Global ETD Search

41	Formation of stars and stellar clusters in galactic environment Smilgys, Romas January 2018 (has links) Star and stellar cluster formation in spiral galaxies is one of the biggest questions of astrophysics. In this thesis, I study how star formation, and the formation of stellar clusters, proceeds using SPH simulations. These simulations model a region of 400 pc and 107 solar masses. Star formation is modelled through the use of sink particles which represent small groups of stars. Star formation occurs in high density regions, created by galactic spiral arm passage. The spiral shock compresses the gas and generates high density regions. Once these regions attain sufficiently high density, self-gravity becomes dominant and drives collapse and star formation. The regions fragment hierarchically, forming local small groups of stars. These fall together to form clusters, which grow through subsequent mergers and large scale gas infall. As the individual star formation occurs over large distances before forming a stellar cluster, this process can result in significant age spreads of 1-2 Myrs. One protocluster is found to fail to merge due to the large scale tidal forces from the nearby regions, and instead expands forming a dispersed population of young stars such as an OB association.
42	To walk upon the grass : the impact of the University of St Andrews' Lady Literate in Arts, 1877-1892 Smith, Elisabeth Margaret January 2014 (has links) In 1877 the University of St Andrews initiated a unique qualification, the Lady Literate in Arts, which came into existence initially as the LA, the Literate in Arts, a higher certificate available to women only. Awarded by examination but as a result of a programme of distance learning, it was conceived and explicitly promoted as a degree-level qualification at a time when women had no access to matriculation at Scottish universities and little anywhere in the United Kingdom. From small beginnings it expanded both in numbers of candidates and in spread of subjects and it lasted until the early 1930s by which time over 36,000 examinations had been taken and more than 5,000 women had completed the course. The scheme had emerged in response to various needs and external pressures which shaped its character. The purpose of this thesis is to assess the nature and achievements of the LLA in its first fifteen years and to establish its place within the wider movement for female equality of status and opportunity which developed in the later decades of the nineteenth century. The conditions under which the university introduced the LLA, its reasons for doing so, the nature of the qualification, its progress and development in the years before 1892 when women were admitted to Scottish universities as undergraduates and the consequences for the university itself are all examined in detail. The geographical and social origins and the educational backgrounds of the candidates themselves are analysed along with their age structure, their uptake of LLA subjects and the completion rates for the award. All of these are considered against the background of the students' later careers and life experiences. This thesis aims to discover the extent to which the LLA was influential in shaping the lives of its participants and in advancing the broader case for female higher education. It seeks to establish for the first time the contribution that St Andrews LLA women made to society at large and to the wider movement for female emancipation. 378.1
43	The harmonious organ of Sedulius Scottus : an introduction and translation of selections of his 'Collectaneum in Apostolum' Sloan, Michael Collier January 2011 (has links) Most of the limited scholarship on Sedulius Scottus focuses on his poems and treatise, De Rectoribus Christianis. As the product of a central ecclesiastical figure in LiÃ¨ge, the intellectual capital of Louis the Germanâs kingdom, Seduliusâ biblical exegesis also deserves study. The Carolingians revered classical society and culture and at the same time sought to become a wholly Christian empire, thus, it is not surprising that the content of Seduliusâ Collectaneum in Apostolum contains both classical and Christian elements. In 1997, J. Frede published a critical edition of Seduliusâ Collectaneum in Apostolum, but there remains today neither a translation nor specific study of this work in any modern language. My thesis seeks to provide an introduction and translation for the Prologue and commentaries on Galatians and Ephesians as contained in Fredeâs critical edition of Sedulius Scottusâ Collectaneum in Apostolum. After situating Sedulius