VictorJuiz/thesis huggingface dataset:
Elucidating the principal role of cholecystokinin neurons of the ventromedial hypothalamic nucleus in energy homeostasis

The central nervous system (CNS) has a crucial role in the maintenance of energy homeostasis by orchestrating a plethora of signals from peripheral organs about the state of energy stores and the current energy intake needed to match energy expenditure. These signals converge into the hypothalamic regions and its complex local circuitry. CNS-derived cholecystokinin (CCK) is acting at central level to modulate energy balance by regulating the neuronal activity of hypothalamic neuronal populations that regulate food intake, energy storage and consumption. Moreover, our recent published work identifies CCK neurons as key integrators of the neuroendocrine negative feedback of glucocorticoids to the PVN. Glucose sensing neurons of the Ventromedial Hypothalamus (VMH) are integrating energy signals and are essential for mounting a counter-regulatory response and glucose homeostasis. VMH is also important in energy expenditure by regulating body weight and thermogenesis. CCK neurons are present in high density in the VMH.The source of endogenous CCK that acts on distinct neuronal components has not been elucidated. The research so far does not address the purpose of CCK neurons in the hypothalamus and their potential role in the network dynamics regarding energy homeostasis.
In this study, we untangle the role of CCK neurons in the VMH nucleus by employing stereotactic intracranial delivery of adeno-associated viruses that result in cell-type specific chemogenetic inhibition or ablation of these neurons. Acute silencing of their neurotransmission with the cre-dependent AAV expression of the chemogenetic tool of Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) increases their daily food intake due to increased meal numbers and eating frequency without meal size or meal duration being affected. CCK ablation by a newly generated double-recombinase-mediated Diphtheria Toxin Receptor (DTR) mouse line or AAV-DTA-mediated ablation resulted in hyperphagia, obesity and hyperglycaemia. We conclude that CCKVMH neurons are implicated in the regulation of food intake, body weight and glucose homeostasis in the adult brain.

Keywords: hyperglycemia
cholecystokinin
glucose
hypothalamus
appetite
obesity
Advisor: Minichiello, L
Titanium and zirconium permethylpentalene chemistry: ethylene polymerisation and small molecule activation

Chapter One
provides an introduction to the chemistry of pentalene and its derivatives encompassing ligand synthesis, organometallic chemistry, and in particular ethylene polymerisation. In the second half, cationic polymerisation is introduced encompassing both main-group and transition-metal initiated polymerisations. The limitations of cationic ethylene polymerisation are highlighted.
Chapter Two
describes the synthesis of a series of related complexes based on the Pn*MCpR(X) motif for application as ethylene polymerisation catalysts. The products are characterised by NMR spectroscopy, single crystal X-ray diffraction, elemental analysis and, where relevant, EPR spectroscopy.
Chapter Three
details the application of aforementioned Pn*MCpR(X) complexes as ethylene polymerisation catalysts, tested in solution co-catalysed by methylaluminoxane, and in the slurry phase, immobilised on a variety of inorganic supports. Very high activities are observed for the zirconium congeners of this non-classic polymerisation motif, with the Cp ligand observed to affect activity more dramatically than the "X" ligand.
Chapter Four
gives an account of mechanistic investigations examining the activity of the Pn*MCpR(X) catalysts. Pre-catalyst activation studies implicate the formation of cationic derivatives, which are rationally synthesised. The unexpected activity of [Pn*ZrCp]+ towards ethylene polymerisation is investigated by in-situ gas uptake measurements and small molecule activation studies, which do not readily accommodate a coordination-insertion mechanism. An alternative cationic initiation mechanism is proposed and explored.
Chapter Five
describes the synthesis of titanium and zirconium hydride and deuteride complexes. Using either LiAlH4/D4 or H2/D2 as the hydrogen source, trimetallic hydride clusters are synthesised. Preliminary investigations into their reactivity with small molecules is presented.
Chapter Six
details the synthesis of reduced permethylpentalene titanium complexes. Chlorine atom abstraction, scrambling of the Pn* ligand, and dinitrogen activation was observed depending on the nature of the reducing agent and the stoichiometry employed.
Chapter Seven
provides experimental details and characterising data for the complexes presented in the preceding five chapters.

