VictorJuiz/thesis huggingface dataset:
The nature and origin of gold mineralization at Damang mine, Ghana
Keywords: gold
thermodynamics
geochronology
Ghana
petrology

The Palaeoproterozoic Birimian terrane of the West African Man Shield is a gold province of global importance. Gold mineralization at the Damang deposit, however, is unique amongst known gold deposits in Ghana. It comprises a stratigraphically controlled auriferous quartz-pebble conglomerate, which is overprinted by later orogenic gold contained in a sub-horizontal fault-fracture quartz vein array. Furthermore, this gold mineralization is hosted in sediments of the Tarkwaian System, rather than volcanics of the underlying Birimian Supergroup. This thesis integrates petrological, geochemical, thermodynamic and geochronological data to investigate the Damang deposit in the context of the regional tectonic and metallogenic framework.
Staurolite-grade, amphibolite facies peak metamorphism at Damang occurred at around 595ºC and 5.5 kbar at 2005±26 Ma. This was immediately followed by a short period (~ 5 Ma) of rapid exhumation, at a rate of approximately 2.6 mm/yr. This decompression led to the formation of the fault-fracture mesh, which was enhanced by the silicification of host rocks during an earlier ‘Pink Haematite’ hydrothermal event that was associated with the intrusion of voluminous dolerite bodies.
Orogenic gold mineralization occurred at the end of this exhumation period at conditions of 400–450ºC and 1–2 kbar. These conditions are in broad agreement with other Ghanaian deposits. A gold-bearing, CO₂-rich (X(CO₂) ~ 0.7), aqueous fluid generated through metamorphic devolatilization reactions close to peak metamorphism and during the subsequent exhumation fed the fault-fracture mesh. This fluid imparted a potassic–carbonation–sulphidation alteration overprint similar to that seen at orogenic gold deposits globally. This alteration signature is characterized and identified with portable infrared spectroscopic techniques. Exhumation rates following gold mineralization were less than 0.01 mm/yr, while 40Ar/39Ar dating of biotites give ages ranging between 1978.8±6.2 Ma and 1898±11 Ma, indicating extremely prolonged (~ 80 Ma) cooling through the interval 300–250ºC.
Ultimately, this thesis demonstrates that the Damang deposit is part of the same regional metallogenic event that formed the other Ghanaian deposits. This implies that the Tarkwaian System elsewhere in Ghana may be prospective for orogenic gold mineralization.
Magma chamber assembly and dynamics of a supervolcano: Whakamaru, Taupo Volcanic Zone, New Zealand
Keywords: supervolcano
magma reservoir
ignimbrite
tephra
crystals

This thesis employs crystal-specific techniques, combined with field observations, petrology, geochemistry and numerical modelling to reconstruct the magmatic system associated with the ~ 340 ka Whakamaru supereruption, New Zealand. Comparisons are drawn with the ~ 74 ka Youngest Toba Tuff (YTT) supereruption.
Whakamaru Group Ignimbrites contain five pumice types, characterised by different mineralogies and crystal contents. Pumice petrography and geochemistry indicate that basaltic magma mixing occurred, possibly triggering eruption. Geothermobarometers suggest an eruption temperature of ~ 770°C and magma storage at ~ 5 km depth. High-resolution thermal records from Ti-in-quartz analysis indicate a thermal pulse of ~ 100°C prior to eruption. Diffusion timescales show multiple recharge events with the most significant event occurring ~ 35 y prior to eruption. Zircon U-Pb data show that most crystallisation occurred at ~ 400 ka, with antecrysts and xenocrysts incorporated. Zircon trace-element data suggest multiple recharge events and complex mixing over ~ 100 ky, consistent with an incrementally growing reservoir. Oxygen-isotope data illustrate that zircon, quartz and feldspar crystallised together in equilibrium, with isotopically homogenous magma sources feeding the reservoir over time.
Whakamaru and YTT tephra thickness and grain-size data were used in ash dispersal modelling. Results indicate the YTT eruption had a ~ 35 km column height and erupted volumes of 1500 – 1900 km³, with deposition from a co-ignimbrite phase; whereas Whakamaru had a Plinian column ~ 45 km high with SE dispersal and a minimum volume of ~ 400 km³. The widespread dispersal of large volumes of fine ash from both eruptions would have had global environmental consequences.
The data are integrated to reconstruct a new Whakamaru magma reservoir model. The complex crystal records indicate the system was characterised by long periods of incremental assembly, mixing, recycling of material, and reactivation during multiple recharge episodes which perturbed the system and primed the magma for eruption.
Poetic genre and economic thought in the long eighteenth century: three case studies
Keywords: poetry
intellectual history
georgic
genre
eighteenth century
satire
classical reception
country house poetry