in his historical context and highlighting the tradition of biblical collectanea, I present external evidence â which demonstrates Seduliusâ familiarity with Donatusâ Vita and Serviusâ commentary on the Aeneid â as well as intertextual links to the latter works to argue that Serviusâ pedagogical commentary served as a literary model for Seduliusâ Collectaneum. I also introduce and explain Seduliusâ organizing template for the Prologue, which is his employment of the classical rhetorical schema, âthe seven types of circumstanceâ. This schema is an important rhetorical tool of many classical and medieval authors that has heretofore been misrepresented as originating from Hermagoras. Seduliusâ literary style and format are examined as matters of introduction, which further reveals the influence of Servius. The commentaries within the Collectaneum in Apostolum are essentially based on older, formative religious writers such as Jerome, Augustine, and Pelagius. Not only do I survey Seduliusâ doctrinal stances on important theological and ecclesiastical issues of his time, but I discuss Seduliusâ reception of the above three authors in particular and demonstrate how his Collectaneum in Apostolum attempts to harmonize their sometimes discordant voices. 227
44	Trends in alluvial channel geometry and streamflow : an investigation of patterns and controls Slater, Louise J. January 2015 (has links) Alluvial river channels are self-formed by the sediment-laden flow that is supplied to them from upstream and the interactions between this flow and the materials forming the channel bed and banks. Thus, any changes in the volumes of solid and liquid discharge or the resistance of the boundary materials can produce adjustments in the form of river channels over time. These shifts may increase or decrease the capacity of a channel to contain flood flows. However, despite a wealth of studies on the average geometry of river channels across different scales and climatic regimes, there has not yet been a systematic assessment of the rates and controls of trends in channel form. Using a combination of USGS data, including manual field measurements and mean daily streamflow data at hundreds of stream gages, this work is the first attempt to quantify how trends in channel geometry develop over decadal timescales and how they contribute to shifts in flood hazard, in comparison with trends in streamflow. Findings reveal that two-thirds of all channel cross-sections studied exhibit significant trends in channel geometry. The majority of the investigated US river channels are eroding, with widening and deepening trends partially offset by decreases in average flow velocity. Rates of change are principally controlled by the channel size. Although large channels develop larger trends, changes are proportionally greater in small channels in percentage terms. A secondary major control is hydrology: rates of change in channel geometry are heightened by the variability and flashiness of flow regimes. Finally, results show that changing flood frequencies can only be accurately quantified when both hydrologic and geomorphic trends are accounted for, and that flood hazard is significantly increasing across the studied sites. These documented trends in channel geometry, hydraulics, and flood hazard have important implications for the management of alluvial channels, navigation, and riverside infrastructure. 551.48
45	Macromolecular Interactions in West Nile Virus RNA-TIAR Protein Complexes and of Membrane Associated Kv Channel Peptides Zhang, Jin 01 July 2013 (has links) Macromolecular interactions play very important roles in regulation of all levels of biological processes. Aberrant macromolecular interactions often result in diseases. By applying a combination of spectroscopy, calorimetry, computation and other techniques, the protein-protein interactions in the system of the Shaw2 Kv channel and the protein-RNA interactions in West Nile virus RNA-cellular protein TIAR complex were explored. In the former system, the results shed light on the local structures of the key channel components and their potential interaction mediated by butanol, a general anesthetic. In the later studies, the binding modes of TIAR RRM2 to oligoU RNAs and West Nile virus RNAs were investigated. These findings provided insights into the basis of the specific cellular protein–viral RNA interaction and preliminary data for the development of strategies on how to interfere with virus replication Macromolecular interaction Thermodynamics tran-cis Isomerization Exchange spectroscopy Shaw2 Kv channel S4-S5 linker S6 Anesthetics DPC micelles Paramagnetic relaxation enhancement West Nile virus RRM2 Binding interactions Molecular docking Isothermal titration calorimetry Adenine H2 Long-range coupling
