VictorJuiz/thesis huggingface dataset:
Characterizing the spatial properties of high harmonic generation

This thesis is concerned with describing a novel technique for characterizing the (spectrally resolved) spatial properties of light. The new approach, known as Scanning Interference Method for Integrated Transverse Analysis of Radiation (SCIMITAR), is a specific implementation of a variable-separation two-pinhole interferometer. Evaluation of the series of interference patterns produced by a SCIMITAR measurement allows the transverse profiles of intensity and spatial phase to be retrieved, while at the same time characterizing the spatial coherence of light. Including a diffraction grating in the simple experimental arrangement permits the spectral dependence of the aforementioned quantities to be measured.
The SCIMITAR technique was demonstrated by characterizing the spatial properties of high harmonic generation (HHG). Excellent agreement with an alternate characterization technique known as SWORD was observed. The spectral dependence of the harmonic spatial properties was also investigated. Evidence suggesting absorption may play a role in shaping the harmonic intensity and spatial coherence was presented. Treating the harmonic radiation as either a fully coherent or partially coherent beam allowed the intensity width, spatial phase curvature and coherence width of the harmonic radiation source to be deduced.
Measurement of the fine variation of the harmonic complex coherence factor (CCF) with pinhole separation revealed distinctive modulations. The Van Cittert-Zernike theorem was modified by including a Gerchberg-Saxton inspired improvement, allowing data missing from the SCIMITAR measurement to be inferred. The harmonic equivalent incoherent source intensity profile was found to be asymmetric with low intensity features isolated away from the optical axis. Calculations of the diffraction pattern produced by illumination of a non-redundant array of pinholes showed that the modulated harmonic properties could adversely influence lensless imaging-type experiments.

Keywords: coherence
x-ray
metrology
ultrafast
Advisor: Hooker, S
Deterministic simulation of multi-beaded models of dilute polymer solutions

We study the convergence of a nonlinear approximation method introduced in the engineering literature for the numerical solution of a high-dimensional Fokker--Planck equation featuring in Navier--Stokes--Fokker--Planck systems that arise in kinetic models of dilute polymers. To do so, we build on the analysis carried out recently by Le~Bris, Leli\`evre and Maday (Const. Approx. 30: 621--651, 2009) in the case of Poisson's equation on a rectangular domain in R2
, subject to a homogeneous Dirichlet boundary condition, where they exploited the connection of the approximation method with the greedy algorithms from nonlinear approximation theory explored, for example, by DeVore and Temlyakov (Adv. Comput. Math. 5:173--187, 1996). We extend the convergence analysis of the pure greedy and orthogonal greedy algorithms considered by Le~Bris, Leli\`evre and Maday to the technically more complicated situation of the elliptic Fokker--Planck equation, where the role of the Laplace operator is played out by a high-dimensional Ornstein--Uhlenbeck operator with unbounded drift, of the kind that appears in Fokker--Planck equations that arise in bead-spring chain type kinetic polymer models with finitely extensible nonlinear elastic potentials, posed on a high-dimensional Cartesian product configuration space D=D1×⋯×DN
contained in RNd
, where each set Di
, i=1,…,N
, is a bounded open ball in Rd
, d=2,3
. We exploit detailed information on the spectral properties and elliptic regularity of the Ornstein--Uhlenbeck operator to give conditions on the true solution of the Fokker--Planck equation which guarantee certain rates of convergence of the greedy algorithms. We extend the analysis to discretized versions of the greedy algorithms.

