78 FR 49769 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Telemanagement Forum

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-15

... the Attorney General and the Federal Trade Commission disclosing changes in its membership. The...; Innova Bilisim Cozumleri, Maslak, TURKEY; Intelli Solutions S.A., Athens, GREECE; International IT House..., GERMANY; Synopsis S.A., Lima, PERU; Trendium, Boulder, CO; University of Witwatersrand, School of...

Conceptualising Transformation and Interrogating Elitism: The Bale Scholarship Programme

ERIC Educational Resources Information Center

Botsis, Hannah; Dominguez-Whitehead, Yasmine; Liccardo, Sabrina

2013-01-01

In this article, we consider the extent to which a scholarship programme at the University of the Witwatersrand (Wits) engages with the challenges of transformation. This scholarship programme highlights the transformative potential of a programme that focuses on excellence for a previously under-represented group, but also demonstrates how this…

Teaching Process Design through Integrated Process Synthesis

ERIC Educational Resources Information Center

Metzger, Matthew J.; Glasser, Benjamin J.; Patel, Bilal; Hildebrandt, Diane; Glasser, David

2012-01-01

The design course is an integral part of chemical engineering education. A novel approach to the design course was recently introduced at the University of the Witwatersrand, Johannesburg, South Africa. The course aimed to introduce students to systematic tools and techniques for setting and evaluating performance targets for processes, as well as…

Gramsci, Doke and the Marginalisation of the Ndebele Language in Zimbabwe

ERIC Educational Resources Information Center

Ndhlovu, Finex

2006-01-01

Clement M. Doke's 1929-1930 research on Zimbabwean languages has played a key role in shaping the tribalised and politicised linguistic terrain that characterises modern Zimbabwe. Doke, professor of linguistics at the University of Witwaters-rand, was commissioned in 1929 by the government of Southern Rhodesia (present-day Zimbabwe) to research…

Perceptions of Computer Science at a South African University

ERIC Educational Resources Information Center

Galpin, Vashti C.; Sanders, Ian D.

2007-01-01

First year students at the University of the Witwatersrand in Johannesburg, South Africa, were surveyed about their perceptions of Computer Science before and towards the end of their first year courses. The aim of this research was to investigate how the students' attitudes changed during these courses and to assess the impact of the innovative…

Water Security and Hydropolitics of the Nile River: South Sudan’s National Security in the 21st Century

DTIC Science & Technology

2011-12-16

Politics of the Nile Basin” (Master’s Thesis, University of Witwatersrand, Johannesburg, 2009). 2 While the Nile Basin is the longest trans- boundary ...conflicts, there may be an area of cooperation among states that share trans- boundary international river systems.32 Other staggering statistics on the...

Emerging Concept of Internationalisation in South African Higher Education: Conversations on Local and Global Exposure at the University of the Witwatersrand (Wits)

ERIC Educational Resources Information Center

Cross, Michael; Mhlanga, Ehpraim; Ojo, Emmanuel

2011-01-01

Rather than paying attention to the specific approaches emerging from different contexts, current debates tend to privilege Western-universalizing concepts of internationalisation, unproblematically accepted as globally established truths. In South Africa, where the legacy of isolation and the dominance of Eurocentricism in academia have inspired…

Research Success and Structured Support: Developing Early Career Academics in Higher Education

ERIC Educational Resources Information Center

Geber, H.

2009-01-01

Entry into a successful academic career is often an arduous process. From career preparation through to doctoral studies and beyond, the journey can be fraught with trials. Why do many academics find difficulty in completing their studies in the minimum time and publishing afterwards? As the University of the Witwatersrand has a strategic goal of…

Shanghai Academic Ranking of World Universities (ARWU) and the "Big Five" South African Research Universities

ERIC Educational Resources Information Center

Boshoff, N.

2009-01-01

This article critically examines the methodology of the Shanghai Academic Ranking of World Universities (ARWU) by generating raw scores for the "big five" South African research universities (Stellenbosch, Cape Town, Kwazulu-Natal, Pretoria and the Witwatersrand, henceforth referred to as SU, UCT, UKZN, UP and WITS) using the ARWU…

Providing Opportunities for Student Self-Assessment: The Impact on the Acquisition of Psychomotor Skills in Occupational Therapy Students

ERIC Educational Resources Information Center

Jay, Julie; Owen, Antonette

2016-01-01

The Occupational Therapy department at the University of the Witwatersrand in South Africa is responsible for ensuring students achieve psychomotor skill proficiency, as it is an essential component of health care practice. The aim of this study was to determine whether the introduction of opportunities to afford self-evaluation better prepared…

'To Go Boldly': Teaching Science Fiction to First-Year Engineering Students in a South African Context

ERIC Educational Resources Information Center

Manià, Kirby; Mabin, Linda Kathleen; Liebenberg, Jessica

2018-01-01

This paper reflects on the teaching of science fiction texts to first-year engineering students at the University of the Witwatersrand as part of a Critical Thinking course that uses literature as a vehicle through which to develop competence in critical literacy and communication. This course aims to equip engineering students, as future…

Genetic and Phylogenetic Characterization of Tataguine and Witwatersrand Viruses and Other Orthobunyaviruses of the Anopheles A, Capim, Guamá, Koongol, Mapputta, Tete, and Turlock Serogroups

PubMed Central

Shchetinin, Alexey M.; Lvov, Dmitry K.; Deriabin, Petr G.; Botikov, Andrey G.; Gitelman, Asya K.; Kuhn, Jens H.; Alkhovsky, Sergey V.

2015-01-01

The family Bunyaviridae has more than 530 members that are distributed among five genera or remain to be classified. The genus Orthobunyavirus is the most diverse bunyaviral genus with more than 220 viruses that have been assigned to more than 18 serogroups based on serological cross-reactions and limited molecular-biological characterization. Sequence information for all three orthobunyaviral genome segments is only available for viruses belonging to the Bunyamwera, Bwamba/Pongola, California encephalitis, Gamboa, Group C, Mapputta, Nyando, and Simbu serogroups. Here we present coding-complete sequences for all three genome segments of 15 orthobunyaviruses belonging to the Anopheles A, Capim, Guamá, Kongool, Tete, and Turlock serogroups, and of two unclassified bunyaviruses previously not known to be orthobunyaviruses (Tataguine and Witwatersrand viruses). Using those sequence data, we established the most comprehensive phylogeny of the Orthobunyavirus genus to date, now covering 15 serogroups. Our results emphasize the high genetic diversity of orthobunyaviruses and reveal that the presence of the small nonstructural protein (NSs)-encoding open reading frame is not as common in orthobunyavirus genomes as previously thought. PMID:26610546

Age-standardized incidence rates of primordial cyst (keratocyst) on the Witwatersrand.

PubMed

Rachanis, C C; Shear, M

1978-11-01

Cases of primordial cysts derived from the records of all the hospital pathology departments and private pathology practices on the Witwatersrand, were recorded for the 10-year period 1965-74. The population at risk (1970 census) was 974,390 Whites and 1,567,280 Blacks. Age-specific morbidity rates for each sex and race were calculated, as well as age-standardized incidence rates standardized against African, World and European standard populations. The age-standardized incidence rates for primordial cysts, standardized against a World standard population, per million per year are 0.61, 0, 4.86 and 3.50 for Black males and females and White males and females, respectively. In the population at risk, primordial cysts are much more common in Whites than in Blacks, the incidence being eight times higher in White males than in Black males. The present study confirms that there is a bimodal age distribution but with a higher incidence of the cyst in the age group 50-64 years than previously suspected. This may be either because a substantial number of cases remain undiagnosed for many years or because there are two groups of primordial cyst: one which is triggered in young patients and the other in older patients.

Raymond Dart as a pioneering primatologist.

PubMed

Strkalj, G; Tobias, P V

2008-01-01

Raymond Dart is best known today for his groundbreaking research in palaeoanthropology. It is often forgotten, however, that Dart was a scientist of many interests, who made significant contributions to various disciplines. One of these is the study of living non-human primates. Dart became aware of the importance of primate studies and their relevance for research in other disciplines early in his career. In the late 1920s Dart established a colony of captive baboons in the Anatomy Department, University of the Witwatersrand, Johannesburg. On these animals, members of his Department, most notably Joseph Gillman and Christine Gilbert, carried out a number of significant behavioural and endocrinological researches. In 1930, as a member of an Italian Scientific Expedition, Dart was involved in hunting a mountain gorilla (for research purposes). He was also active in primate field studies. In 1957 he and Phillip Tobias founded a Witwatersrand University Uganda Gorilla Research Unit for the study of the Virunga mountain gorillas. The unit produced pioneering studies, conducted by Jill Donisthorpe, on the behaviour of these primates in their natural habitat. At the same time Dart was actively engaged in conservation of the mountain gorillas. He also studied South African chacma baboons in the wild. In the field of primate studies Raymond Dart figures prominently as a pioneering catalyst as well as researcher and conservationist.

Age-standardized incidence rates of ameloblastoma and dentigerous cyst on the Witwatersrand, South Africa.

PubMed

Shear, M; Singh, S

1978-07-01

Although a great deal is known about the incidence of cancer, including oral cancer, no such study has been done on odontogenic tumors and jaw cysts. There are therefore no standardized data which would allow for comparative incidences in different countries and between different groups. In the present study, cases of ameloblastomas and dentigerous cysts derived from the records of all the hospital pathology departments and private pathology practices on the Witwatersrand, were recorded for the 10-year period 1965--1974. The population at risk (1970 census) was 974,390 Whites and 1,567,280 Blacks. The annual incidence rates, standardized against the standard world population, for ameloblastomas per million population are 1.96, 1.20, 0.18 and 0.44 for Black males, females and White males, females, respectively. The equivalent four figures for dentigerous cysts are 1.18, 1.22, 9.92 and 7.26. These figures show that ameloblastoma is very much more common in Blacks than Whites in the population at risk. Conversely, dentigerous cysts are much more common in Whites. This makes it unlikely that dentigerous cysts predispose to ameloblastoma formation. These epidemiologic observations give rise to speculation as to whether some component of the South African Black diet or other environmental substance might possibly be an etiologic factor in ameloblastoma.

Energy budgets of mining-induced earthquakes and their interactions with nearby stopes

USGS Publications Warehouse

McGarr, A.

