VictorJuiz/thesis huggingface dataset:
Tuning the dimensionality and interactions in transition metal oxides: a μSR study
Keywords: muon spin rotation
superconductivity
transition metal oxide
magnetism

This thesis is concerned with how the physical properties of transition metal oxides change due to chemical substitution or intercalation. Experiments using the muon-spin relaxation and rotation (μSR) techniques were carried out at the ISIS Facility (UK) and the Paul Scherrer Institute (CH). In conjunction with the μSR results, the results of heat capacity and magnetic susceptibility experiments are used to provide complementary information on the same samples. Investigations of the properties of the layered triangular lattice magnets NaNiO2 and LiNiO2 are presented. For NaNiO2, all three experimental techniques are used to provide a full survey of the thermodynamic and magnetic properties of this compound. For LiNiO2, μSR studies of notionally stoichiometric and Mg-doped samples were carried out. These showed that Mg doping causes a significant change in the magnetic dynamics of the material, but neither sample exhibits long-range magnetic order. The magnetic ordering of the extensively studied perovskite compounds LaTiO3 and YTiO3 is investigated using μSR. The results were in agreement with previous neutron diffraction studies of the two compounds, but clarified the orientation of the magnetic moments in LaTiO3. It was also possible to make a detailed comparison between the μSR results and those of dipole field calculations of the magnetic field at possible muon stopping sites, allowing these to be deduced and compared with results in other well characterized transition metal oxides. The two titanium chain compounds NaTiSi2O6 and TiOCl exhibit spin gap formation at unusually high temperatures due to unconventional dimerization mechanisms. A model allowing the comparison of X-ray diffraction data, dimerization, and the magnitude of the spin gap is proposed. This is tested against both magnetic susceptibility and μSR data for both compounds. For NaTiSi2O6 both experimental techniques are in reasonable agreement, whereas in TiOCl the results are conclusively different. The origin of this disparity in TiOCl is explored. The intercalation of organic chain molecules into Bi based high-temperature superconductors has previously been demonstrated to extend the interlayer spacing by a factor of up to three without changing the superconducting transition temperature. μSR is used to investigate the London penetration depth, as a function of interlayer spacing, of two series of such samples. The results show a simple trend corresponding to a constant density of superconducting electron pairs in each layer. The consequences of this result are discussed in the context of previously identified scaling relations between superconducting parameters. Results of experiments excluding the possibility of magnetic order and muon-organic radical formation in these samples are presented, as well a preliminary study of the field distributions in a mosaic of intercalated crystallites.
Hybrid tractability of constraint satisfaction problems with global constraints
Keywords: constraint programming
global constraints
configuration
complexity
tractability
hypergraph

A wide range of problems can be modelled as constraint satisfaction problems (CSPs), that is, a set of constraints that must be satisfied simultaneously. Constraints can either be represented extensionally, by explicitly listing allowed combinations of values, or intensionally, whether by an equation, propositional logic formula, or other means. Intensionally represented constraints, known as global constraints, are a powerful modelling technique, and many modern CSP solvers provide them. We give examples to show how problems that deal with product configuration can be modelled with such constraints, and how this approach relates to other modelling formalisms.
The complexity of CSPs with extensionally represented constraints is well understood, and there are several known techniques that can be used to identify tractable classes of such problems. For CSPs with global constraints, however, many of these techniques fail, and far fewer tractable classes are known. In order to remedy this state of affairs, we undertake a systematic review of research into the tractability of CSPs. In particular, we look at CSPs with extensionally represented constraints in order to understand why many of the techniques that give tractable classes for this case fail for CSPs with global constraints. The above investigation leads to two discoveries.
First, many restrictions on how the constraints of a CSP interact implicitly rely on a property of extensionally represented constraints to guarantee tractability. We identify this property as being a bound on the number of solutions in key parts of the instance, and find classes of global constraints that also possess this property. For such classes, we show that many known tractability results apply. Furthermore, global constraints allow us to treat entire CSP instances as constraints. We combine this observation with the above result, and obtain new tractable classes of CSPs by dividing a CSP into smaller CSPs drawn from known tractable classes.
Second, for CSPs that simply do not possess the above property, we look at how the constraints of an instance overlap, and how assignments to the overlapping parts extend to the rest of the problem. We show that assignments that extend in the same way can be identified. Combined with a new structural restriction, this observation leads to a second set of tractable classes.
We conclude with a summary, as well as some observations about potential for future work in this area.
On the specification and analysis of secure transport layers
Keywords: secret
confidential
channel
security
authenticated
authentication
computer security
secrecy
confidentiality
secure transport layer

