VictorJuiz/thesis huggingface dataset:
The Oseen-Frank theory of liquid crystals
Keywords: Line field models
Liquid Crystal
Oseen-Frank
Homotopy Classes

This thesis concerns the minimization of the Oseen-Frank bulk free energy. The structure is as following: in Chapter 1, we will give a brief introduction to the Oseen-Frank theory and the Landau-de Gennes theory. Also we will introduce some established results related to the two theories. In Chapter 2, we define first in Section 2.1 the degree for a vector field n ∈ H1/2(𝕊1; 𝕊1); and then in Section 2.2 the degree for an H1/2 vector field from a Lipschitz boundary ∂w to 𝕊1: In Section 2.3, we prove the fact that vector fields subject to some given boundary conditions and degree constraints in a given exterior N-connected domain can be written explicitly, and the result is stated in Proposition 2.3.6. We began in Chapter 3 by focusing on the existence and uniqueness of minimizers for a modified one-constant Oseen-Frank energy subject to some prescribed boundary conditions in a 2D circular domain Ω = {x ∈ &Ropf;2 | 0 < a < |x| < ∞} and derive some ‘nice’ asymptotic behaviour at ∞ of the minimizer. In Chapter 4, we make the problem studied in Chapter 3 more complicated by adding more ‘holes’ in the domain. Then by introducing the homotopy classes for vector fields subject to prescribed boundary conditions, we prove that there exists a unique minimizer for a modified oneconstant Oseen-Frank energy in each homotopy class and we still have the ‘nice’ asymptotic behaviour of the minimizer in each homotopy class. Also, there exists a minimizer in the union of these homotopy classes, although this minimizer may not be unique. Then in Chapter 5, we work with line fields on the boundary in the given exterior N-connected Lipschitz domain. By introducing an auxiliary vector field and modifying the definition of homotopy classes in Chapter 4, we prove the uniqueness of the minimizing line field in each homotopy class. Also the result proved in Chapter 5 applies to both orientable and non-orientable line fields on the boundaries, and when the given boundary line field is orientable, it is equivalent to our result proved in Chapter 4. Finally, in Chapter 6, we study the 2D non-equal constant case (i.e. without assuming k1 = k2 = k3, and k4 = 0) in a one-circular domain. In particular, in Section 6.1 we assume the vector fields are radius-independent and derive the minimizers to the Oseen-Frank bulk free energy subject to prescribed degree constraint on the circular boundary. Then in Section 6.2 we show that the result proved in Section 6.1 will also hold when one of the Frank elastic constant is zero (degenerate case), but will be in a different function space W1,1(Ω;𝕊1). At last in Section 6.3 we will show that the minimizers derived in Section 6.1 and Section 6.2 are in general not minimizers for the radius-dependent case.
Systematic studies of the sweet potato and its wild relatives
Keywords: sweet potato
systematics
morning glories
crop wild relatives
Ipomoea
phylogenetics
Polynesia

Phylogenetic studies on the genus Ipomoea, and specifically on the species closely related to the sweet potato, have been hindered by limited taxon and character sampling. Any study that aims to investigate the phylogenetic relationships within a megadiverse genus such as Ipomoea, with an estimated 800 species, must rely on a comprehensive data set that covers as much diversity as possible, in order to provide accurate and robust phylogenetic inference.
In this thesis, I present a comprehensive phylogenetic study of the genus Ipomoea and of the group of species closely related to the sweet potato using genomic-scale data. The aim of this study was to provide a phylogenetic framework with which to understand the diversity existing within the genus and to inform taxonomic decisions. The phylogenies presented here identify several recurrent patterns in the evolution of Ipomoea, for instance the multiple origin of storage roots and the existence of multiple episodes of long-distance dispersal by natural means.
I also address several questions pertaining to the sweet potato that have been a matter of debate for decades but remained unanswered until recently. Our genome-scale data facilitated comprehensive phylogenies for all wild species that are most closely related to the sweet potato. Our phylogenies resolve that sweet potato is monophyletic and had a single origin, as well as identified the wild species that is its closest relative: Ipomoea trifida, with all other extant species more distantly related. In addition, our studies corroborate the existence of two sweet potato chloroplast lineages and infer that one of them resulted from a hybridisation between sweet potato and I. trifida following species divergence.
Finally, I also address a question that has been of interest for over two centuries: the presence of the sweet potato, an American crop, in Polynesia in pre-European times.
The construction and validation of the primary scientific reasoning test
Keywords: Scientific Reasoning
Test of Scientific Reasoning
Primary School Science
Scientific Thinking
Construct Validation

