The Japanese Hobbit

Tolkien, J.R.R. The Hobbit. Translations into Japanese

The effect of microstructure and fatigue on the acoustoelastic response of aerospace materials

This thesis presents work relating to the measurement of the nonlinear acoustoelastic response of several materials with respect to microstructure and fatigue life. The nonlinear acoustoelastic response measures the acoustoelastic coefficient of a material. During normal usage components are subject to stresses that while not sufficient to cause fracture cause fatigue, gradually weakening the component. Linear ultrasonic methods have been shown to be poor at detecting fatigue. However, there is evidence that the accumulation of fatigue damage gives the material a nonlinear elastic response that can be probed by ultrasound. A potential technique to monitor fatigue is produced by monitoring changes in the response of nonlinear ultrasonic techniques. Several methods of detecting material nonlinearity using acoustic waves have been proposed. In this thesis a system using the collinear mixing of ultrasonic waves is developed. By measuring the velocity change of a probe wave due to the induced stress from a pump wave, a measure of the nonlinearity is obtained. By using laser ultrasound techniques we gain the benefits of high spatial and temporal resolution. This is important when investigating the nonlinear response of a material as there is evidence that the microstructure affects the nonlinear response of a material. Single point measurements of the acoustoelastic coefficient are taken. In polycrystalline materials the measurement is found to vary with location. A technique is developed to measure the spatial variation of the acoustoelastic coefficient. A relationship between the acoustoelastic coefficient of a material and the underlying microstructure is found. The technique to monitor the spatial variation of the acoustoelastic coefficient is used to monitor the change in samples as they are fatigued. The acoustoelastic coefficient is found to change with fatigue by a larger proportion (9-30%) than linear velocity measurements (0.5-0.6%). Spatial variation of the acoustoelastic coefficient indicated a complex relationship between fatigue and the acoustoelastic coefficient of a material. The implications and further work required from the observed changes in the acoustoelastic coefficient with microstructure and fatigue are discussed

Evolution of three Pyrenophora cereal pathogens: recent divergence, speciation and evolution of non-coding DNA

Three of the most important fungal pathogens of cereals are Pyrenophora tritici-repentis, the cause of tan spot on wheat, and Pyrenophora teres f. teres and Pyrenophora teres f. maculata, the cause of spot form and net form of net blotch on barley, respectively. Orthologous intergenic regions were used to examine the genetic relationships and divergence times between these pathogens. Mean divergence times were calculated at 519 kya (±30) between P. teres f. teres and P. teres f. maculata, while P. tritici-repentis diverged from both Pyrenophora teres forms 8.04 Mya (±138 ky). Individual intergenic regions showed a consistent pattern of co-divergence of the P. teres forms from P. tritici-repentis, with the pattern supported by phylogenetic analysis of conserved genes. Differences in calculated divergence times between individual intergenic regions suggested that they are not entirely under neutral selection, a phenomenon shared with higher Eukaryotes. P. tritici-repentis regions varied in divergence time approximately 5–12 Mya from the P. teres lineage, compared to the separation of wheat and barley some 12 Mya, while the P. teres f. teres and P. teres f. maculata intergenic region divergences correspond to the middle Pleistocene. The data suggest there is no correlation between the divergence of these pathogens the domestication of wheat and barley, and show P. teres f. teres and P. teres f. maculata are closely related but autonomous. The results are discussed in the context of speciation and the evolution of intergenic regions

The effect of microstructure and fatigue on the acoustoelastic response of aerospace materials