46	The deglaciation of the northwest sector of the last British-Irish ice sheet : integrating onshore and offshore data relating to chronology and behaviour Small, David January 2013 (has links) It is now accepted that the last British-Irish Ice Sheet (BIIS) was highly dynamic and drained by numerous fast flowing ice streams. This dynamic nature combined with its maritime location made the BIIS sensitive to the rapid climate change that characterised the Last Glacial Interglacial Transition. Gaining an understanding of the behaviour of the BIIS at this time is important to explore the nature of forcing between ice sheets and climate. This thesis presents new chronological data relating to the deglaciation of the northwest sector of the BIIS (NW-BIIS) from onshore dating of moraines using cosmogenic exposure dating. This improved chronological framework is supported by offshore data in the form of a newly constructed Ice Rafted Detritus (IRD) record from the offshore sediment core MD95-2007. These data suggest that deglaciation commenced sometime after 18 ka and that the NW-BIIS was located close to the present day shoreline by 16 ka. Further provenance analysis of the IRD using U-Pb dating of detrital minerals demonstrates that during the Last Glacial-Interglacial Transition MD95-2007 was being supplied distal IRD from a source(s) to the west. The absence of diagnostic Scottish material suggests that after retreat to the coastline at 16 ka calving margins were not re-established during Greenland Interstadial 1. By combining these results with existing data relating to the deglaciation of the NW-BIIS it is possible to summarise the deglaciation history of the NW-BIIS from the continental shelf to mountainous source regions and compare this to numerical models of BIIS behaviour during this time. With a better understanding of the chronology of NW-BIIS retreat it is possible to relate the timing of initial deglaciation to possible forcing factors and gain a better understanding of the response of a marine based sector of an ice sheet to rapid climate change. 551.31
47	Decreasing Boot Time in an Embedded Linux Environment Hedberg, Alexander, Al Abduallah, Ahmed January 2023 (has links) - Linux Boot time Decrease Boot Time Yocto Project Init-System init-systems SystemD SysVinit Runit OpenRC s6-rc User Space Faster Boot BSc Thesis Computer Science Computer Engineering Computer Sciences Datavetenskap (datalogi)
48	Winning a race with no finish line : assessing the strategy of interstate competition Skold, Martin January 2018 (has links) This dissertation offers a framework for understanding the strategies of states engaged in competition for regional hegemony. Although international relations literature refers extensively to such competition and obliquely to states' strategies, to date little has been done to show how states' strategies in such competition may be analyzed. Drawing on a variety of strategic literature, this dissertation synthesizes a theoretical approach to analyzing the strategies of states engaged in regional security competition. Employing insights drawn from business strategy, this dissertation argues for an essentially asymmetric understanding of fundamental policy goals for states engaged in competition for regional hegemony, with one state attempting to maintain a dominant position and another attempting, by focusing limited resources, to supplant it. The competition is understood metaphorically (based on an anecdote from the end of the Cold War) as a “race with no finish line,” with the reigning hegemon attempting to extend the race and the challenger attempting to create a finish line and cross it. With homage to realism, liberalism, and constructivism, possible state goals are categorized as belonging to three realms: security, welfare, and intangible goals. These are used as metrics for a state's success or failure in any given competitive scenario, as well as the resources at its disposal. Drawing on military strategic literature, this thesis then applies decision-cycle analysis to state competitive behavior. The conclusions from this analysis are then synthesized into a framework for analysis of similar regional competitive scenarios, the first such framework yet devised for such purposes. A case study: the “Dreadnought Race” between Britain and Germany prior to World War One, is then examined, in which states' performance is analyzed in the competitive scenario in light of the above strategic precepts.
