VictorJuiz/thesis huggingface dataset:
Essays on economic mobility

This thesis is a collection of three essays with contributions to the intergenerational and intra-generational mobility literature. The essay on full risk insurance and measurement error examines the likelihood that measurement error may reconcile observed departures from perfect rank immobility in insurable consumption with the mobility predictions of full risk insurance, by generating spurious rank-breaking transitions. The essay shows that under certain assumptions full risk insurance predicts perfect rank immobility and that there exists ranges of error covariance matrices for which the mobility predictions of full risk insurance plus measurement error can not be rejected in the Peruvian data. A novel approach to test these mobility predictions is presented. The essay on discrete time-states Markov chain models applied to welfare dynamics shows that models with higher order may fit data better than the popular first-order, stationary model, and that the order of the chain, in turn, affects the estimation of equilibrium distributions. A best-practice methodology to conduct homogeneity tests between two samples with different optimal order is proposed, and an index by Shorrocks, based on the trace of the transition matrix, is extended to discrete Markov chain models with higher order. The essay on cohort heterogeneity in intergenerational mobility of education shows how cohort heterogeneity affects the analysis of cross-group homogeneity and long-term prospects of a welfare variable, based on transition matrix analysis. The essay compares the transition matrices of Peruvian groups divided by gender and ethnicity and finds genuine reductions in heterogeneity of the mobility regimes between male and female and between indigenous and non-indigenous groups among the youngest cohorts. The essay proposes a methodology to conduct first-order stochastic dominance analysis with equilibrium distributions and shows that among the youngest cohorts past stochastic dominance of male over females and non-indigenous over indigenous disappear in the long term.

Keywords: risk insurance
mobility indices
intergenerational mobility
non-parametric methods
Advisor: Fafchamps, M
Seismic source parameter determination using regional intermediate-period surface waves

In general, the depths of shallow earthquakes are poorly resolved in current catalogues. Variations in depth of ±10 km can significantly alter the tectonic interpretation of such earthquakes. If the depth of a seismic event is in error then moment tensor estimates can also be significantly altered. In the context of nuclear-test-ban monitoring, a seismic event whose depth can be confidently shown to exceed say, 10km, is unlikely to be an explosion.
Surface wave excitation is sensitive to source depth, especially at intermediate and short periods, owing to the approximate exponential decay of surface wave displacements with depth. The radiation pattern and amplitude of surface waves are controlled by the depth variations in the six components of the strain tensor associated with the surface wave eigenfunctions. The potential exists, therefore, for improvements to be made to depth and moment tensor estimates by analysing surface wave amplitudes and radiation patterns.
A new method is developed to better constrain seismic source parameters by analysing 100-20s period amplitude spectra of fundamental-mode surface waves. Synthetic amplitude spectra are generated for all double-couple sources over a suitable depth range and compared with data in a grid-search algorithm. Best fitting source parameters are calculated and appropriate bounds are placed on these results.
This approach is tested and validated using a representative set of globally-distributed events. Source parameters are determined for 14 moderately-sized earthquakes (5.4 ≤ Mw ≤ 6.5), occurring in a variety of tectonic regimes with depths calculated between 4-39km. For very shallow earthquakes the use of surface wave recordings as short as 15s is shown to improve estimates of source parameters, especially depth.
Analysis of aftershocks (4.8 ≤ Mw ≤ 6.0) of the 2004 great Sumatra earthquake is performed to study the depth distribution of seismicity in the region. Three distinct tectonic regimes are identified and depth estimates calculated between 3-61km, including the identification of one CMT depth estimate to be in error by some 27km.

Advisor: Woodhouse, J
Numerical and experimental studies of shallow cone penetration in clay

The fall-cone test is widely used in geotechnical practice to obtain rapid estimates of the undrained shear strength of cohesive soil, and as an index test to determine the liquid limit. This thesis is concerned with numerical modelling of the penetration of solids by conical indenters, and with interpretation of the numerical results in the context of the fall-cone test. Experimental studies of shallow cone penetration in clay are also reported, with the aim of verifying the numerical predictions. The practical significance of the results, in terms of the interpretation of fall-cone test results, is assessed. Results are reported from finite element analyses with the commercial codes ELFEN and Abaqus, in which an explicit dynamic approach was adopted for analysis of continuous cone indentation. Quasi-static analyses using an elastoplastic Tresca material model are used to obtain bearing capacity factors for shallow cone penetration, taking account of the material displaced, for various cone apex angles and adhesion factors. Further analyses are reported in which a simple extension of the Tresca material model, implemented as a user-defined material subroutine for Abaqus, is used to simulate viscous rate effects (known to be important in cohesive soils). Some analyses with the rate-dependent model are displacement-controlled, while others model the effect of rate-dependence on the dynamics of freefall cone indentation tests. Laboratory measurements of the forces required to indent clay samples in the laboratory are reported. Results from displacement-controlled tests with imposed step-changes in cone speed, and from freefall tests, confirm that the numerical rate-dependent strength model represents the observed behaviour well. Some results from experiments to observe plastic flow around conical indenters are also presented. Finally, additional numerical analyses are presented in which a critical state model of clay plasticity is used to study the variation of effective stress, strain and pore pressure around cones in indentation tests at various speeds.