Keywords: high-dimensional PDE
numerical analysis
Fokker-Planck equations
spectral methods
polymer solutions
greedy algorithms
Mathematics Subject Classification (2000): 65N15,65D15,41A63,41A25
statistical mechanics
nonlinear spproximation
Advisor: Süli, E
Rich clients and poor patrons

Quis Dives Salvetur (QDS) is a small but fascinating homiletic treatise composed by Clement of Alexandria which seeks to address certain problems concerning the salvific status of wealthy Christians. The aim of this thesis is to ascertain the beliefs and actions that Clement wants his wealthy readers to adopt as a result of reading this discourse. This study presupposes that Clement's views on wealth did not change drastically over the period of time since composing his other works. The implication is that the complex philosophical and theological concepts in QDS may be illuminated from similar treatments in his other works.
This study shows that the Graeco-Roman philosophical and cultural conventions of friendship play fundamental roles in the two rubrics under which many of the key concepts in QDS may be grouped. Salvation is ultimately friendship and sonship with God, and is the telos of philosophical and ethical ascent, where the believer becomes like God in his apathetic and beneficent nature. Clement adapts the Stoic doctrine of oikeiosis to describe the way in which a believer progresses from a nascent self-knowledge and self-love at regeneration to the knowledge of God and love of God at his adoption as son and friend. Salvation in QDS is not purely an individualistic pursuit, rather it is located in the church as the ideal philosophical community of friends, where relations are grounded on an ethic of reciprocity.
This study challenges the dominant view held by modern scholars that the whole of QDS is devoted to vindicating the possibility that the rich can be saved even as rich. This view ignores the fact that the rich are to strive for the gnostic state of apatheia. Having devoted the first half of the treatise to showing that the wealthy are called to salvation, Clement counsels them, in the second half, to distribute their superfluous possessions indiscriminately to those less well-off in their community, while retaining a frugal self-sufficiency. Concomitant with indiscriminate almsgiving, rich believers must undertake a second repentance which requires them to submit to an advanced Christian who will act as their spiritual patron, guide and advocate before God.

Advisor: Tuckett, C
Anisotropic intermolecular forces in rare gas-hydrogen halide systems

The thesis is concerned with the derivation of anisotropic intermolecular potentials from experimental data. For the rare gas - hydrogen halide systems the most useful experimental results are those from molecular beam rotational spectra of van der Waals complexes and from pressure broadening of hydrogen halide rotational spectra by rare gases. Intermolecular potentials for the Ar.HCl system had previously been obtained from each of these experiments separately, but none of the potentials proposed succeeded in reproducing all the available data.
In the present work, improved theoretical methods are developed for the calculation of molecular beam spectra and line broadening cross sections from a proposed intermolecular potential. The methods developed are substantially faster than those previously available, allowing their use in a least squares procedure to determine potential parameters. Several possible parameterisations of the intermolecular potential are then considered for Ar.HCl, and least squares fits of potential parameters to experimental results are performed for this system. Measurements of total differential cross sections and second virial coefficients are included in the least squares fits, in addition to the experiments mentioned above. The experimental data demonstrate conclusively that the equilibrium geometry of Ar.HCl is linear, with the atomic arrangement as written. The equilibrium intermolecular distance is 400±3 pm, with an absolute well depth of 18andpm;10 cm-1 . The only feature of the potential which is not well determined by the experimental results is the behaviour around the linear Ar.Cl-H geometry.
The results for Ar.HCl are then extended to the systems Ne.HCl, Kr.HCl and Xe.HCl, allowing the dependence of the intermolecular potential on the rare gas to be considered. The molecular beam spectra for Ne.HCl can be fitted only by a potential with a secondary minimum at the linear Ne.Cl-H geometry, in addition to the primary minimum at the linear Ne.H-Cl geometry. The experimental results for the other rare gas - HC1 systems are not very sensitive to this feature of the potential, and the potentials for these are constrained to be similar to that for Ne.HCl in this region. The potential surfaces for all the rare gas - HC1 systems have similar shapes, and appear to be nearly conformal.
Finally, intermolecular potentials are obtained for the systems Ar.HF, Kr.HF and Xe.HF from molecular beam spectra. The experimental data for these systems are less extensive than for the HC1 systems, and the potentials obtained are reliable only in the region of the absolute minimum. The HF systems are considerably more anisotropic than the HC1 systems, and it is suggested that this is principally due to greater induction forces in the HF systems. Experiments are suggested which would provide further information on the intermolecular potentials for both HF and HC1 systems, and predictions of the results are made using the current best fit potentials.

