VictorJuiz/thesis huggingface dataset:
The mechanical response of low to high density Rohacell foams
Keywords: microscopy
high strain rate
Foam
density
temperature

The main aim of this thesis is to generate a deeper understanding of the mechanical behaviour of cellular materials, specifically for their use in aerospace applications. A closed-cell polymer foam material (Rohacell) of various foam densities was chosen for this investigation, and a comprehensive experimental study was conducted which generated significant findings that hitherto have not been reported in the literature.
The research presented in this study revealed the following: The quasistatic response of Rohacell foam displays a compression/tension asymmetry in moduli and strength. In-situ experiments revealed that different macroscopic collapse mechanisms at different foam densities drove this behaviour.
Improved experimental methods were developed to characterise the material response at various loading rates. Under compressive loading, as the relative density and loading rate increased, a transition in material behaviour from a ductile to brittle response at very high rates (~5x10^3 s^-1) was found, and tests conducted at different temperatures were used to validate and provide a better understanding of the causes for the observed rate dependency.
The compression and tension properties of pre-crushed Rohacell foam loaded in different directions were measured, and with the use of three-point-bend tests it was shown that when the foams’ tension/compression asymmetry, or the changes in stiffness and strength due to pre-crushing (i.e. strain-induced anisotropy), are neglected, this leads to incorrect predictions of the foams’ structural response. Finally, a review of some existing Finite Element foam material models was conducted, and their ability to predict the foam response under complex loading was identified.
The new data and understanding generated from this thesis will allow engineers and researchers, who are developing constitutive models for predicting the response of foam materials, specifically in aerospace applications, to account for more aspects of the mechanical behaviours in their Finite Element models.
On two-phase flow models for cell motility
Keywords: poroviscoelastic
two-phase flow
cell motility
poroviscous

The ability of cells to move through their environment and spread on surfaces is fundamental to a host of biological processes; including wound healing, growth and immune surveillance. Controlling cell motion has wide-ranging potential for medical applications; including prevention of cancer metastasis and improved colonisation of clinical implants. The relevance of the topic coupled with the naturally arising interplay of biomechanical and biochemical mechanisms that control cell motility make it an exciting problem for mathematical modellers.
Two-phase flow models have been widely used in the literature to model cell motility; however, little is known about the mathematical properties of this framework. The majority of this thesis is dedicated to improving our understanding of the two-phase flow framework. We first present the simplest biologically plausible two-phase model for a cell crawling on a flat surface. Stability analyses and a numerical study reveal a number of features relevant to modelling cell motility. That these features are present in such a stripped-down two-phase flow model is notable. We then proceed to investigate how these features are altered in a series of generalisations to the minimal model. We consider the effect of membrane-regulated polymerization of the cell's actin network, the effect of describing the network as viscoelastic, and the effect of explicitly modelling myosin, which drives contraction of the actin network.
Validation of hydrodynamical models for cell crawling and spreading requires data on cell shape. The latter part of the thesis develops an image processing routine for extracting the three-dimensional shape of cells settling on a flat surface from confocal microscopy data. Models for cell and droplet settling available in the literature are reviewed and we demonstrate how these could be compared to our cell data. Finally, we summarise the key results and highlight directions for future work.
Failure of condition
Keywords: restitution
failure of consideration
unjust enrichment

This thesis is an investigation of a doctrine generally known as ‘failure of consideration’, but which I term ‘failure of condition’. I have two principal aims. First, to clarify quite what the doctrine of failure of condition is. Secondly, to explain why it has the effects it does – in particular, why it justifies the response of restitution. The doctrine, at core, concerns conditional transfers: when a transfer is made conditionally, and the condition fails, the transfer can be recovered. For this reason, I term the doctrine ‘failure of condition.’ I investigate the nature of this relationship and argue that the reason why the transfer is conditional is that the agent’s intention to make the transfer was itself conditional. The justification of restitution is a more complex affair than is customarily accepted – but there is a valid justification lurking not far from the surface of orthodoxy.
A secondary concern of the thesis is to re-examine an old theory in the field of common mistake, frustration and termination following a breach of contract. It used to be thought that these doctrines could be explained by failure of condition. That theory has fallen out of favour – it seems that no one accepts it today. This rejection rests upon a confusion over the nature of the doctrine of failure of condition. Once the nature of this doctrine has been clarified, we can see how closely the various doctrines align with one another; we can also see where the true difficulty with the failure of condition explanation lies.
Haemodynamic status and management of shock in children with severe febrile illness
Keywords: volume expansion
resuscitation
management
malaria
malnutrition
fluids
colloids
shock
children

