VictorJuiz/thesis huggingface dataset:
On some computations of refined Donaldson-Thomas invariants

Donaldson and Thomas defined Donaldson-Thomas (DT) invariants for moduli spaces of sheaves on proper Calabi-Yau threefolds in [DT,T]. The definition has been extended to more general moduli spaces of objects in 3-Calabi-Yau categories, and in the last few years there has been an increasing interest in studying refinements of DT invariants. This thesis is devoted to the computation of the generating series of refined DT invariants in some geometric examples.
In Chapter 2 we compute the generating series of refined DT invariants for the moduli space 𝑀n,r of higher rank framed sheaves on ℙ3, generalizing the result of [BBS] for the Hilbert scheme of n points on ℂ3. We describe 𝑀n,r as a global critical locus by means of the Beilinson spectral sequence, and compute the generating series using motivic wallcrossing. We interpret the result as a count of r-tuples of weighted 3D partitions in analogy with the refined topological vertex [IKV].
In Chapter 3 we study the refined DT invariants for the moduli space Prn,d of higher rank (framed) stable pairs on the resolved conifold. Applying twice the Beilinson spectral sequence, we identify Prn,d with the moduli space of PT-stable representations of the r-framed conifold quiver with superpotential, generalizing a result of [NN11]. We compute a product expansion for the generating series of refined DT invariants of Prn,d, and we compare our results with the partition function counting U(1)-instantons on the minimal resolution of an Ar-1 surface singularity.
In Chapter 4 we study the universal generating series of motivic DT invariants for deformations of graded 3-Calabi-Yau algebras. We consider Jacobi algebras which are derived equivalent to the resolved conifold and the resolution of a line of An-singularities, and investigate their marginal deformations. The universal series of motivic DT invariants are affected by the deformations, and their variation is interpreted in terms of virtual classes of some special representation varieties associated to the quiver.

Keywords: Donaldson-Thomas invariants
Moduli spaces of sheaves and pairs
Calabi-Yau algebras
Quivers
Advisor: Szendroi, B
Modifications to the spectrum of radiation from black holes

Despite their name, there is clear theoretical evidence that black holes emit radiation. The nature and spectrum of this radiation depends on many features of the black hole and the emitted particles. With the profound implications that black hole evaporation has on our understanding of the marriage of quantum mechanics and general relativity, it is essential to study the details of this radiation in new contexts.
In this thesis we examine certain important modifications to the spectrum of radiation from black holes that can occur. Firstly, we study the case that the particles emitted by the black hole are spatially extended, rather than pointlike, and find that the rate of emission is suppressed by a factor which depends sensitively on the size of the particle. We then study the emission of electrically charged particles from black holes from a perspective that elucidates the physical picture of emission; namely, in terms of tunnelling of particles both through the horizon and the external electric field. We finally consider the cosmological consequences of modifying the mass-temperature relation of black holes by supposing that they can radiate into higher dimensions. In particular, we argue that current constraints on the density of black holes in the universe are evaded in certain extra-dimensional theories, in which black holes are substantially colder than their four-dimensional counterparts.

Advisor: March-Russell, J
Solidarity as a transformative practice

In this thesis, I investigate the meaning, importance, and potential of political solidarity. By studying existing theories and reflecting on real-world cases, I present a normative account of solidarity suited to confront the globalized, overlapping injustices we face in our world today. I argue in Chapter 1 that we should conceptualize solidarity as a political bond, realized through action, that unites members of social groups on the basis of a shared understanding of reality and a shared commitment to justice; and as a socially, interpersonally, and personally transformative practice. In Chapter 2, I consider a question familiar from feminist debates: whether and how a cohesive political unity can make sense of the divergent experiences, interests, and needs of the social groups it brings together. I argue that acknowledging and mitigating the relations of asymmetric power that exist between solidary agents is a precondition for unity. I then consider the numerous challenges solidary individuals face when attempting to relate to each other prefiguratively, as equals, within entrenched structures of domination in Chapter 3. I propose a series of diachronic norms to guide solidary agents in navigating power and knowledge asymmetries. In Chapter 4, I turn to the process of personal transformation undergone by solidary agents. I examine what sort of knowledge individuals gain through solidarity, how new knowledge translates into changed motivations, and the nature of these transformed motivations. I conclude by suggesting that solidarity discloses possibilities for freedom.

