7,966 Works

Subgrid scale modelling of transport processes.

Adam S Candy
Consideration of stabilisation techniques is essential in the development of physical models if they are to faithfully represent processes over a wide range of scales. Careful application of these techniques can significantly increase flexibility of models, allowing the computational meshes used to discretise the underlying partial differential equations to become highly nonuniform and anisotropic, for example. This exibility enables a model to capture a wider range of phenomena and thus reduce the number of parameterisations...

Fibroblast growth factors in gastrointestinal development, homeostasis and injury

Su Sin Ding
Fibroblast growth factors (FGFs) and their receptors (FGFRs) are essential for controlling cell growth and proliferation, angiogenesis, wound healing and tumourigenesis. In mammals, there are twenty-three FGFs and five FGFRs, with each FGFR having different ligand binding specificities. FGFs are thought to act in a paracrine manner, in which they are secreted by one cell and activate FGFRs on another cell type, and such interaction helps to establish the fundamental crosstalk between epithelium and mesenchyme...

Modelling and control of coupled infinite-dimensional systems

Xiaowei Zhao
First, we consider two classes of coupled systems consisting of an infinite-dimensional part [sigma]d and a finite-dimensional part [sigma]f connected in feedback. In the first class of coupled systems, we assume that the feedthrough matrix of [sigma]f is 0 and that [sigma]d is such that it becomes well-posed and strictly proper when connected in cascade with an integrator. Under several assumptions, we derive well-posedness, regularity and exact (or approximate) controllability results for such systems on...

Optical scattering for security applications

Peter R Seem
Laser Surface Authentication (LSA) has emerged in recent years as a potentially disruptive tracking and authentication technology. A strong need for such a solution in a variety of industries drove the implementation of the technology faster than the scientific understanding could keep up. The drive to miniaturise and simplify, the need to be robust against real-world problems like damage and misuse, and not least, intellectual curiosity, make it clear that a firmer scientific footing is...

Cardiovascular magnetic resonance of the arterial wall

Niall Gerald James Keenan
BACKGROUND Atherosclerosis is the single greatest cause of mortality and morbidity in the developed world. Cardiovascular magnetic resonance (CMR) is a non-invasive imaging technique which can interrogate the arterial wall and identify atherosclerotic disease. CMR can provide quantitative volumetric data of atherosclerosis burden which have begun to be used in clinical trials, however comparatively few studies have been performed. We aimed to validate this approach ex vivo, to use it to characterise a normal population...

On improving the performance of optimistic distributed simulations

Nikolaos Dimakis
This report investigates means of improving the performance of optimistic distributed simulations without affecting the simulation accuracy. We argue that existing clustering algorithms are not adequate for application in distributed simulations, and outline some characteristics of an ideal algorithm that could be applied in this field. This report is structured as follows. We start by introducing the area of distributed simulation. Following a comparison of the dominant protocols used in distributed simulation, we elaborate on...

The use of botanical synergists to increase the efficacy of natural pyrethrins

Anna Khot
Insecticide resistance is an important aspect of pest control on both crop pests and vectors of animal diseases. Resistance can be caused by a number of mechanisms, one of which is enhanced detoxification of the insecticide by metabolic enzymes. Synergists may be used in insecticide formulations to inhibit metabolic defences in the insect, allowing the insecticide to reach its target site and kill the insect, thus enhancing the effect of the insecticide. This PhD project...

Environmental control of sepalness and petalness in waterilies

Kate Annabelle Warner
Existing models of perianth evolution are inadequate to explain morphological variation in tepals of early-divergent angiosperms as conventional concepts regarding the perianth include an unstated assumption that the characteristics of sepalness (possessing sepal-like characters) and petalness (possessing petal-like characters) must be fixed to entire individual organs. However, initial observations found that in Nuphar Smith, Nymphaea L. (Nymphaeaceae) and Schisandra Michx. (Schisandraceae), sepaloid (green) and petaloid (colourful) patches can both occur on the same individual perianth...

Modelling multiple-material flows on adaptive unstructured meshes.

Cian Wilson
The ability to distinguish between regions with different material properties is essential when numerically modelling many physical systems. Using a dual control volume mesh that avoids the problem of corner coupling, the HyperC face value scheme is extended to multiple dimensions and applied as a device for material advection on unstructured simplex meshes. The new scheme performs well at maintaining sharp interfaces between materials and is shown to produce small advection errors, comparable to those...

