VictorJuiz/thesis huggingface dataset:
Generation of uncorrelated photon-pairs in optical fibres
Keywords: quantum optics
spontaneous four wave mixing
photon
entanglement
photon pair
biphoton

Light, which is composed of discrete quanta, or photons, is one of the most fundamental concepts in physics. Being an elementary entity, the behaviour of photons is governed by the rules of quantum mechanics. The ability to create, manipulate and measure quantum states of light is not only useful in foundational tests of quantum theory, but also in a wide range of quantum technologies – which aim to utilize non-classical properties of quantum systems to perform tasks not possible with classical resources. Only recently has it been possible to control the properties of number states of light, which have a fixed photon-number. Two-photon states are central to testing fundamental physical theories (such as locality and reality) and the implementation of quantum information technologies. The versatility of photon-pair states is en- abled by the potential entanglement properties it can posses. Thus controlling the correlations between photons is crucial to both pure and applied physics. To produce a single photon, a photon-pair state can be used. Detection of one photon indicates its twin’s existence. Many applications, such as optical quantum computation, require pure indistinguishable single photons. Heralding single pho- tons from a photon-pair will, in general, produce single photons in a mixed quantum state due to correlations within the pair. A common approach to creating photon-pairs is through the nonlinear sponta- neous four-wave mixing interaction in optical fibres. This thesis presents a theoreti- cal and experimental implementation of a scheme to tailor the spectral correlations within the pairs. Emphasis is placed on engineering the two-photon state such that they are completely uncorrelated. Spatial entanglement is naturally avoided due to the discrete nature of the optical fibre modes. Spectral correlations are eliminated by careful choice of dispersion characteristics and conditions. The purity of the photons generated by this scheme is demonstrated by means of two-photon inter- ference from independent sources. We measure a purity of (85.9 ± 1.6)% with no spectral filtering, exhibiting the usefulness of this source for quantum technologies and applications.
Optical spectroscopy of wide bandgap semiconductor nanoscale structures
Keywords: nanocolumn
GaN

The optical properties of GaN nanocolumn structures containing InGaN quantum disks are investigated by optical microphotoluminescence spectroscopy using pulsed lasers, and cathodo- luminescence. The results are analyzed in the context of current theories regarding an inho- mogeneous strain distribution in the disk which has been theorized to generate lateral charge separation in the disks by strain induced band bending, an inhomogeneous polarization field distribution, and Fermi surface pinning. Simulations of the strain distribution for the relevant materials and structures are also performed, and the results analysed. It is concluded from ex- perimental measurements that no extreme lateral separation of carriers occurs in the quantum disks under investigation. Internal field screening by an increased carrier density in the QDisks at higher excitation densities is observed via a blue-shift of the emission and a dynamically changing decay time. Other possible explanations for these effects are discussed and discounted.
Microphotoluminescence studies are also carried out on a single GaN nanocolumn struc- ture that has been removed from its growth substrate and dispersed onto a patterned grid. An analysis of the dynamics of the carriers in the nanocolumn is presented. Suppression of the GaN luminescence from the area of the column in the vicinity of the InGaN QDisk in addition to a delayed emission from the QDisk relative to the GaN is observed. Time resolved spatial maps of the luminescence intensity from the column are also presented, illustrating the evolution of the carrier density in the system.
Additional, albeit early-stage, work on novel structures based on the production of GaN nanocolumns, namely nanotubes and nanopyramids, is also presented.
Computational neuroscience of natural scene processing in the ventral visual pathway
Keywords: ventral visual system
VisNet
invariance
object recognition

Neural responses in the primate ventral visual system become more complex in the later stages of the pathway. For example, not only do neurons in IT cortex respond to complete objects, they also learn to respond invariantly with respect to the viewing angle of an object and also with respect to the location of an object. These types of neural responses have helped guide past research with VisNet, a computational model of the primate ventral visual pathway that self-organises during learning. In particular, previous research has focussed on presenting to the model one object at a time during training, and has placed emphasis on the transform invariant response properties of the output neurons of the model that consequently develop. This doctoral thesis extends previous VisNet research and investigates the performance of the model with a range of more challenging and ecologically valid training paradigms. For example, when multiple objects are presented to the network during training, or when objects partially occlude one another during training. The different mechanisms that help output neurons to develop object selective, transform invariant responses during learning are proposed and explored. Such mechanisms include the statistical decoupling of objects through multiple object pairings, and the separation of object representations by independent motion. Consideration is also given to the heterogeneous response properties of neurons that develop during learning. For example, although IT neurons demonstrate a number of differing invariances, they also convey spatial information and view specific information about the objects presented on the retina. A updated, scaled-up version of the VisNet model, with a significantly larger retina, is introduced in order to explore these heterogeneous neural response properties.
Higher-order queries and applications
Keywords: function
database
lambda calculus
higher-order
XML