Most in-hospital deaths secondary to infections in under-five deaths within sub-Saharan Africa (SSA) occur in the initial 24 hours of admission and shock has been identified as a major risk factor for the early deaths. However, controversies exist on the appropriate clinical diagnosis of shock, choice of ideal fluid for resuscitation (crystalloid or colloid), and safety of fluid resuscitation in severe malnutrition or severe malaria. This thesis investigates these aspects and also reviews the evidence base of current paediatric fluid resuscitation guidelines for children (aged >60 days and ≤12 years) with severe febrile illnesses.
Capillary refill time >2 seconds, weak pulse volume, or bradycardia, in the presence of abnormal temperature and severe disease are predictive of impaired perfusion (defined by lactic acidosis) and death. Tachycardia and temperature gradient are neither associated with increased risk of death nor predictive of hypoperfusion. Existing international definitions of shock have low sensitivities (FEAST=44%, WHO=2%, and ACCM=59%) and high specificities (FEAST=82%, WHO=100%, and ACCM=66%) for diagnosis of impaired perfusion. Clinical criteria derived (called derived shock) had a sensitivity of 30% and specificity of 93%.
Shock in children with severe febrile illnesses in Kilifi has a complex presentation but mainly presents with hyperdynamic circulation (high cardiac index) and vasodilatation. Cases with low cardiac index (myocardial dysfunction) are relatively rare but increase the risk of mortality when present.
Synthetic colloids (gelofusine, hydroxyethyl starch 130/0.4 (HES), and dextran 70) are safe for use in fluid resuscitation in children with severe malaria. However, HES is the most promising compared to other synthetic colloids concerns still remain about its renal safety. However, further evaluation of synthetic colloids for treatment of shock is not warranted due to the findings of FEAST trial.
A Pilot trial shows that bolus isotonic fluids are safe, have better efficacy, and produce faster resolution of shock compared to low-sodium solutions at volumes and rates recommended by WHO in children with severe malnutrition.
Evidence available from all ten the trials in children with sepsis show that fluid resuscitation using crystalloids and colloids result in similar survival. However, fluid bolus resuscitation results in increased mortality compared to no bolus (control) in children in SSA. This finding excludes children with gastroenteritis, trauma, burns, and malnutrition. Colloids are better than crystalloids for severe dengue shock but both have similar efficacy in moderate dengue shock.
The regular histories formulation of quantum theory
Keywords: interpretation
quantum mechanics
quantum theory
consistent histories
regular histories
histories

A measurement-independent formulation of quantum mechanics called ‘regular histories’ (RH) is presented, able to reproduce the predictions of the standard formalism without the need to for a quantum-classical divide or the presence of an observer. It applies to closed systems and features no wave-function collapse.
Weights are assigned only to histories satisfying a criterion called ‘regularity’. As the set of regular histories is not closed under the Boolean operations this requires a new con- cept of weight, called ‘likelihood’. Remarkably, this single change is enough to overcome many of the well-known obstacles to a sensible interpretation of quantum mechanics. For example, Bell’s theorem, which makes essential use of probabilities, places no constraints on the locality properties of a theory based on likelihoods. Indeed, RH is both counter- factually definite and free from action-at-a-distance.
Moreover, in RH the meaningful histories are exactly those that can be witnessed at least in principle. Since it is especially difficult to make sense of the concept of probability for histories whose occurrence is intrinsically indeterminable, this makes likelihoods easier to justify than probabilities.
Interaction with the environment causes the kinds of histories relevant at the macroscopic scale of human experience to be witnessable and indeed to generate Boolean algebras of witnessable histories, on which likelihoods reduce to ordinary probabilities. Further- more, a formal notion of inference defined on regular histories satisfies, when restricted to such Boolean algebras, the classical axioms of implication, explaining our perception of a largely classical world.
Even in the context of general quantum histories the rules of reasoning in RH are remark- ably intuitive. Classical logic must only be amended to reflect the fundamental premise that one cannot meaningfully talk about the occurrence of unwitnessable histories.
Crucially, different histories with the same ‘physical content’ can be interpreted in the same way and independently of the family in which they are expressed. RH thereby rectifies a critical flaw of its inspiration, the consistent histories (CH) approach, which requires either an as yet unknown set selection rule or a paradigm shift towards an un- conventional picture of reality whose elements are histories-with-respect-to-a-framework.
It can be argued that RH compares favourably with other proposed interpretations of quantum mechanics in that it resolves the measurement problem while retaining an essentially classical worldview without parallel universes, a framework-dependent reality or action-at-a-distance.
Periodically driven atomic systems
Keywords: ultracold atoms
Floquet theory
spectroscopy
BEC
ion traps

