Intense chemical weathering accompanies physical instability at the site of a repeatedly active landslide in North Derbyshire. In order to describe and quantify the chemical weathering, a programme of water sampling and analysis was devised. A sequence of reactions are proposed, based on theresults of this work, to account for the observed concentrations of chemical species in the drainage waters. It is thought that pyrite oxidation, accelerated by the presence of catalytic bacteria, is responsible for the considerable acidity of these waters. Additional reactions involving carbonates and silicates occur at strictly comparable rates and consume over 99% of the acidity prior to the water's emergence in a number of ochre-precipitating springs. Analysis of the solid reactants and products confirms the suggested sequence of events and suggests a number of ways in which chemical weathering might be related to slope stability. Clay minerals appear to be little affected by weathering, and the growth of precipitate minerals such as gypsum in joints and on bedding planes might be a more important mechanism in shale breakdown. After this initial rapid physical disintegration, chemical weathering, at the surface, proceeds relatively slowly. Chemical processes build up stresses within the rocks and possibly help to maintain any inherent planes of weakness. Ultimately landslide movement is triggered by increases in porewater pressures brought about by fluctuations in local ground water levels.

No description available.

The aim of this study was to test a predictive model of the geomorphological and sedimentological effects of floods resulting from the sudden drainage of ice-dammed lakes (jokulhlaups). A process-based, conceptual model for channel and sedimentary characteristics was tested within a jokulhlaup routeway near Sondre Stromfjord, west Greenland. River channel change resulting from a jokulhlaup monitored in 1987 was studied in three channel types along the flood routeway: deltaic, high gradient bedrock-controlled, and low gradient confined valley sandur. Flood powers, sediment supply and channel resistance to erosion were found to vary considerably between the channel types. Consequently, amounts of channel change and the character of the sedimentary record showed extreme variation. In addition, parts of the jokulhlaup channel which experienced backwater effects may have experienced two sediment transport peaks. Variations between the character of deposits found within each of the three channel types reflect local differences in sediment supply, stream power and channel resistance to erosion. Deposition in the delta and the sandur records sedimentation related to a number of jokulhlaups, whilst the spillway and the bedrock-confined channel provide a record of the action of the last jokulhlaup as low stage deposits, as well as that of the earliest flood events as high stage deposits. This study has shown that it is possible to predict the morphology of channel macroforms. The internal structure of these macroforms is strongly dependent upon both the amount and character of sediment supplied to the channel during a jokulhlaup. The more detailed the knowledge of the controlling variables for any one channel, the more detailed the resulting predictions are. At present, the model concerns only the products of turbulent, Newtonian, water floods. It may, however, be possible to predict thresholds marking the transition to non-Newtonian flows where sediment supply conditions and hydrograph characteristics are known. The model may also be used in reverse to reconstruct the magnitude and frequency of former jokulhlaups where sufficient geomorphological and sedimentary evidence is available.

This thesis focuses on two main areas: the synthesis of novel anti-metabolites of 1-deoxy- D-xyulose-5-phosphate (DXP) and the stereoelectronics which influence the conformation of fluoromethyl groups in organic compounds. DXP, a sugar phosphate, has recently been established as a key biosynthetic intermediate to a number of plant and bacterial co-enzymes and vitamins. Chapter 1 describes the role of DXP in three biosynthetic pathways; in the formation of the isoprenoid building block isopentenyl pyrophosphate, and the vitamins B(_1) and B(_6). A new strategy to novel antibiotics and / or herbicides is proposed by the inhibition of DXP metabolism. A description of phosphonates as hydrolytically stable phosphate mimics is presented, including fluorine phosphonates that enable fine tuning of these mimics. Synthetic targets are designed as inhibitors of the DXP reductoisomerase catalysed reaction from DXP to 2-C-methyl-D-erythritol-4-phosphate (MEP). In Chapter 2 the successful synthesis of the CH(_2) phosphonate analogues of DXP and MEP is described. The DXP analogue was initially approached via the diethyl phosphonate ester, however it proved necessary in the end to prepare the dibenzyl ester followed by hydrogenation. Synthesis towards the CF2, and the a-fluorinated ketone, phosphonate analogues of DXP were incomplete due to low yields. Further syntheses is described towards the reduced form of the CH2 phosphonate analogue of DXP, and to a compound related to fosmidomycin. Chapter 3 describes fluorine's stereoelectronic influence in determining the conformations of fluoromethyl containing organic compounds through n/π-σ* conjugation and gauche effects. Solid state evidence for the influence of these effects is presented through the first X-ray crystallographic data of fluoromethylaromatics and β-fiuoroethylamides respectively. Structures of bis-2,6-(fluoromethyl)pyridine and its N-oxide displayed fluoromethyl conformations with the C-F bond co-planar to the aromatic ring whereas benzyl fluoride and 4-bromobenzyl fluoride displayed conformafions with the C-F bond orthogonal to the aromatic ring. Structures of N-(2-fluoroethyl)-3,5-dinitrobenzamide and N-(2-fluoroethyl)-4-nitrobenzamide reveal a fluorine / amide gauche effect.

