No description available.

This thesis describes the development and applications of sub-micron current-perpendicular-to plane devices fabricated by three-dimensional etching with a focused ion beam microscope. This technique was applied to a range of materials, including the study of c-axis Josephson junctions in the high temperature superconductor Tl2Ba2CaCu2O8, the fabrication of superconducting quantum interference devices with sub-micron loop areas, and GaN light emitting diodes. The main body of research was carried out in the study of Nb based Josephson junctions working at a temperature of 4.2 K. Junctions with normal metal, insulating and ferromagnetic barriers were characterised, as well as the first metallic antiferromagnetic Josephson junctions using γ-Fe50Mn50 as the barrier. 'Pseudo-spin-valve' Josephson junctions were also created using aCo/Cu/Fe20Ni80 barrier. In this case the relative orientation of the magnetic moments of the Co and Fe20Ni80 could be changed with an applied magnetic field. The magnetoresistance and critical current of the device showed a strong correlation, implying a direct influence of the magnetic structure of the device on the critical current.

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published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Zoology / Master / Master of Philosophy

published_or_final_version / abstract / Biological Sciences / Doctoral / Doctor of Philosophy

Neonatal necrotizing enterocolitis (NEC) is the most common gastrointestinal disease in premature babies. Despite significant morbidity and mortality, the cause of this disease remains unclear and there are no preventative treatments available. Prematurity and enteral feeding of infant formula are considered to be the primary risk factors for development of NEC. Interestingly, the incidence of NEC is six to ten times lower in breast-fed babies compared to those that were formula-fed. The factors responsible for the protective effect of breast milk against NEC have not been identified, but epidermal growth factor (EGF) is one of the most promising candidates. EGF is found at high concentrations in human milk, but is not present in any commercial formula. Mothers with extremely premature babies have 50-80% higher levels of EGF in their breast milk compared to mothers with full term infants. This suggests that EGF plays an important role in the development of premature infants. Our studies have shown that supplementation of EGF into formula significantly reduces the incidence of NEC in a neonatal rat model. However, the mechanisms underlying this EGF-mediated reduction of NEC are not understood. The overall hypothesis of this dissertation is that the protective effect of EGF in NEC pathogenesis is mediated via increased expression of pro-survival genes and strengthening of the mucosal barrier. The results of the studies within this dissertation demonstrate that treatment with EGF significantly decreases intestinal epithelial cell apoptosis at the site of NEC injury by up-regulating anti-apoptotic genes and down-regulating pro-apoptotic genes. Furthermore, supplementation of formula with EGF strengthens the mucosal barrier by inducing accelerated maturation of ileal goblet cells and mucin-2 production. In addition, EGF treatment normalizes expression of crucial tight junction proteins in the ileum. Consequently, EGF treatment results in a significant decrease in intestinal paracellular permeability and improved barrier function. Results from these studies will provide significant contributions to the understanding of EGF-mediated reduction of NEC, which may lead to development of therapeutic strategies for the treatment of human NEC.

No description available.

No description available.

No description available.