Keywords: rate-dependent behaviour
soil mechanics
finite element method (FEM)
laboratory testing
kaolin
particle image velocimetry (PIV)
cohesive soils
Advisor: Martin, C
Processing, structure and properties of Al-matrix composites

Three classes of Al-matrix composite were manufactured to combine dissimilar metals and incorporate structural hierarchy, in an attempt to develop unusual combinations of mechanical properties.
The first class combined a brittle, nano-quasicrystalline forming Al-3Fe-2Cr-2Ti phase with a ductile Al-4Cu phase into a layered structure using low pressure plasma spraying (LPPS). By using a substrate with multi-scale topological features, an ultra-thick (>2mm) deposit was successfully sprayed, which was subsequently consolidated by hot rolling to reduce residual porosity. The microstructure comprised a 'brick-wall' structure consisting of a convoluted arrangement of inter-leaved discreet droplet splats. Structure-property relationships were studied for four volume fractions of ductile additions and in-situ electron microscopy of beams subjected to 3-point bending suggested the ductile additions were providing additional toughening to the composite by a crack-bridging mechanism.
The second class of composite investigated highly deformed microstructures of Al with 20vol% additions of either Sn or Ti. Nano-scale fibrous structures of the minority additions were achieved via an accumulative extrusion method, where extruded rod was abraded, degreased, bundled and re-extruded. This process was repeated to create refined microstructures while retaining a large material section. Fracture properties were studied in three point bending and crack growth monitored using Digital Image Correlation (DIC) to produce strain fields of the deforming beam surface. Modest changes were observed in mechanical properties with weak interfaces between poorly bonded extruded rods dominating fracture behaviour. Whiskers formed on polished surfaces of extruded Al-20vol%Sn and were monitored in real time by electron microscopy. Growth rates of up to 2.8nm/s were measured, which exceeds re- ported values in the literature on electroplated coatings by at least one order of magnitude. This may provide a convenient new means of studying whisker formation and calls into question current growth models.
The third class of composite combined heavily rolled sheets of Al-20vol%Sn and Al-20vol%Ti with glass fibre/epoxy sheets to produce a laminate with multi-scale architecture. This laminate was designed as a proof-of-concept hierarchical material with structures ranging from the near millimetre scale of the metal-polymer layers, to the micro-sized glass fibre reinforcement of the epoxy and the nano-scale filamentary/lamellar microstructure of the highly deformed metal sheets. Fracture of such laminates was investigated in 3-point bending with continuous optical monitoring.

Keywords: deformation processed
plasma spray
metal composite
Advisor: Grant, P
The objectivity of freedom: a systematic commentary on the introduction to Hegel’s Philosophy of Right

The introduction (§§1-33) to Hegel’s Philosophy of Right is the key to the work’s structure, its argumentative strategy and it functions as a foundation for Hegel’s practical philosophy in general. Its explanatory potential is best realised by situating it within the systematic context of the Encyclopedia of Philosophical Sciences and the Science of Logic. This interpretative strategy reveals that for Hegel, the true site of agency is ‘the concept’ and that particular individuals and their arbitrary activity are at best the concept’s ‘appearance’. This does not render their activity ‘false’ but describes how willing and freedom are ‘for us’ as self-conscious subjects that confront an external world. For Hegel, ‘true’ freedom in the sense of ‘self-determination to itself’ resides with the universal and singular concept that negatively unites itself with its objectivity to form what he calls the ‘Idea of the will’ or ‘right’.
This interpretation contradicts the mainstream of contemporary Hegel scholarship since its proponents either deny the reality of the universal concept as agent or absolutely differentiate between the concept’s activity (subjective action) and its objective reality (norms, institutions). This prevents the interpreter from appreciating that it is Hegel’s concept that is manifest in form of particular willing subjects and their socio-political context. Since most commentators associate ‘activity’ or ‘freedom’ primarily with particular subjects, their notions of freedom are, by Hegel’s standards, either empty and fail to describe actual willing or they fall short of the standard of ‘true freedom’, viz. ‘self-determination to itself’ because their agents’ freedom depends on something that differs from the agents.1 The present commentary argues that such a dilemma can be avoided by an interpretation that attributes agency to Hegel’s concept. By determining itself to be Idea, the universal concept determines itself (as subject) to itself (as object) and rational agency and rational institutions are grasped as aspects of the same entity. This is what Hegel calls the unconditioned Idea of right or ‘objective freedom’.