2000-01-01

In the early 1960's, N.G.W. Cook, using an underground network of geophones, demonstrated that most Witwatersrand tremors are closely associated with deep level gold mining operations. He also showed that the energy released by the closure of the tabular stopes at depths of the order of 2 km was more than sufficient to account for the mining-induced earthquakes. I report here updated versions of these two results based on more modern underground data acquired in the Witwatersrand gold fields. Firstly, an extensive suite of in situ stress data indicate that the ambient state of crustal stress here is close to the failure state in the absence of mining even though the tectonic setting is thoroughly stable. Mining initially stabilizes the rock mass by reducing the pore fluid pressure from its initial hydrostatic state to nearly zero. The extensive mine excavations, as Cook showed, concentrate the deviatoric stresses, in localized regions of the abutments, back into a failure state resulting in seismicity. Secondly, there appears to be two distinct types of mining-induced earthquakes: the first is strongly coupled to the mining and involves shear failure plus a coseismic volume reduction; the second type is not evidently coupled to any particular mine face, shows purely deviatoric failure, and is presumably caused by more regional changes in the state of stress due to mining. Thirdly, energy budgets for mining induced earthquakes of both types indicate that, of the available released energy, only a few per cent is radiated by the seismic waves with the majority being consumed in overcoming fault friction. Published by Elsevier Science Ltd.In the early 1960's, N.G.W. Cook, using an underground network of geophones, demonstrated that most Witwatersrand tremors are closely associated with deep level gold mining operations. He also showed that the energy released by the closure of the tabular stopes at depths of the order of 2 km was more than sufficient to account for the mining-induced earthquakes. I report here updated versions of these two results based on more modern underground data acquired in the Witwatersrand gold fields. Firstly, an extensive suite of in situ stress data indicate that the ambient state of crustal stress here is close to the failure state in the absence of mining even though the tectonic setting is thoroughly stable. Mining initially stabilizes the rock mass by reducing the pore fluid pressure from its initial hydrostatic state to nearly zero. The extensive mine excavations, as Cook showed, concentrate the deviatoric stresses, in localized regions of the abutments, back into a failure state resulting in seismicity. Secondly, there appears to be two distinct types of mining-induced earthquakes: the first is strongly coupled to the mining and involves shear failure plus a coseismic volume reduction; the second type is not evidently coupled to any particular mine face, shows purely deviatoric failure, and is presumably caused by more regional changes in the state of stress due to mining. Thirdly, energy budgets for mining induced earthquakes of both types indicate that, of the available released energy, only a few per cent is radiated by the seismic waves with the majority being consumed in overcoming fault friction.

On a Divisibility Relation for Lucas Sequences

DTIC Science & Technology

2016-01-08

Université Bordeaux 1 & CNRS, 351 cours de la Libération, 33405 Talence, France b School of Mathematics and Statistics, Wuhan University, Wuhan 430072...China c School of Mathematics , University of the Witwatersrand, Private Bag X3, Wits 2050, South Africa d Instituto de Matemáticas, Universidad de...Valparaíso, Chile e Naval Postgraduate School, Applied Mathematics Department, Monterey, CA 93943-5216, USA a r t i c l e i n f o a b s t r a c t

Undergraduate training in the atraumatic restorative treatment (ART) approach--an activity report.

PubMed

Mickenautsch, S; Rudolph, M J

2002-09-01

The Division of Public Oral Health at the University of the Witwatersrand conducted a 2-week ART training course for 5th year dental students in the School of Oral Health Sciences. Students were taught both theoretical knowledge and clinical skills in ART. Course evaluation showed that the course achieved its aims and objectives and was considered a worthwhile experience by students. However, there were some limitations to the format of the programme. We recommend that ART should be integrated as part of clinical student training in the BDS curriculum.

A method of assessing facial profile attractiveness and its application in comparing the aesthetic preferences of two samples of South Africans.

PubMed

Morar, Ajay; Stein, Errol

2011-06-01

Numerous studies have evaluated the perception of facial attractiveness. However, many of the instruments previously used have limitations. This study introduces an improved tool and describes its application in the assessment of the preferred facial profile in two sample groups. Cross-sectional study. Two sites were involved: a rural healthcare facility (Winterveldt, Northwest Province) and the campus of the University of the Witwatersrand (Johannesburg, Gauteng Province). Adult females and males selected from amongst first, attendees at the healthcare facility, and second, staff of the University of the Witwatersrand. Eight androgynous lateral facial profile images were created using a morphing software programme representing six transitions between two anchoring extremes in terms of lip retrusion/protrusion vs protrusion/retrusion. These images were presented to, and rated by, two mixed male/female groups of rural and of urban habitat using a pre-piloted form. Statistical analysis of the responses obtained established the preferred facial profile by gender in each group. The perception of facial attractiveness varied marginally between rural and urban black South Africans. There was no statistically significant difference between females and males in the rural group (P=0·2353) and those in the urban sample (P=0·1318) with respect to their choice of ideal facial profile. Females and males in both the rural and urban groups found extreme profile convexity unappealing. By contrast, a larger proportion of rural females, rural males and urban females demonstrated a preference for extreme profile concavity. The research tool described is a useful instrument in the assessment of facial profile attractiveness.

Evaluation of aeolian emissions from gold mine tailings on the Witwatersrand

NASA Astrophysics Data System (ADS)

Ojelede, M. E.; Annegarn, H. J.; Kneen, M. A.

2012-01-01

The Witwatersrand is known for the high frequency of aeolian dust storm episodes arising from gold mine tailings storage facilities (TSFs). Source and ambient atmosphere are poorly characterized from the point of view of particle size distribution and human health risk assessment. For years, routine monitoring was limited to sampling of dust fallout ⩾30 μm. Sampling and analyses of source and receptor material was conducted. Thirty-two bulk soils were collected from TSF along the east-west mining corridor, and size distribution analysis was performed in the range 0.05-900 μm using a Malvern® MS-14 Particle Size Analyser. Ambient aerosols in the range 0.25-32 μm were monitored at two separate locations using a Grimm® aerosol monitor, in the vicinity of three large currently active and a dormant TSF. Statistical analyses indicate that TSFs are rich in fine erodible materials, particularly active TSFs. Concentration of ⩽PM5 and ⩽PM10 components in source material was: recent slimes (14-24 vol.%; 22-38 vol.%), older slimes (6-17 vol.%; 11-26 vol.%) and sand (1-8 vol.%; 2-12 vol.%). Concentrations of airborne aerosols were below the South African Department of Environmental Affairs 24-h limit value of 120 μg m -3. With wind speeds exceeding 7 ms -1, ambient concentration reached 2160 μg m -3. This maximum is several times higher than the limit value. Erosion of tailings storage facilities is a strong driver influencing ambient particulate matter loading with adverse health implications for nearby residents.

Geological indicators for impact: The anomalous case of the Vredefort structure, South Africa

NASA Technical Reports Server (NTRS)

Antoine, L. A. G.; Reimold, W. U.

1988-01-01

The Vredefort Dome is located within and almost central to the Witwatersrand basin in its presently known extent. It exposes a central Archean granite core which is surrounded by a collar of supracrustal rocks. These collar rocks outline a strong polygonal geometry. The Archean core is comprised of two concentric zones, the Outer Granite Gneiss (OGG), and the core central Inlandsee Leucogranofels (ILG). The rocks of the inner core display granulite facies metamorphism, while the OGG is in amphibolite facies. The inner core is believed from recent drill hole information to be underlain by mafic and ultramafic gneisses, the extent of which cannot be assessed at present. A fairly broad zone of charnockites separates the OGG and ILG domains. This zone is characterized by a high concentration of pseudotachylite and ductile shearing. Whereas a number of other domical structures are located within or surrounding the Witwatersrand basin, the Vredefort structure is anomalous, in that it has: a partly polygonal geometry; extensive alkali intrusives in the northwestern sector; granophyre dykes (ring-dykes peripheral to the contact collar-basement and NW-SE or NE-SW trending dykes within the Archean basement); contact metamorphism of the collar supracrustal rocks; the overturning of collar supracrustals in the northern sectors; deformation phenomena widely regarded as representing shock metamorphism (pseudotachylite, (sub)planar microdeformation features in quartz, shatter cones and occurrences of high-P quartz polymorphs); a positive 30 mgal gravity anomaly; and high amplitude magnetic anomalies. Recent geophysical, structural and petrological evidence pertinent for the identification of the processes that led to the formation of the Vredefort structure are summarized.

Ventilatory Function in Relation to Mining Experience and Smoking in a Random Sample of Miners and Non-miners in a Witwatersrand Town1

PubMed Central

Sluis-Cremer, G. K.; Walters, L. G.; Sichel, H. S.

1967-01-01

The ventilatory capacity of a random sample of men over the age of 35 years in the town of Carletonville was estimated by the forced expiratory volume and the peak expiratory flow rate. Five hundred and sixty-two persons were working or had worked in gold-mines and 265 had never worked in gold-mines. No difference in ventilatory function was found between the miners and non-miners other than that due to the excess of chronic bronchitis in miners. PMID:6017134

Chemistry and palynology of carbon seams and associated rocks from the Witwatersrand goldfields, South Africa

USGS Publications Warehouse

Ebert, L.B.; Robbins, E.I.; Rose, K.D.; Kastrup, R.V.; Scanlon, J.C.; Gebhard, L.A.; Garcia, A.R.

1990-01-01

Carbon seams in the Witwatersrand System of South Africa host some of the richest gold concentrations in the world. A study of the microscopic characteristics in thin sections and acid residues, and of the chemical and physical nature of the carbon-bearing phases, was undertaken to gain some understanding of the biological precursors and thermal changes that have occurred since the seams were buried. The HClHF acid-resistant organic tissues in this Early Proterozoic coal are filamentous and spherical, which are typical morphologies for microorganisms. The tissues are carbonized black as would be expected for metamorphic rocks, so usual palynological techniques were of limited use. Therefore, the chemical and physical nature of the organic remains was studied by H C ratios, X-ray diffraction (XRD), 13C nuclear magnetic resonance (NMR), reductive chemistry, crosspolarization/magic angle spinning NMR (CP/MAS), and electron spin resonance (ESR). The H C ratios of the samples examined are similar to those of semi-anthracite and petroleum cokes from delayed cokers. XRD shows graphite is not present and that the gold is in elemental form, not chemically bound or intercalated between carbon planes. NMR shows that both aromatic and paraffinic carbons are present. Integration of the carbon NMR spectra suggests that 80% of the carbon is sp2-hybridized and 20% is sp3-hybridized. Reductive chemistry shows that the benzenoid entities are larger than common polynuclear aromatic hydrocarbons such as perylene and decacyclene. Dipolar dephasing CP/MAS NMR suggests the presence of two types of paraffinic carbons, a rigid methylene group and a rotating methyl group. The narrowing of the ESR linewidth between room temperature and 300??C shows that the materials examined have not previously been subjected to temperatures as high as 300??C. ?? 1990.