A major task of science education is to foster scientific reasoning. Despite extensive research, it is still unclear how best to assess this cognitive proficiency; a limited consensus of its nature has arguably constrained the development of classroom assessments of scientific reasoning. Therefore, this research aimed to develop a valid and reliable test of scientific reasoning – the Primary Scientific Reasoning Test (PSRT) – for primary-aged pupils. Developments in science education, as well as emerging and novel insights across substantive literature, formed the theoretical framework underlying the PSRT.
A mixed methodology was used to develop and validate the PSRT over four phases. The first phase developed the theoretical framework and the draft items. In the next phase, an 18-member expert panel from Singapore and England evaluated and endorsed the conceptual validity of the construct and the content validity of the draft items. The third phase field-tested and refined the draft instrument with 138 Year 7 pupils from four Singapore secondary schools. In the fourth and last phase, 431 Year 6 pupils from six Singapore primary schools attempted the finalised 100-item PSRT. Results from psychometric analysis using Rasch modelling supported inferences of a unidimensional construct underlying the test, and examination of the item difficulty estimates produced evidence that the order of difficulties generally accorded with the framework of scientific reasoning.
Given that the explanatory concepts in the framework generally explained the pupils’ performance and drawing on the strength and scope of other evidence, the thesis concludes that the PSRT displayed reasonably strong construct validity. This conclusion supports the use of PSRT as a valid and reliable measure of scientific reasoning for primary-aged pupils. The theoretical basis of the PSRT and its construction procedures also bear lessons for test developers and researchers. Overall, the study contributes clarification and understanding about the nature and assessment of scientific reasoning, particularly for primary-aged pupils.
The evolution of Leszek Kołakowski’s religious thought
Keywords: Leszek Kołakowski
Leszek Kolakowski
Religious thought

This thesis examines the entire work of the Polish philosopher Leszek Kołakowski (1927–2009), and argues that religious questions were at the heart of his thought from the very beginning of his intellectual career. Furthermore, it maintains that Kołakowski’s youthful engagement with Communism in Stalinist Poland, along with his later historical inquiries into various strands of modern philosophy were, in fact, phases in his development as a religious philosopher.
The thesis, which relies on a textual analysis of Kołakowski’s published and unpublished works, argues that the investigation of consecutive texts from the late 1940s to the late 1980s shows a gradual ‘evolution’ in Kołakowski’s attitude to religion – developing from a militant Stalinist to a conservative apologist for Christianity. To this effect, the thesis is structured chronologically. The methodology employed is that of ‘qualified contextualism’, which recognises the fundamental importance of historical context in investigating philosophical questions, yet acknowledges that traditional contextualism does not suffice in explaining the ideas from the past.
The entire intellectual trajectory of Kołakowski can be summarised as the quest for the most satisfactory formula for an Absolute being that not only serves as the source of ethical normativity but also endows human lives with a sense of meaningfulness. In his studies of secular philosophical systems, Kołakowski asserts that people cannot establish moral values for themselves and need a transcendent metaphysical reality. Although he was a sympathiser, Kołakowski never officially committed to any institutional form of religion. The apparent Christian synthesis between the concepts of a loving Person and an eternal Absolute seemed irreconcilable for him. It is on these grounds that this thesis concludes the mature Kołakowski can be called a religious thinker, but not a Christian thinker. ‘Kołakowski’s God’ is a being that is closer to the Neoplatonic Absolute, one that overcomes contingency of human life and makes it meaningful.
Sex, signalling, and steroids: regulation of nuclear size and intracellular trafficking in secondary cells in the D. melanogaster male accessory gland
Keywords: nuclear growth
male accessory gland
steroid signalling
BMP signalling
Hedgehog signalling