This thesis presents work relating to the measurement of the nonlinear acoustoelastic response of several materials with respect to microstructure and fatigue life. The nonlinear acoustoelastic response measures the acoustoelastic coefficient of a material. During normal usage components are subject to stresses that while not sufficient to cause fracture cause fatigue, gradually weakening the component. Linear ultrasonic methods have been shown to be poor at detecting fatigue. However, there is evidence that the accumulation of fatigue damage gives the material a nonlinear elastic response that can be probed by ultrasound. A potential technique to monitor fatigue is produced by monitoring changes in the response of nonlinear ultrasonic techniques. Several methods of detecting material nonlinearity using acoustic waves have been proposed. In this thesis a system using the collinear mixing of ultrasonic waves is developed. By measuring the velocity change of a probe wave due to the induced stress from a pump wave, a measure of the nonlinearity is obtained. By using laser ultrasound techniques we gain the benefits of high spatial and temporal resolution. This is important when investigating the nonlinear response of a material as there is evidence that the microstructure affects the nonlinear response of a material. Single point measurements of the acoustoelastic coefficient are taken. In polycrystalline materials the measurement is found to vary with location. A technique is developed to measure the spatial variation of the acoustoelastic coefficient. A relationship between the acoustoelastic coefficient of a material and the underlying microstructure is found. The technique to monitor the spatial variation of the acoustoelastic coefficient is used to monitor the change in samples as they are fatigued. The acoustoelastic coefficient is found to change with fatigue by a larger proportion (9-30%) than linear velocity measurements (0.5-0.6%). Spatial variation of the acoustoelastic coefficient indicated a complex relationship between fatigue and the acoustoelastic coefficient of a material. The implications and further work required from the observed changes in the acoustoelastic coefficient with microstructure and fatigue are discussed

Mentoring and you

This research based case study explores and illustrates the benefits of mentoring and the place of clinical governance in enhancing dental care practice

Intraspecific variability in Phaeocystis antarctica?s response to iron and light stress

Phaeocystis antarctica is an abundant phytoplankton species in the Southern Ocean, where growth is frequently limited by iron and light. Being able to grow under low iron conditions is essential to the species’ success, but there have been hints that this ability differs among clones. Here, we compare the growth, cell size and chlorophyll a concentrations of four P. antarctica clones cultured under different iron and light conditions. Iron was provided either as unchelated iron (Fe′) or bound to the bacterial siderophore desferrioxamine B, representing, respectively, the most and least bioavailable forms of iron which phytoplankton encounter in the marine environment. The growth rate data demonstrate that the clones vary in their ability to grow using organically bound iron, and that this ability is not related to their ability to grow at low inorganic iron concentrations. These results are consistent at low and high light. Physiologically, only three of the four clones shrink or decrease the concentration of chlorophyll a in response to iron limitation, and only one clone decreases colony formation. Together, our data show that P. antarctica clones 1) respond to the same degree of iron limitation using different acclimation strategies, and 2) vary in their ability to grow under the same external iron and light conditions. This physiological diversity is surprisingly large for isolates of a single phytoplankton species.KEL was supported by the Robert and Delpha Noland Summer Internship, which funded her travel to and accommodation in Australia. The Australian Research Council (DP130100679 to MJE) is acknowledged for funds to support this study

Iron Availability Influences Silicon Isotope Fractionation in Two Southern Ocean Diatoms (Proboscia Inermis and Eucampia Antarctica) and a Coastal Diatom (Thalassiosira Pseudonana)