49	MSK1 regulates homeostatic and experience-dependent synaptic plasticity Corrêa, Sonia A.L., Hunter, C.J., Palygin, O., Wauters, S.C., Martin, K.J., McKenzie, C., McKelvey, K., Morris, R.G., Pankratov, Y., Arthur, J.S., Frenguelli, B.G. January 2012 (has links) No / The ability of neurons to modulate synaptic strength underpins synaptic plasticity, learning and memory, and adaptation to sensory experience. Despite the importance of synaptic adaptation in directing, reinforcing, and revising the behavioral response to environmental influences, the cellular and molecular mechanisms underlying synaptic adaptation are far from clear. Brain-derived neurotrophic factor (BDNF) is a prime initiator of structural and functional synaptic adaptation. However, the signaling cascade activated by BDNF to initiate these adaptive changes has not been elucidated. We have previously shown that BDNF activates mitogen- and stress-activated kinase 1 (MSK1), which regulates gene transcription via the phosphorylation of both CREB and histone H3. Using mice with a kinase-dead knock-in mutation of MSK1, we now show that MSK1 is necessary for the upregulation of synaptic strength in response to environmental enrichment in vivo. Furthermore, neurons from MSK1 kinase-dead mice failed to show scaling of synaptic transmission in response to activity deprivation in vitro, a deficit that could be rescued by reintroduction of wild-type MSK1. We also show that MSK1 forms part of a BDNF- and MAPK-dependent signaling cascade required for homeostatic synaptic scaling, which likely resides in the ability of MSK1 to regulate cell surface GluA1 expression via the induction of Arc/Arg3.1. These results demonstrate that MSK1 is an integral part of a signaling pathway that underlies the adaptive response to synaptic and environmental experience. MSK1 may thus act as a key homeostat in the activity- and experience-dependent regulation of synaptic strength. Analysis of Variance ; Animals ; Brain-derived neurotrophic factor ; Cells ; Cytoskeletal proteins ; Dendritic spines ; Environment ; Enzyme inhibitors ; Excitatory postsynaptic potentials ; Female ; Gene expression regulation ; Green fluorescent proteins ; Hippocampus ; Homeostasis ; Male Mice; Inbred C57BL ; Transgenic ; Nerve tissue proteins ; Neuronal plasticity ; Neurons ; Patch-clamp techniques ; Point mutation ; Receptors; AMPA ; Ribosomal protein S6 kinases ; Signal transduction ; Sodium channel blockers ; Synapses ; Tetrodotoxin ; Time factors ; REF 2014
50	A Global Kinase and Phosphatase Interaction Network in the Budding Yeast Reveals Novel Effectors of the Target of Rapamycin (TOR) Pathway Sharom, Jeffrey Roslan 31 August 2011 (has links) In the budding yeast Saccharomyces cerevisiae, the evolutionarily conserved Target of Rapamycin (TOR) signaling network regulates cell growth in accordance with nutrient and stress conditions. In this work, I present evidence that the TOR complex 1 (TORC1)-interacting proteins Nnk1, Fmp48, Mks1, and Sch9 link TOR to various facets of nitrogen metabolism and mitochondrial function. The Nnk1 kinase controlled nitrogen catabolite repression-sensitive gene expression via Ure2 and Gln3, and physically interacted with the NAD+-linked glutamate dehydrogenase Gdh2 that catalyzes deamination of glutamate to alpha-ketoglutarate and ammonia. In turn, Gdh2 modulated rapamycin sensitivity, was phosphorylated in Nnk1 immune complexes in vitro, and was relocalized to a discrete cytoplasmic focus in response to NNK1 overexpression or respiratory growth. The Fmp48 kinase regulated respiratory function and mitochondrial morphology, while Mks1 linked TORC1 to the mitochondria-to-nucleus retrograde signaling pathway. The Sch9 kinase appeared to act as both an upstream regulator and downstream sensor of mitochondrial function. Loss of Sch9 conferred a respiratory growth defect, a defect in mitochondrial DNA transmission, lower mitochondrial membrane potential, and decreased levels of reactive oxygen species. Conversely, loss of mitochondrial DNA caused loss of Sch9 enrichment at the vacuolar membrane, loss of Sch9 phospho-isoforms, and small cell size suggestive of reduced Sch9 activity. Sch9 also exhibited dynamic relocalization in response to stress, including enrichment at mitochondria under conditions that have previously been shown to induce apoptosis in yeast. Taken together, this work reveals intimate connections between TORC1, nitrogen metabolism, and mitochondrial function, and has implications for the role of TOR in regulating aging, cancer, and other human diseases. Target of Rapamycin budding yeast Saccharomyces cerevisiae yeast kinase phosphatase protein-protein interactions TOR nutrients growth rapamycin signaling network metabolism nitrogen catabolite repression retrograde response glutamate dehydrogenase glutamine glutamate alpha-ketoglutarate cell size aging lifespan mitochondria uncoupled respiration petite reactive oxygen species free radical theory of aging apoptosis cancer glutaminolysis TORC1 Nnk1 Fmp48 Mks1 Sch9 Gdh2 Ure2 ribosomal protein S6 kinase S6K cell biology molecular biology 0307 0379 0369 0410 0306

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