Higher-order transformations are ubiquitous within data management. In relational databases, higher-order queries appear in numerous aspects including query rewriting and query specification. In XML databases, higher-order functions are natural due to the close connection of XML query languages with functional programming.
The thesis investigates higher-order query languages that combine higher- order transformations with ordinary database query languages. We de- fine higher-order query languages based on Relational Algebra, Monad Algebra, and XQuery. The thesis also studies basic problems for these query languages including evaluation, containment, and type inference. We show that even though evaluating these higher-order query languages is non-elementary, there are subclasses that are polynomially reducible to evaluation for ordinary query languages.
Our theoretical analysis is complemented by an implementation of the languages, our Higher-Order Mapping Evaluation System (HOMES). The system integrates querying and query transformation in a single higher- order query language. It allows users to write queries that integrate and combine query transformations. The system is implemented on top of traditional database management systems. The evaluation algorithm is optimized by a combination of subquery caching techniques from relational and XML databases and sharing detection schemes from functional programming.
Crossmodal correspondences and attention in the context of multisensory (product) packaging design 
Keywords: packaging
crossmodal correspondences

The term 'crossmodal correspondence' refers to the tendency for people to match information across the senses. In this thesis, the associations between taste/flavour (tastants and words) information with shapes and colours is investigated. Furthermore, such correspondences are addressed in the context of multisensory packaging design. The focus in this thesis is on the way in which taste/flavour information can be communicated by means of the visual elements of product packaging. Through a series of experiments, I demonstrate that people associate tastes and the roundness/angularity of shapes, and that taste quality, hedonics, and intensity influence such correspondences. However, packaging roundness/angularity does not seem to drive these associations. Additionally, I demonstrate that culture and context systematically influence colour/flavour associations. Importantly, the results reported in this thesis suggest that taste/shape correspondences can influence taste expectations as a function of the visual attributes of product packaging. The results reported here also reveal that colour can influence the classification of, and search for, flavour information on a product’s packaging. It turns out that the strength of the association between a flavour category and a colour is crucial to such an effect. The implications of these findings are discussed in light of the theories of crossmodal correspondences, its applications, and directions for future research.
Plato and Liberalism
Keywords: Plato
Liberalism
freedom

Plato is generally regarded as notoriously anti-liberal, a reputation which is based mainly upon his most famous political work, the Republic. However, a more comprehensive view of his political thought reveals a much more nuanced picture. In this essay, I offer a comparison between modern liberalism and Plato's political thought, as presented in his three major political dialogues, the Republic, the Statesman, and the Laws, on the topic of freedom, as well as four secondary topics: (1) rule of law (2) legal reform (3) consent of the ruled (4) democracy. I begin with a brief account of modern liberalism and then proceed to evaluate each of the three dialogue on the above five topics. Although Plato's most famous political work, it is here argued that the Republic says surprisingly little on all these topics other than freedom because several of its most prominent proposals, including its famous philosopher-rulers, are not presented for implementation in actual politics. The Statesman, the briefest of the three, is argued to exhort rule of law and legal reform, but say little on the other topics. The most space will be dedicated to the Laws, which will be shown to offer detailed comment on each topic. The city the Laws depicts will be argued to be not one in which a docile citizenry is ruled over by an Inquisitorial Nocturnal Council, but a city ruled by law which cultivates the rational capacities of its citizens, who are thoroughly involved in government. However, this city will also prove to be one in which strong restrictions are placed on the sorts of freedoms that liberalism values. On the four secondary topics, Plato's thought will be argued to be largely in agreement with modern liberalism. However, on freedom it will be argued there is large disagreement, with Plato shown to attach little value to the liberal notion of freedom, though taking freedom very seriously in his own right.
Stereoselective synthesis of disubstituted allylic alcohols by Wittig-Schlosser type reaction
Keywords: olefination
B-lithiooxy ylides
allylic alcohols