This thesis is concerned with a variety of topics grouped together under the general theme of periodically driven atomic systems. Periodic driving is ubiquitous in most techniques used in atomic physics, be it laser cooling, ion trapping or AC magnetic fields. An in-depth understanding of the behaviour of such systems can be provided through Floquet theory which will develop as a central theme in the following chapters.
The thesis is divided in two parts: neutral atoms, and ions and biomolecules. In the first part I discuss a new 41K-87Rb mixture experiment, built during the first year of my DPhil. This species combination has some very broad and low-loss interspecies Feshbach resonances that are instrumental for carrying out the experiments discussed in the first chapter. Unfortunately, the mixture experiment had to be put aside and our attention was shifted to Time-Averaged Adiabatic Potentials (TAAPs) and how these can be extended using multiple Radio-Frequency (RF) fields. This technique opens up the way for precise interferometric measurements. Lastly, the peculiar behaviour of Modulation Transfer Spectroscopy (MTS) of 39K is investigated and a linearising transformation for four-wave mixing processes is presented.
In the second part we turn our attention to charged ions and biomolecules and the techniques of ion trapping. We propose a novel technique for co-trapping charged particles with vastly different mass-to-charge ratios and thoroughly explore its consequences. The behaviour of the trap and the stability of equations with periodic coefficients in general is studied using Floquet theory. The normal modes and symmetries of the system also need to be considered in relation to the effectiveness of the sympathetic cooling of the ions. Small systems were simulated using a Molecular Dynamics (MD) approach in order to capture the effect of micromotion and other heating processes.
Search for new physics in the dijet invariant mass spectrum at 8 TeV
Keywords: jets
exotic searches
high energy physics

A search for resonance signals from new physics models was performed using the ATLAS dijet invariant mass spectrum at a center-of-mass energy of 8 TeV. The full dataset from the 2012 data-taking period was used, corresponding to an integrated luminosity of 20.3 fb−1. The analysis covered a mass range from 250 GeV to 4.5 TeV and found no evidence of an excess anywhere in the spectrum. Upper mass limits were set at 95% CL on both model- specific benchmark new physics signals and on two different generic resonance forms: a Gaussian shape and a Breit-Wigner shape which accounted for pdf and detector effects. The analysis excluded excited quarks below 4.06, heavy W' bosons below 2.45, colour-octet scalars below 2.70, leptophobic chiral excited bosons W* below 1.75, and quantum black holes below 5.66 and 5.62 for the Qbh and BlackMax generators respectively.
Organic-inorganic hybrid photovoltaics based on organometal halide perovskites
Keywords: solar cell
perovskites
organic-inorganic hybrids
photovoltaics

This thesis details the development of a novel photovoltaic device based on organometal halide perovskites. The initial focus of this thesis begins with the study of lighttrapping strategies in solid-state dye-sensitised solar cells (detailed in chapter 3). While I report enhancement in device performance through the application of near and far-ﬁeld light-trapping techniques, I ﬁnd that improvements remain step-wise due to fundamental limitations currently employed in dye-sensitised solar cell technology— notably, the available light-sensitising materials. I found a promising yet under researched family of materials in the methyl ammonium tri-halide plumbate perovskite (detailed in chapter 4). The perovskite light-sensitiser was applied to the traditional mesoscopic sensitised solar cell device architecture as a replacement to conventional dye yielding world-record breaking photo-conversion e!ciencies for solid-state sensitised solar cells as high as 8.5%. The system was further developed leading to the conception of a novel device architecture, termed the mesoporous superstructured solar cell (MSSC), this new architecture replaces the conventional mesoporous titanium dioxide semiconductor with a porous insulating oxide in aluminium oxide, resulting in very low fundamental losses evidenced through high photo-generated open-circuit voltages of over 1.1 V. This development has delivered striking photo-conversion ef- ﬁciencies of 10.9% (detailed in chapter 6).
The 'Full Liberty of Public Writers': special treatment of institutional journalistic speech in English law 
Keywords: freedom of speech
journalism
press freedom
freedom of the press