Keywords: Permethylpentalene
Polymerisation
Pentalene
Mechanism
Ethylene
Advisor: O'Hare, D
Development of high-resolution cavity beam position monitors for use in low-latency feedback systems

The FONT beam-based, intra-train feedback system has been designed to provide beam position stabilisation in single-pass accelerators. A FONT feedback system utilising position information from three high-resolution cavity beam position monitors (BPMs) has been commissioned at the interaction point (IP) of the Accelerator Test Facility 2 (ATF2) at KEK, Japan. The ultimate goal of the feedback in the IP region is to stabilise the low-emittance electron beam to the nanometre level. The operation, optimisation and resolution performance of this IP system forms the subject of this thesis.
The IP feedback system makes use of beam position measurements from the BPMs to drive an upstream kicker and provide a local correction. The BPMs have a fast decay time of ~25 ns to allow bunches within the beam train to be resolved. The operation of the IP BPMs, the noise floor, and position sensitivity to phase are discussed in detail. Attempts are made to diagnose an unwanted ~60 MHz oscillation in the cavity signals, which is bunch charge-dependent and thus likely beam generated.
The BPM resolution estimate was notably improved from 50 nm to 20 nm using waveform integration in analysis of the BPM signals. A multi-parameter fit was used to address inaccurate calibrations and charge-dependencies to achieve more consistent resolution performance and produce a best-ever resolution estimate for the BPMs of 17.5 ± 0.4 nm.
A novel mode of IP beam position stabilisation using two BPMs as input to the feedback has been successfully demonstrated. The beam position was stabilised to 57 ± 4 nm, as measured at an independent BPM. Feedback performance was improved to this level by sampling the waveform to optimise bunch-to-bunch correlation. Analysis suggests correction capability could be enhanced by firmware waveform integration to achieve a measurable beam stabilisation of ~40 nm in the future.

Advisor: Burrows, P
Papers on the polarization of congress

This dissertation, a collection of independent papers, explores the polarization of the United States Congress through the lens of primary elections, campaign finance, and party structures during a pivotal moment in American political history. Paper 1 focuses on the top two primary format and its potential in producing moderate candidates and legislators, while Paper 2 expounds on the deleterious consequences it poses for the party system as a whole, particularly in this modern era of both high polarization and high fragmentation. Paper 3 examines the Downsian median voter theorem from the perspective of primary election voters, asking if general election wins/losses beget the nomination of more ideological/moderate nominees next cycle. Ultimately, the article illustrates that the parties instead retain consistent records through both election wins and losses, linked to credibility concerns from position changes as well as the inability of members to disentangle from national party identities. Its companion paper, Paper 4, takes that Downsian question to elites in Washington, D.C. Through original interviews with twenty-three individuals including former members of Congress, leadership, congressional staff, and think tank scholars, I describe the electoral and legislative pressures that prevent officeholders from responding to their median voter, especially among those in swing districts most exposed to the risks of partisan behavior. Paper 5, the final paper, brings together the themes of those preceding it by analyzing the ways in which outside interference, specifically political action committees and more inclusive primary elections, propagates legislative caucus fragmentation and weakens official leadership. This work plays one minor role in providing prescriptive steps to improve and empower channels of dialogue in the U.S. legislative branch—in spite of larger systemic sorting along geographical and partisan lines—and ensure the mediation of ideology between voters and their elected representatives results in policy solutions rather than gridlock.