A quasi-Hertzian stress field from an internal source: A possible working model for the Vredefort structure

NASA Technical Reports Server (NTRS)

Antoine, L. A. G.; Reimold, W. U.; Colliston, W. P.

1992-01-01

The Vredefort structure is a large domal feature about 110 km southeast of Johannesburg, South Africa, situated within and almost central to the large intracratonic Witwatersrand Basin. This structure consists of an Archean core of ca. 45 km in diameter, consisting largely of granitic gneiss, surrounded by a collar of metasedimentary and metavolcanic supracrustal rocks of the Dominian Group, Witwatersrand and Ventersdorp Supergroups, and Transvaal Sequence. The interpretation of images of the gravity and magnetic fields over Vredefort has permitted the delineation of several important features of the structure and of its environment. The outline of the collar strata is a prominent feature of both the gravity and the magnetic fields. The Vredefort structure shares this distinctive geometry with other structures (e.g., Manicouagan, Decaturville, Sierra Madera) of debated impact origin. In all these, successively older strata with steep outward dips are encountered while traversing inward to the center of the structure. A further attribute of these structures is the shortening of the outcrop of a particular stratigraphic unit compared to the original perimeter of that unit. To account for the geometric attributes of the Vredefort structure a mechanical scheme is required where there is radial movement of horizontal strata toward, with uplift in, the center of the Vredefort structure. Two models can be proposed: (1) one in which there is a rapid rise and violent disruption of cover rocks in response to expansion of a fluid accumulation; and (2) one in which there is, in contrast, a nonexplosive, quasi-Hertzian stress field resulting from a diapiric process. Both models can accommodate the geometry and structural components of Vredefort.

Seismology at the Australian National University; an interview with Anton L. Hales

USGS Publications Warehouse

Spall, H.

1980-01-01

Dr. Anton L. Hales is a leading seismologist who has just retired as Director of the Research School of Earth Sciences at the Australian National University (ANU), Canberra. Prior to that, he headed the Geosciences Division at the University of Texas at Dallas, and, before that, he was Director of the Bernard Price Institute of Geophysical Research at the University of the Witwatersrand Johannesburg, South Africa. he is about to step down as President of the International Geodynamics Commission. Dr. Hales' research has involved marine geophysics, the travel times of seismic waves, and the structure of the Earth's crust and upper mantle. 

Urbanization in Africa since independence.

PubMed

Tarver, J D

1994-01-01

Over 185 million inhabitants were added to the urban areas of Africa between 1950 and 1990. Botswana, Lesotho, Namibia, South Africa, and Swaziland is the most highly urbanized, with 55% in 1990; while less than a quarter of Eastern Africa's population is living in urban centers. By the year 2015 more than half of Africa's population will be living in urban areas. Many parts of Africa have suffered prolonged droughts, overgrazing, locust infestations, and desertification. Millions have become refugees from natural disasters, political oppression, and rural poverty. The large exodus from Africa's rural areas has gone to cities but the large cities have attracted disproportionately large numbers of destitute migrants. Alexandria (1 million), Cairo (2.4 million) and the Witwatersrand in South Africa were the only African urban agglomerations with at least one million inhabitants in 1950. By 1990 the two Egyptian cities together had 12.7 million inhabitants and the Witwatersrand some 5 million, whereas the other 25 urban agglomerations with a million inhabitants each in 1990 had a total population of about 51 million. Lagos, Kinshasa, and Algiers ranged from 3 to 7.7 million. The capitals are the largest cities in at least 54 of the 59 countries and territories. Lagos, Nairobi, and Dar es Salaam are disproportionately larger than the next most populous cities in their countries. The 28 urban agglomerations with at least one million inhabitants had a total population of 70 million in 1990, and are projected to reach 100 million in the year 2000. Overall, Africa's urban population is projected to increase by approximately 135 million in the 1990-2000 decade (from 217 million to 352 million). About 105 million of the growth probably will occur in the smaller urban centers. The total African urban population is likely to reach one billion inhabitants within the next 50 years. It stood at 32 million in 1950. Presently, the United Nations projects 912 million urban residents (57% of the total population) by 2025.

Geochemical and hydrological constraints on the deep subsurface terrestrial ecosystems

NASA Astrophysics Data System (ADS)

Silver, B.; Onstott, T.; Hinton, S.; King, H.; Sherwood Lollar, B.; Lippmann-Pipke, J.

2008-12-01

Pore water and fluid inclusion compositions were determined on pristine rock cores from the Ventersdorp and Witwatersrand Supergroup by leaching experiments in order to constrain the origin of the chemical nutrients in the fracture water of the Witwatersrand basin. Subsequent chemical extractions including fusion analyses of the rock cores constrained the redox relevant mineral abundances of these strata. The resulting data set was used in mixing models with meteoric water from the overlying Transvaal dolomitic aquifer. The model also incorporated dissolved gas concentrations, radiogenic and radiolytic reactions, mineral dissolution and oxidation reactions, mineral equilibria and microbial redox reactions at rates that were varied over the course of one million years. Results revealed pore water and fluid inclusion leachates rich in Na, Ca, Si, Cl, acetate, SO42- and formate, with the resulting inferred fluid inclusion concentrations exceeding pore water concentrations, which in turn exceeded fracture water concentrations in nearly all observed elements. The model successfully simulated dissolved He and Cl concentrations with a mixing rate of 1e-5 L/year, corresponding to a fracture water velocity of 1 mm/year. Upon examining the viability of Fe reduction, SO42- reduction, acetogenesis, methanogenesis, NO3- reduction, anaerobic NH3 oxidation and HS- oxidation, model results indicate that SO42-reduction is the dominant metabolic process at high and low salinities and can be sustained at rates of 1.2e-12 M SO42- s-1 for biomasses of 2e8 cells/mL water. Final electron acceptor and donor concentrations and Free Energy Flux (FEF) calculations suggest that acetogenesis is not the source of acetate, nor is the syntrophic degradation of light hydrocarbons the source of the observed carboxylic acids. Ambient concentrations are instead likely the result of production via the thermally activated step-wise decarboxylation of abiogenic hydrocarbons and consumption by carboxylic acid utilizing metabolic reactions consistent with phylogenetic data showing few acetogens, no hydrocarbon oxidizers and a significant abundance of acetoclastic methanogens.

Preliminary evidence for the involvement of budding bacteria in the origin of Alaskan placer gold

USGS Publications Warehouse

Watterson, J.R.

1992-01-01

Lacelike networks of micrometre-size filiform gold associated wtih Alaskan placer gold particles are interpreted as low-temperature pseudomorphs of a Pedomicrobium-like budding bacterium. Submicron reproductive structures (hyphae) and other morphological features similar to those of Pedomicrobium manganicum occur as detailed three-dimensional facsimiles in high purity gold in and on placer gold particles from Lillian Creek, Alaska. In a scanning electron microscope survey, the majority of gold particles at nine Alaskan placer deposits appear to include gold that has accumulated chemically at low temperatures in and on the cells of P. manganicum. Similar bacterioform gold from a Paleozoic deposit in China and from the Precambrian Witwatersrand deposit in South Africa may indicate that bacterioform gold is widespread. -Author

Determinants of racial fertility differentials in some urban areas of South Africa.

PubMed

Chimere-Dan, O

1994-01-01

Results of a survey of some urban areas in the Pretoria-Witwatersrand-Vereenining region show differential impacts of proximate and socioeconomic factors on the fertility of urban blacks and whites. Timing of starting and ending of childbearing and the reproductive behaviour of women who have never been married account for the major differences in fertility levels. White women confine their childbearing career to the 20-39 age range, while black women utilise the entire 15-49 age range. The fertility level is quite high among black women who have never been married (in contrast to never married white women). With the exception of breast-feeding, racial patterns in other proximate determinants of fertility do not suggest the observed racial differentials in fertility.

An assessment of early mandibular growth.

PubMed

Hutchinson, E F; L'Abbé, E N; Oettlé, A C

2012-04-10

Quantification of skeletal data has been shown to be an effective and reliable method of demonstrating variation in human growth as well as for monitoring and interpreting growth. In South Africa as well as internationally, few researchers have assessed mandibular growth in late fetal period and early childhood and therefore standards for growth and age determination in these groups are limited. The purpose of this study was to evaluate growth in the mandible from the period of 31 gestational weeks to 36 months postnatal. A total of 74 mandibles were used. Dried mandibles were sourced from the Raymond A. Dart Collection (University of Witwatersrand), and cadaveric remains were obtained from the Universities of Pretoria and the Witwatersrand. The sample was divided into four groups; 31-40 gestational weeks (group 1), 0-11 months (group 2), 12-24 months (group 3), and 25-36 months (group 4). Twenty-one osteological landmarks were digitized using a MicroScribe G2. Ten standard measurements were created and included: the maximum length of mandible, mandibular body length and width, mandibular notch width and depth, mental foramen to inferior border of mandible, mandibular basilar widths bigonial and biantegonial, bigonial width of mental foramen and mental angle. Data were analyzed using PAST statistical software and Morphologika2 v2.5. Statistically significant differences were noted in the linear measurements for all group comparisons except between groups 3 and 4. The mandible morphologically changed from a round, smooth contour anteriorly to adopt a more sharp and narrow adult shape. A progressive increase in the depth and definition of the mandibular arch was also noted. In conclusion, the mandible initially grows to accommodate the developing tongue (up to 11 months), progressive dental eruption and mastication from 12 to 36 months. Mastication is associated with muscle mass development; this would necessitate an increase in the dimensions of the mandibular notch and associated muscle attachment sites. These findings might be valuable in the estimation of age in unidentified individuals and to monitor prenatal growth of the mandible for the early diagnosis of conditions associated with stunted mandibular growth. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

The Vredefort Dome: Review of geology and deformation phenomena and status report on current knowledge and remaining problematics (five years after the cryptoexplosion workshop)

NASA Technical Reports Server (NTRS)

Reimold, W. U.