The world is becoming strongly dependent on computers, and on distributed communication between computers. As a result of this, communication security is important, sometimes critically so, to many day-to-day activities. Finding strategies for discovering attacks against security protocols and for proving security protocols correct is an important area of research. An increasingly popular technique that is used to simplify the design of security protocols is to rely on a secure transport layer to protect messages on the network, and to provide protection against attackers. In order to make the right decision about which secure transport layer protocols to use, and to compare and contrast different secure transport protocols, it is important that we have a good understanding of the properties that they can provide. To do this, we require a means to specify these properties precisely. The aim of this thesis is to improve our understanding of the security guarantees that can be provided by secure transport protocols. We define a framework in which one can capture security properties. We describe a simulation relation over specifications based on the events performed by honest agents. This simulation relation allows us to compare channels; it also allows us to specify the same property in different ways, and to conclude that the specifications are equivalent. We describe a hierarchy of confidentiality, authentication, session and stream properties. We present example protocols that we believe satisfy these specifications, and we describe which properties we believe that the various modes of TLS satisfy. We investigate the effects of chaining our channel properties through a trusted third party, and we prove an invariance theorem for the secure channel properties. We describe how one can build abstract CSP models of the secure transport protocol properties. We use these models to analyse two single sign-on protocols for the internet that rely on SSL and TLS connections to function securely. We present a new methodology for designing security protocols which is based on our secure channel properties. This new approach to protocol design simplifies the design process and results in a simpler protocol.
Mathematical and computational modelling of tissue engineered bone in a hydrostatic bioreactor
Keywords: numerical simulation
hydrostatic pressure
bone
mathematical modelling
tissue engineering
multiphase model

In vitro tissue engineering is a method for developing living and functional tissues external to the body, often within a device called a bioreactor to control the chemical and mechanical environment. However, the quality of bone tissue engineered products is currently inadequate for clinical use as the implant cannot bear weight. In an effort to improve the quality of the construct, hydrostatic pressure, the pressure in a fluid at equilibrium that is required to balance the force exerted by the weight of the fluid above, has been investigated as a mechanical stimulus for promoting extracellular matrix deposition and mineralisation within bone tissue. Thus far, little research has been performed into understanding the response of bone tissue cells to mechanical stimulation.
In this thesis we investigate an in vitro bone tissue engineering experimental setup, whereby human mesenchymal stem cells are seeded within a collagen gel and cultured in a hydrostatic pressure bioreactor. In collaboration with experimentalists a suite of mathematical models of increasing complexity is developed and appropriate numerical methods are used to simulate these models. Each of the models investigates different aspects of the experimental setup, from focusing on global quantities of interest through to investigating their detailed local spatial distribution. The aim of this work is to increase understanding of the underlying physical processes which drive the growth and development of the construct, and identify which factors contribute to the highly heterogeneous spatial distribution of the mineralised extracellular matrix seen experimentally.
The first model considered is a purely temporal model, where the evolution of cells, solid substrate, which accounts for the initial collagen scaffold and deposited extracellular matrix along with attendant mineralisation, and fluid in response to the applied pressure are examined. We demonstrate that including the history of the mechanical loading of cells is important in determining the quantity of deposited substrate. The second and third models extend this non-spatial model, and examine biochemically and biomechanically-induced spatial patterning separately. The first of these spatial models demonstrates that nutrient diffusion along with nutrient-dependent mass transfer terms qualitatively reproduces the heterogeneous spatial effects seen experimentally. The second multiphase model is used to investigate whether the magnitude of the shear stresses generated by fluid flow, can qualitatively explain the heterogeneous mineralisation seen in the experiments. Numerical simulations reveal that the spatial distribution of the fluid shear stress magnitude is highly heterogeneous, which could be related to the spatial heterogeneity in the mineralisation seen experimentally.
Income splitting, settlements and avoidance: taxing the family on business profits
Keywords: family taxation
husband and wife
income splitting
settlements

In a progressive income tax system with an individual tax unit, high-rate taxpayers have an incentive to split income with lower-rate family members to minimise the family’s total tax burden. This raises equity and neutrality concerns. Adopting a spousal tax unit limits the gains from income splitting, but the individual is the better choice on privacy, autonomy, equality, definitional, marriage neutrality and work incentive grounds. Once the individual is chosen as the income tax unit, the control model provides a strong policy basis for attributing both earned and unearned income to individuals. Income splitting, however, undermines this model as well as the individual tax unit.
This thesis focuses on the UK’s approach to income-splitting in family businesses. The relevant UK income tax rules, particularly the settlements provisions, are inadequate for the task. Various possible reforms are examined. Incorporating a transfer pricing or ‘reasonableness’ test into the settlements provisions would strengthen these rules, but would make taxpayer compliance with an uncertain regime even more difficult. Another option is to expand the scope of employment tax by moving the borderline between employees and the self-employed or companies. Deeper structural reforms could be made to enhance the neutrality of taxation on different legal forms of economic activity. This would reduce the incentives to incorporate for tax savings, including from income splitting. Integration of income tax and NICs is one such option; a dual income tax is another. A TAAR or GAAR also could be pursued. Ultimately, some combination of these various reform options could provide a partial solution to this challenging issue.
Trapping ultracold atoms in time-averaged adiabatic potentials
Keywords: TAAP
adiabatic potential
BEC