MA (Social Work), Faculty of Humanities, University of the Witwatersrand, 1995

MMed, Ophthalmology, Faculty of Health Sciences, University of the Witwatersrand / Aim To determine and document the demographic profile, clinical features, associations and clinical and visual outcomes in black African patients with idiopathic intracranial hypertension (IIH) attending St John Eye Hospital during 2006 and 2007. Method A retrospective descriptive study was conducted on black African IIH patients. Patient files and data of 21 of 32 IIH patients, seen in the Neuro-ophthalmology clinic at St John Eye Hospital over a two year period (2006 and 2007), were available and this study is based on these 21 patients. All 21 patients fulfilled the modified Dandy criteria for the diagnosis of IIH. Information obtained from files of the 21 patients were recorded on a data capture sheet. The demographics, initial (presenting) and final visual acuities and visual fields, initial and final clinical symptoms and signs, associations and treatment modalities were recorded on the data capture sheet. Visual and clinical outcomes were determined by comparing the final with the initial (presenting) symptoms and signs. The minimum follow-up period between the initial and the final visit was two months. Patients were regarded as legally blind if they had severe to profound visual acuity and/or visual field loss. Results All 21 patients were female and black African. Mean age was 31.2 ± 8.9 years (range 16 – 50 years). Mean period of follow up was 19.9 ± 20.1 months (range 2 – 77 months). 71.4% were obese. All patients presented with symptoms. The commonest presenting symptom was headache (90%) followed by visual loss (67%), transient visual obscurations (38%) and diplopia (29%). The results of the presenting signs were as follows: Seven eyes (17%) had visual acuity loss (most of which were mild [9.5%]), seven patients (33%) had abduction deficits, four patients (9.5%) had unilateral abnormal pupil reactions and all patients had papilloedema. Of the recorded associations seven patients (33%) were hypertensive, six (29%) were on contraception (two [9.5%] were on oral contraception) and two (9.5%) were taking prednisone prior to presentation. After the initial visit, all 21 vi IIH patients were treated with acetazolamide (Diamox) and weight loss was recorded in three patients (14%). Two patients (9.5%) had optic nerve sheath fenestrations (ONSF), two (9.5%) had lumbar-peritoneal shunts (LPS) and six (28.6%) had multiple lumbar punctures (LP’s). The outcome analysis was as follows: Symptoms in 19 patients (90%) improved but 16 patients (76%) still had papilloedema. Two patients (9.5%) had abduction deficits at the final visit. Visual acuity loss occurred in five eyes (12%) at the final visit compared to seven eyes (17%) at the initial visit (presentation). From the initial visit (presentation) to the final visit, visual acuity in seven eyes (16%) improved, 31 eyes (74%) remained stable and four eyes (10%) worsened. Although visual fields in 33 eyes (79%) improved from the initial to the final visit, 36 eyes (86%) still had visual field loss at the final visit. 26% of eyes had severe to profound visual impairment i.e. were legally blind, at the final visit. Conclusion The results of 21 black African IIH patients reported in this study were similar to some other studies with regards to demographics, clinical features and clinical and visual outcomes. An association between IIH and oral contraceptives, steroids and hypertension could not be established. Although symptoms resolved in most patients, a significant number of patients still had papilloedema and visual field loss following treatment. Despite treatment, a quarter of the patients were legally blind at the final visit, indicating that this condition is not benign.