Advisor: Howard, B
Contract enforcement in post-Soviet Ukrainian business

Using the findings of a five-year ethnographic study, this thesis examines the contractual relationships that prevail in low-technology moderately competitive industries characteristic of the contemporary Ukrainian economy. The research reports on how contracts are enforced and how the stability of business relationships is ensured in Ukraine.
The established view of many scholars that business efficiency is held back in most post-Soviet economies by frequent contractual violations and dysfunctional courts is not entirely supported by the research underpinning this thesis: in Ukraine, contract enforcement is generally effective enough to allow stability in day-to-day transactions, and the commercial courts do provide adequate backing.
Although the mechanisms used to enforce contracts in Ukraine are generally similar to those found in developed countries, there are distinctive features within the overall pattern. In particular, firms rely extensively on repeated interactions and self-enforcing devices while signing short-term formal contracts and avoiding interdependency between trading partners. They do not rely on their reputation or business association memberships and they make no use of private arbitration. Instead, a few legal institutions dating back to the Soviet period proved adaptable and viable in a market economy.
When transactions involve either state-owned companies or the exercise of administrative resources, contract enforcement becomes problematic. Illegal kickbacks from suppliers and the coercive use of state machinery come into play, and asking a court to enforce a contract is more costly and less effective than in other cases. However, the author shows that in the typical everyday transactions of Ukrainian private firms, the state and its administrative resources are involved in the minority of cases, and that they do not undermine the dominant pattern of orderly contractual dealings.
The thesis concludes that the contractual pattern prevalent in Ukraine effectively serves straightforward traditional buyer-seller transactions but it is ill-suited to meet the requirements of globalized trade, production diversification and technological progress. Adaptations of the existing system to meet these requirements are likely to depend upon changes in the wider business environment, namely upon institutions constraining the coercive power of the state.

Keywords: post-Soviet transition
dispute resolution
courts
Ukraine
contract enforcement
reputation
Advisor: Kurkchiyan, M
Decker, C
Living the liminal: facilitating pilrimage on the Isle of Iona, Scotland

This thesis spotlights a social group pilgrimage site staff heretofore neglected in anthropological research. The main subjects are the Resident Group ('ressies') working at the lona Community's guest centres. Based on an accumulative 16-month fieldwork, the ethnographic evidence challenges the assumptions that pilgrims' 'sacred' encounters are unmediated, that site staff passively acquiesce with the dominant ideology, and that the production of pilgrimage experience is unproblematic. Building on existing paradigms of pilgrimage as 'contested', 'movement'-oriented, and a form of'practice', the Turners' classic view of pilgrimage as rite de passage is deployed to show that 'place' and 'landscape' are key themes in people's understanding of and engagement with this ancient pilgrimage isle today.
Part I lays the theoretical and methodological groundwork and introduces the research locale, locating it within recent Celtic revivalisms. It also addresses how the lona Community (ressies' employers) situate their religio-political vision within the wider sociological and theological contexts of contemporary British Christianity.
Part II recounts the historical and contemporary formulations of lona pilgrimage and tourism. A Heideggerian perspective of 'dwelling' illuminates how devotees appropriate lona's 'sacred' geography as a resource for personal revelation and self- transformation. Ethnographic accounts of visitors' 'Iona experience' are provided as a comparative foil to the site staff who enable this distinctive pilgrimage encounter.
Part III explores ressies' motivations, discourses, and experiences at lona as a locus of 'holistic' work (and worship). It elucidates their complex relationship with the lona Community and how ressies contest their idealised corporate identity. Van Gennep's concept of 'liminality' and Ardener's 'paradox of remote places' emerge as central themes in analysing ressies' 'betwixt and between' 'selves'. An investigation of the social and ideological structures of the Resident Group setup as a 'total institution' further reveals the impact of the 'leaving lona' rhetoric and reality upon ressies' post-Iona lives.