1992-01-01

The Vredefort structure located in the center of the Witwatersrand basin in South Africa and the Sudbury structure in Canada are widely considered the two oldest and largest impact structures still evident on Earth. Both structures are very similar in a number of geological aspects (e.g., association with major economic ore deposits, similar ages of ca. 2 Ga, abundant pseudotachylite as well as shatter cone occurrences, overturned collar). However, whereas the geological community generally accepts an impact origin for the Sudbury structure, a number of researchers are still reluctant to accept this for the Vredefort Dome. Therefore, the aim of this review is to present new data, highlight the most obvious shortcomings in the current database, and to summarize the major arguments in the genetic controversy.

Exploitation of the vulnerable in research: Responses to lessons learnt in history.

PubMed

Dhai, Amaboo

2017-05-24

The Nuremberg Trials raised insightful issues on how and why doctors who were trained in the Hippocratic tradition were able to commit such egregious and heinous medical crimes. The vulnerable were considered to be subhuman, of decreased intelligence, of no moral status and lacking human dignity. The reputation of the medical profession had been undermined, professionalism questioned and the doctor-patient relationship damaged as a result of the Nazi medical experiments. The World Medical Association's Declaration of Helsinki has been hailed as one of the most successful efforts in rescuing medical research from the darkness of the scandals and tragedies in health research. The first Research Ethics Committee in South Africa was established in 1966 at the University of the Witwatersrand. From the mid-1970s other institutions followed suit. The promulgation of the National Health Act No. 61 of 2003, in 2004, resulted in strong protectionism for research participants in the country.

A GIS approach to seismic risk assessment with an application to mining-related seismicity in Johannesburg, South Africa

NASA Astrophysics Data System (ADS)

Liebenberg, Keagen; Smit, Ansie; Coetzee, Serena; Kijko, Andrzej

2017-08-01

The majority of seismic activity in South Africa is related to extensive mining operations, usually in close proximity to densely populated areas where a relatively weak seismic event could cause damage. Despite a significant decrease in mining operations in the Witwatersrand area, the number of seismic events appears to be increasing and is attributed to the acid mine drainage problem. The increased seismicity is raising concern amongst disaster management centres and in the insurance industry. A better understanding is required of the vulnerability and the size of the potential loss of people and infrastructure in densely populated Johannesburg and its surrounding areas. Results of a deterministic seismic risk, vulnerability, and loss assessment are presented by making use of a geographic information system (GIS). The results illustrate the benefits of using GIS and contribute to a better understanding of the risk, which can assist in improving disaster preparedness.

Phillip V. Tobias as an anatomist.

PubMed

Strkalj, Goran; Pather, Nalini

2013-05-01

The article outlines the career of the renowned South African scientist Phillip Vallentine Tobias. While he made substantial contributions to a number of scientific disciplines, Tobias spent most of his career teaching anatomy at his alma mater, University of the Witwatersrand, Johannesburg, and saw himself primarily as an anatomist. The first part of this article presents Tobias' major contributions to science and demonstrates that his profound knowledge of anatomy was the basis of many of his groundbreaking research accomplishments. The second part of the article focuses on Tobias' career in anatomy and his significant contribution to anatomy teaching and administration, particularly in establishing and organizing the Anatomical Society of Southern Africa. The article also demonstrates how Tobias' academic career was constrained by the oppressive system of apartheid South Africa and how social engagement was an integral part of his intellectual activities. Copyright © 2012 Wiley Periodicals, Inc.

Quartz-pebble-conglomerate gold deposits: Chapter P in Mineral deposit models for resource assessment

USGS Publications Warehouse

Taylor, Ryan D.; Anderson, Eric D.

2018-05-17

Quartz-pebble-conglomerate gold deposits represent the largest repository of gold on Earth, largely due to the deposits of the Witwatersrand Basin, which account for nearly 40 percent of the total gold produced throughout Earth’s history. This deposit type has had a controversial history in regards to genetic models. However, most researchers conclude that they are paleoplacer deposits that have been modified by metamorphism and hydrothermal fluid flow subsequent to initial sedimentation.The deposits are found exclusively within fault-bounded depositional basins. The periphery of these basins commonly consists of granite-greenstone terranes, classic hosts for lode gold that source the detrital material infilling the basin. The gold reefs are typically located along unconformities or, less commonly, at the top of sedimentary beds. Large quartz pebbles and heavy-mineral concentrates are found associated with the gold. Deposits that formed prior to the Great Oxidation Event (circa 2.4 giga-annum [Ga]) contain pyrite, whereas younger deposits contain iron oxides. Uranium minerals and hydrocarbons are also notable features of some deposits.Much of the gold in these types of deposits forms crystalline features that are the product of local remobilization. However, some gold grains preserve textures that are undoubtedly of detrital origin. Other heavy minerals, such as pyrite, contain growth banding that is truncated along broken margins, which indicates that they were transported into place as opposed to forming by in situ growth in a hydrothermal setting.The ore tailings associated with these deposits commonly contain uranium-rich minerals and sulfides. Oxidation of the sulfides releases sulfuric acid and mobilizes various metals into the environment. The neutralizing potential of the tailings is minimal, since carbonate minerals are rare. The continuity of the tabular ore bodies, such as those of the Witwatersrand Basin, has allowed these mines to be the deepest in the world. The extreme depths create engineering complications and safety issues for the miners, such as rock bursts as a result of pressure release.The richness of these deposits makes them a desirable exploration target. However, the likelihood of future discoveries is minimal. Small deposits found in the United States include those found at Nemo in the Black Hills of South Dakota and Deep Lake in the Sierra Madre of Wyoming.

Interdisciplinary Environmental Summer Study Abroad in Southern Africa as a Mechanism for the Development of an International Research and Education Consortium

NASA Astrophysics Data System (ADS)

Swap, R. J.; Sabea, H.; Annegarn, H.; Ford, C.; Netshandama-Funyufunyu, V.; Omara-Ojungu, P.; Vaz, K.; Ribeiro, N.; Twine, W.; Terni, C.; Estes, L.

2005-12-01

We describe an interdisciplinary course for non-specialist undergraduates in which the students experience firsthand issues of regional environmental complexity and have the unique opportunity to gain insight into the role the environment plays in shaping the people and culture of southern Africa. Undergraduates receive 3 hours of credit both in Environmental Science and Anthropology for the ``People, Culture and Environment of Southern Africa" study abroad program. The program is an intensive introduction to the physical geography, history and culture of the region and involves an intensive blend of in-class lectures and field trips with daily debriefing discussions. Over the duration of the 30 day program, students are exposed to elements of geology, ecology, hydrology and atmospheric science and how the interconnectedness of these different aspects of the physical environment help shape the history of the people and their culture in the region. Information about logistics and course development as well as to how this summer study abroad program has contributed to the development and expansion of the Southern Africa Virginia Networks and Associations (SAVANA) consortium will be detailed. The program builds upon more than 12 years of relationships between UVA faculty and their southern African colleagues developed during the course of several regional scale research programs with the most recent being the Southern African Regional Science Initiative - SAFARI 2000. Students enrolled with the UVA program are joined by their counterparts and interact with faculty from institutional partners both in the classroom and in the field. Participants operate out of four major locations: Johannesburg, RSA (Univ. of the Witwatersrand); Thohoyondou, RSA (Univ. of Venda); Maputo, MOZ (Univ. of Eduardo Mondlane); and Acornhoek, RSA (Univ. of the Witwatersrand - Rural Facility). Class size is limited to 15 students from UVA and about 6 SAVANA consortium students. This pairing with SAVANA students provides a unique, `round-the clock' learning experience for both U.S. and southern African students. Program participants have come from a variety of student backgrounds and majors including: Anthropology, African American Affairs, Architecture, Biology, English, Environmental Thought and Practice, Environmental Science, History, International Relations, Political Science, Psychology, Sociology and Women's Studies. Many course alumni have participated in Peace Corps, Teach for America, Americorps as well as to volunteer in South Africa or have pursued graduate degrees often related to various aspects of their experience.

Atmospheric Chemistry Over Southern Africa

NASA Technical Reports Server (NTRS)

Gatebe, Charles K.; Levy, Robert C.; Thompson, Anne M.

2011-01-01

During the southern African dry season, regional haze from mixed industrial pollution, biomass burning aerosol and gases from domestic and grassland fires, and biogenic sources from plants and soils is worsened by a semi-permanent atmosphere gyre over the subcontinent. These factors were a driver of several major international field campaigns in the 1990s and early 2000s, and attracted many scientists to the region. Some researchers were interested in understanding fundamental processes governing chemistry of the atmosphere and interaction with climate change. Others found favorable conditions for evaluating satellite-derived measurements of atmospheric properties and a changing land surface. With that background in mind a workshop on atmospheric chemistry was held in South Africa. Sponsored by the International Commission for Atmospheric Chemistry and Global Pollution (ICACGP; http://www.icacgp.org/), the workshop received generous support from the South African power utility, Eskom, and the Climatology Research Group of the University of the Witwatersrand, Johannesburg, South Africa. The purpose of the workshop was to review some earlier findings as well as more recent findings on southern African climate vulnerability, chemical changes due to urbanization, land-use modification, and how these factors interact. Originally proposed by John Burrows, president of ICACGP, the workshop was the first ICACGP regional workshop to study the interaction of air pollution with global chemical and climate change. Organized locally by the University of the Witwatersrand, the workshop attracted more than 60 delegates from South Africa, Mozambique, Botswana, Zimbabwe, France, Germany, Canada, and the United States. More than 30 presentations were given, exploring both retrospective and prospective aspects of the science. In several talks, attention was focused on southern African chemistry, atmospheric pollution monitoring, and climate processes as they were studied in the field campaigns such as Transport and Atmospheric Chemistry Near the Equator-Atlantic (TRACE-A), Southern African Fire-Atmosphere Research Initiative (SAFARI-92), and Southern African Regional Science Initiative (SAFARI 2000). Since those large international efforts, satellites have matured enough to enable quantifiable measurements of regional land surface, atmosphere, and ocean. In addition, global and chemical transport models have also been advanced to incorporate various data. Thus, the timing of the workshop was right for a full-fledged re-assessment of the chemistry, physics, and socio-economical impacts caused by pollution in the region, including a characterization of sources, deposition, and feedbacks with climate change.