The fruit fly, Drosophila melanogaster, can be a useful in vivo model for understanding the biology of cells and the signalling pathways by which this biology is regulated. My Dissertation focuses on the accessory glands of male D. melanogaster, where two types of cells—main cells and secondary cells—are responsible for producing many seminal fluid proteins. The work presented in this Dissertation describes some of the aspects of secondary cell biology that are involved in controlling the growth and secretory activity of these cells.
Secondary cells are secretory cells, and they contain large intracellular compartments—some of which accumulate proteins destined for secretion. The BMP ligand, Decapentaplegic (Dpp), is one such protein, which can regulate secondary cell biology via an autocrine signalling mechanism. Previous work has shown that BMP signalling regulates a D. melanogaster steroid receptor—the ecdysone receptor (EcR)—to form a BMP/EcR signalling axis that controls secondary cell nuclear growth.
In this Dissertation, I show that the BMP/EcR signalling axis regulates the expression of the D. melanogaster initiator caspase, DRONC, and that this caspase and other related regulators control intracellular trafficking in secondary cells. I propose that this process might be orchestrated via non-apoptotic mobilisation of the cytoskeleton. In addition, I show that secondary cells produce the lipoprotein, Hedgehog, and that it is released into the seminal fluid. Like Dpp, Hedgehog seems to signal back into secondary cells to regulate their biology and nuclear growth. This growth is reduced when hedgehog (and its downstream signalling components) is knocked-down in secondary cells. Conversely, activating the Hedgehog-dependent transcription factor, Cubitus interruptus (Ci), promotes this growth. Like BMP signalling, autocrine Hedgehog signalling might play an important role in coordinating growth and secretion in secondary cells.
Previous studies have shown that secondary cell nuclei grow after mating. In an effort to understand how this growth is regulated, I identified the BMP/EcR signalling axis as a key regulator—alongside cell cycle regulators, like Cyclin D and Cyclin E. My work shows that secondary cell nuclei seem to grow after mating, partly as the result of BMP/EcR-dependent increases of the secondary cell DNA content—perhaps to increase the cells’ biosynthetic potential. This suggests that secondary cell nuclei can grow via two distinct mechanisms: one that is mating-dependent, and one that is not. Altogether, the work presented in this Dissertation describes important roles for steroid signalling and sexual activity in the regulation of secondary cell biology. This complex co-ordination of BMP- and steroid signalling might also be relevant to other organisms.
Figlie di Omero. Verso un'epica femminile.
Keywords: epic
Amelia Rosselli
women's writing
italian poetry
experimental poetry
Patrizia Vicinelli
plurilingualism

This thesis aims to establish the literary terms in which it is possible to identify Amelia Rosselli (1930-1996) and Patrizia Vicinelli (1943-1991) as the first female writers of epic poetry in the Italian language. The Parte prima (Premesse e intenzioni) presents a discussion on the secular exclusion of women from the literary canon, and in particular on the implicit separation between epic and lyric, as originally producers of gender anxiety (Gilbert and Gubar) and genre anxiety (Susan Friedman). With an additional focus on the Italian context (the manifesto “Fragili Guerriere”), it explores the socio-literary reasons for many contemporary female poets, writing and performing in Italian language, claim access to epic genre and consider Amelia Rosselli and Patrizia Vicinelli as magistrae in the deconstruction of the male epic tradition and reconstitution of the genre. They consciously and deliberately force the genre, as a literary and political act, in order for it to serve their perspectives as women. The Parte Seconda is a close-reading of the authors’ poemetti: La Libellula (1969) and Impromptu (1981) by Rosselli, Non sempre ricordano (1985) and I fondamenti dell’essere (1994) by Vicinelli. Despite the apparent distance between these authors, the intertextual analysis identifies in the renegotiation of the female subject as heroic and the authoriality of women poets the most radical closeness between their poetics. Through the gender and genre critical lens constructed in the Parte Prima and its application for a close reading of primary sources in the Parte Seconda, this thesis argues that Rosselli and Vicinelli produce foundational texts in which women’s subjects auto-genesis is explored and established through a distinctively epic voice.
Brazilian concretism in Chilean neo-avant-garde poetry
Keywords: Neo-Avant-Garde
Materiality of language
Juan Luis Martínez
Cecilia Vicuña
Readerly participation
Committed art
Poetry under dictatorship
Rodrigo Lira

