air Races, and the Canadian Governor-General’s Cup Air Race. Some of the most notable races were the 1954 International Air Race, where Dorothy met with President Batista of Cuba, and the Governor-General’s Cup Air Race, where she won 1st place in 1953 and 1956 (and was the only woman competing). In 1958, she was also the first Canadian woman to solo pilot a helicopter. That same year she obtained her Airline Transport Licence. She also wrote several articles on aviation, contributing to publications such as Canadian Aviation and Air Facts, a U.S. aviation magazine. In addition to these articles, Dorothy authored several books about her life, as well as a selection of poems and articles by Ethelwyn Wetherald. As planes became more expensive, Dorothy spent less time flying, instead pursuing an interest in sailing. She and her husband bought a sailboat and became members of the Niagara-on-the-Lake Sailing Club. In 2003, Dorothy was awarded the Order of Canada for her accomplishments. She also wrote a regular column for the Voice of Pelham in 2012-2013, called A Century in Pelham. Dorothy celebrated her 100th birthday in 2011, and remains an active member of the community.

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A distinctive period of global change occurred during the PUocene between the warm Miocene and subsequent Quaternary cooling. Samples from Ocean Drilling Project Site 11 79 (-5586 mbsl, 41°4'N, 159°57'E), Site 881 (-5765 mbsl, 47°6.133'N, 161°29.490'E) and Site 882 (-3255 mbsl, 50°22'N, 167°36'E) were studied to determine the magnitude and composition ofterrigenous flux to the western mid-latitude North Pacific and its relation to climate change in East Asia since the mid-Pliocene. Dust-sized particles (including pollen), sourced from the arid regions and loess plateaus in East Asia are entrained by prevailing westerly winds and transported to the midlatitude northwest North Pacific Ocean. This is recorded by peaks in the total concentration of pollen and spores, as well as the mean grain size of allochthonous and autochthonous silicate material in abyssal marine sediments. Aridification of the Asian interior due to the phased uplift of the Himalayan-Tibetan Plateau created the modem East Asian Monsoon system dominated by a strengthening of the winter monsoon. The winter monsoon is further enhanced during glacials due to the expansion of desert and steppe environments at the expense ofwoodlands and forests recorded by the composition of palynological assemblages. The late Pliocene-Pleistocene glacials at ODP Sites 1 179, 881, and 882 are characterized by increases in grain size, magnetic susceptibility, pollen and spore concentrations around 3.5-3.3, 2.6-2.4, 1.7-1.6, and 0.9-0.7 Ma (ages based on magnetostratigraphic and biostratigraphic datums). The peaks during these times are relatively rich in pollen taxa derived primarily from steppe and boreal vegetation zones, recording cool, dry climates. The overall size increase of sediment and abundance of terrestrial palynomorphs record enhanced wind strength. The increase in magnitude of pollen and spore concentrations as well as grain size record global cooling and Northern Hemisphere glaciation. The peaks in grain size as well as pollen and spore abundance in marine sediments correlate with the mean grain size of loess in East Asia, consistent with the deflation of unarmoured surfaces during glacials. The transport of limiting nutrients to marine environments enhanced sea surface productivity and increased the rate of sediment accumulation.

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Six lefthanded artist-educators were interviewed to attempt to discover any patterns t6 their perceptions and experiences. Artists have their own culture and priorities. According to the literature, lefthanded people appear more likely to suffer from dyslexia, allergies, asthma and other auto-immune diseases as well as machinery and equipment injuries. Patterns emerging suggested that lefthanded people indeed suffer more from dyslexia. More startling was the distinct possibility that many artists have traumatic childhood histories. This would commonly include negative school experiences, and for a significant number sexual assault, perceived or actual abandonment by parents, and/or consistently low selfesteem. The researcher discovered possible reasons why creative people frequently have problems at school, why they tend to be rebellious and anti-establishment oriented, how many of them perceive societal rules, and why they are more likely to be lefthanded. These characteristics all have significant implications for art school administrators.

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One of the main objectives of the mid-Atlantic transect is to improve dating resolution of sequences and unconfonnity surfaces. Dinoflagellate cysts from two Ocean Drilling Program boreholes, the onshore Leg 174AX Ocean View Site and Leg 174A continental shelf Site 1071, are used to provide age estimates for sequences and unconfonnities fonned on the New Jersey continental margin during the Miocene epoch. Despite the occasional lack of dinocysts in barren and oxidized sections, dinocyst biochronology still offers greater age control than that provided by other microfossils in marginal marine environments. An early Miocene to late Miocene chronology based on ages detennined for the two study sites is presented. In addition, .palynofacies are used to unravel the systems tract character of the Miocene sequences and provide insight into the effects of taphonomy and preservation of palynomorphs in marginal marine and shelf environments under different ~ea level conditions. More precise placement of maximum flooding surfaces is possible through the identification of condensed sections and palynofacies shifts can also reveal subaerially exposed sections and surfaces not apparent in seismic or lithological analyses. The problems with the application of the pollen record in the interpretation of Miocene climate are also discussed. Palynomorphs provide evidence for a second-order lowering of sea level during the Miocene, onto which higher order sea level fluctuations are super-imposed. Correlation of sequences and unconfonnities is attempted between onshore boreholes and from the onshore Ocean View borehole to offshore Site 1071.