This thesis describes the trapping and manipulation of ultracold atoms in time-averaged adiabatic potentials (TAAP). The time-averaged adiabatic potential, proposed in [Phys. Rev. Lett. 99, 083001 (2007)], uses resonant radio frequency (rf) radiation to couple the different magnetic substates of a hyperfine level manifold. The resultant dressed states are time-averaged and produce smooth and versatile trapping geometries. More specifically, we apply rf-radiation (MHz) to a quadrupole magnetic field, which results in an ellipsoidal trapping potential for rubidium-87 atoms in the F=1 manifold. This geometry is time-averaged with the help of oscillating (kHz) Helmholtz fields.
We develop a convenient loading scheme for the TAAP which uses a standard TOP trap and suffers negligible atom losses and heating. Subsequently we characterize the TAAP trap itself and observe low heating rates and sufficient lifetimes (>3s). Furthermore it is possible to use a second, weaker rf-field to evaporatively cool the atoms to quantum degeneracy [Phys. Rev. A. 81, 031402 (2010)]. This opens up a route for further experiments in this potential: we show how atoms can be trapped in a double well potential and a ring trap geometry. Additionally a process to instigate rotation in these potentials by rotating the polarization of the rf-radiation is developed and implemented. This allows us to impart angular momentum onto the atomic cloud and spin it into a ring.
"All Conflict is Local"
Keywords: violence
civil conflict
civil war

Previous civil war analyses have approached conflict as a single category with limited exceptions, and this thesis project assesses whether differentiating conflicts by their type and intensity using a local-level geo-referenced analytical approach produces differing results for sub-groups of conflicts. The conflicts are divided into 1) governmental hostilities, where the aim of the armed non-state group is to capture the state, and 2) territorial hostilities, where the aim of the armed non-state group is to capture increased autonomy or secession for a territorial claim. The conflicts are also differentiated by intensity into 1) low-intensity conflicts, with fewer than 1000 battle-related deaths per year, and 2) civil wars, with 1000 or more battle-related deaths per year. The results demonstrate that conflicts with differing insurgent goals and intensities of battle are correlated with markedly different factors. There are three factors – local population density, change in local rainfall, and statewide GDP growth – that are significant to both governmental and territorial hostilities but have opposite signs for the two sets. Only one variable – Polity IV scores – showed a consistently significant correlation for governmental and territorial hostilities. There are no factors that are significant to both low-intensity conflict and higher-intensity civil war. These findings suggest that approaching all conflicts as a single class, particularly at the local level, may not reveal significant differences in factors correlated with conflict. Modeling of local conflict will require differentiation of conflicts into salient sub-groups. For policymakers and practitioners, this research suggests that there is not a one-size-fits-all approach for conflict prevention but that strategies need to be targeted to specific types of conflict.
Designing a 3.8-GeV/c muon-decay ring and experiment sensitive to electronvolt-scale sterile neutrinos
Keywords: neutrino factory
sterile neutrino
nuSTORM

The liquid-scintillator neutrino-detector (LSND) and mini booster neutrino experiment (MiniBooNE) experiments claim to observe the oscillation ῡµ→ ῡe, which can only be explained by additional neutrinos and is a claim that must be further tested. This thesis proposes a new accelerator and experiment called νSTORM to refute or confirm the oscillation these claims by studying the CPT-equivalent channel νe→νµ. A 3.8-GeV/c muon decay ring is proposed with neutrino detectors placed 20 m and 2000 m from the decay ring. The detector technology would be a magnetized iron sampling calorimeter, where the magnetic field is induced by a superconducting transmission line. In a frequentist study, the sensitivity of this experiment after 5 years would be >10σ. The range of the thesis discussion starts with the proton front-end design and ends with neutrino parameter estimation. After describing the phenomenology of sterile neutrinos, the facility and detector performance work is presented. Finally, the systematics are explained before the sensitivity and parameter-estimation works are explained.
Complaint in Scotland c. 1424 - c. 1500
Keywords: Complaint
Lament
Chaucer
Book History
Medieval Literature
Older Scots Literature