Keywords: elections
polarization
political parties
congress
Advisor: Eggers, A
Soluble catalysts for aprotic Li-O2 batteries

Aprotic lithium-air (O2) batteries have attracted significant interest due to their high theoretical specific energy. In an aprotic Li-O2 cell, O2 is reduced to form Li2O2 on discharge and the process is reversed on charge. Li2O2 is an insulating and insoluble solid, leading ultimately to poor cycling rates, low capacities and early cell death if it formed on the electrode surface. This is exacerbated by formation of Li2CO3 due to the cathode degradation with the presence of Li2O2 surface film. It is therefore desirable to form Li2O2 particles in solution, typically in batteries with high donor number electrolyte solvents that can dissolve the LiO2 intermediate. However, such solvents are more susceptible to nucleophilic attack by the reduced oxygen species, resulting in undesired side reactions.
This project focuses on tackling the dilemma by promoting solution phase formation of Li2O2 in relatively stable low donor number solvents. Phenol was investigated as a protic additive that acts as a phase-transfer catalyst, dissolving Li2O2, avoiding electrode passivation and forming large particles of Li2O2. Discharge mediators were studied to shift O2 reduction to Li2O2 in solution via a new route that avoids the LiO2 intermediate, so that it increases the discharge potential, suppresses the growth of the Li2O2 thin film on the cathode surface, and thus postpones the cell death, increases the discharge capacity 80-100 fold and permits high discharge capacities with relatively high rates.
However, Li2O2 particles growing via solution mechanism is disconnected from the electrode surface and therefore electronically isolated during charging, which requires redox mediators on charging. By combining discharge and charge mediators, the dual-mediator Li-O2 cell in this project was able to sustain cycling with capacities of 2 mAh cm-2areal at a rate of 1 mA cm-2areal over 50 cycles. By forming/decomposing Li2O2 in solution and avoiding high charge potentials, the carbon instability is significantly mitigated.

Advisor: Bruce, P
Reflections on the intellectual foundations for metaphysical ground

"This essay is a plea for ideological toleration", wrote Rosen (2010) on the idioms of metaphysical dependence, and especially '(metaphysical) ground'. This thesis is likewise a plea for ideological clarity. Much work on ground has connected it to "metaphysical explanation" – perhaps distinct from its causal cousin – and maintained that ground is somehow ineluctably wrapped up with it. Unfortunately, there is hardly consensus about what "explanation" is; the term 'explanation' is itself highly ambiguous, and is used by many philosophers in various guises, often without recognition and in theoretically risky ways.
It is my aim here to bring some lucidity to debates about ground vis-à-vis "explanation". To do so, I will do a few things. I will begin by trying to home in on the phenomenon of interest in the literature on ground – which I refer to as constitutive determination,/em> – absent potentially distracting talk of "explanation". Next, I will consider the varieties of "explanation" relevant to ground-theoretic discourse, imposing some basic conditions on constraints on things that may plausibly be so named. Given these considerations, I will then try to throw into relief some metaphysical and greater philosophical commitments of several of ground's biggest supporters – including and centrally those regarding the nature of "explanation" – drawing connections between them when possible, and demonstrating their (dis)agreements too. Ultimately, I believe that certain significant beliefs about "ground" may illicitly trade in ambiguities of "explanation", intentionally or not, leading to either erroneous theoretical posits, or the right ones for the wrong reasons. As such, I will offer what I take to be the most promising position for the realist who recognizes a seemingly unified phenomenon of constitutive determination – namely, that of a metaphysical dependence relation holding between entities or phenomena of arbitrary ontological category – and attempt to demonstrate where I think some philosophers who instead offer a more restricted relation, such as one holding only between facts, have been led astray. All told, without recognition of vital distinctions among the varieties of explanation, "explanation"-talk may be more harmful than helpful in theorizing about "ground".

Keywords: Facts
Explanation
Grounding
Causation
Ontology
Metaphysics
Determination relation
Philosophy
Advisor: Pickup, M
Void and spatiality in Epicurus’ letter to Herodotus