Keywords: action theory
idealism
free will
Hegel
Advisor: Inwood, M
The evolution of technology and adaptive economic behaviour

This thesis studies the role of learning as a mechanism of economic change. Two areas are considered where this would seem to be important. First, how firms learn about new technology; and secondly, how agents learn to behave in interactive situations.
A model of research and development is presented which models the process by which firms solve specific design problems. This may be by individual experimental search or by partial imitation. In the latter case, a close parallel is drawn between biological evolution, based on genetic reproduction, and technological evolution, based on firms blending existing technologies. Some economic implications of these processes are explored, including their application to stochastic learning curves, patent design and the transfer of technology to developing countries.
The thesis continues by critically assessing the analogy between biological and cultural evolution often used to model how agents learn to behave in interactive situations. It is argued that the methods used by economists exploiting this analogy are often ill-suited to an economic context. Models are presented which deal with specific issues in the transition from a biological context to an economic context, including models of partnership formation, models of imperfect imitation, and models without payoff-monotonic dynamics. The issue of imperfect imitation is expanded upon in an evolutionary model of the infinitely repeated prisoners' dilemma, where it is shown that the problem of inter-generational copying fidelity may allow one to restrict attention to strategies with a very simple stochastic structure.
Analogues of Antibacterial Natural Products 

Analogues of Antibacterial Natural Products Elizabeth Anne Heaviside, St Catherine’s College, University of Oxford DPhil Thesis, Trinity Term 2012 This thesis is concerned with the synthesis and biological evaluation of structural mimics for the natural products 16-methyloxazolomycin and lemonomycin which display potent biological activity including antibacterial and antitumour activity. Chapter 1 explores methods and approaches to the discovery of new antibacterial drugs and the challenges faced in this respect. It also gives an overview of the properties of the natural products investigated in the following chapters and summarises previous synthetic approaches to these molecules published in the scientific literature. Chapter 2 describes the work carried out towards the synthesis of the diazabicyclo[3.2.1]octane unit of the tetrahydroisoquinoline antitumour antibiotic lemonomycin. The intended retrosynthesis of the natural product led to a 2,5-disubstituted pyrrolidine bearing a 1ʹ-amino functional group; a series of routes were explored for the synthesis of this unit. Using (S)-pyroglutamic acid, strategies using Eschenmoser and thiolactim ether coupling reactions were investigated. A sequence based on the formation of a pyrrolidine ring from the cyclisation of an appropriately substituted oxime ether derived from L-phenylalanine was then implemented but a competing Beckmann rearrangement/Grob fragmentation prevented access to the desired heterocycle. Preliminary investigations were also carried out on the modification of cyclic imines derived from oxime ethers which did not undergo Beckmann rearrangement. Chapter 3 describes the synthesis of a library of densely functionalised tetramic acid and pyroglutamate mimics for the right-hand fragment of 16-methyloxazolomycin, and their coupling with a gem-dimethylamide unit mimicking the middle fragment of the natural product. Tetramates were accessed through the Dieckmann cyclisation of N-acyloxazolidines and were derivatised with various alkyl halides. The pyroglutamates were accessed via the highly diastereoselective aldol cyclisation of N-acyloxazolidines formed by the amide coupling of a threonine derived oxazolidine and β-keto-acids. A series of β-keto-acids were synthesised through the acylation and subsequent ring-opening/decarboxylation reaction of Meldrum’s acid. The formation of right-hand/middle fragment adducts was explored using cycloaddition, alkylation and Sonogashira chemistry before a Wittig protocol led to the formation of adducts (E)- and (Z)- 402 and 403. Biological evaluation of the compounds synthesised in this chapter was carried out using both broth and hole-plate bioassays and active compounds were identified. Of particular note was that the Wittig adducts displayed a higher level of activity against Gram-negative E. coli than either the pyroglutamate or amide motifs alone.