PREFACE: International Workshop on Discovery Physics at the LHC (Kruger2014)

NASA Astrophysics Data System (ADS)

Cleymans, Jean

2015-06-01

The third biannual conference on 'Discovery Physics at the LHC' was held on December 1-6 2014 at the Kruger Gate Hotel in South Africa. Over 100 participants attended from Austria, Australia, Belgium, Brazil, Canada, China, the Czech Republic, France, Germany, Italy, the Netherlands, Norway, Poland, South Africa, Switzerland, the UK and the USA. The latest results from the Large Hadron Collider as well the latest theoretical insights were presented. With the majestic Kruger National Park in the background this led to a very stimulating conference with many exchanges taking place. The proceedings reflect the high level of the conference. The financial contributions from the SA-CERN programme, the UCT-CERN Research Centre, the University of Johannesburg, the University of the Witwatersrand and iThemba L.A.B.S. are gratefully acknowledged. Local Organizing Committee: Z. Buthelezi J. Cleymans (chair) S. H. Connell A. S. Cornell T. Dietel S. Förtsch N. Haasbroek A. Hamilton W. A. Horowitz B. Mellado Z. Z. Vilakazi S. Yacoob

Orogenic gold and geologic time: A global synthesis

USGS Publications Warehouse

Goldfarb, R.J.; Groves, D.I.; Gardoll, S.

2001-01-01

Orogenic gold deposits have formed over more than 3 billion years of Earth's history, episodically during the Middle Archean to younger Precambrian, and continuously throughout the Phanerozoic. This class of gold deposit is characteristically associated with deformed and metamorphosed mid-crustal blocks, particularly in spatial association with major crustal structures. A consistent spatial and temporal association with granitoids of a variety of compositions indicates that melts and fluids were both inherent products of thermal events during orogenesis. Including placer accumulations, which are commonly intimately associated with this mineral deposit type, recognized production and resources from economic Phanerozoic orogenic-gold deposits are estimated at just over one billion ounces gold. Exclusive of the still-controversial Witwatersrand ores, known Precambrian gold concentrations are about half this amount. The recent increased applicability of global paleo-reconstructions, coupled with improved geochronology from most of the world's major gold camps, allows for an improved understanding of the distribution pattern of orogenic gold in space and time.

The innovation of the subspecialty of Paediatric Virology: An interview with Research Professor of Molecular Virology Anna Kramvis

PubMed Central

Mammas, Ioannis N.; Spandidos, Demetrios A.

2017-01-01

Professor Anna Kramvis, Research Professor of Molecular Virology at the University of the Witwatersrand in Johannesburg, South Africa, talks about direct-acting antiviral treatments against hepatitis C virus (HCV), as well as the perspective of the development of an effective vaccine against HCV. She emphasises the necessity of vaccination against hepatitis B virus (HBV), highlighting that it is very important that vaccination should be administered at birth in order to prevent mother-to-child transmission (MTCT) of HBV. Professor Kramvis states that vaccination against HBV is safe and that HBV and HCV infections are not contraindications for breastfeeding. Regarding the challenge of Paediatric Virology, she believes that it is a field that during the last years is increasing exponentially, while she concurs that Paediatric Virology subspecialty will be a popular choice for infectious diseases subspecialists. In the context of the 3rd Workshop on Paediatric Virology, which will be held in Athens on October 7th, 2017, Professor Kramvis will give her key lecture on MTCT of HBV and HCV. PMID:29042915

The innovation of the subspecialty of Paediatric Virology: An interview with Research Professor of Molecular Virology Anna Kramvis.

PubMed

Mammas, Ioannis N; Spandidos, Demetrios A

2017-10-01

Professor Anna Kramvis, Research Professor of Molecular Virology at the University of the Witwatersrand in Johannesburg, South Africa, talks about direct-acting antiviral treatments against hepatitis C virus (HCV), as well as the perspective of the development of an effective vaccine against HCV. She emphasises the necessity of vaccination against hepatitis B virus (HBV), highlighting that it is very important that vaccination should be administered at birth in order to prevent mother-to-child transmission (MTCT) of HBV. Professor Kramvis states that vaccination against HBV is safe and that HBV and HCV infections are not contraindications for breastfeeding. Regarding the challenge of Paediatric Virology, she believes that it is a field that during the last years is increasing exponentially, while she concurs that Paediatric Virology subspecialty will be a popular choice for infectious diseases subspecialists. In the context of the 3rd Workshop on Paediatric Virology, which will be held in Athens on October 7th, 2017, Professor Kramvis will give her key lecture on MTCT of HBV and HCV.

PREFACE: International Workshop on Discovery Physics at the LHC (Kruger2012)

NASA Astrophysics Data System (ADS)

Cleymans, Jean

2013-08-01

The second conference on 'Discovery Physics at the LHC' was held on 3-7 December 2012 at the Kruger Gate Hotel in South Africa. In total there were 110 participants from Armenia, Belgium, Brazil, Canada, Czech Republic, France, Germany, Greece, Israel, Italy, Norway, Poland, USA, Russia, Slovakia, Spain, Sweden, United Kingdom, Switzerland and South Africa. The latest results from the Large Hadron Collider, Brookhaven National Laboratory, Jefferson Laboratory and BABAR experiments, as well as the latest theoretical insights were presented. Set against the backdrop of the majestic Kruger National Park a very stimulating conference with many exchanges took place. The proceedings reflect the high standard of the conference. The financial contributions from the National Institute for Theoretical Physics (NITHeP), the SA-CERN programme, the UCT-CERN Research Centre, the University of Johannesburg, the University of the Witwatersrand and iThemba Labs—Laboratory for Accelerator Based Science are gratefully acknowledged. Jean Cleymans Chair of the Local Organizing Committee Local Organizing Committee Oana Boeriu Jean Cleymans Simon H Connell Alan S Cornell William A Horowitz Andre Peshier Trevor Vickey Zeblon Z Vilakazi Group picture

New U Pb SHRIMP zircon age for the Schurwedraai alkali granite: Implications for pre-impact development of the Vredefort Dome and extent of Bushveld magmatism, South Africa

NASA Astrophysics Data System (ADS)

Graham, I. T.; De Waal, S. A.; Armstrong, R. A.

2005-12-01

The Schurwedraai alkali granite is one of a number of prominent ultramafic-mafic and felsic intrusions in the Neoarchaean to Palaeoproterozoic sub-vertical supracrustal collar rocks of the Vredefort Dome, South Africa. The alkali granite intruded the Neoarchaean Witwatersrand Supergroup and has a peralkaline to peraluminous composition. A new zircon SHRIMP crystallization age of 2052 ± 14 Ma for the Schurwedraai alkali granite places it statistically before the Vredefort impact event at 2023 ± 4 Ma and within the accepted emplacement interval of 2050-2060 Ma of the Bushveld magmatic event. The presence of the alkali granite and associated small ultramafic-mafic intrusions in the Vredefort collar rocks extends the southern extremity of Bushveld-related intrusions to some 120 km south of Johannesburg and about 150 km south of the current outcrop area of the Bushveld Complex. The combined effect of these ultramafic-mafic and felsic bodies may have contributed to a pronouncedly steep pre-impact geothermal gradient in the Vredefort area, and to the amphibolite-grade metamorphism observed in the supracrustal collar rocks of the Vredefort Dome.

Edinburgh, the Scottish pioneers of anatomy and their lasting influence in South Africa.

PubMed

Correia, J C; Wessels, Q; Vorster, W

2013-11-01

The history of the origin of anatomy education in South Africa is the history of an arduous journey through time. The lasting influence of Edinburgh came in the form of Robert Black Thomson. He was a student and assistant of Sir William Turner who gave rise to the first chair of anatomy and the establishment of a department at the South African College, known today as University of Cape Town. Thomson was later succeeded by Matthew Drennan, a keen anthropologist, who was revered by his students. This Scottish link prevailed over time with the appointment of Edward Philip Stibbe as the chair of anatomy at the South African School of Mines and Technology, which later became the University of the Witwatersrand. Stibbe's successor, Raymond Arthur Dart, a graduate of the University of Sydney, was trained in an anatomy department sculpted on that of Edinburgh by Professor James Thomas Wilson. Wilson's influence at the University of Sydney can be traced back to Edinburgh and William Turner through Thomas Anderson Stuart. Both Dart and Robert Broom, another Scot, were considered as Africa's wild men by the late Professor Tobias. Here, the authors explore the Scottish link and origins of anatomy pedagogy in South Africa.

A profile of students receiving counselling services at a university in post-apartheid South Africa.

PubMed

Bowman, Brett; Payne, Jarrod

2011-12-01

The purpose of this study was to describe a profile of students seeking counselling at a racially diverse university in post-apartheid South Africa as a means to demonstrate the importance of routinely collecting and analysing student counselling data at university-based centres across the country. Student data were extracted from the only two counselling centres based at the University of the Witwatersrand in Johannesburg that provided services to 831 students during 2008. The 26 243 students that did not seek counselling during this period formed the comparison group. These data were analysed using logistic regression. Black, female and students within the 21-25 year age category were more likely to receive counselling, and presenting problems varied by population group. Given the country's past and continued levels of social asymmetry, we argue that the development of standardised university-based reporting systems able to describe the characteristics and presenting problems of students seeking counselling across South African universities should be prioritised by its higher education sector. Timely access to information of this kind is crucial to the generation of evidence-based mental health interventions in a population that is especially important to the country's development vision.

A tectonic reconstruction of accreted terranes along the paleo-Pacific margin of Gondwana

NASA Astrophysics Data System (ADS)

Bammel, Brandon

The southern oceanic margin of Gondwana was nearly 40,000 km long or 24,854.8 miles. The southern margin was the result of the Terra Australis orogen. Spanning 18,000 km or 11,184.7 miles and is proposed as one of the largest and longest lived orogens in Earth history. The paleo-Pacific margin of Gondwana consisted of segments of the Australian-Antarctic craton, southern South America (modern Argentina and Chile), southern South Africa, Marie Byrdland, New Zealand and its adjacent continental shelf, the Ellsworth Mountains, and the Transantarctic Mountains. The process of terrane accretion has played a substantial part in the assembly of the continents as they look today. The paleo-Pacific margin of Gondwana was an active region of terrane accretion from the Neoproterozoic to the Late Mesozoic. This research study examines the accretion of terranes across the paleo-Pacific Gondwana margin to provide a comprehensive reconstruction. A paleogeographic basemap was created using PALEOMAP Project maps and the geology data was provided by the School of Geoscience from the University of Witwatersrand of South Africa. Location and data analyzed for terranes were collected building a PDF library of journal articles across numerous geological publications.

