Activity profiling for minimally invasive surgery

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Embryogeny in Haemmanthus Albiflos Jacquin

There has been concern over the controversial position of the genus Allium in the classification scheme. Allium has been put into the Liliaceae because of its superior ovary and into the Amaryllidaceae because of umbels subtended by membranaceous bracts. The first purpose of this investigation is to study the embryogenesis and subsequent embryogeny of Haemanthus to evaluate affinities between Allium and Haemanthus. Since Allium has stalked cotyledons, it was thought that we could appeal to Haemanthus embryogenesis for evidence as to its relationships, since it is a genus which has been considered both primitive with the Amaryllidaceae and related to Allium. If Haemanthus is shown to have stalked cotyledons, this would tend to support the position that Allium may be closely related to the Amaryllidaceae. If not, this would tend to discourage adoption of the hypothesis that Allium is related to the Amaryllidaceae. Another phenomenon recognized in Haemanthus is the difficulty of obtaining high percentage of fruit-set. In an inflorescence of about 100 flowers only about 10 fruits are produced. Each fruit contains one or two seeds and very rarely three seeds. The second purpose is to study (1) pollen grain viability; (2) developmental stages in micro and megasporogenesis; and (3) the effects of hand-pollination on fruit-set

A new individual-based modelling framework for bacterial biofilm growth applied to cold plasma treatment

Biofilms are colonies of bacteria attached to the surface at a solid-fluid interface. Bacteria in biofilm produce exopolysaccharides (EPS) that form a gel-like matrix in which the bacteria are embedded. Biofilms have numerous consequences in industrial and medical settings, both positive (bioreactors, digestion) and negative (blocking, as corrosive damage of materials/devices, food contamination, clinical infection). The use of antibiotics or mechanical clearing can be effective at removing biofilms, but such treatments are not always effective or appropriate in all situations. Recently, non-thermal atmospheric plasma treatments have been proposed as an alternative (or complementary) form of treatment, that can target sites of infection with minimal damage to the surroundings (e.g. host cells in a clinical setting). These plasmas generate a multitude of chemical species, most of which are very short lived, that can infiltrate and diffuse into the biofilm killing the bacteria within. The aim of this thesis is to develop a multi-dimensional mathematical model to investigate the effect of a non- thermal plasma on biofilms in time and space and to identify key factors that determine effectiveness of the treatment. Most of the chemical products of cold plasmas are too short lived, or too reactive, to be effective in killing the biofilms, it is the longer live species, e.g. ozone, hydrogen peroxide, acid species, that penetrated the biofilm and do the most damage. However, the EPS in biofilms is an effective barrier against ozone and hydrogen peroxide. No published biofilm model combines multi-dimensional growth with a detailed description of EPS production, hence a new mathematical model is developed and applied to simulating plasma treatment. The thesis is split broadly into two parts. The first part presents a new biofilm model framework that simulates growth in response to any number of substrates (e.g. nutrient, oxygen). The model combines an Individual based model (IbM) description of bacteria (individuals or clusters) and substrates are described as a continuum. Novel features of the framework are the assumption that EPS forms a continuum over the domain and the explicit consideration of cellular energy (ATP). Simulations of this model demonstrate the contrast between biofilm grown with topical nutrient sources (forming irregular, bumpy biofilm) and basal nutrient source with topical oxygen such as biofilm grown on agar (forming regular spatially uniform biofilms). The former is in broad agreement with experiments whilst the latter, to our knowledge, has been the subject of very little experimental study. The second part extends the modelling framework to consider the effect of the plasma species. The simulations demonstrate that penetration is a key factor in their effectiveness, for which EPS plays a key role in preventing spread within and beyond the plasma treated zone. The simulations provide estimates of the timescale of equilibration of the main plasma species, predict the effect of combining these species and demonstrate how the constituents of the biofilm can change following treatment. A number of recommended suggestions for future theoretical and experimental study are discussed in the conclusions

Measuring Electric Charge and Molecular Coverage on Electrode Surface from Transient Induced Molecular Electronic Signal (TIMES).

Charge density and molecular coverage on the surface of electrode play major roles in the science and technology of surface chemistry and biochemical sensing. However, there has been no easy and direct method to characterize these quantities. By extending the method of Transient Induced Molecular Electronic Signal (TIMES) which we have used to measure molecular interactions, we are able to quantify the amount of charge in the double layers at the solution/electrode interface for different buffer strengths, buffer types, and pH values. Most uniquely, such capabilities can be applied to study surface coverage of immobilized molecules. As an example, we have measured the surface coverage for thiol-modified single-strand deoxyribonucleic acid (ssDNA) as anchored probe and 6-Mercapto-1-hexanol (MCH) as blocking agent on the platinum surface. Through these experiments, we demonstrate that TIMES offers a simple and accurate method to quantify surface charge and coverage of molecules on a metal surface, as an enabling tool for studies of surface properties and surface functionalization for biochemical sensing and reactions

Second language naming predicts left temporal pole integrity in aging bilinguals

There is numerous of evidence showing the left temporal pole (TP) is involved specifically in object naming. It is believed which functions as a semantic hub (Lambon Ralph & Patterson, 2008) and is involved in lexical retrieval (Tranel, 2009). Interestingly, both naming ability and TP grey matter values deteriorate with age. In this study, we investigated the effect of increased proficiency in the first language (L1) and second language (L2) on TP structural values in healthy bilingual seniors. Thirty-six healthy bilinguals (55 to 78 age-old) were selected within the multilingual population in Hong Kong. They underwent structural MRI and the grey matter density (GMD) were analysed using Voxel-based Morphometry approach. Their bilingual demographic characteristics were examined and regressed with the structural values. The results indicated an age effect on the left TP, and a negative correlation between local GM values and the overall naming performance. Surprisingly, this correlation was significant only for naming in L2 but not L1. These suggest that there is a universal structural decline in the left TP for both monolingual and bilingual speakers. And, with better L2 naming, the left TP may be better tuned. This may induces structural benefits and protection effect against healthy aging.published_or_final_versionSpeech and Hearing SciencesBachelorBachelor of Science in Speech and Hearing Science