During the eighteenth century, the dominant rhetorical and explanatory power of civic humanism was gradually challenged by the rise of a new organising language in political economy. Political economic thought permitted radically different descriptions of what laudable private and public behaviour might be: it proposed that self-interest was often more beneficial to society at large than public-mindedness; that luxury had its uses and might not be a threat to liberty and political integrity; that landownership was no particular guarantee of virtue or disinterest; and that there was nothing inherently superior about frugality and self-sufficiency. These new ideas about civil society formed the intellectual basis of a large body of verse written during the long eighteenth century (at mid-century in particular), in which poets engaged enthusiastically with political economic arguments and defences of commercial activity, and celebrated the wealth and plenty of Britain as a modern trading nation. The work of my thesis is to examine a contradiction in the way in which these political economic ideas were handled. Forward-looking and confident poetry on public themes did not develop pioneering forms to suit the modernity of its outlook: instead, poets articulated such themes in verse by appropriating and reframing traditional genres, which in some cases involved engaging with inherited moral values and philosophical preferences entirely at odds with the intellectual material in hand. This inventive kind of generic revision is the central interest of the thesis. It aims to describe a number of problematic meeting points between new political economic thought and handed-down poetic formulae, and it will focus attention on some of the ways in which poets manipulated the forms and tropes they inherited in order to manage – and make the most of – the resulting contradictions.
Iron anchors and mooring in the ancient Mediterranean (until ca. 1500 CE)
Keywords: ancient history
mooring
nautical technology
anchors
ancient Mediterranean
iron anchors

This dissertation examines ancient anchoring practice in the Mediterranean through ca. 1500 CE, as well as the history and technological developments of iron anchors, which are among the most important tools inherited from the ancient world. The methodology employed is holistic in synthesizing archaeological finds, textual, and iconographic evidence, and includes statistical and geographical analysis based on a substantial catalogue of ancient anchor finds. An experimental project is also included where anchor reconstructions were used in the sea and their utility tested.
Mooring is one of the least studied aspects of everyday life for the people of the ancient Mediterranean. It has been elucidated that in most circumstances beaching would not have been a practical option, even for warships and the smallest cargo vessels. Rather, vessels were equipped with specialized gear for mooring off or near undeveloped shores. This included ship's boats enabling access to the shore. Lower draft vessels, particularly galleys, could approach unbuilt shores and employ mooring stakes and cables, and the ship's landing-ladder would be deployed into shallow water. Where available, however, ships would benefit from built quays which facilitated goods transport.
The iron stock-anchor displays the greatest longevity of any anchoring tool, evinced as early as the 5th c. BCE, and appears to have achieved dominance over wooden types by the 3rd c. CE. From its conception the iron-stock anchor undergoes a broad range of gradual changes to its form and features. The earliest known finds take a 'V' form in the bulk-arms and gradually develop through rounded to 'T' and 'Y' forms in the Byzantine Period. The stocks evolve from removable iron types, to permanent forms entirely of wood. Reintroduction of upward-oriented arm designs from northern Europe around the 13th c. CE, and incorporation of hydraulic mechanized smithing developments, heralded a revolution of anchoring technology. Larger, stronger and more efficient anchors were being produced to standardized dimensions and quality, promoting larger ships, and ultimately resulting in novel characteristics of navigation.
Essays on aid and regional integration in East Africa
Keywords: CGE
regional integration
East Africa
border effect