Applicants for employment who are HIV positive: a recent case.

PubMed

Du Plessis, M

2000-01-01

This paper presents a case between South African Airways (SAA) and an applicant for employment who did not volunteer information about his HIV status. The matter between Jacques Charl Hoffmann, an HIV-infected man applying for a position as flight attendant, and SAA was heard before Judge Hussain in the Witwatersrand Local Division. Mr. Hoffmann contended that SAA had unfairly discriminated against him solely on the basis of his HIV-positive status. He argued that such unfair discrimination violated his constitutional rights to dignity, equality, fair labor practices, and privacy. Considered as a whole, Judge Hussain found that the policy of SAA was justified and substantiated. It is noted that the policy is not selectively applied against those persons who are HIV-positive, instead it is directed at detecting all kinds of disabilities that make employment as a flight attendant unsuitable. To the judge, the "unsuitability" of an applicant is to be considered against the policy's consideration of "medical, safety, and operational grounds". In conclusion, the court found it justifiable for the airline to conduct medical examinations of aspiring flight attendants, and its refusal to employ Mr. Hoffmann was not an act of unfair discrimination.

Availability of free oxygen in deep bottom water of some Archean-Early Paleoproterozoic ocean basins as derived from iron formation facies analyses

NASA Astrophysics Data System (ADS)

Beukes, N. J.; Smith, A.

2013-12-01

Archean to Early Paleoproterozoic ocean basins are commonly, although not exclusively, depicted as rather static systems; either permanently stratified with shallow mixed oxygenated water overlying anoxic deep water or with a totally anoxic water column. The anoxic water columns are considered enriched in dissolved ferrous iron derived from hydrothermal plume activity. These sourced deposition of iron formations through precipitation of mainly ferrihydrite via reaction with free oxygen in the stratified model or anaerobic iron oxidizing photoautotrophs in the anoxic model. However, both these models face a simple basic problem if detailed facies reconstructions of deepwater microbanded iron formations (MIFs) are considered. In such MIFs it is common that the deepest water and most distal facies is hematite rich followed shoreward by magnetite, iron silicate and siderite facies iron formation. Examples of such facies relations are known from jaspilitic iron formation of the ~3,2 Ga Fig Tree Group (Barberton Mountainland), ~ 2,95 Ga iron formations of the Witwatersrand-Mozaan basin and the ~2,5 Ga Kuruman Iron Formation, Transvaal Supergroup, South Africa. Facies relations of these MIFs with associated siliciclastics or carbonates also indicate that the upper water columns of the basins, down to below wave base, were depleted in iron favoring anoxic-oxic stratification rather than total anoxia. In the MIFs it can be shown that hematite in the distal facies represents the earliest formed diagenetic mineral; most likely crystallized from primary ferrihydrite. The problem is one of how ferrihydrite could have been preserved on the ocean floor if it was in direct contact with reducing ferrous deep bottom water. Rather dissolved ferrous iron would have reacted with ferrihydrite to form diagenetic magnetite. This dilemma is resolved if in the area of deepwater hematite MIF deposition, the anoxic ferrous iron enriched plume was detached from the basin floor due to buoyancy in slightly oxygenated cold deep ocean water. Ferrihydrite, precipitated along the oxic-anoxic interface along the bottom of the buoyant plume could then settle to the floor of the basin without interference of dissolved ferrous iron. This model requires that oxygen, derived from photosynthesis in shallow water, circulated down to deep water creating a slightly oxygenated ocean basin system invaded by buoyant anoxic ferrous plumes. In areas where these plumes came in contact with the basin floor, magnetite and/or carbonate facies iron formation formed; the latter in areas of highest organic carbon influx. Extensive glacial diamictites in the Witwatersrand-Mozaan basin argues for climatic zonation in the Mesoarchean driving deep ocean currents. This model may explain why the rise of oxygen in the atmosphere was so long delayed after development of oxygenic photosynthesis; simply because in the dynamic ocean system oxygen could come into contact with much larger volumes of reduced species in the water column and along the ocean floor than in a static stratified system. It also impacts on reconstruction of microbial communities in Archean oceans.

Health Risk Assessment of Heavy Metals in Soils from Witwatersrand Gold Mining Basin, South Africa.

PubMed

Kamunda, Caspah; Mathuthu, Manny; Madhuku, Morgan

2016-06-30

The study evaluates the health risk caused by heavy metals to the inhabitants of a gold mining area. In this study, 56 soil samples from five mine tailings and 17 from two mine villages were collected and analyzed for Asernic (As), Lead (Pb), Mercury (Hg), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Nickel (Ni), Copper (Cu) and Zinc (Zn) using ICP-MS. Measured concentrations of these heavy metals were then used to calculate the health risk for adults and children. Their concentrations were such that Cr > Ni > As > Zn > Cu > Co > Pb > Hg > Cd, with As, Cr and Ni higher than permissible levels. For the adult population, the Hazard Index value for all pathways was found to be 2.13, making non-carcinogenic effects significant to the adult population. For children, the Hazard Index value was 43.80, a value >1, which poses serious non-carcinogenic effect to children living in the gold mining area. The carcinogenic risk was found to be 1.7 × 10(-4) implying that 1 person in every 5882 adults may be affected. In addition, for children, in every 2725 individuals, 1 child may be affected (3.67 × 10(-4)). These carcinogenic risk values were both higher than acceptable values.

Health Risk Assessment of Heavy Metals in Soils from Witwatersrand Gold Mining Basin, South Africa

PubMed Central

Kamunda, Caspah; Mathuthu, Manny; Madhuku, Morgan

2016-01-01

The study evaluates the health risk caused by heavy metals to the inhabitants of a gold mining area. In this study, 56 soil samples from five mine tailings and 17 from two mine villages were collected and analyzed for Asernic (As), Lead (Pb), Mercury (Hg), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Nickel (Ni), Copper (Cu) and Zinc (Zn) using ICP-MS. Measured concentrations of these heavy metals were then used to calculate the health risk for adults and children. Their concentrations were such that Cr > Ni > As > Zn > Cu > Co > Pb > Hg > Cd, with As, Cr and Ni higher than permissible levels. For the adult population, the Hazard Index value for all pathways was found to be 2.13, making non-carcinogenic effects significant to the adult population. For children, the Hazard Index value was 43.80, a value >>1, which poses serious non-carcinogenic effect to children living in the gold mining area. The carcinogenic risk was found to be 1.7 × 10−4 implying that 1 person in every 5882 adults may be affected. In addition, for children, in every 2725 individuals, 1 child may be affected (3.67 × 10−4). These carcinogenic risk values were both higher than acceptable values. PMID:27376316

Sex determination from the radius and ulna in a modern South African sample.

PubMed

Barrier, I L O; L'Abbé, E N

2008-07-18

With a large number of unidentified skeletal remains found in South Africa, the development of population specific osteometric standards is imperative. Forensic anthropologists need to have access to a variety of techniques to establish accurate demographic profiles from complete, fragmentary and/or commingled remains. No research has been done on the forearm of African samples, even though these bones have been shown to exhibit sexual dimorphism. The purpose of this paper is to develop discriminant function formulae to determine sex from the radius and ulna in a South African population. The sample consisted of 200 male and 200 female skeletons from the Pretoria Bone (University of Pretoria) and Raymond A. Dart (Witwatersrand University) collections. Sixteen standard anthropometric measurements were taken from the radius (9) and ulna (7) and subjected to stepwise and direct discriminant function analysis. Distal breadth, minimum mid-shaft diameter and maximum head diameter were the best discriminators of sex for the radius, while minimum mid-shaft diameter and olecranon breadth were selected for the ulna. Classification accuracy for the forearm ranged from 76 to 86%. The radius and ulna can be considered moderate discriminators for determining sex in a South African group. However, it is advised that these formulae are used in conjunction with additional methods to determine sex.

Reframing Vulnerability: Mozambican Refugees’ Access to State-Funded Pensions in Rural South Africa

PubMed Central

2012-01-01

Researchers at the South African Medical Research Council/University of the Witwatersrand Rural Public Health and Health Transitions Research Unit (Agincourt) fieldsite in rural South Africa consider Mozambican residents more vulnerable than others in the local population. These self-settled refugees, many of whom are still not South African citizens, primarily came to South Africa in the 1980s during the Mozambican Civil War. This perceived economic vulnerability is rooted in their difficulties in accessing social grants, until recently legally available only to those with South African citizenship documentation. This paper focuses on semi-structured interviews with 30 ‘older’ women of Mozambican-descent living in the Agincourt area. These interviews highlight three important aspects of vulnerability; the respondents: (1) perceive a risk of deportation despite their having lived in the country for 20 years, (2) are unable to easily access social grants, namely the state-funded old-age pension, and (3) struggle to make ends meet when faced with daily needs and crisis situations. All three of these vulnerabilities were mediated to some extent by these women’s resourcefulness. They generated ties to South Africa through obtaining identification-documents, used these documents to access pensions, and used the pensions to help them sustain their multigenerational households. PMID:19142721

Closing the barrier between disease and health outcomes in Africa through research and capacity development

PubMed Central

Kramer, Beverley; Libhaber, Elena

2018-01-01

ABSTRACT Background: While the burden of disease in Africa is high, health research emanating from the continent is low. Building human capacity and research infrastructure to close the gap between research and disease is thus of great imporatance. Objective: In order to improve research outputs and postgraduate training in the Faculty of Health Sciences, University of the Witwatersrand, the Health Sciences Research Office put in place a series of strategic initiatives over time. Methods: A range of strategic activities, for both postgraduate students and academic staff, were developed in parallel and sequentially over a period of approximately nine years (2008–2016). The latter years were a time of consolidation of the programmes. Outcomes of these activities were ‘measured’ by increases in publications, decreases in time to graduation and enrichment of the research environment. Results: A doubling of research publications and an increase in citations occurred over the period under review. In addition, there was a decrease in the time postgraduate students took to graduate. Conclusions: A varied, but structured research management plan may be of value in African and other developing health sciences institutions to enable the increase in research outputs and capacity development, desperately needed to close the barrier between disease and health. PMID:29370732

Third molar impaction and agenesis: influence on anterior crowding.