Advisor: Barnes, R
Simulation studies of monodisperse self-assembly

The processes by which anisotropic colloidal and nanoscale particles may come together to form ordered monodisperse structures are not well understood. The canonical example of such a system is provided by the assembly of virus capsids, in which tens to thousands of particles of one or a few types assemble efficiently into ordered, highly symmetrical shells. Other examples include a wide variety of protein oligomers, and there is interest in producing analogous systems of synthetic particles.
In this thesis I study the self-assembly of simple model particles, consisting of spheres decorated with attractive patches. I consider in detail the assembly of clusters of particles corresponding to the Platonic solids. For the majority of these structures assembly is found to be efficient over a wide range of parameter space. The optimal conditions represent a compromise between thermodynamic stability and kinetic accessibility.
We consider two versions of the model, with and without constraints on the torsion angle of bound particles. In both cases the structures with triangular faces are found to assemble most easily. In the absence of torsional constraints dodecahedra will not assemble under any set of parameters as a result of the preferential formation of disordered aggregates. With torsional constraints included all of the Platonic solids assemble successfully and the behaviour of the model is considerably changed. In particular disordered aggregates become far less favourable.
I explore possible methods of assembling larger structures, either via “hierarchical” assembly where small clusters are first assembled and then used as building blocks in another stage of assembly, or by a templating method in which an inner cluster acts as a template for a larger outer cluster. These approaches are studied using the “Virtual Move Monte Carlo” cluster move algorithm, the behaviour of which we examine in some detail.

Keywords: Self-assembly
monodisperse
virus
Monte Carlo
simulation
Advisor: Louis, AA
Doye, JPK
Asymmetric synthesis of heterocycles via cation-directed cyclizations and rearrangements

The aim of this project was to utilize chiral cation-directed catalysis in the asymmetric synthesis of novel hererocycles. This goal was initially realized by the synthesis of azaindolines in high yields and enantioselectivities (Chapter 2).
Extension of this methodology to substrates bearing two stereogenic centres was successful, although control over both diastereoselectivity and enantioselectivity in this process was modest.
Finally the synthesis of heterocycles utilizing cation-directed rearrangement processes was examined, with proof of concept obtained for a novel asymmetric cyclization to form xanthenes.

Keywords: Asymmetric catalysis
phase-transfer catalysis
methodology
Advisor: Smith, M
The role of two pore channels (TPCs) in pancreatic beta cell stimulus-secretion coupling

This thesis presents an investigation into the role of the recently identified two pore channels (TPCs) in beta-cell stimulus-secretion coupling. TPCs are the receptors for calcium mobilising messenger nicotinic acid adenine dinucleotide phosphate (NAADP) located in the membrane of acidic intracellular calcium stores. It is proposed that they are responsible for the ATP-sensitive potassium channel (KATP channel) independent pathway of stimulus-secretion coupling; and that this pathway is not subordinate to the KATP channel dependent pathway; but an alternative explanation of stimulus-secretion coupling in its own right.
The first section of this thesis presents a characterisation of sub-membrane calcium signals observed in primary mouse beta-cells in response to glucose and the membrane-permeable acetoxymethyl ester form of NAADP (NAADP-AM) using the non-ratiometric fluorescent calcium indicator fluo-4 and total internal reflection (TIRF) microscopy. These are compared to global cytosolic calcium changes observed with epifluorescence microscopy. Factors affecting the shape and time course of responses are investigated, and pharmacological tools used to provide evidence for the role of intracellular calcium release from acidic stores mediated by NAADP.
Having characterised the calcium responses of beta-cells using TIRF; the second part of the thesis examines the effects of knocking out TPC2 (single KO), or both TPC1 and TPC2 (DKO) on these responses; after an initial assessment of pancreatic islet and beta-cell morphology using electron microscopy. Gender differences in beta-cell responses to glucose and NAADP are assessed in both wild type and knockout animals.
Finally, the third section presents the discovery of elementary calcium release events in pancreatic beta-cells. The current project visualises what are likely the triggering events for the global calcium signals examined in sections one and two. They take the form of localised calcium release in response to NAADP-AM and glucose; akin to sparks and puffs observed by stimulation with cADPR and IP3. Optical quantal analysis demonstrates the quantal nature of the events and estimates the size of the unitary calcium release unit (CRU) for NAADP.