Keywords: Lemonomycin
Antibiotic
Oxazolomycin
Natural Product
16-Methyloxazolomycin
Synthesis
Antibacterial
Advisor: Moloney, M
Orthogonal tight binding model for silicon carbide

A new orthogonal tight binding (OTB) model for the silicon carbide (Si-C) system is presented. The model is parameterized in the reduced TB form which provides a critical step towards the development of an analytic bond-order potential (BOP) for Si-C. Coarse-grained from density functional theory (DFT), through TB, analytic BOPs address a number of the deficiencies of current interatomic potentials for Si-C including the neglect of explicit π-bonding and more accurate σ-bond contributions. Furthermore, the new reduced OTB model is important within TB in its own right as the first simple, selfconsistent OTB model parameterized specifically for SiC without the use of any averaging of elemental interactions. Selfconsistency is achieved through local charge neutrality (LCN). The distance-dependent functions used to define the Hamiltonian matrix elements in the two-centre approximation were obtained directly from given DFT-projected data, and repulsive parameters were fit to DFT binding energies. The electronic structure, binding energies, and heat of formation for the groundstate structures are reproduced well with no spurious groundstate structures found in a database of over 200 unique crystal structures. The significant improvements over existing OTB models for elemental Si and C and the binary SiC results show good promise for further applicability in modelling a wide range of phenomena in Si-C such as thin film growth or interfaces in general.

Keywords: Carbon
Silicon carbide
Bond-order potentials
Model development
Orthogonal tight binding
Materials modelling
Advisor: Pettifor, D
Drautz, R
Kolmogorov, A
High resolution structural studies of membrane proteins using solid state NMR

NMR crystallography is a new and developing area. Unlike solution state NMR, solid state NMR has the potential for structural studies of large, motionally restricted biological macromolecules, such as proteins in crystals which may, or may not, diffract. However, finding the best and the most useful sample form and geometry is still a major obstacle to rapid progress. Little has been reported about protein sample preparation for any class of protein for NMR crystallography, mainly since the availability of NMR labelled proteins is still not routine, especially for eukaryotic membrane proteins. The amino acid L-glutamate is the major excitatory neurotransmitter in the brain. Details of glutamate binding to any of its main brain or sensory receptors are not well resolved at the atomic level. In an effort to resolve the glutamate binding mechanism by solid state NMR methods, full-length taste and brain mGluR4 were expressed in E. coli, but proved to be toxic for the cells. The ligand-binding domains (LBD) of mGluR4, with various fusions for the periplasmic expression and with various fusions for expression in the cytoplasm therefore, were used. Solubilisation and then purification of the LBD from inclusion bodies is still under way, no crystals of mGluR4 for NMR were, therefore, grown. Initial NMR spectra of labelled 13C, 15N and 17O glutamate have been recorded to verify sensitivity requirements. Using homology modelling, a model for the truncated version of the ligand binding domain of mGluR4 has been constructed as a basis for designing solid state NMR experiments to probe the ligand binding site in the receptor. Bacteriorhodopsin is a large membrane protein and a model for G-protein coupled receptors (GPCRs). Spectra of bacteriorhodopsin produced in H. salinarium in purple membrane are reported here and compared to spectra of the protein crystallised from bicelles. Optimal conditions for producing spectra suitable for spectral assignment are reported as an initial step towards spectral resolution. Three differently labelled samples of bacteriorhodopsin were prepared to test the applicability of the various assignment strategies and the effects of deuteration on quality of solid state NMR spectra of a large, crystalline membrane protein.

Keywords: solid state nmr
membrane proteins
Advisor: Watts, A
Rethinking the bronze-iron transition in Iran: copper and iron metallurgy before the Achaemenid Period

Iran, a country rich in mineral resources, has a long history of metal working. Copper objects first appeared in the 7th millennium BC and in the following millennia, copper became the material of choice for the production of many objects. Artefacts of iron began to appear in the mid 2nd millennium BC and by the mid 1st, iron had replaced bronze for most uses, but the reasons for this change remain unclear.
This thesis seeks to examine the transition from bronze to iron metallurgy from a new angle. By looking at changes in copper-based metallurgy between the Bronze Age and the Iron Age, it attempts to better understand the context in which iron metallurgy developed. To that end, the results of previously published chemical analyses of over 5000 copper-based objects from Iran and neighbouring regions and the lead isotope analyses of about 380 objects were assembled in a database.
The tin, arsenic, nickel, antimony and silver concentrations in particular are studied. The data is divided into 16 metal groups based on the absence or presence of the latter four elements. The study of the main groups allows us to describe interesting new patterns of metal movement and recycling. It appears that before the end of the Bronze Age, a number of copper sources and/or trade routes from both east and west declined, leading to a reliance on more local sources for copper and tin in the Iron Age. The practice of recycling from the 3rd millennium BC onward is also evidenced.
Overall, it seems that iron appeared within a thriving bronze industry, with a good access to metal resources and a developed understanding of the possibilities offered by copper (alloying, recycling, mixing…). Was it then the more ‘permanent’ nature of iron that attracted the ancient metal-workers and led to its advent?

Keywords: copper
iron
archaeometallurgy
Iran
Advisor: Pollard, A