This thesis tackles issues related to regional integration, trade costs and aid, with empirical work related to the East African Community (EAC). The common thread is the impact of various types of trade costs on the structure and functioning of the economies of EAC member states. The first chapter introduces the literature and chapters 2, 3 and 4 constitute the core of the thesis.
Chapter 2 develops a three-good, two-country duality-based general equilibrium model to investigate the effects of different types of aid and preferential trade on welfare and relative prices. The model is innovative in two ways: (i) a regionally tradable good is introduced, the price of which is determined endogenously, (ii) a regional infrastructure good, bought with aid monies, is brought in which lowers trade costs within the region. Using comparative statics, the properties of the model are explored in terms of the effects of tariff and aid shocks on welfare and relative prices.
Chapter 3 develops a Computable General Equilibrium (CGE) model calibrated on Uganda and Kenya to gauge the importance of chapter 2’s results. The regional spill-over is now modeled as regional public capital serving as an input in both countries’ production functions. The simulations show how Kenya effectively exports some of the standard aid-induced real exchange rate appreciation to Uganda through a regional trade channel. Distributionally, Kenya’s urban and Uganda’s rural households win—which corresponds to regional comparative advantage patterns. Abolishing the intra-regional tariff increases welfare in Uganda and reduces it in Kenya, showing the ambiguous welfare results of Customs Unions known since Viner.
Chapter 4 gauges the importance of border effects in Eastern Africa by testing the law-ofone- price (LOP) hypothesis on a consumer price data-set covering 24 goods in 39 cities in 4 countries. Using level regressions a significant border effect is found, whilst distance also plays a big role, both between and within countries. Neither the nominal exchange rate, nor non-tariff barriers (NTBs) reduce the border effect very much, even though both variables are significant. Looking at specific goods, markets for staple foods are the most integrated. As for the impact of the Customs Union between Tanzania, Uganda and Kenya (since 2005), there is a positive integration effect for the Kenya-Uganda border. Finally, Kenya’s political crisis at the end of 2007 can be linked to higher departures from the LOP throughout the region and can thus be said to have had clear knock-on effects for the landlocked EAC countries that depend on it as a transit country.
Spray forming of Si-Al alloys for thermal management applications
Keywords: thermal management
silicon
aluminium
spray-forming
CE7

This thesis describes the processing and characterisation of Al-70Si alloys manufactured by gas atomised spray forming at Sandvik-Osprey (Neath, UK) and Oxford University using a newly commissioned spray forming pilot-plant facility. Spray formed Al-70Si (CE7) provides an attractive balance of thermophysical properties making it suitable for thermal management applications. Microstructural characterisation of CE7 was conducted using optical microscopy, image analysis, electron probe micro analysis (EPMA) and electron backscatter diffraction (EBSD). Microscopy revealed an interpenetrating network microstructure consisting of fine, randomly oriented polycrystalline primary Si interpenetrated by large, α-Al grains devoid of eutectic Si. Mechanical testing and thermal cycling simulated a service environment and revealed for the first time crack initiation, growth and blunting mechanisms, the effect of intermetallic phases on the bulk mechanical properties, and anisotropy effects resulting from macrosegregation of Al during solidification. A relationship between the inter-phase interface length and the fracture toughness has been proposed and methods of interface length refinement have been investigated, including chill casting and spray forming. Spray formed CE7 modified with separate additions of B, P, P+Ce and Sr have been microstructurally and mechanically characterised and compared with binary CE7. While alloy additions were effective in refining primary and eutectic Si in chill cast alloys, spray formed alloys showed little change in interface length. Particle injection of Si-Al powder was effective in refining the scale of the spray formed microstructure, and improving mechanical properties. The deleterious effect of intermetallic phases on bulk mechanical properties has been demonstrated and highlighted the importance of melt cleanliness and materials control during manufacturing.
Behaviour of uniformly dimpled colloidal particles
Keywords: soft matter
colloids