The work presented in this thesis describes the development of reactions of β-lithiooxyphosphonium ylides and aldehydes to form disubstituted allylic alcohols in a regio- and stereoselective fashion.
Firstly, β-lithiooxyphosphonium ylides prepared from methylenetriphenyl-phosphorane and aldehydes, were shown to react with a second aldehyde to access allylic alcohols. The regio- and stereoselectivity in the formation of the double bond was shown to be greatly influenced by the nature of both the first and the second aldehyde used, and by the lack of further substitution on the phosphorane used. This one-pot methodology was used in the synthesis of a simple natural product (E)-4-(3,4-dimethoxyphenyl)-but-3-en-2-ol, previously synthesised in four steps.
Secondly, β-lithiooxyphosphonium ylides prepared in situ from α-lithiated terminal epoxides and triphenylphosphine, were shown to react with aldehydes, with retention of the selectivity in the formation of the double bond. To the best of our knowledge, this represents the first examples of the generation of β-oxido phosphonium ylides by the trapping of metalated epoxides with a phosphine.
A sieve problem over the Gaussian integers
Keywords: L-functions
Gaussian integers
Riemann Hypothesis
Sieve Theory
Gaussian primes

Our main result is that there are infinitely many primes of the form a² + b² such that a² + 4b² has at most 5 prime factors.
We prove this by first developing the theory of L
-functions for Gaussian primes by using standard methods. We then give an exposition of the Siegel--Walfisz Theorem for Gaussian primes and a corresponding Prime Number Theorem for Gaussian Arithmetic Progressions.
Finally, we prove the main result by using the developed theory together with Sieve Theory and specifically a weighted linear sieve result to bound the number of prime factors of a² + 4b². For the application of the sieve, we need to derive a specific version of the Bombieri--Vinogradov Theorem for Gaussian primes which, in turn, requires a suitable version of the Large Sieve. We are also able to get the number of prime factors of a² + 4b² as low as 3 if we assume the Generalised Riemann Hypothesis.
“That which was missing”: the archaeology of castration
Keywords: anthropometry
palaeopathology
bioarchaeology
social theory
castration
gender

Castration has a long temporal and geographical span. Its origins are unclear, but likely lie in the Ancient Near East around the time of the Secondary Products Revolution and the increase in social complexity of proto-urban societies. Due to the unique social and gender roles created by castrates’ ambiguous sexual state, human castrates were used heavily in strongly hierarchical social structures such as imperial and religious institutions, and were often close to the ruler of an imperial society. This privileged position, though often occupied by slaves, gave castrates enormous power to affect governmental decisions. This often aroused the jealousy and hatred of intact elite males, who were not afforded as open access to the ruler and virulently condemned castrates in historical documents. These attitudes were passed down to the scholars and doctors who began to study castration in the late 19th and early 20th centuries, affecting the manner in which castration was studied. Osteometric and anthropometric examinations of castrates were carried out during this period, but the two World Wars and a shift in focus meant that castrate bodies were not studied for nearly eighty years. Recent interest in gender and sexuality in the past has revived interest in castration as a topic, but few studies of castrate remains have occurred. As large numbers of castrates are referenced in historical documents, the lack of castrate skeletons may be due to a lack of recognition of the physical effects of castration on the skeleton.
The synthesis and generation of methods for more accurate identification of castrate skeletons was undertaken and the results are presented here to improve the ability to identify castrate skeletons within the archaeological record.
Playing politics
Keywords: collective action
labour movements
trade union
Indonesia