The fractionation of silicon (Si) isotopes was measured in two Southern Ocean diatoms (Proboscia inermis and Eucampia Antarctica) and a coastal diatom (Thalassiosira pseudonana) that were grown under varying iron (Fe) concentrations. Varying Fe concentrations had no effect on the Si isotope enrichment factor (ε) in T. pseudonana, whilst E. Antarctica and P. inermis exhibited significant variations in the value of ε between Fe-replete and Fe-limited conditions. Mean ε values in P. inermis and E. Antarctica decreased from (± 1SD) −1.11 ± 0.15‰ and −1.42 ± 0.41 ‰ (respectively) under Fe-replete conditions, to −1.38 ± 0.27 ‰ and −1.57 ± 0.5 ‰ (respectively) under Fe-limiting conditions. These variations likely arise from adaptations in diatoms arising from the nutrient status of their environment. T. pseudonana is a coastal clone typically accustomed to low Si but high Fe conditions whereas E. Antarctica and P. inermis are typically accustomed to High Si, High nitrate low Fe conditions. Growth induced variations in silicic acid (Si(OH)4) uptake arising from Fe-limitation is the likely mechanism leading to Si-isotope variability in E. Antarctica and P. inermis. The multiplicative effects of species diversity and resource limitation (e.g., Fe) on Si-isotope fractionation in diatoms can potentially alter the Si-isotope composition of diatom opal in diatamaceous sediments and sea surface Si(OH)4. This work highlights the need for further in vitro studies into intracellular mechanisms involved in Si(OH)4 uptake, and the associated pathways for Si-isotope fractionation in diatoms.The Australian Research Council (DP130100679) and the Australian Antarctic Division (AAD Project 3120) are acknowledged for financial support of this wor

Reviews

Miscellany. . Reviewed by George Colvin. Wilkie Collins: A Critical and Biographical Study. Dorothy L. Sayers, ed. E.R. Gregory. Reviewed by J. R. Christopher. Bloodhounds of Heaven: The Detective in English Fiction from Godwin to Doyle. Ian Ousby. Reviewed by J. R. Christopher. The Dark Tower and Other Stories. C.S. Lewis, Ed. Walter Hooper. Reviewed by Nancy-Lou Patterson. The Mythology of Middle-earth. Ruth S. Noel. Reviewed by Nancy-Lou Patterson. Faeries. Brian Froud and Alan Lee. Reviewed by Robert S. Ellwood Jr.. Eschatus. Bruce Pennington. Reviewed by Robert S. Ellwood Jr.. The Lord of the Rings. Ralph Bakshi, director; Saul Zaentz, producer. Reviewed by Steven C. Walker. The Lord of the Rings. Ralph Bakshi, director; Saul Zaentz, producer. Reviewed by Dale Ziegler

Why are biotic iron pools uniform across high- and low-iron pelagic ecosystems?

Dissolved iron supply is pivotal in setting global phytoplankton productivity and pelagic ecosystem structure. However, most studies of the role of iron have focussed on carbon biogeochemistry within pelagic ecosystems, with less effort to quantify the iron biogeochemical cycle. Here we compare mixed-layer biotic iron inventories from a low-iron (~0.06nmol L-1) subantarctic (FeCycle study) and a seasonally high-iron (~0.6nmol L-1) subtropical (FeCycle II study) site. Both studies were quasi-Lagrangian, and had multi-day occupation, common sampling protocols, and indirect estimates of biotic iron (from a limited range of available published biovolume/carbon/iron quotas). Biotic iron pools were comparable (~100±30pmol L-1) for low- and high-iron waters, despite a tenfold difference in dissolved iron concentrations. Consistency in biotic iron inventories (~80±24pmol L-1, largely estimated using a limited range of available quotas) was also conspicuous for three Southern Ocean polar sites. Insights into the extent to which uniformity in biotic iron inventories was driven by the need to apply common iron quotas obtained from laboratory cultures were provided from FeCycle II. The observed twofold to threefold range of iron quotas during the evolution of FeCycle II subtropical bloom was much less than reported from laboratory monocultures. Furthermore, the iron recycling efficiency varied by fourfold during FeCycle II, increasing as stocks of new iron were depleted, suggesting that quotas and iron recycling efficiencies together set biotic iron pools. Hence, site-specific differences in iron recycling efficiencies (which provide 20-50% and 90% of total iron supply in high- and low-iron waters, respectively) help offset the differences in new iron inputs between low- and high-iron sites. Future parameterization of iron in biogeochemical models must focus on the drivers of biotic iron inventories, including the differing iron requirements of the resident biota, and the subsequent fate (retention/export/recycling) of the biotic iron