Keywords: solidarity
domination
intersectionality
justice
social movements
mutuality
knowledge
prefiguration
standpoint theory
power asymmetries
transformation
feminism
deference
transformative experience
Advisor: Fraser, R
Three essays on measuring political behaviour

Fundamental issues of political representation persist in modern democratic states. Policies favoured by large majorities of the population are not acted upon by elected representatives. Direct forms of democratic policymaking are increasingly used to settle policy disputes. And the amount of money in politics continues to grow. At the same time, new sources of data allow us to test the political behaviour of democratic actors in novel ways. Across three papers, this thesis explores how representation and policymaking operate in modern democratic systems and how researchers should measure political behaviour in these contexts.
In Chapter 2, I ask why popular legislation is passed by direct democratic means instead of by the legislature? I use a combination of district-level voting data, ideological estimates of financial donors, and a survey of state legislators to test competing theories of ballot initiative success in the United States. I argue that direct democratic policymaking is necessary when issues lie outside mainstream policy networks. Legislators appear averse to policies that are novel, untested, or go against the preferences of their financial supporters. In Chapter 3, I show how experimentalists can make valid statistical inferences when their data contains group-level structures. I illustrate this guidance using both Monte Carlo simulations and a review of experimental publications over the past three years. In Chapter 4, I examine how campaign finance disclosure affects vote choice in both representative and direct democratic contexts. Applying the lessons of the previous chapter, I use conjoint experiments to show that while voters can use disclosure information to inform vote choice, these effects are crowded out once partisan, ideological and issue cues are made explicit. Across all three chapters, I develop inferential techniques designed to account for limitations of observed data and, in particular, incomplete data.

Keywords: reponsiveness
campaign finance
representation
measurement
quantitative
experiments
variance
Advisor: Eggers, A
Motion capture and musculoskeletal simulation tools to measure prosthetic arm functionality

The incidences of major upper limb (UL) loss or absence are increasing, while the prosthetic outcomes have remained poor. The human UL relies on the coordination of each of its joints (and the trunk in some instances) to achieve function; and this function, along with the sensory capabilities provided by the hand, is impaired due to amputations or absence of the UL (or a part thereof). Typical prosthetic devices that are used to supplement this missing function (and structure) lack controllable distal joint(s) necessitating compensatory movements during functional task execution. There is evidence in the literature that suggests that such compensatory movements are linked to poor prosthetic outcomes as well as secondary complications (such as repetitive strain injuries) in the contralateral arm owing to overuse. Most studies objectively characterising these movements have focussed on various types of kinematic and kinetic analyses. However, no studies have aimed at understanding these compensatory movements through a detailed musculoskeletal (MSK) model-based approach. Gaining better insights into compensatory movements is likely to be an essential step in measuring the functionality of a prosthetic arm.
The overall aim of this research is to use motion capture and state-of-the-art MSK simulation tools to measure prosthetic arm functionality. It is hypothesised that by comparing the functional performance of prosthesis limb users (simulated or actual) during select task execution with that of non-disabled individuals, we can identify and better understand prominent ‘functional disparities’ and help propose solutions to remedy these issues. In this study, select functional or goal-oriented tasks were performed in a standardised manner by non-disabled individuals and prosthetic limb users (both simulated and actual) in a three-dimensional optical motion capture laboratory setting. The measured motion data was then used to drive a detailed biomechanical (or MSK) model to calculate outputs such as joint angles, joint loading, and muscle loading.
This study adds to the kinematic (i.e. joint angles) and kinetic (i.e. joint and muscle loading) database of UL movements necessary to understand how a simulated (constraint-induced) or an actual transradial prosthesis user with a lack of a controllable distal joint(s) compensates relative to non-disabled individuals. The results provide valuable information such as increased disparities in joint angles, joint forces and moments during prosthesis usage (both actual and simulated) for characterising compensatory movements. By gaining in vivo information about the movement patterns adopted by prosthetic limb users, prosthetic devices and rehabilitation protocols could be personalised to enhance aspects such as function to improve prosthetic outcomes in the long-term.

Keywords: Sensitivity analysis
Affordable prosthetics
Motion analysis
Kinematics
Musculoskeletal modelling
Model validation
In Vivo analysis
Device personalisation
Compensatory movements
Kinetics
Upper limb prosthesis
Advisor: Thompson, M
The great debate: disruptions, identity politics and foreign policy in post-Cold War Greece