Since the collapse of the New Order regime in 1998, democratisation and economic liberalisation have combined to create both opportunities and constraints for the revival of organised labour in Indonesia. The picture of post-authoritarian labour movements painted by various scholars is almost universally bleak, portraying helpless trade unions in the face of economic impasse and the undemocratic remnants of the old forces. Being overtly cautious of the new democracy, this line of analysis has not done justice to Indonesian labour movements. It overestimates the ghost of the old dictatorship and underestimates the power of budding organised labour.
Using trade union as the unit of analysis, this dissertation seeks to offer a different view of Indonesian labour movements. It looks at shifting political opportunities in the regions and the agency of trade unions which constitute a political force that is far from being consolidated but has certainly made a significant contribution to the broadening of democratic politics. In negotiating pressures that originate from an increasingly liberalised economy, trade unions have adopted a strategy which is called „playing politics‟ in this dissertation. The term means that in the absence of significant market power, trade unions enter into the realm of power politics primarily by organising labour as social movements and attempt to ally with political elites, exploit the conflicts that emerge within state institutions and between the state and business, and try to join the ruling classes.
In developing this argument, this dissertation makes two contributions to the study of labour politics in Indonesia: its reassessment of the historiography of the first ten years of post-authoritarianism and its offer of insights into possible future directions of labour politics.
Britain and the end of Empire: a study of colonial governance in Cyprus, Kenya and Nyasaland against the backdrop of the internationalisation of empire and the evolution of a supranational human rights culture and jurisprudence, 1938-1965
Keywords: human rights
Cyprus
Kenya
empire
Nyasaland

This thesis traces British colonial governance and the workings of the late colonial state from 1938 until the end of empire in the early 1960s in Cyprus, Kenya and Nyasaland. It proposes that colonial governance operated in place and time back and forth across a spectrum, typified by polarities of (i) 'soft' management and regulation of colonial populations in the 1940s, and (ii) 'hard' control exemplified by the use of harsh physical coercion in the 1950s, although both 'soft' and 'hard' approaches - and hybrid variants somewhere in between - were always, in truth, sides of the same coin.
British colonial governance is examined through the filter of three approximate, although not rigidly linear, 'phases': (1) a 'soft' phase of development and welfare from 1938-45, during which the rhetoric of governance was distinguished by the language of benevolence, in the attempt to re-legitimise empire, (2) the post-war period from 1945-1950, when Britain played a leading role in establishing supranational institutions promoting universal human rights and also, and however reluctantly, extended a modified human rights regime to its colonies, and (3) the swing to 'hard' governance during emergency periods in Cyprus (1955-59), Kenya (1952-60) and Nyasaland (1959-60), during which Britain strove to resolve the dichotomy between competing domestic and international demands of (a) maintenance of empire, often through the use of coercive physical measures, and (b) promotion of universal human rights on the world stage. This was all played out, at least in part, as an albeit muted ideological confrontation between opposing post-war visions of global order - the very survival of the old imperial system pitched against the implicitly decolonising thrust of the universal human rights movement as enshrined in the Universal Declaration of Human Rights (1948) and the European Convention on Human Rights (1950). This thesis argues that by 1959 and in part as a consequence of the cumulative political impact of allegations of human rights and other abuses during emergency periods, Britain could no longer reconcile these competing visions of colonial governance and world order, nor sustain its empire and colonial rule by force.
Aspects of modelling solid tumours
Keywords: Cancer
tumours
chemotherapy
angiogenesis

This thesis considers aspects of modelling solid tumours. We begin by considering the common assumption that nutrient or drug concentrations in avascular tumour spheroids are radially symmetric. We derive a simple Poisson equation for biomolecular diffusion into an avascular tumour, but with highly oscillatory boundary conditions due to the surrounding capillary network. We find that the assumption of radial symmetry is legitimate for biomolecules that are taken up in sufficient quantities by proliferating cancer cells; however radially symmetric profiles need not be observed otherwise.
We then investigate how the gap between an avascular tumour and the neighbouring vasculature varies as the tumour grows. This is explored by (i) using scaling arguments based on ordinary differential equations, (ii) coupling the rate of oxygen flux from the vasculature to oxygen evolution within the tumour, and (iii) deriving a system of six coupled non-linear partial differential equations modelling the tumour evolution. It is found that as the tumour grows any initial gap between the tumour and neighbouring vasculature closes since there is no mechanism which would sufficiently up-regulate non-cancerous cell proliferation. This is in contrast to the intra-cornea implantation observations, upon which several mathematical models are based.
Finally, we study the growth and treatment of a vascular tumour subjected to chemotherapies, particularly when the therapies can exhibit an anti-angiogenic effect and resistance to the therapy is incorporated. A multi-compartment model is derived for the evolution of a tumour undergoing treatment and parameters are estimated, with extensions to incorporate numerous different therapy protocols in the literature. We find that anti-angiogens can be effective, though the appropriate scheduling is counter-intuative and contradicts many standard therapy rules. We conclude that chemotherapy protocol design is very sensitive to the mode of action of the drug and simple general strategies will, in many cases, not be the most effective.