This thesis analyses the notion of void (to kenon) in Epicurus’ Letter to Herodotus: I argue that void should not be identified with space, but only with the empty intervals between bodies.
The thesis is composed by four chapters. In Chapter 1, I maintain that the Epicurean void is meant to fulfil two different functions (that I call the ‘elemental’ and the ‘spatial’ functions): I discuss the historical roots of the attribution of these functions to the void, and suggest how they could be brought together in a unitary, hybrid conception.
In Chapter 2, I examine how void, interpreted in this way, could make motion possible. I focus on the eixis of void, which I do not interpret in terms of receptivity, and draw a comparison with a contemporary metaphysical theory of holes to show that the resulting conception is coherent.
In Chapter 3, I discuss the theory of the minimae partes in the atom, offering an original interpretation of the notions of 'part' and 'division' on which the theory relies.
In Chapter 4, I analyse the consequences of this theory for the structure of void. I argue that the theory of minima naturally leads to suppose that motion is quantized: because of the Isomorphism Thesis, also time and spatial magnitudes must be composed by minima. However, I conclude that void in itself has not a granular structure, but is affected by the quantization only in a very peculiar and restricted sense.

Keywords: Epicurus
Space
Void
Advisor: Marmodoro, A
Powder based processing of novel dispersion strengthened copper alloys for fusion applications

Copper (Cu) has high thermal conductivity and is thus ideal for high heat flux, thermal heat sink applications in fusion power applications. Divertor designs for future fusion power plants will expose Cu alloys to extreme thermal (>10 MW m−2) and neutron fluxes (200 dpa) that destabilise the microstructure of Cu. To improve stability, strength and creep resistance, alloying additions are used commercially, but these compromise thermal conductivity. Dispersed oxide particles may offer the opportunity for improved mechanical stability and creep resistance even at very low volume fractions (<1%) while avoiding large reductions in thermal conductivity. However there are few studies on the processing-performance of oxide dispersion strengthened Cu alloys.
In this thesis, novel oxide dispersion strengthened Cu alloys were prepared by room temperature mechanical alloying of Y2O3 and the mechanism of dispersion investigated. A small fraction of Y2O3, up to 1%, was shown to disperse effectively during mechanical alloying at room temperature in Cu. Both severe fragmentation and some local disassociation of the Y and O occurred, allowing for re-precipitation of fine nanoparticles <10 nm during consolidation and exposure to elevated temperatures. A model alloy of Cu-2 wt.% Y2O3 alloy had a mean oxide particle diameter of 7.1 ± 6.0 nm and a mean particle number density of 8.24 × 1022 m−3 following consolidation.
Ternary Ti additions were investigated for nanoparticle refinement and best design alloy with a composition of Cu-0.25Y2O3-0.25Ti was produced that had a mean nanoparticle diameter of 3.2 ± 1.5 nm and a mean particle number density of 2.36 × 1023 m-3 , which after thermal ageing for 545 h at 350 ◦C, was largely unchanged iii at 3.8 ± 1.7 nm, and 1.74 × 1023 m-3 respectively. Comparing favourably with commercial Al2O3 dispersion strengthened Cu, the alloy had a narrower particle size distribution and a higher particle number density. The fine dispersed oxide nanoparticles gave good grain boundary pinning, retaining an ultrafine mean grain size of 220 nm after thermal ageing. Thermal conductivity of the Ti-containing alloy was 332 ± 16W m−1 K−1 , and the addition of Ti increased the thermal conductivity with increasing temperature. The creep resistance was evaluated by small punch testing and in-house produced alloys outperformed commercial alloys at 350 ◦C. The work in this thesis indicates that mechanically alloyed Cu-Y2O3 or Cu-Y2O3-Ti alloys, with further development and evaluation, have potential as thermal heat-sink materials for fusion divertor application.

Keywords: Dispersion Strengthened
Copper
Divertor
Fusion
Advisor: Grant, P
Lozano-Perez, S
Essays on credit and default under the presence of collateral

This thesis is a collection of three essays, which study a range of topics related to leverage, credit and default under the presence of collateral. The essay on belief disagreement and leverage proposes a novel approach in general equilibrium frameworks to assess how beliefs affect equilibrium and contract origination. Binding collateral constraints raise asset prices above the fundamental value. The model establishes that changes in market average belief rather than belief disagreement drives the asset price movement. The essay on mortgages and Minsky effect presents a micro-founded framework to study the macroeconomic effect of mortgage default, and shows that the endogenous leverage of the mortgage contract together with the bank capital determine the comovement of prices, leverage and credit extension. Default is more severe after good states than after bad states, due to high leverage and risk-taking. Minsky effect amplifies the financial instability. The essay on systemic risk measurement presents a calibration method for equilibrium models of banking systems, identifies channels that co-determine the distress dependence structures in the banking system, and the results suggest that the “Minsky effect”, in addition to the widely accepted feedback channels such as the interbank lending and common exposure, serves as a systemic risk amplification mechanism.