PubMed

Esan, Temitope; Schepartz, Lynne A

2017-02-01

Background Third molar influence on anterior crowding is controversial, but they are assumed to play a major role in compromising dental arch space. Aim To evaluate the relationship among impaction, agenesis and crowding in black South African males. Subjects and method Mandibles and maxillae of 535 black South African males in the Raymond A. Dart Collection of Human Skeletons, University of the Witwatersrand were examined for anterior crowding and third molar agenesis and impaction. Dental crowding was determined using Little's irregularity index. Results Individuals with impaction showed more moderate-to-extreme crowding than those with agenesis. Bilateral third molar presence was more frequently associated with ideal-to-minimal crowding. Weak positive but significant correlations between crowding and impaction were found (mandible, ρ = 0.154, p = 0.000; maxilla ρ = 0.130, p = 0.000). The direction was the opposite for bilateral presence of molars (mandible, ρ = -0.135, p = 0.02; maxilla, ρ = -0.111, p = 0.010). Odds of mandibular crowding were greatest in individuals with impaction (OR = 3.22, CI = 1.716-6.05, p < 0.001). Maxillary results were similar. Conclusion Third molar impaction plays a role in anterior crowding. Third molar presence was not associated with anterior crowding, while agenesis did not explain absence of crowding.

Cyanide hazards to plants and animals from gold mining and related water issues

USGS Publications Warehouse

Eisler, R.; Wiemeyer, Stanley N.

2004-01-01

Highly toxic sodium cyanide (NaCN) is used by the international mining community to extract gold and other precious metals through milling of high-grade ores and heap leaching of low-grade ores (Korte et al. 2000). The process to concentrate gold using cyanide was developed in Scotland in 1887 and was used almost immediately in the Witwatersrand gold fields of the Republic of South Africa. Heap leaching with cyanide was proposed by the U.S. Bureau of Mines in 1969 as a means of extracting gold from low-grade ores. The gold industry adopted the technique in the 1970s, soon making heap leaching the dominant technology in gold extraction (Da Rosa and Lyon 1997). The heap leach and milling processes, which involve dewatering of gold-bearing ores, spraying of dilute cyanide solutions on extremely large heaps of ores containing low concentrations of gold, or the milling of ores with the use of cyanide and subsequent recovery of the gold-cyanide complex, have created a number of serious environmental problems affecting wildlife and water management. In this account, we review the history of cyanide use in gold mining with emphasis on heap leach gold mining, cyanide hazards to plants and animals, water management issues associated with gold mining, and proposed mitigation and research needs.

Pseudotachylitic breccia in mafic and felsic rocks

NASA Astrophysics Data System (ADS)

Kovaleva, Elizaveta; Huber, Matthew S.

2017-04-01

Impact-produced pseudotachylitic breccia (PTB) is abundant in the core of the Vredefort impact structure and was found in many pre-impact lithologies (e.g., Reimold and Colliston, 1994; Gibson et al., 1997). The mechanisms involved in the process of forming this rock remain highly debated, and various authors have discussed many possible models. We investigate PTB from two different rock types: meta-granite and meta-gabbro and test how lithology controls the development of PTB. We also report on clast transport between different lithologies. In the core of the Vredefort impact structure, meta-granite and meta-gabbro are observed in contact with each other, with an extensive set of PTB veins cutting through both lithologies. Microstructural analyses of the PTB veins in thin sections reveals differences between PTBs in meta-granite and meta-gabbro. In granitic samples, PTB often develops along contacts of material with different physical properties, such as a contact with a migmatite or pegmatite vein. Nucleation sites of PTB have features consistent with ductile deformation and shearing, such as sigmoudal-shaped clasts and dragged edges of the veins. Preferential melting of mafic and hydrous minerals takes place (e.g., Reimold and Colliston, 1994; Gibson et al., 2002). Refractory phases remain in the melt as clasts and form reaction rims. In contrast, PTB in meta-gabbro develop in zones with brittle deformation, and do not exploit existing physical contacts. Cataclastic zones develop along the faults and progressively produce ultracataclasites and melt. Thus, PTB veins in meta-gabbro contain fewer clasts. Clasts usually represent multi-phase fragments of host rock and not specific phases. Such fragments often originate from the material trapped between two parallel or horse-tail faults. The lithological control on the development of PTB does not imply that PTB develops independently in different lithologies. We have observed granitic clasts within PTB veins in meta-gabbro, demonstrating clast transport between lithologies. PT melt in meta-gabbro has a two-phase structure: a phase free of granitic clasts, and a phase that contains granitic clasts. This also indicates that melt in both rock types was mobile during the same period of time, and that physical mixing and chemical exchange occurred between the two melts. Thus, PTB cuts across the contact between granite and gabbro, and is not restricted by the contact (e.g., Reimold and Colliston, 1994). These differences in nucleation and propagation of PTB based on rock type must be considered when discussing the formation mechanisms of impact-generated PTB. References: Gibson R.L., Reimold W.U., Ashley A.J., Koeberl C. (2002) Metamorphism of the Moon: A terrestrial analogue in the Vredefort dome, South Africa? Geology 30:475-478. Gibson R.L., Reimold W.U., Wallmach T. (1997) Origin of pseudotachylite in the lower Witwatersrand Supergroup, Vredefort Dome (South Africa): constraints from metamorphic studies. Tectonophysics 283:241-262. Reimold W.U., Colliston W.P. (1994) Pseudotachylites of the Vredefort Dome and the surrounding Witwatersrand Basin, South Africa. Geological Society of America Special Papers 293:177-196.

Blood, sweat and plaster casts: Reviewing the history, composition, and scientific value of the Raymond A. Dart Collection of African Life and Death Masks.

PubMed

Houlton, T M R; Billings, B K

2017-10-01

This paper addresses the history, composition and scientific value of one of the most comprehensive facemask collections in Africa, the Raymond A. Dart Collection of African Life and Death Masks. Housed within the School of Anatomical Sciences at the University of the Witwatersrand (South Africa), it comprises 1110 masks (397 life, 487 death, 226 unknown). Life masks represent populations throughout Africa; death masks predominately southern Africa. Males preponderate by 75%. Recorded ages are error prone, but suggest most life masks are those of <35 year-olds, death masks of 36+ year-olds. A total of 241 masks have associated skeletons, 209 presenting a complete skull. Life masks date between 1927 and c.1980s, death masks 1933 and 1963. This historical collection presents uncanny associations with outmoded typological and evolutionary theories. Once perceived an essential scientific resource, performed craniofacial superimpositions identify the nose as the only stable feature maintained, with the remaining face best preserved in young individuals with minimal body fat. The facemask collection is most viable for teaching and research within the history of science, specifically physical anthropology, and presents some value to craniofacial identification. Future research will have to be conducted with appropriate ethical considerations to science and medicine. Copyright © 2017 Elsevier GmbH. All rights reserved.

Return to the Taung cave paradigm.

PubMed

McKee, Jeffrey K

2016-02-01

The Taung hominin fossil was recovered in 1924 during quarry operations in the tufa formations of the Buxton Limeworks. Reconstructions of the depositional environment of the juvenile Australopithecus skull have concentrated on the types of caves that form within the tufa. Hopley et al. (Am J Phys Anthropol 151 (2013) 316-324) proposed a new model in which the pink carbonate deposits, in which many of the Taung fossils are found, formed as open terrestrial pedogenic deposits. The objective here is to challenge that notion. Observations of the depositional environments at Taung are based upon the University of the Witwatersrand paleontological excavations at the Buxton Limeworks from 1988 to 1993, and subsequent laboratory analysis of the fossils and sediments. Hopley et al. (Am J Phys Anthropol 151 (2013) 316-324) conflate numerous distinct outcroppings of the pink carbonates as a single "unit." The excavations revealed numerous fossiliferous deposits that differ greatly in taphonomic origins and formation processes, and that cannot be considered a "unit" despite the commonality of pink carbonates. There are deposits that fit the model proposed by Hopley et al. (Am J Phys Anthropol 151 (2013) 316-324), but they are not the ones that yielded the most significant fossils. Most of the fossiliferous deposits, including those most likely to have yielded the Taung hominin, are best reconstructed as being of karst origins. © 2015 Wiley Periodicals, Inc.

Preparatory report for workshop on maternity and neonatal services policy for the PWV.

PubMed

Fonn, S; Philpott, H

1995-06-01

This article discusses a review undertaken to assess quality of care within maternity and neonatal services in Pretoria, Witwatersrand, and Vereeniging, South Africa. One researcher met with nurses and doctors from 17 hospitals and clinics with public and private services. Another researcher met with 13 groups of 146 women. Findings indicate that services were too far away and transportation was a problem. Ambulances and taxis were costly. Services should be close by, available 24 hours/day, and offer quality health care. Women expressed a willingness to travel distances for quality care. Women appreciated good relations and services capable of handling complications. Women preferred services where discrimination by race or social status was not practiced. The most frequently cited problem was negative interpersonal client-staff relations. Women reported a strong desire to have partners present at delivery and with paternity leave. The most common desires were for sonograms, food at prenatal clinics, education at the prenatal clinic, and other information on a variety of topics. Women desired knowledge about the symptoms of labor, sexually transmitted diseases, contraception, and parenting skills. Other topics were risk factors, hygiene, breast feeding, postnatal depression, the physiology of pregnancy, sources of help, nutrition, and vaccinations. Women desired a comprehensive examination, a choice of appointment times, and attentive nursing. Women expressed their views on good postnatal services, services in general, better patient-staff communication, mortality, and stillbirths. 11 recommendations were made.

A metagenomic window into carbon metabolism at 3 km depth in Precambrian continental crust

PubMed Central

Magnabosco, Cara; Ryan, Kathleen; Lau, Maggie C Y; Kuloyo, Olukayode; Sherwood Lollar, Barbara; Kieft, Thomas L; van Heerden, Esta; Onstott, Tullis C

2016-01-01

Subsurface microbial communities comprise a significant fraction of the global prokaryotic biomass; however, the carbon metabolisms that support the deep biosphere have been relatively unexplored. In order to determine the predominant carbon metabolisms within a 3-km deep fracture fluid system accessed via the Tau Tona gold mine (Witwatersrand Basin, South Africa), metagenomic and thermodynamic analyses were combined. Within our system of study, the energy-conserving reductive acetyl-CoA (Wood-Ljungdahl) pathway was found to be the most abundant carbon fixation pathway identified in the metagenome. Carbon monoxide dehydrogenase genes that have the potential to participate in (1) both autotrophic and heterotrophic metabolisms through the reversible oxidization of CO and subsequent transfer of electrons for sulfate reduction, (2) direct utilization of H2 and (3) methanogenesis were identified. The most abundant members of the metagenome belonged to Euryarchaeota (22%) and Firmicutes (57%)—by far, the highest relative abundance of Euryarchaeota yet reported from deep fracture fluids in South Africa and one of only five Firmicutes-dominated deep fracture fluids identified in the region. Importantly, by combining the metagenomics data and thermodynamic modeling of this study with previously published isotopic and community composition data from the South African subsurface, we are able to demonstrate that Firmicutes-dominated communities are associated with a particular hydrogeologic environment, specifically the older, more saline and more reducing waters. PMID:26325359

Training of disaster managers at a masters degree level: from emergency care to managerial control.