by Lui Kong Kei, Walter. / Thesis submitted in: July 1999. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 115-122). / Abstracts in English and Chinese. / ABSTRACT --- p.i / 摘要 --- p.iv / ACKNOWLEDAGE --- p.vi / LIST OF FIGURES --- p.xi / LIST OF TABLES --- p.xiii / LIST OF APPENDIX --- p.xiii / ABBREVATIONS --- p.xiv / Chapter CHAPTER ONE: --- INTRODUCRION --- p.2 / Chapter 1.1 --- DEFINITION --- p.2 / Chapter 1.2 --- HISTORICAL BACKGROUND --- p.2 / Chapter 1.3 --- ADVANTAGES AND CLINICAL APPLICATION OF IONTOPHORESIS --- p.5 / Chapter 1.3.1 --- ADVANTAGES OF IONTOPHORESIS --- p.6 / Chapter 1.3.2 --- CLINICAL APPLICATION OF IONTOPHORESIS --- p.7 / Chapter 1.4 --- STRUCTURE AND ELECTRICAL PROPERTIES OF SKIN --- p.7 / Chapter 1.4.1 --- SKIN STRUCTURE --- p.8 / Chapter 1.4.2 --- SKIN PERMSELECTIVITY --- p.9 / Chapter 1.4.3 --- ELECTRICAL PROPERTIES OF SKIN --- p.9 / Chapter 1.5 --- PRINCIPLES OF IONIC TRANSPORT IN AN ELECTRIC FIELD --- p.10 / Chapter 1.6 --- THEORETICAL BASIS --- p.12 / Chapter 1.6.1 --- NERNST-PLANCK THEORY OF DRUG DELIVERY BY IONTOPHORESIS --- p.12 / Chapter 1.6.2 --- CONVECTIVE FLOW --- p.14 / Chapter 1.6.3 --- THEORETICAL TREATMENT OF CONVECTIVE FLOW --- p.15 / Chapter 1.6.4 --- THE ENHANCEMENT RATIO (ER) --- p.16 / Chapter 1.6.5 --- ALTERATIONS IN THE PERMEABILITY OF SKIN AND DAMAGE FACTOR (DF) --- p.16 / Chapter 1.7 --- PATHWAYS FOR TRANSPORT --- p.17 / Chapter 1.8 --- FACTORS AFFECTING IONTOPHORETIC DELIVERY --- p.19 / Chapter 1.8.1 --- ELECTIC CURRENT --- p.19 / Chapter 1.8.1.1 --- CURRENT DENSITY --- p.20 / Chapter 1.8.1.2 --- CURRENT MODES --- p.21 / Chapter 1.8.1.2.1 --- Direct Current (DC) --- p.21 / Chapter 1.8.1.2.2 --- Pulsed Direct Current (PDC) --- p.21 / Chapter 1.8.1.2.3 --- Comparing Direct Current (DC) with Pulsed Direct Current (PDC) --- p.23 / Chapter 1.8.1.2.4 --- Pulsed Short-circuit Pulsed Direct Current (PSPDC) --- p.24 / Chapter 1.8.2 --- PHYSIOCHEMICAL PROPERTIES OF THE PERMEANT --- p.26 / Chapter 1.8.3 --- ELECTROLYTE COMPOSITION --- p.28 / Chapter 1.8.4 --- BIOLOGICAL FACTORS --- p.30 / Chapter 1.9 --- IN-VITRO EXPERIMENT DESIGN --- p.30 / Chapter 1.9.1 --- SKIN AND SYNTHETIC MEMBRANE IN IONTOPHORETIC RESEARCH --- p.30 / Chapter 1.9.2 --- DIFFUSION CELL --- p.32 / Chapter 1.9.3 --- ELECTRODES --- p.33 / Chapter 1.10 --- THE PURPOSE OF PRESENT STUDY --- p.34 / Chapter CHAPTER TWO: --- MATERIALS AND METHODS --- p.35 / Chapter 2.1 --- MATERIAL --- p.35 / Chapter 2.1.1 --- ANIMAL MODEL --- p.35 / Chapter 2.1.2 --- APPARATUS AND INSTRUMENTS --- p.35 / Chapter 2.1.3 --- REAGENTS --- p.37 / Chapter 2.2 --- METHODS --- p.38 / Chapter 2.2.1 --- PREPARATION OF THE SIDE-BI-SIDE DIFFUSION CELL --- p.38 / Chapter 2.2.1.1 --- MEMBRANE PREPARATION FOR SKIN PERMEABILITY STUDIES --- p.38 / Chapter 2.2.1.2 --- MOUNTING THE TISSUE MEMBRANE IN SIDE-BI-SIDE DIFFUSION CELL --- p.39 / Chapter 2.2.1.3 --- STABILIZING THE TISSUE MEMBRANE AND TESTING FOR