Application of vertical seismic profiling for the characterisation of hard rock

Seismic imaging in hard rock environments is gaining wider acceptance as a mineral exploration technique and as a mine-planning tool. However, the seismic images generated from hard rock targets are complex due to high rock velocities, low contrasts in elastic rock properties, fractionated geology, complicated steep dipping structures and mineralogical alterations. In order to comprehend the complexity and utilise seismic images for structural mapping and rock characterisation, it is essential to correlate these images to known geology. An ideal tool for this purpose is Vertical Seismic Profiling or VSP. The VSP method can provide not only a means to correlate seismic images to geology but also to study the properties of the transmitted seismic field as it is modified by different rock formations, the origin of the reflected events and the corresponding reflector geometry. However, the VSP technique is rarely used in hard rock environments because of the cost and operational issues related to using clamping geophones in exploration boreholes, which are 96 mm or less in diameter. Consequently the main objective of this research is to produce an efficient VSP methodology that can be readily deployed for mineral exploration.An alternative to the clamping geophone is the hydrophone. Hydrophones are suspended in, and acoustically coupled to the borehole wall through, the borehole fluid. Borehole acoustic modes known as "tube-waves" are generated by seismic body waves passing the water column and are guided in the borehole due to the high acoustic impedance contrast between the rock and fluid. Tube-waves are 1-2 orders in magnitude higher in amplitude than seismic signal and mask reflected energy in hydrophone VSP profiles. As such the use of borehole hydrophone arrays to date has been restricted to direct body wave measurements only. I have effectively mitigated tube-waves in hydrophone VSP surveys with specific acquisition methodologies and refined signal processing techniques. The success of wavefield separation of tubewaves from hydrophone data depends critically upon; having high signal to noise ratio, well sampled data, pre-conditioning of the field data and processing in the field record (FFID) domain. Improvements in data quality through the use of high viscosity drilling fluids and baffle systems have been tested and developed. The increased signal to noise ratio and suppression of tube-wave energy through these technologies greatly enhances the performance of hydrophone VSP imaging.Non-standard wavefield separation techniques successfully removed strong coherent tube-wave noise. The additional wavefield separation steps required to remove high amplitude tube-waves does degrade the overall result with some fidelity and coherency being lost. However, a direct comparison of hydrophone and borehole clamping geophone VSP surveys has been conducted in the Kambalda nickel district and the two methodologies produced comparable results. The difference was that the hydrophone data were collected in a fraction of the time compared to clamping geophone equipment with significantly less risk of equipment loss and with reduced cost.The results of these field experiments and the data processing methodology used, demonstrate the potential of hydrophone VSP surveys in the small diameter boreholes typical of hard rock exploration. Thus, these results show that hydrophone VSP is a viable, cost effective and efficient solution that should be employed more routinely in hard rock environments in order to enhance the value of the surface seismic datasets being acquired

Characterization of Mauritius parakeet (Psittacula eques) microsatellite loci and their cross-utility in other parrots (Psittacidae, Aves).

We characterized 21 polymorphic microsatellite loci in the endangered Mauritius parakeet (Psittacula eques). Loci were isolated from a Mauritius parakeet genomic library that had been enriched separately for eight different repeat motifs. Loci were characterized in up to 43 putatively unrelated Mauritius parakeets from a single population inhabiting the Black River Gorges National Park, Mauritius. Each locus displayed between three and nine alleles, with the observed heterozygosity ranging between 0.39 and 0.96. All loci were tested in 10 other parrot species. Despite testing few individuals, between seven and 21 loci were polymorphic in each of seven species tested

Feasibility of borehole reflection seismology for hard rock mineral exploration

Complex geological models typical of hard rock mineral exploration in the Yilgarn Craton of Western Australiahave been created. Through full waveform synthetic modeling, borehole reflection seismology has been tested inthese environments with borehole geometries typical of hard rock exploration techniques. One such example ispresented here. Synthetic testing has shown that borehole reflection seismic sections suffer from lack of aperture in the down-dip direction. Thus Large offsets and higher shot density is required on the down-dip side of the borehole to compensate for this. However at large offsets wavefield identification is complex and correct separation of wavefields for imaging is difficult. These limitations and acquisition specific geometries and processing are discussed here. Initial field studies conducted during a pilot study show potential for seismic imaging from angled boreholes

An exploration of selection criteria of club cricketers in the greater Cape Town area

Magister Psychologiae - MPsych (Psychology)Since the advent of cricket in the 16th century the process of team selection has been fervently debated. However, only a handful of research papers can be found on this topic. In South Africa specifically, this process is further complicated by the country's apartheid past. This current study is imperative in order to explore selection criteria used by cricket selectors and coaches. A further aim of the current study is to explore cricket players' perceptions of which factors they deem as important in their own selection. The study used a Symbolic Internationalism (SI) theory as a theoretical framework. Purposive sampling was used to select a sample of 10 participants consisting of players, coaches and selectors from various cricketing institutions within the greater Cape-Town area. A qualitative approach was used to conduct the study, including semi-structured individual interviews and data was analysed using thematic analysis. This thematic analysis presented in two thematic categories, with corresponding themes discussed accordingly. These thematic categories were "Selection criteria that could be, or is used" and "What factors affect team selection". Participants revealed several factors that affect the selection of the team ranging from player availability to pitch conditions. In terms of Selection Criteria, the participants focused on the physiological attributes of an ideal player, however also mentioned key psychological attributes such as awareness, resilience, mental strength and adaptability. This research study identified several elements which coaches should incorporate into their training schedules, and that players can work on privately. Furthermore, this study seeks to contribute to the limited knowledge base available with regard to Cricket Team Selection in South Africa. The ethical principles adhered to in this study were informed confidentiality, anonymity, voluntary participation and being informing participants of their right to withdraw from the study at any point with no repercussions