Advisor: Tsomocos, D
Morrison, A
Electronic structures of novel quantum materials studied by spatially angle-resolved photoemission spectroscopy

This thesis describes the studies on the electronic structures of several novel quantum materials by using the Angle-Resolved Photoemission Spectroscopy (ARPES) technique:
Topological Dirac semimetals represent a new state of quantum matter that offers a platform for realizing many exotic physical phenomena. Our ARPES experiment systematically revealed the electronic structures of MSiS (M=Zr, Hf) family and confirmed the Dirac line-nodes states in both compounds. By comparing the spin-orbit coupling (SOC) effect, we demonstrated that the degeneracy of bands at certain positions of Brillouin zone (BZ) are protected by non-symmorphic symmetry of the crystal.
Two dimensional (2D) semiconductors with high carrier mobility and moderate band gap are particularly attractive for their potential broad applications in electronic devices. By using both ARPES and scanning tunneling microscopy (STM) techniques, we comprehensively revealed the electronic structure of newly discovered air-stable oxide semiconductor Bi2O2Se. Surface patterns (consisting of 50% Se vacancies) were found on the cleaved sample surface. Remarkably, we found no evidence of undesired in-gap states even in the presence of these surface defects.
Spatially resolved ARPES technique has been recently developed, which features its ability to focus the incident beam into submicron region. By using the technique, we studied the electronic structure of square graphene system. The sides of the graphene are found to be aligned with underlying Cu <110> direction, indicating the important role of substrate during the growth of graphene. In addition, large domain twisted bilayer graphene (tBLG) was artificially constructed. The van Hove singularity in its band structure caused by interlayer interaction was directly revealed by our ARPES measurement.

Advisor: Chen, Y
Seed security, agrobiodiversity and production risk in smallholder agriculture in Eastern Ethiopia

This doctoral thesis presents three original research papers investigating aspects of agricultural production in small-farming households in two regions of Ethiopia. While answering specific research questions, the articles are connected and motivated by an interest in essential themes of agricultural development: access to seed, the use and conservation of agrobiodiversity as well as strategies to manage production risk in smallholder agriculture.
The first article analyses patterns of agrobiodiversity in three communities with comparatively favourable farming conditions and good market access in the East Shewa zone of Eastern Ethiopia. Using original panel data of more than 300 households collected in 2011 and 2013, the study shows that the least vulnerable households grow a larger portfolio of food crops and wheat varieties. Based on these findings, the role of agrobiodiversity for ex ante risk management and alternative incentives for portfolio diversification are discussed.
The second article investigates the effects of a fungal crop disease on agricultural production of households in East Shewa using household level panel data during and after an epidemic outbreak of yellow rust in 2010/11. Findings suggest that while varietal diversity in wheat does not increase, roughly thirty percent of households make changes in their varietal portfolio and reduce wheat cultivation in response to the disease. Disease resistant varieties are only available to 16 percent of all households with preferential access to agricultural resources.
The third article presents a mixed methods study of a highly developed informal seed insurance network among subsistence‐oriented small farmers in two communities in the West Hararghe zone of Ethiopia. Based on a survey and interviews with 150 farmers, we find that the vast majority of small farmers actively participate in informal seed assistance by giving or receiving small quantities of seed without compensation. We argue that the seed assistance through gifts is practiced to insure against hunger ex ante and facilitate access to crop genetic resources in a centre of crop origin and diversity.

Keywords: Wheat Rust
Risk
Advisor: Gollin, D
Dercon, S