THE TIGNTNESS --- p.40 / Chapter 2.2.1.4 --- SILIVER/SILVER CHORIDE ELECTRODE (Ag/AgCl) --- p.41 / Chapter 2.2.2 --- IN-VITRO IONTOPHORETIC PERMEATION EXPERIMENT --- p.42 / Chapter 2.2.2.1 --- IONTOPHORETIC PERMEATION KINETICS OF MANNITOL --- p.42 / Chapter 2.2.2.1.1 --- Reagents --- p.42 / Chapter 2.2.2.1.2 --- In-vitro experiment process --- p.43 / Chapter 2.2.2.1.3 --- Testing parameters --- p.43 / Chapter 2.2.2.1.4 --- Sampling and assay --- p.44 / Chapter 2.2.2.1.5 --- Data analysis --- p.44 / Chapter 2.2.2.2 --- IONTOPHORETIC PERMEATION KINETICS OF ANGIOTENSIN II --- p.46 / Chapter 2.2.2.2.1 --- Reagents --- p.46 / Chapter 2.2.2.2.2 --- In-vitro experiment process and testing parameters --- p.47 / Chapter 2.2.2.2.3 --- Sampling and assay --- p.47 / Chapter 2.2.2.2.4 --- Data analysis --- p.47 / Chapter 2.2.3 --- IMPEDANCE MEASUREMENT OF EXCISED SKIN --- p.48 / Chapter 2.2.4 --- INFLUENCE OF IONTOPHORESIS ON THE IMPEDANCE OF EXCISED FULL-THICKNESS NUDE MOUSE SKIN --- p.50 / Chapter 2.2.4.1 --- Experiment process --- p.50 / Chapter 2.2.4.2 --- Measurement and data analysis --- p.51 / Chapter 2.2.5 --- PASSIVE SOLUTE TRANSPORT EXPERIMENT --- p.52 / Chapter 2.2.5.1 --- PASSIVE TRANSPORT OF TRITIATED WATER --- p.52 / Chapter 2.2.5.1.1 --- Reagents --- p.53 / Chapter 2.2.5.1.2 --- Experimental process --- p.53 / Chapter 2.2.5.1.3 --- Assay and data analysis --- p.55 / Chapter 2.2.5.2 --- PASSIVE TRANSPORT OF MANNITOL --- p.55 / Chapter 2.2.5.2.1 --- Reagents --- p.56 / Chapter 2.2.5.2.2 --- Experimental process --- p.56 / Chapter 2.2.5.2.3 --- Assay and data analysis --- p.58 / Chapter 2.2.6 --- STATISTIC METHODS USED FOR ANALYSIS --- p.59 / Chapter CHAPTER THREE: --- RESULTS --- p.60 / Chapter 3.1 --- RESULTS OF IN-VITRO IONTOPHORETIC PERMEATION EXPERIMENTS --- p.60 / Chapter 3.1.1 --- IONTOPHORETIC PERMEATION KINETICS OF MANNITOL --- p.60 / Chapter 3.1.2 --- IONTOPHORETIC PERMEATION KINETICS OF ANGIOTENSIN II --- p.69 / Chapter 3.2 --- RESULTS OF EFFECT OF IONTOPHORESIS ON THE IMPEDANCE OF THE EXCISED FULL-THICKNESS NUDE MOUSE SKIN --- p.78 / Chapter 3.3 --- SOLUTE TRANSPORT EXPERIMENTS --- p.81 / Chapter 3.3.1 --- WATER TRANSPORT EXPERIMENT --- p.81 / Chapter 3.3.2 --- MANNITOL TRANSPORT EXPERIMENT --- p.86 / Chapter CHAPTER FOUR: --- DISCUSSION --- p.93 / Chapter 4.1 --- ANIMAL MODEL --- p.93 / Chapter 4.2 --- EXPERIMENTAL CONDITION OF DIFFUSION PERMEATION CELL --- p.94 / Chapter 4.3 --- IN- VITRO PERMEATION EXPERIMENTS --- p.95 / Chapter 4.3.1 --- MANNITOL --- p.95 / Chapter 4.3.2 --- ANGIOTENSIN II --- p.95 / Chapter 4.3.3 --- RESULTS OF IONTOPHORETIC PERMEATION STUDIES --- p.97 / Chapter 4.4 --- INFLUENCE OF IONTOPHORESIS ON THE SKIN IMPEDANCE --- p.99 / Chapter 4.5 --- SOLUTE TRANSPORT EXPERIMENT --- p.102 / Chapter 4.6 --- FUTURE PROSPECTS --- p.106 / Chapter CHAPTER FIVE: --- CONCLUSION --- p.107 / APPENDIX ONE --- p.108 / APPENDIX TWO --- p.109 / REFERENCE --- p.115