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The palynology of Ocean Drilling Program Site 1007, leeward of the present Bahamas Bank, provides insights into upper Oligocene–lower Pleistocene dinoflagellate cyst associations in the tropical Americas. These associations are reviewed along with the sedimentary paleoenvironment to provide context for a morphological study of the cystdefined dinoflagellate Operculodinium bahamense and its comparison with the thecadefined dinoflagellate Protoceratium reticulatum which produces a cyst assignable to the cyst-defined genus Operculodinium. Detailed reconstructions of the tabulation in both species reveal strong similarities, having a sexiform hyposomal tabulation and L-type or modified L-type ventral organization. Protoceratium reticulatum has dextral torsion of the hypotheca, requiring assignation of the genus to the subfamily Cribroperidinioideae, whereas Operculodinium bahamense has neutral torsion requiring assignation to the subfamily Leptodinioideae. Results either imply polyphyletic origins for the genus Operculodinium or that combinations of ventral organization and torsion cannot always be applied rigidly to subdivide the family Gonyaulacaceae.

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This is the first detailed study of organic-walled dinoflagellate cysts (dinocysts) and acritarchs for the latest Miocene–Middle Pleistocene of Ocean Drilling Program Site 1000 in the Caribbean Sea. Well-preserved and moderately diverse dinocysts and other palynomorphs reflect the interplay between neritic (carbonate-platform sourced) and oceanic species. The dinocyst biostratigraphy is tied to an existing marine isotope stratigraphy for the interval 5.5–2.2 Ma. For the interval 5.5–3.8 Ma, palynological samples are coupled to published sea-surface temperature estimates based on planktonic foraminiferal Mg/Ca. Changes in dinocyst assemblage composition are noted at ca. 4.6 Ma when shoaling of the Central American Seaway caused a temperature rise in the Caribbean, ca. 3.8–3.6 Ma, during the cold Marine Isotope Stage M2 when pronounced warming occurred, at ca. 2.7 Ma where possible weak cooling may reflect the onset of Northern Hemisphere glaciation, and in the Middle Pleistocene presumably reflecting global cooling and sea-level fall.

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ABSTRACT Photosystem II (PSII) of oxygenic photosynthesis has the unique ability to photochemically oxidize water, extracting electrons from water to result in the evolution of oxygen gas while depositing these electrons to the rest of the photosynthetic machinery which in turn reduces CO2 to carbohydrate molecules acting as fuel for the cell. Unfortunately, native PSII is unstable and not suitable to be used in industrial applications. Consequently, there is a need to reverse-engineer the water oxidation photochemical reactions of PSII using solution-stable proteins. But what does it take to reverse-engineer PSII’s reactions? PSII has the pigment with the highest oxidation potential in nature known as P680. The high oxidation of P680 is in fact the driving force for water oxidation. P680 is made up of a chlorophyll a dimer embedded inside the relatively hydrophobic transmembrane environment of PSII. In this thesis, the electrostatic factors contributing to the high oxidation potential of P680 are described. PSII oxidizes water in a specialized metal cluster known as the Oxygen Evolving Complex (OEC). The pathways that water can take to enter the relatively hydrophobic region of PSII are described as well. A previous attempt to reverse engineer PSII’s reactions using the protein scaffold of E. coli’s Bacterioferritin (BFR) existed. The oxidation potential of the pigment used for the BFR ‘reaction centre’ was measured and the protein effects calculated in a similar fashion to how P680 potentials were calculated in PSII. The BFR-RC’s pigment oxidation potential was found to be 0.57 V, too low to oxidize water or tyrosine like PSII. We suggest that the observed tyrosine oxidation in BRF-RC could be driven by the ZnCe6 di-cation. In order to increase the efficiency of iii tyrosine oxidation, and ultimately oxidize water, the first potential of ZnCe6 would have to attain a value in excess of 0.8 V. The results were used to develop a second generation of BFR-RC using a high oxidation pigment. The hypervalent phosphorous porphyrin forms a radical pair that can be observed using Transient Electron Paramagnetic Resonance (TR-EPR). Finally, the results from this thesis are discussed in light of the development of solar fuel producing systems.

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The active metabolite of vitamin A, retinoic acid (RA), is involved in memory formation and hippocampal plasticity in vertebrates. A similar role for retinoid signaling in learning and memory formation has not previously been examined in an invertebrate species. However, the conservation of retinoid signaling between vertebrates and invertebrates is supported by the presence of retinoid signaling machinery in invertebrates. For example, in the mollusc Lymnaea stagnalis the metabolic enzymes and retinoid receptors have been cloned from the CNS. In this study I demonstrated that impairing retinoid signaling in Lymnaea by either inhibiting RALDH activity or using retinoid receptor antagonists, prevented the formation of long-term memory (LTM). However, learning and intermediate-term memory were not affected. An additional finding was that exposure to constant darkness (due to the light-sensitive nature of RA) itself enhanced memory formation. This memory-promoting effect of darkness was sufficient to overcome the inhibitory effects of RALDH inhibition, but not that of a retinoid receptor antagonist, suggesting that environmental light conditions may influence retinoid signaling. Since RA also influences synaptic plasticity underlying hippocampal-dependent memory formation, I also examined whether RA would act in a trophic manner to influence synapse formation and/or synaptic transmission between invertebrate neurons. However, I found no evidence to support an effect of RA on post-tetanic potentiation of a chemical synapse. Retinoic acid did, however, reduce transmission at electrical synapses in a cell-specific manner. Overall, these studies provide the first evidence for a role of RA in the formation of implicit long-term memories in an invertebrate species and suggest that the role of retinoid signaling in memory formation has an ancient origin.