This thesis provides the first account of complaint in Older Scots literature. It argues for the coherent development of a distinctively Scottish complaining voice across the fifteenth century, characterised by an interest in the relationship between amatory and ethical concerns, between stasis and narrative movement, and between male and female voices.
Chapter 1 examines the literary contexts of Older Scots complaint, and identifies three paradigmatic texts for the Scottish complaint tradition: Ovid’s Heroides; Boethius’s De Consolatione Philosophiae; and Alan of Lille’s De Planctu Naturae.
Chapter 2 concentrates on the complaints in Oxford, Bodleian Library MS Arch. Selden. B. 24 (c. 1489-c. 1513). It considers afresh the Scottish reception of Lydgate’s Complaint of the Black Knight and Chaucer’s Anelida and Arcite, and also offers original readings of three Scottish complaints preserved uniquely in this manuscript: the Lay of Sorrow, the Lufaris Complaynt, and the Quare of Jelusy.
Chapter 3 focuses on the relationship between complaint and narrative, arguing that the complaints included in the Buik of Alexander (c. 1438), Lancelot of the Laik (c. 1460), Hary’s Wallace (c. 1476-8), and The Buik of King Alexander the Conquerour (c. 1460-99) act as catalysts for narrative movement and subvert the complaint’s traditional identity as a static form.
Chapter 4 is a study of complaint in Robert Henryson’s three major works: the Morall Fabillis (c. 1480s); the Testament of Cresseid (c. 1480-92); and Orpheus and Eurydice (c. 1490-2), and argues that Henryson consistently connects the complaint form with the concept of self-knowledge as part of wider discourses on effective governance.
Chapter 5 presents the evidence that a text’s identity as a complaint influenced its presentation in both manuscript and print witnesses. The witnesses under discussion date predominantly from the sixteenth century; the chapter thus also uses them to explore the complaints’ later reception history.
Design and synthesis of small molecule chemical probes for bromodomain-containing proteins.
Keywords: organic chemistry
medicinal chemistry
structure-based drug design
epigenetics
bromodomains

Bromodomains (BRDs) are protein modules which bind to acetylated lysines on histones and transcriptional regulating proteins. BRD-containing proteins are involved in a large variety of critical cellular processes and their misregulation, or mutation of the genes encoding for them, has been linked to pathogenesis in humans. The generation of chemical probes (potent, selective and cell permeable small molecules) in cellular experiments to investigate the biological role of the BRDs is thus desirable.
A chemical probe for the CREB (cyclic-AMP response element binding protein) binding-protein (CBP) and E1A binding protein (p300) BRDs was developed, starting from a low molecular weight, weak and non-selective dimethylisoxazole benzimidazole compound. Parallel synthesis was used to optimise the initial hit into a weak, but selective CBP inhibitor. Further modification of the two N-1 and C-2 moieties of the benzimidazole scaffold, led to highly potent and selective CBP inhibitors. Structure-guided design was then applied to optimise the selectivity of the series for CBP over the first domain of bromodomain-containing protein 4 BRD4(1). A strategy to reduce the flexibility of the N-1 and C-2 ethylene linker groups through the incorporation of conformational constraints led to inhibitors with increased selectivity. The optimal compound was highly potent for the CBP and p300 BRDs (Kd 21 nM and 32 nM, respectively) and selective over BRD4(1) (40-fold and 27-fold, respectively). On-target cellular activity was observed in a fluorescence recovery after photobleaching (FRAP) assay (0.1 μM), a p53 reporter gene assay (IC50 1.5 μM) and a Förster resonance energy transfer (FRET) assay (5 μM).
A weak indolizine bromodomain-containing protein 9 (BRD9) inhibitor was used as the starting point for the development of a BRD9/BRD7 chemical probe. Analogues were synthesised via [3+2] cycloadditions. An optimised compound was found to be highly potent (68 nM) and selective over BRD4(1) (34-fold). On-target cellular activity was observed in a FRAP assay (5 μM). Efforts were made to improve the cellular activity through the introduction of an ionisable centre to aid solubility. A selection of piperazine analogues were shown to be potent and selective, and these compounds warrant further investigation of their selectivity and cellular activity.
Overall, the work has led to the first potent and selective inhibitors of the CBP/p300 and BRD9 BRDs. It also highlights the role of structural analysis in the development of inhibitors that modulate protein-protein interactions.
Further results on Gram's Law
Keywords: Turing's Method
Gram's Law
zeta function
Rosser Rule

This thesis shows that Gram's Law and the Rosser Rule (methods for locating zeroes of the Riemann zeta-function) fail in a positive proportion of cases. A weaker version of Gram's Law is shown to be true in a positive proportion of cases. Also included are theorems on Turing's Method and its extensions to Dirichlet L-functions and Dedekind zeta-functions.