This thesis illuminates poetic works by three Chilean experimental poets, Cecilia Vicuña (1947-), Juan Luis Martínez (1942-1993) and Rodrigo Lira (1949-1981) by showing how they develop and expand upon Brazilian concrete poetics (1950sonward). Brazilian concrete poetry, characteristically a-syntactic, and focusing on the word and poem as object, creatively and often playfully performs a critique of the ways in which we interact with language and literature. I argue that the Chilean recovery of the experimentations of concrete poetry transfers the critique of language from an international sphere to the severe political reality of Chilean politics, particularly during or in relation to the dictatorship of Augusto Pinochet.
In the introduction, I situate the three Chilean poets and the Brazilian concretists within the categories of ‘neo-avant-garde’, ‘anthropophagic’ and ‘visual’ poetry. In the first chapter, I demonstrate how Martínez, like the concrete poets, uses the page rather than the line as the unit of poetry in order to question the relationship between the signifier and signified, the author and the text, and society and the text, ultimately expressing a political critique of Chile. In my second chapter, I argue that, in keeping with the object poems produced by concrete poets, Vicuña’s ‘plastic’ poetry (that is, one that can be continuously mouldable for the reader) invites the reader to participate with her in the creation of more equitable social formations. In the final chapter, I show that, following the line of antipoetics, Lira, challenging his literary lineage, uses the technique of détournement to create particularly Chilean versions of concrete poetry’s conceptualisation of object-poems. In this project, I hope to make visible the work of relatively unknown writers of enormous talent and to contribute significantly to the literary history of the Latin American avant-garde.
The moral significance of empathy
Keywords: Empathy

In this thesis, I argue that empathy is morally significant because it plays an important role in informing our moral deliberations. Empathy should be thought of not as an alternative to rational deliberation about how we are to act, but rather as an important input into such deliberation.
I focus on exploring what we learn when we empathize with the suffering of another person. Standard epistemic defences of empathy say only that such empathy will give us knowledge of which affective states the suffering person is feeling. I add to those defences by arguing that empathy with a suffering person also gives us additional types of knowledge about the affective states that this person is feeling. Most significantly, I argue that empathizing with a suffering person gives us knowledge of the strength of one of our reasons to help that person. I call this the Normative Epistemic Claim.
In chapter 1, I contextualize my approach within the recent philosophical discussion of empathy. In the following chapter, I explore the relationship between empathy and altruism, and argue that there is an unanswered question about how empathy gives rise to altruistic motivation. I suggest that we should answer this question by considering the idea that empathy gives us phenomenal knowledge about the affective states of other people. I defend this idea in chapter 3, where I also relate it to the debate about phenomenal knowledge that has been stimulated by Frank Jackson’s example of Mary, the scientist who comes to see colour for the first time. In chapter 4, I begin to show the importance of phenomenal knowledge to moral deliberation. I argue that by giving us such knowledge, empathy with a suffering person also gives us knowledge of how intrinsically bad that person’s suffering is for them. In chapter 5, I extend this approach to defend the Normative Epistemic Claim. Finally, in chapter 6, I summarize the role of empathy in moral deliberation and broaden my discussion to include consideration of the significance that empathy has in inhibiting harming and in directing us to promote the joy of other people.
Hybrid circuit QED with spin ensembles and carbon-nanotube-based superconducting qubits
Keywords: Quantum Information Processing
Superconducting Qubits
Quantum Transport
Spin Ensembles
Carbon Nanotubes