This paper is an investigation into one aspect of the constitutionality of journalistic freedom in the law of England and Wales. It argues that there are instances where the law provides special treatment for the expression of institutional journalists, and that this is legitimate. The paper has two distinct parts, the doctrinal and the theoretical. Chapter one is doctrinal, and establishes that the law does provide special treatment to institutional journalistic speech. It classifies such treatment, demonstrating that these privileges come in different forms, and create different layers of rights. These forms can be distinguished according to whether the privileges are afforded to institutional journalists or functional journalism, or merely to general speech. The theoretical part of this paper forms chapters two and three. Chapter two assumes that the provision of special treatment to institutional journalists is justified where institutional journalistic speech particularly promotes free speech values. It argues that institutional journalistic speech does indeed perform such a function, by virtue of particular characteristics it possesses, namely reach and reputation, which are employed in processes such as reporting, investigating and interrogating. Chapter three considers the counter-arguments to this position. First it considers some arguments that challenge the thesis assumed in chapter two, and then it considers more specific criticisms of the provision of special treatment to institutional journalistic speech. It concludes that, while these limit the validity of the law’s affording special treatment to institutional journalistic speech, they do not extinguish it.
Investigation of the contribution of cutaneous HPV E6 proteins towards the development of non melanoma skin cancer
Keywords: BAK
Integrin Beta 1
Apoptosis
HPV

Sunlight is the main aetiological agent in the development of non melanoma skin cancer (NMSC), the most commonly diagnosed cancer in the fair skinned population. Mounting epidemiological and molecular data suggest that infection with cutaneous Human papillomavirus (HPV) may act as a co-factor in the early stages of NMSC development. The viral E6 protein can inhibit the apoptotic response to UV induced damage, partly through proteasomal degradation of the pro-apoptotic protein BAK. Upon UV damage, BAK undergoes a series of activating modifications that are linked to changes in phosphorylation status. BAK activation commits a cell to apoptosis through mitochondrial permeabilisation.
The aim here was to elucidate the underlying mechanism of HPV5 E6-mediated BAK degradation. Mutation of lysine 113 in BAK and siRNA knockdown of a novel HPV5 E6 associated ubiquitin ligase, HERC1, prevented HPV5 E6 mediated-BAK degradation. A proximity ligation in situ assay showed an interaction between HERC1 and BAK in cells, which was dependent on the presence of the E6 protein and UV irradiation. Probing the BAK conformation and phosphorylation status suggests E6 targets a dephosphorylated BAK monomer before mitochondrial permeabilisation occurs, leading to the proposal of a mechanism for the interaction of BAK with HERC1 which depends on the activation status of BAK and a putative BH3 domain identified in HERC1.
Additional work identifies β1-integrin as an interacting protein of a conserved YHDW amino acid motif at the C-terminus of certain β1 HPV E6 proteins. Only expression of E6 proteins with the YHDW motif (HPV5 and 8) in keratinocytes disrupted β1 integrin membrane localisation, altered expression of β1 integrin downstream effectors, such as focal adhesion kinase, and increased cell migration. Mutation of W157A in the HPV5 E6 YHDW motif reduced these effects.
Together, this work furthers the understanding of mechanisms by which infection with HPV may promote the early stages of NMSC development.
Early-type disk galaxies
Keywords: spiral
s0
kinematics
galaxy evolution
early-type
galaxy formation
bars
galaxies
stellar populations
dynamics
bulge
disk

In this thesis I investigate the dynamics and stellar populations of a sample of 28 edge-on early-type (S0--Sb) disk galaxies, 22 of which host a boxy or peanut-shaped bulge. I begin by constructing mass models of the galaxies based on their observed photometry and stellar kinematics. Subject to cosmologically motivated assumptions about the shape of dark haloes, I measure in a purely dynamical way their stellar and dark masses. I make a preliminary comparison between the dynamically determined stellar masses and those predicted by stellar population models.
I then compare the Tully-Fisher (luminosity--velocity) relations of the spirals and S0s in the sample. I show that S0s are systematically fainter at a given rotational velocity, but the amount by which they are fainter is less than expected by models in which they are the products of truncation of star formation in spirals. This raises the possibility that S0s are smaller or more concentrated than spirals of the same mass.
I then study the vertical structure of the boxy and peanut-shaped bulges of a subset of the sample. Among this sample of five galaxies, I find one example in which the stellar populations show no evidence that the bulge and the disk formed in different processes, and in which the bulge is in perfectly cylindrical rotation, i.e. its line-of-sight velocity does not change with height above the disk. This galaxy is probably a pure disk galaxy. However, even with this small sample, I also show that cylindrical rotation and homogeneous stellar populations are not ubiquitous properties of boxy and peanut-shaped bulges.
Finally I analyse central and radial trends in the stellar populations of the bulges of full sample of 28 galaxies. I find that, at a given velocity dispersion, the central stellar populations of these barred early-type disk galaxies are identical to those of elliptical galaxies, which suggests that secular evolution does not dominate the centre of these galaxies. However, the radial metallicity gradients are shallower than those of ellipticals. This is qualitatively consistent with chemodynamical models of bar formation, in which radial inflow and outflow smears out pre-existing gradients.