Uniformly dimpled colloidal particles are studied using laser scanning confocal microscopy and optical tweezing, alongside real-space image analysis. In particular, a comparison is made between the behaviour of these particles with that of isotropic spherical particles of the same size and polydispersity.
We begin by detailing the synthetic techniques as well as the methods used for both experiments and simulations in this work. We then probe the structures and ordering exhibited by the dimpled particles and their spherical counterparts at a single featureless wall. Only the first layer at the wall is observed, and pronounced differences in both the translational and orientational order between the two types of particle is found. Furthermore, we show that the presence of the dimple leads to disordered structures that develop over time. Next, we reduce the dimensionality of the system to quasi-two and study the depletion induced interactions in a monolayer of colloidal particles at a single featureless wall. Using both confocal microscopy and Monte Carlo simulations, we illustrate the selectivity of the depletion interaction with regard to particle shape and polymer size. A level of complexity is then added to the problem by introducing a second colloidal system of small spherical particles. The resulting binary mixture, still with additional non-adsorbing polymer and in a monolayer at a wall, allows us to investigate so-called “lock and key” binding. We show that the inclusion of a lock particle cavity, whose shape and size is complementary to those of the key particle, significantly favours binding behaviour, which is further improved by using a depletant consisting of a small polymer and charge-screening salt. Finally, the depletion induced force between lock and key particles at contact is directly measured using optical tweezers. The dependence of the force due to depletion upon the overlap volume between the particles is illustrated, and we find that the strongest force is produced when the key is held within the cavity of the dimpled lock, demonstrating semiquantitative agreement with theoretical predictions.
Variable density shallow flow model for flood simulation
Keywords: flood simulation
variable density
numerical modelling
shallow water equations
debris flows
liquid-species mixture
shallow flow model
sediment

Flood inundation is a major natural hazard that can have very severe socio-economic consequences. This thesis presents an enhanced numerical model for flood simulation. After setting the context by examining recent large-scale flood events, a literature review is provided on shallow flow numerical models. A new version of the hyperbolic horizontal variable density shallow water equations with source terms in balanced form is used, designed for flows over complicated terrains, suitable for wetting and drying fronts and erodible bed problems. Bed morphodynamics are included in the model by solving a conservation of bed mass equation in conjunction with the variable density shallow water equations. The resulting numerical scheme is based on a Godunov-type finite volume HLLC approximate Riemann solver combined with MUSCL-Hancock time integration and a non-linear slope limiter and is shock-capturing. The model can simulate trans-critical, steep-fronted flows, connecting bodies of water at different elevations.
The model is validated for constant density shallow flows using idealised benchmark tests, such as unidirectional and circular dam breaks, damped sloshing in a parabolic tank, dam break flow over a triangular obstacle, and dam break flow over three islands. The simulation results are in excellent agreement with available analytical solutions, alternative numerical predictions, and experimental data. The model is also validated for variable density shallow flows, and a parameter study is undertaken to examine the effects of different density ratios of two adjacent liquids and different hydraulic thrust ratios of species and liquid in mixed flows. The results confirm the ability of the model to simulate shallow water-sediment flows that are of horizontally variable density, while being intensely mixed in the vertical direction. Further validation is undertaken for certain erodible bed cases, including deposition and entrainment of dilute suspended sediment in a flat-bottomed tank with intense mixing, and the results compared against semi-analytical solutions derived by the author.
To demonstrate the effectiveness of the model in simulating a complicated variable density shallow flow, the validated numerical model is used to simulate a partial dam-breach flow in an erodible channel. The calibrated model predictions are very similar to experimental data from tests carried out at Tsinghua University. It is believed that the present numerical solver could be useful at describing local horizontal density gradients in sediment laden and debris flows that characterise certain extreme flood events, where sediment deposition is important.
The political economy of state-business relations in Morocco
Keywords: state-business relations in Morocco