Hydrophone VSP surveys in hard rock

Seismic imaging in hard rock environments is gaining wider acceptance as an exploration technique and as a mine-planning tool. To date, 13 successful case studies have been acquired in Australia. The images generated from hard rock targets exhibit large levels of complexity and their interpretations remain an active area of study. To assist the imaging and better understand the source of the reflections observed, vertical seismic profiling (VSP) can be employed. This technique is not readily applied to hard rock environments because cost and operational issues often prove prohibitive. We propose the use of hydrophone arrays as a cost effective solution to VSP acquisition. We highlight the key challenges in using these receivers and propose solutions to overcome them. By careful acquisition methodologies and refined signal processing techniques, the tube waves that have up to now compromised the use of hydrophones for VSP acquisition can be effectively mitigated. We show that the data acquired with hydrophones compare favorably to that acquired with conventional 3C geophones. The data acquired with hydrophones come at a fraction of the cost and deployment time required for conventional acquisition procedures. Our results show that hydrophone vertical seismic acquisition is a viable, cost effective, and efficient solution that should be employed more routinely in hard rock environments to enhance the value of the surface data sets being acquired

Data from a study of Guinea worm infection in northern Nigeria, 1971-1974

This data collection contains: (a) a listing of the demographic and clinical features of 563 patients with guinea worm infection collected over a period of four years (1971-1974) in northern Nigeria; (b) summary tables of the clinical features of patients with guinea worm including those with arthritis; (c) a listing of the bacteria cultured from guinea worm ulcers, and (d) a listing of the antibiotics used or treatment of guinea worm

A Brief Review of Inhalation Toxicology and the Development of a Research Proposal to Demonstrate the Relevance of an Established Mouse Bioassay to Biodefense Objectives

In a program announcement in 2005, The Office of Biodefense Research, the National Heart, Lung and Blood Institute, and the National Institutes of Health expressed concern about an issue of significant public health importance: the "US population's potential exposure to aerosolized, inhaled harmful chemicals possibly liberated as part of bioterrorism attacks against assembled groups of the civilian populace". The primary stated objective of the program was to "encourage research about how the upper respiratory tract and lungs respond to acute exposure to highly toxic chemicals and subsequent inhalation, so that preventive strategies can be improved, antidotes devised to lessen initial irritation of mucosal surfaces, mucosal absorption minimized, and acute lung injury causing pulmonary edema counteracted". In the context of this objective, a review of the basic and applied science of inhalation toxicology was undertaken and a research proposal developed to demonstrate the relevance of an established mouse bioassay, documented to identify and quantify the effects of inhaled agents at all three regions of the respiratory tract, by evaluating the inhalation toxicity of methyl isocyanate, an agent known to affect all three regions of the respiratory tract. Human observational methyl isocyanate exposure data from the Bhopal industrial accident are available, as are experimental animal exposure data, offering the opportunity to further establish the reproducibility and validity of the bioassay. In addition, the mouse biosassay detects effects of inhaled agents at concentrations below those at which histopathological changes occur, enabling the rapid screening of administered treatments and antidotes for effectiveness. This capacity is of fundamental importance in the development of future therapeutic agents. With experience gained in the practical management of the experimental apparatus with the methyl isocyanate proposal, a study using the mouse bioassay to reproduce unpublished data investigating therapeutics against the inhalation toxicity of ricin would be proposed at a future date. Ricin is of outmost importance for biodefense since it is extremely potent and readily available. Furthermore, no antidote or treatment exists against this agent and the unpublished data on possible treatment should be pursued.

Parametric optimization study of a lithium-ion cell

Lithium-ion cell technology is well known for its high power and energy density in the automotive application. This paper presents development of a 1D electrochemical model which can be used to predict 18650 lithium-ion cell performance under different operating conditions. COMSOL Multiphysics 5.2a software has been utilized to develop the electrochemical model to predict the cell behaviour under various discharge rates. This tool uses the finite element method (FEM) to solve the conservation equations of charge and species in solid and electrolyte phase. And Butler-Volmer equation for reaction rates of lithium insertion and extraction. In an event that the electrochemical parameters of the cell are not known, determination of these parameters by measurements or experiments is a difficult and challenging task. An attempt has been made in this paper to estimate unknown cell parameters by two methods, first by performing a parametric study on cell parameters such as particle radius, diffusion coefficient, porosity etc. within a known range from literature studies and analyse the sensitivity of these parameters on the model results. Secondly, to improve the accuracy of the simulation results, COMSOL optimization module is used and the simulation results are validated against the experimental data. Apart from the discharge profiles, the proposed model can also be used to study the time dependent distribution of lithium-ion concentration, electrolyte concentration, lithium diffusivity and ionic conductivity in the cell