Polypeptide extraction using reverse micelles

Selina Lavinia Gunther
The reverse micelle (RM) extraction of human IgG4 monoclonal antibodies (MAbs), humanized IgG4 MAb B72.3 Fab fragments and horse heart cytochrome-c was investigated. The effects of system parameters on forward (FE) and backward (BE) extraction was examined, and optimal extraction conditions were determined. Sodium bis(2-ethylhexyl)sulfosuccinate (AOT), bis(2-ethylhexyl)phosphate (HDEHP), isooctane and corn oil were the model surfactants and solvents. Precipitate formation was investigated, and non-ionic (polyoxyethylene(4) lauryl ether i.e. Brij 30) and counterionic (trioctylmethylammonium chloride i.e....

Binning of the primordial power spectrum and optimal galaxy survey design

Paniez Paykari
The power spectrum describes the fluctuations in the Universe and encodes much of the cosmological information. Hence measuring different types of power spectra is of great importance in cosmology today. In this thesis we try to constrain two of these power spectra, the primordial power spectrum and the galaxy power spectrum. First we analyse the binning of the primordial power spectrum. The primordial power spectrum describes the initial perturbations in the Universe which eventually grew...

Economic values, distributional impacts and conservation outcomes for coral reef marine protected areas

Venetia Hargreaves-Allen
Marine protected areas (MPAs) are the dominant global strategy to counter widespread coral reef degradation, which threatens these coral reef ecosystems, the biodiversity they support, and the direct and indirect benefits they provision for millions of stakeholders, many of whom are in developing countries and have a high reliance on natural resources. Insufficient understanding of the conditions that enable MPAs to achieve their conservation and development goals means MPAs are yet to achieve their full...

Carbon nanotubes as fire gas sensors

Ruth Elizabeth Pearce
Multi walled carbon nanotubes (MWCNTs) possess properties that make them particularly relevant for sensing applications in both the gas and liquid phase. This study presents an evaluation of cheap readily available CVD grown MWCNTs for use as fire gas sensors. Current fire detectors exploit heat and smoke detectors and it is hoped that the inclusion of gas detectors will increase the speed and reliability of detection. In order to prepare a variety of different MWCNTs...

Studies on Resistance to Vegetative (Vip3A) and Crystal (Cry1A) Insecticidal Toxins of Bacillus thuringiensis in Heliothis virescens (Fabricius)

Brian R Pickett
Bacillus thuringiensis (Bt) toxins expressed in commercial transgenic crop varieties are all δ-endotoxins (Cry toxins) but the identification of novel vegetative insecticidal proteins (Vip toxins) has extended the range of insecticidal proteins derived from Bt. One such Vip toxin, Vip3A, primarily targets the midgut epithelium cells of susceptible insects as Cry toxins do, although they appear to have different binding sites. The present study investigated the comparative toxicity of Vip3A, Cry1Ab and Cry1Ac against Heliothis...

Acyclic stereocontrol in the Claisen rearrangement

Alexander O'Brien
This thesis examines the issues of acyclic stereocontrol in the Claisen rearrangement, with particular emphasis on the effects of exopericyclic stereocentres – i.e. those adjacent to the array of atoms directly involved in the sigmatropic process. It is divided into three main parts: The first section provides a review of the field of acyclic stereocontrol. The models used to explain the development of relationships between stereocenters in systems lacking well-defined conformational constraints are discussed. This...

The regulation of Fibronectin matrix assembly by Tenascin-C

Wing Sum To
Fibronectin (FN) is a ubiquitous component of the extracellular matrix (ECM). Its assembly into 3D fibrillar matrices is essential during development and tissue repair to maintain tissue architecture and provide environmental signals to cells. However, FN deposition must be tightly regulated as excessive assembly is a major hallmark of fibrotic diseases and cancer. Tenascin-C (TN-C) is a large, multi-domain ECM glycoprotein that co-localizes with newly synthesized FN fibrils in vivo during development, wound repair and...

Synchronisation in dynamically coupled maps

Adele Peel
The central aim of this thesis is to better understand the dynamics of a set of dynamically coupled map systems previously introduced by Ito & Kaneko in a series of papers (Phys. Rev. Lett. 88 (2002), no. 2, 028701 and Phys. Rev. E 67 (2003), no. 4, 046226). The current work extends Ito & Kaneko’s studies to clarify the changes in macrodynamics induced by the differences in microdynamics between the two systems. A third system...