1 v. (various pagings) : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D.)--University of Adelaide, Dept. of Human Physiology and Pharmacology, 1972

The effects of interconnect length on the reliability of dual-damascene Cu metallization have been investigated. As in Al-based interconnects, the lifetimes of Cu lines increase with decreasing length. However, unlike Al-based interconnects, no critical length exists, below which all Cu lines are ‘immortal’. Furthermore, we found multi-modal failure statistics for long lines, suggesting multiple failure mechanisms. Some long Cu interconnect segments have very large lifetimes, whereas in Al segments, lifetimes decrease continuously with increasing line length. It is postulated that the large lifetimes observed in long Cu lines result from liner rupture at the bottom of the vias, which allows continuous flow of Cu between the two bond pads. As a consequence, the average lifetimes of short lines and long lines can be higher than those of lines with intermediate lengths. / Singapore-MIT Alliance (SMA)

In this thesis, we study the mathematical modelling of some problems that involve surface effects. These include an optical biosensor, which uses optical principles qualitatively to convert chemical and biochemical concentrations into electrical signals. A typical sensor of this type was constructed in Badley et al., [6], and Jones et al., [18],but diffusion was considered in only one direction in [18] to simulate the reaction between the antigen and the antibody. For realistic applications, we propose the biosensor model in R3. Our theoretical approach is explicitly presented since it is simple and directly applicable to the numerical part of the thesis. In particular, we present existence and uniqueness results based on Maximum Principle and weak solution arguments. These ideas are later applied to systems and to the numerical analysis of the approximate discretized problems.It should be noted that without one dimensional symmetry, the equations can not be decoupled in order to reduce the problem to a single equation. We also show the long time monotonic convergence to the steady state. Next, a finite volume method is applied to the equations, and we obtain existence and uniqueness for the approximate solution as well as the convergence of the the first order temporal norm and the L2 spatial norm. We illustrate the results via some numerical simulations. Finally we consider a mathematically related system motivated by lagoon ecology. We show that under suitable conditions on the coecients, the system has a periodic solution under harvesting conditions. The mathematical techniques now depend on estimates for periodic parabolic problems. / Applied Mathematics