This thesis seeks to understand how state-business relations are affected by wider societal transformations. These transformations influence the potentially crony capitalist type of state society relations. I analyzed the evolution of state-business relations in Morocco. I highlighted three different factors which affected state-business relations and potentially can offset negative consequences of crony capitalism. Fragmentation of state institutions, political factions and economic actors and the maintenance of cross-cutting alliances by the monarchy have resulted in a fragmented-multiclass state. In addition, the changing nature of the role of the state in the economy had profound implications on state-business relations in Morocco. Paradoxically, the fragmented nature of Morocco, which is the result of cross-cutting coalitions between the monarchy and society, meant that the state did not fall exclusively in the hands of private interests. The pivotal position of the monarchy in economic and political life has enabled the monarchy to fragment opposition and forge diverse alliances to maintain its support-base. My theoretical approach using a macro-historical analysis coupled with process tracing of various policy domains proved to be a useful methodology for this type of research which falls in the nexus of politics and economics. Given this my thesis made a contribution to both Middle East studies as well as the wider literature on state-business relations. In addition, my research contributes to the wider debate on the resilience of monarchies in the aftermath of the Arab spring.
The role of the cytoplasmic domain of the macrophage scavenger receptor MARCO in adhesion and uptake
Keywords: cellular binding
macrophage
endocytosis
MARCO
receptor biology
scavenger receptors

The macrophage receptor with collagenous structure (MARCO) is a class A scavenger receptor. Class A scavenger receptors are multifunctional type II transmembrane glycoproteins that have roles in modified lipoprotein uptake, innate immunity, and macrophage adhesion. It has been shown that the extracellular cysteine-rich domain of MARCO is important for ligand binding, but the role of the cytoplasmic N-terminal domain has not yet been characterised. The aim of this study was to investigate the role of the cytoplasmic domain in cell adhesion and motility, ligand binding and uptake.
Two truncated forms of human MARCO were used in this study: N- MARCO lacks the entire cytoplasmic domain; Nmyr MARCO includes the membrane-proximal putative myristoylation site, but lacks the rest of the cytoplasmic domain. The constructs were expressed in transiently transfected HEK 293T cells. The Nmyr MARCO mutant had reduced cell surface expression, an effect that was even more apparent in cells transfected with NMARCO. This indicates that the putative myristoylation site is not obligatory for cell surface expression of MARCO, but increases cell surface expression of the protein. When bound to ligand, the two mutants demonstrated a significant increase in cell surface expression, while the cell surface expression of the full-length MARCO remained unchanged. This indicates that the cytoplasmic tail affects membrane trafficking and the regulation of cell surface expression.
Maleylated proteins are ligands for scavenger receptor A and other scavenger receptors. This study demonstrates that maleylated bovine serum albumin (MalBSA) is also a ligand for MARCO and this modified protein was used to study MARCO-mediated adhesion and ligand binding. The results show that the cytoplasmic domain of MARCO is not required for binding to MalBSA coated particles. Interestingly, the Nmyr MARCO mutant showed a decreased ability to bind soluble MalBSA compared to the full-length protein indicating that the cytoplasmic domain may be necessary for endocytosis. The cytoplasmic domain of MARCO appeared to be absolutely required for adhesion to tissue culture plastic, anti-MARCO antibody PLK-1 coated surfaces and suspension grade plastic, and a lesser extent to MalBSA coated surfaces. MARCO mediated adhesion was shown not to require the presence of serum and divalent cations. Studies performed with murine primary resident peritoneal macrophages on a MalBSA coated surface indicated that MARCO is responsible for increased chemokinesis.
The results of this study show that the cytoplasmic domain of MARCO affects cell surface expression, endocytosis and adhesion. Further research is needed to determine if and how the cytoplasmic domain on MARCO participates in signalling required for these processes and if it affects cell motility.