Characterisation of ADAMTS-4 endocytosis by chondrosarcoma cells and chondrocytes

Kathryn Owen
Aggrecan is one of the most abundant components of the articular cartilage matrix and its degradation by aggrecanases is considered to be a key early event in the development of osteoarthritis. This study investigates whether the extracellular level of ADAMTS-4 (a disintegrin and metalloproteinase with thrombospondin type 1 motifs-4), one of the most studied aggrecanases, can be regulated by receptor-mediated endocytosis. Exogenously-added ADAMTS-4 disappeared from the medium of HTB94 cells and TCA-soluble degradation products of...

Transient optical studies of photoinduced charge transfer in semiconductor quantum dot solar cells

Henry C. Leventis
Semiconductor quantum dots (also referred to as 'nanocrystals‘) are well suited as light-harvesting agents in solar cells because they are robust, have tuneable effective band gaps, and are easy to process. The research presented in this thesis is targeted towards the study of excitonic solar cells employing semiconductor nanocrystals as a light harvesting component. Gaining control of the interfacial charge transfer processes in operation in these devices forms a crucial part of any attempt to...

Tailoring the nanostructure of sol-gel derived bioactive glasses and investigating their interactions with proteins

Sen Lin
Sol-gel derived bioactive glasses with the 70S30C composition (70 mol% SiO2 and 30 mol% CaO) have high potential as materials for bone regeneration and devices for sustained drug delivery. They bond to bone and have a unique tailorable nanoporosity, which affects protein adsorption and cellular response. The first aim of this thesis is to fully characterise the evolution of the nanoporous structure of sol-gel derived bioactive glass for the first time, to fully understand its...

Thermal design of air-cooled axial flux permanent magnet machines

David A. Howey
Accurate thermal analysis of axial flux permanent magnet (AFPM) machines is crucial in predicting maximum power output, and a number of heat transfer paths exist making it difficult to undertake a general analysis. Stator convective heat transfer is one of the most important and least investigated heat transfer mechanisms and therefore is the focus of the present work. Experimental measurements were undertaken using a thin-film electrical heating method based on a printed circuit board heater...

Indexed dependence metadata and its applications in software performance optimisation

Lee William Howes
To achieve continued performance improvements, modern microprocessor design is tending to concentrate an increasing proportion of hardware on computation units with less automatic management of data movement and extraction of parallelism. As a result, architectures increasingly include multiple computation cores and complicated, software-managed memory hierarchies. Compilers have difficulty characterizing the behaviour of a kernel in a general enough manner to enable automatic generation of efficient code in any but the most straightforward of cases. We...

Vaccinia virus protein B14, an inhibitor of NF-κB activation, and its counterpart in MVA

Laura Ellen McCoy
Vaccinia virus (VACV) encodes multiple proteins which modulate NF-[kappa]B activation to evade the host immune response. One example is B14, a virulence factor that reduces NF-[kappa]B activation via interaction with IKK [Beta]. B14 has orthologues in many VACV strains, including modified virus Ankara (MVA), which lacks many of the immunomodulators present in other VACV strains. Here, the MVA counterpart of B14, protein 183, was characterised. 183R was both removed from MVA and inserted into the...

Investigation of genetics and genomics in asthma

Aristea Dimitriou Binia
Asthma is the most common disease of childhood in the westernised world, affecting one child in seven in the United Kingdom alone. It is a complex disease involving both genetic and environmental factors. The financial burden for sufferers approximates £1 billion per annum in the UK and 80% of the sum is attributable to the patients with the severe, “difficult/therapy-resistant” form of the disease. Previously, a Genome Wide Association Study (GWAS) for childhood asthma identified...

The socio-technical dynamics of chemical feedstock transitions : the case of renewable raw materials in the UK

Simon J. Bennett
Much public and private effort is being directed towards the development of more sustainable chemical feedstocks, yet the associated complexities of technological transitions and the technical, institutional and policy-related challenges they raise are often not wholly recognised. This thesis aims to develop an understanding of the key dynamics of technological change in the chemical industry, with respect to changes in feedstocks and the influence of the changing energy (and climate policy) landscape. It builds on,...

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