In this thesis, I explain the variance of Greek foreign policy outcomes by focusing on its most recent historical period. Since the end of the Cold War, Athens has displayed variance in its foreign policy behavior within and across issues, shifting from co-operation to defection from the international community or opting to stay inactive. I offer an analytical framework in order to understand the causal chain(s) leading to differing policy outcomes. I first discuss the dominant paradigms of IR theory, Liberalism and Realism. Arguably, both go a long way towards explaining the restraints and opportunities of states. However, since both hypotheses internalize states as unitary actors responding to external incentives, many questions are left unanswered. Hence, I also explore whether and to what extent decision-making and ultimately the policy outcome can be understood through the prism of national identity. I underline the continuity of Greek identity through Greece’s modern history as an independent state but argue that the variance in Greek foreign policy is the product of an Identity characterized by a structural dichotomy as individuals or groups that attach different meanings to their common Identity can respond very differently to similar challenges. Thus, I examine whether ‘soft’ and ‘hard liners’ engaged in what I term a Great Debate on two levels: first, in the wider society amongst Identity Warriors, including the Church, the media and civil society; second, within the political elite, as a more instrumental analysis about end-means relationships in the context of political action must be considered. An enabling environment for the political process is thus created, with ‘soft’ and ‘hard line’ political agents struggling to gain the highest level of acceptance of their policies. Through the study of three particular moments in Greece’s post-1989 foreign policy story, e.g. the 1999 Greco-Turkish rapprochement, the 2004 Cyprus Annan plan and the 1992 Macedonian name dispute, I examine how this great debate plays out, on both levels of analysis, amongst Identity Warriors and political agents, and under what conditions the policy outcome is determined.

Advisor: Anastasakis, O
Nicolaïdis, K
Bioinspired MWCNT-reinforced alumina composite materials

Nacre, a ceramic composite found in seashells, has baffled scientists due to its extraordinary mechanical properties. Consequently, nacre has been a main source of inspiration to create strong and tough ceramic composites that mimic nacre’s microstructure. The precise microstructural features responsible for its unique combination of high strength and toughness are however debated, and efforts to mimic and improve upon nature’s design have not led to commercial applications of ceramic nacre-like composites.
This dissertation details the replication of nacre’s microstructural architecture with technical ceramics and nanomaterials. Instead of nacre’s calcium carbonate building blocks, alumina was used, and instead of its organic phase, multi-walled carbon nanotubes (MWCNTs) were incorporated. To design a nacreous microstructure, freeze casting of alumina nanoparticles was used to template a microstructure of aligned lamellae over macroscopic length scales. Although successful, the fabricated lamellar microstructures’ macroscopic orientation was hard to consistently reproduce using this technique and the resulting composites, unlike nacre, fail in a completely brittle fashion. Therefore, alumina platelets that closely resemble the platelets in nacre were investigated. A recipe to homogeneously coat these platelets in situ with MWCNT was developed, and MWCNT growth and catalyst modification was studied in-depth. The resulting combined building blocks were sintered into a composite that displays a graceful failure mechanism like nacre does, with several toughening mechanisms observed to be active. In addition, nacre-like alumina/MWCNT composite materials have been synthesised using a variety of MWCNT dispersion techniques. All studied nacre-like composites showed characteristic macroscopic interlocking behaviour and remain interlocked after crack initiation which prevented complete failure and gave these composites a residual strength. Pure nacre-like alumina specimens have also been tested in high strain rate and impact tests, where these materials showed a significant improvement over nontextured alumina.

Keywords: Nanomaterials
Biomimetic
Composites
Carbon nanotubes
Ceramics
Advisor: Todd, R
Grobert, N
Truthmaker Ontology

Truthmaker Ontology is the metaontological thesis that ontology should be framed as a search for truthmakers: the things in the world in virtue of which true representations are true. This dissertation develops Truthmaker Ontology in new ways, arguing that it offers an attractive mode of thinking about the subject matter and method of ontological inquiry. I begin by arguing that, if ontology is to live up to its aspirations to be a serious enterprise, we must abandon the orthodox view that ontology concerns what there is. The remaining chapters develop Truthmaker Ontology as an alternative. First, I clarify the two central notions on which my version of the approach rests: the truthmaking relation between truths and their truthmakers, and the grounding relation between truths and other truths. I then use these two notions to develop a heterodox view of the subject matter of ontology, whereby ontological status comes apart from what it’s true to say there is. Briefly, what has ontological status is just what makes a contribution as a fundamental truthmaker. Since not everything that can truly be said to exist is a fundamental truthmaker, the question of whether ‘There are Fs’ is true doesn’t settle the ontological question about Fs. Next I turn to questions of method, starting with the methodologically important notion of ontological commitment: the ontological commitments of a theory, I claim, are the entities its holders rationally ought to admit as truthmakers. I then discuss the implications of Truthmaker Ontology for the measure of ontological parsimony, which I compare favourably to the recent view that parsimony only measures a theory’s requirements on what is ontologically basic. I close by consolidating the case for Truthmaker Ontology, arguing that it avoids the pitfalls of orthodoxy and has attractive consequences for some perennial ontological debates.