Circuit quantum electrodynamics has received an increasing amount of attention over the last decade in light of its potential use in quantum information processing. The underlying principle of this architecture is the coherent coupling between microwave photons stored in superconducting resonators and superconducting qubits made from non-linear, non-dissipative electrical circuits. This architecture can be extended to other solid-state systems with transition frequencies in the microwave regime, such as nuclear and electron spins or Andreev bound states. These hybrid devices would allow the coherent exchange of information between such systems and superconducting qubits mediated by a microwave resonator. This could lead to advances in quantum information processing and new insights in the physics governing these interacting systems.
In this dissertation experimental work with different types of hybrid quantum circuits is presented. A first experiment investigates the coherent coupling of microwave photons with a spin ensemble in a correlated and uncorrelated state. The coupling strength and magnetic resonance is studied as a function of temperature and magnetic field direction. A pronounced temperature dependent anisotropy of the magnetic resonance is observed, which can be attributed to the onset of antiferromagnetic correlations in the spin ensemble when cooled below T=4 K. A simple one-dimensional model gives a good description of this anisotropy.
A next experiment studies the transport characteristics of carbon nanotubes electrically accessed with normal and superconducting contacts. These devices were characterised using both DC and RF reflectometry techniques. The carbon nanotube devices with superconducting contacts exhibit transport characteristics of Josephson junctions with critical currents of up to Ic~18 nA, as well as multiple Andreev reflections. These semiconductor-superconductor hybrid Josephson junctions are then used to realise a carbon-nanotube-based superconducting qubit with voltage tunable transition frequency using a local electrostatic gate. Strong coupling (g~100 MHz) to a coplanar waveguide resonator is demonstrated via a resonator frequency shift dependent on applied gate voltage. Qubit parameters are extracted from spectroscopy and correspond well to the DC measurements of the carbon nanotube Josephson junctions. Qubit relaxation and coherence times in the range 10-100 ns are observed.
The hybrid devices investigated in this work present potential building blocks for more extensive hybrid architectures for quantum information processing.
Photoswitchable dyes for super-resolution microscopy
Keywords: Fluorescent dyes
Photochromism
Super-resolution microscopy
Bioimaging

This thesis describes the synthesis and characterisation of photoswitchable synthetic dyes for application in super-resolution microscopy of biological systems.
Chapter 1 introduces the field of super-resolution microscopy. A variety of techniques are described, with a particular focus on the reversible saturable optical fluorescence transitions (RESOLFT) approach. For RESOLFT application, a dyad molecular design is proposed, which comprises a reversible photoswitch and an emissive dye. Major classes of these components are presented, followed by a discussion of the criteria required for RESOLFT dyes.
Chapter 2 reports preparation of spiropyran photoswitches and a derived dyad. Properties of the switches are characterised, including photoconversion and resistance to photodegradation. The dyad system is also examined by live cell confocal imaging.
Chapter 3 focuses on switches from the spirooxazine family that is closely related to the spiropyran family. Synthesis and crystal structure are described, and detailed examination of the photoswitching behaviour by spectroscopic measurements is then presented. Subsequent switching kinetic investigations using ultrafast spectroscopies are reported.
Chapter 4 continues to describe a series of spirooxazine-based dyads. Their switching behaviour is assessed in live cells, and the applicability in RESOLFT microscopy is also tested. The photophysical properties of these dyads are comprehensively characterised and compared, providing insights into the molecular design for future work.
Chapter 5 explores the possibility of selectively labelling biomolecules of interest by incorporating bioconjugation techniques into the dyad design. Several synthetic approaches led to a series of compounds, and comparison of their cell images suggests key factors for further considerations.
Chapter 6 demonstrates the RESOLFT potential of the dyad in liposomes. The switching behaviour is investigated in different types of liposomes, and detailed imaging analyses are reported, highlighting the varying performance of the dyad in different systems.
Chapter 7 summarises the conclusions described in this work.