Keywords: Calcium Signalling
Stimulus-Secretion Coupling
NAADP
TPC
Pancreatic Beta Cells
Two Pore Channels
Advisor: Galione, A
Operators on banach spaces of Bourgain-Delbaen type

The research in this thesis was initially motivated by an outstanding problem posed by Argyros and Haydon. They used a generalised version of the Bourgain-Delbaen construction to construct a Banach space
X
K
for which the only bounded linear operators on
X
K
are compact perturbations of (scalar multiples of) the identity; we say that a space with this property has very few operators. The space
X
K
possesses a number of additional interesting properties, most notably, it has
e
l
l
1
dual. Since
e
l
l
1
possesses the Schur property, weakly compact and norm compact operators on
X
K
coincide. Combined with the other properties of the Argyros-Haydon space, it is tempting to conjecture that such a space must necessarily have very few operators. Curiously however, the proof that
X
K
has very few operators made no use of the Schur property of
e
l
l
1
. We therefore arrive at the following question (originally posed in cite{AH}): must a HI,
m
a
t
h
c
a
l
L
i
n
f
t
y
,
e
l
l
1
predual with few operators (every operator is a strictly singular perturbation of
l
a
m
b
d
a
I
) necessarily have very few operators?
We begin by giving a detailed exposition of the original Bourgain-Delbaen construction and the generalised construction due to Argyros and Haydon. We show how these two constructions are related, and as a corollary, are able to prove that there exists some
d
e
l
t
a
>
0
and an uncountable set of isometries on the original Bourgain-Delbaen spaces which are pairwise distance
d
e
l
t
a
apart.
We subsequently extend these ideas to obtain our main results. We construct new Banach spaces of Bourgain-Delbaen type, all of which have
e
l
l
1
dual. The first class of spaces are HI and possess few, but not very few operators. We thus have a negative solution to the Argyros-Haydon question. We remark that all these spaces have finite dimensional Calkin algebra, and we investigate the corollaries of this result. We also construct a space with
e
l
l
1
Calkin algebra and show that whilst this space is still of Bourgain-Delbaen type with
e
l
l
1
dual, it behaves somewhat differently to the first class of spaces.
Finally, we briefly consider shift-invariant
e
l
l
1
preduals, and hint at how one might use the Bourgain-Delbaen construction to produce new, exotic examples.

Keywords: Operator Algebras
Banach spaces
Bourgain-Delbaen spaces
Advisor: Haydon, R
Bearing capacity of perforated offshore foundations under combined loading

This thesis presents experimental work and numerical analysis that has been undertaken to assess the bearing capacity of perforated offshore foundations. Perforated foundations may be used to support subsea infrastructure, including as mudmats into which a number of perforations have been made, or as grillages which consist of a series of structurally connected strip footings. Larger gravity base foundations, such as for offshore wind turbines or oil and gas platforms, may adopt a single central perforation. The advantages of using perforated foundations can include reduced material requirements and easier offshore handling as a result of smaller weight and lower hydrodynamic forces during deployment. Limited guidance currently exists for assessing the bearing capacity of these foundation types.
Bearing capacity of perforated foundations has been examined in this thesis under conditions of combined vertical, horizontal and moment loading which is typical in offshore settings. Undrained soil conditions have been considered, except for the case of grillages in which drained conditions are often most relevant. Experimental work has included centrifuge testing of ring and square annular foundations on clay, and 1g testing of grillage foundations on sand. Finite element modelling has also been undertaken to assess perforated foundation capacity. A Tresca material subroutine (UMAT) and an adaptive meshing scheme have been developed to improve the accuracy of the finite element analysis carried out.
The results showed that perforated foundations can be an efficient foundation solution for accommodating combined loading. As a ratio of their vertical load capacity, perforated foundations may be able to withstand higher moment and horizontal loads compared with unperforated foundations. The experimental and numerical results have been used to develop design expressions that could be employed by practitioners to estimate the vertical and combined load bearing capacity of these foundation types.

Keywords: Tresca model
perforated foundations
Bearing capacity
adaptive meshing
combined loading
Advisor: Byrne, B
Martin, C