Keywords: Ontology
Grounding
Metaontology
Fundamentality
Ontological Commitment
Truthmaking
Ontological Method
Advisor: Rodriguez-Pereyra, G
A study of Mandarin homophony

An investigation into the distribution of homophones was conducted using a large written corpus (Da, 2007). Both tone and homophony were found to be systematically uneven, with a tendency toward clustering. Syllables with the full complement of tones have, on average, higher homophone densities than those with fewer tonally-specified syllables, indicating a beneficial role of increasing homophone density in lexical processing. Three experiments were conducted to test this hypothesis. In Experiment 1, participants were shown tonally-unspecified pinyin and asked to produce a character. Participants gave the most frequent character matching the pinyin, except when two characters of differing homophone density but similar lexical frequency were in direct competition (e.g. the two highest frequency wan characters were associated with different tones). In this case, it was found that the slightly lower frequency, but higher homophone density character was selected, indicating a facilitative role of homophone density. In Experiment 2, participants were shown tonally-specified pinyin followed by characters, and asked to judge whether the two matched. Character frequency (not the cumulative frequency of all homophones) was found to be the primary determinant of response time, with higher frequency characters responded to faster than lower frequency characters regardless of homophone density. However, increasing homophone density was found to speed responses for all frequencies. High frequency characters were always faster than low frequency characters, but low frequency characters with high homophone density were faster than low frequency characters with low homophone density. In Experiment 3, participants read aloud characters embedded in context sentences. High frequency words were more reduced (i.e. shorter in duration) than low frequency homophone mates. High frequency characters with many homophones were shorter than high frequency characters with few homophones, while the opposite held for low frequency characters.

Keywords: Chinese
Mandarin
Homophones
Phonetics
Advisor: Payne, E
Antiphon the Sophist's critique of law

Antiphon has often been singled out by scholars as the Sophist who gave expression to the most radical critique of law. He is often spoken of as an immoralist thinker, who recommended that people reject the established laws and pursue solely what is in their self-interest. In this thesis, the grounds for ascribing the label of immoralist to Antiphon will be assessed. I will argue that it is misguided to view Antiphon in this regard on two principal counts: his purpose in 'On Truth' is to underline the inconsistencies and failings of existing legislation, and in no way to advocate for people to disregard the laws in force; in both 'On Truth' and in 'On Concord,' he shows an attachment to the laws, and in the second of the two works, he even advances a reason for why they should be regarded as salutary and beneficial.

Keywords: Antiphon
The Sophists
anomia and friendlessness
Ancient Greek social contract theories
nomos-phusis distinction
Sophistic legal thought
Advisor: Scott, D
Rood, T
Structuring disruption: narrative insurrection in Morkinskinna

This thesis analyses the function of the þættir in the construction of royal biographies in Morkinskinna, a thirteenth-century compendium of konungasǫgur. The narratological approach employed as the foundation of this study demonstrates the disruptive utility of the þættir within the wider narrative discourse, with these discordant narrative structures acting in concert with the introduction of unruly characters. This effect is termed as narrative insurrection and is persistent throughout the text, forming a key element in the representation of strife in Norwegian elite society from 1030-1157. The consequent instability of narrative history in Morkinskinna means that different kings’ tactics for dealing with challenges to their authority come to be the primary method by which their legacies are assessed and their reigns are presented.
Chapter two provides a comprehensive literature review of previous scholarship relating to the form and function of the þættir and the structure of Morkinskinna. Chapter three rejects amplification and interlacing as methods for understanding Morkinskinna; instead a full investigation of the narrative discourse of the text leads to the production of narrative insurrection as a more suitable theoretical framework by which to understand Morkinskinna. Chapter four examines the narrative discourse of other konungasǫgur in relation to Morkinskinna and the ways in which royal biographies are structured within different texts in the genre. Chapter five provides historical context as to the organisation of the hirð to argue that the depiction of this elite institution is central to the narrative history of Morkinskinna and that the hirð is depicted with a degree of flexibility in the text for literary purposes. Chapter six considers the harmonious hirðir of kings who, despite being renowned for the benevolence, do not tolerate challenges to their authority and suppress unruly figures who seek to enter their hirðir. Chapter seven details the unruly hirðir, wherein more combative kings utilise the disruptive presence of marginal figures to the mutual benefit of both parties, demonstrating an alternate style of productive rule in the process.

Keywords: Old Norse
Royal Biography
narrative history
narrative structure
narratology
Sagas of Kings
Saga literature
Morkinskinna
narrative insurrection
þættir
Advisor: O’Donoghue, H