PubMed

Macfarlane, Campbell; Joffe, Anthony Lyle; Naidoo, Shan

2006-01-01

The world has faced huge disasters over the last few decades and concerns have been expressed by nearly all international agencies involved that there is a scarcity of managerial skills to deal with the mitigation and management of disasters. Disaster risks are also on the increase throughout Africa and Southern Africa because of changes in the development process, settlement patterns and conflicts in the region. Emergency physicians are but one important resource in dealing with disasters. The need for a comprehensive multisectoral approach to disasters and more importantly to deal with its mitigation is becoming increasingly evident, especially in developing countries. Hence, the need for specially trained professionals in disaster management. In an effort to improve national, regional and continental capacity, and in support of the South African Disaster Management Act, the University of the Witwatersrand, Johannesburg, South Africa, has developed a Master of Public Health degree in Disaster Management. The MPH is aimed at preparing professionals from health and allied fields to play leadership roles in the management, improvement and evaluation of health and the health-care system. Emergency physicians have an important role to play in the development of disaster medicine and disaster management programmes and it is important that they engage in this activity, collaborating with colleagues of various other disciplines as appropriate. The following paper outlines the background to the programme and the current programme.

Characterization of active members in C and N cycles in the subsurface environment of the Witwatersrand Basin

NASA Astrophysics Data System (ADS)

Lindsay, M. R.; Lau, C. M.; Tetteh, G.; Snyder, L.; Kieft, T. L.; Lollar, B. S.; Li, L.; Maphanga, S.; van Heerden, E.; Onstott, T. C.

2012-12-01

Fracture fluid from various depths and locations in Beatrix gold mine (Gold Fields Ltd.), located in the Welkom region on the 2.9 Ga Witwatersrand Basin of South Africa has been previously studied. Research has shown differential geochemistry data and distinctive community structure which varies from the dominance of different Proteobacterial classes in waters with paleometeoric 18O and 2H signatures including methanotrophs to one dominated by Firmicutes including Candidatus Desulforudis audaxviator-like taxa, which are associated with more saline waters with high concentrations of dissolved H2, hydrocarbons from water-rock reaction and 18O and 2H signatures above the Global Meteoric Water Line. Archaea seem to be a minority and all are euryarchaeota including methanogenic genera. The question is:Which of them are actively driving the subsurface C and N cycles? At shaft 3 on level 26, 1.3 kmbls, fracture water from 42 m behind the tunnel wall located in the Main quartzite formation was collected and analyzed. The temperature, pH, Eh, dissolved O2 and salinity of this hydrocarbon-containing fracture water ranged from 35 to 38°C, 8.2 to 8.8, -30 to -100 mV, 0.3 to 30 μM and 4.2 to 4.3 ppt, respectively. Gas comprised 60% CH4 and 20% N2. The same fracture formerly yielded Halicephalobus mephisto, the first reported subsurface nematode. Microorganisms were captured on filters in two field seasons. Defined by 16S rDNA, 2011 January sample contains β-Proteobacteria (50%), Firmicutes (39%) and α- and γ-Proteobacteria (7%). Of the Firmicutes, 90% were represented by Ca. D. audaxviator. All archaea detected are closestly related to sequences also reported from South African gold mines, with Crenarchaeota accounting for 77% of the clones. Prospective methane-oxidation and production were assessed by amplifying genes encoding for particulate methane monooxygenase alpha subunit (pmoA) and methyl-coenzyme M reductase alpha subunit (mcrA). PmoA genes of Type II methanotrophs were found three times more than Type I methanotrophs. A pmoA gene sequence represents 42% of the library matches only and is identical to a putative protein sequence annotated on Ca. D. audaxviator genome, but further analysis is required to validate its candidature of methanotrophy. The cluster of mcrA gene sequences is related to a novel group of anaerobic methanotrophs (ANME) defined by environmental sequences. 2011 July samples from the same borehole revealed an absence of Firmicutes. Two β-Proteobacterial sequences dominated the bacterial 16S rDNA clone library, accounting for 54% and 25%. The first 16S rRNA clone library for the region confirmed a complete lack of Firmicutes with active Proteobacteria (71% α-, 17% β- and 6% γ-Proteobacteria). Only 3% of the active community is confidently inferred as methylotrophs while 22% belongs to N2 fixer Rhizobium sp. which has been demonstrated to stimulate methanotrophic growth and 28% is related to Polymorphum gilvum, which is known for n-alkane degradation. Active members responsible for CH4 metabolism will be supported by presenting the results of archaeal 16S rRNA, pmoA, mcrA and nitrogenase gene diversities. The lack of Firmicutes in July samples could be attributed to collection methods: different filter membrane, faster flowrate but shorter sampling duration, and less total volume of water filtered.

Automated image processing method for the diagnosis and classification of malaria on thin blood smears.

PubMed

Ross, Nicholas E; Pritchard, Charles J; Rubin, David M; Dusé, Adriano G

2006-05-01

Malaria is a serious global health problem, and rapid, accurate diagnosis is required to control the disease. An image processing algorithm to automate the diagnosis of malaria on thin blood smears is developed. The image classification system is designed to positively identify malaria parasites present in thin blood smears, and differentiate the species of malaria. Images are acquired using a charge-coupled device camera connected to a light microscope. Morphological and novel threshold selection techniques are used to identify erythrocytes (red blood cells) and possible parasites present on microscopic slides. Image features based on colour, texture and the geometry of the cells and parasites are generated, as well as features that make use of a priori knowledge of the classification problem and mimic features used by human technicians. A two-stage tree classifier using backpropogation feedforward neural networks distinguishes between true and false positives, and then diagnoses the species (Plasmodium falciparum, P. vivax, P. ovale or P. malariae) of the infection. Malaria samples obtained from the Department of Clinical Microbiology and Infectious Diseases at the University of the Witwatersrand Medical School are used for training and testing of the system. Infected erythrocytes are positively identified with a sensitivity of 85% and a positive predictive value (PPV) of 81%, which makes the method highly sensitive at diagnosing a complete sample provided many views are analysed. Species were correctly determined for 11 out of 15 samples.

Precambrian uranium-bearing quartz-pebble conglomerates: exploration model and United States resource potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Houston, R.S.; Karlstrom, K.E.

1979-11-01

Uranium has been discovered in fluvial quartz-pebble conglomerates in most of the Precambrian shield areas of the world, including the Canadian, African, South American, Indian, Baltic, and Australian shields. Occurrences in these and other areas are shown. Two of these occurrences, the Huronian supergroup of Canada and the Witwatersrand deposit of South Africa contain 20 to 30 percent of the planet's known uranium reserves. Thus it is critical that we understand the origin of these deposits and develop exploration models that can aid in finding new deposits. Inasmuch as these uranium-bearing conglomerates are confined almost entirely to rocks of Precambrianmore » age, Part I of this review begins with a discussion of Precambrian geology as it applies to the conglomerates. This is followed by a discussion of genetic concepts, a discussion of unresolved problems, and finally a suggested exploration model. Part II summarizes known and potential occurrences of Precambrian fossil placers in the world and evaluates them in terms of the suggested exploration model. Part III discusses the potential for important Precambrian fossil-placer uranium deposits in the United States and includes suggestions that may be helpful in establishing an exploration program in this country. Part III also brings together new (1975-1978) data on uranium occurrences in the Precambrian of the Wyoming Province. Part IV is a complete bibliography of Precambrian fossil placers, divided according to geographical areas. In total, this paper is designed to be a comprehensive review of Precambrian uranium-bearing fossil placers which will be of use to uranium explorationists and to students of Precambrian geology.« less

Studies on the Nature and Aetiology of Respiratory Disability in Witwatersrand Gold-Miners Free of Radiological Silicosis

PubMed Central

Becklake, Margaret R.; Zwi, Saul; Lutz, W.

1959-01-01

In an investigation into the cause of symptoms in gold-miners who have no radiological silicosis, the relationship of dyspnoea and physiological disturbances to dust exposure was examined. Forty-five subjects, aged 41 to 45 years, with normal chest radiographs and long service underground were chosen for study from the population of miners past and present. Thirty-four men only were tested, but the validity of the sample was checked by comparison with a similar group of miners reported previously. Each individual's dust exposure was estimated in “particle-hours”. A detailed history, including smoking habits, was followed by a clinical examination and a battery of lung function tests in each case. No significant relationship was found between dyspnoea and dust exposure or smoking. However, a negative correlation was observed between dust exposure and effort tests, implying that exercise capacity appeared best in those men whose dust exposure was greatest. Possible reasons for this finding are discussed. On the other hand, dyspnoea did correlate with airway obstruction and hyperventilation on effort, indicating a physiological rather than a psychological basis for the symptoms. Further, the higher incidence of cough, sputum, and rhonchi in the more disabled subjects suggested that chronic bronchitis might be the basis of their symptoms, but the cause of the bronchitis remains to be identified. It seems that dust exposure alone was not the cause, but the findings do not exclude the possibility of its being related to the occupation of mining with stresses such as inhalation of fumes and rapid changes in temperature, humidity, and altitude. PMID:13798146

The nature of a deformation zone and fault rock related to a recent rockburst at Western Deep Levels Gold Mine, Witwatersrand Basin, South Africa

NASA Astrophysics Data System (ADS)

Stewart, R. A.; Reimold, W. U.; Charlesworth, E. G.; Ortlepp, W. D.

2001-07-01

In August 1998, a major deformation zone was exposed over several metres during mining operations on 87 Level (2463 m below surface) at Western Deep Levels Gold Mine, southwest of Johannesburg, providing a unique opportunity to study the products of a recent rockburst. This zone consists of three shear zones, with dip-slip displacements of up to 15 cm, that are oriented near-parallel to the advancing stope face. Jogs and a highly pulverised, cataclastic 'rock-flour' are developed on the displacement surfaces, and several sets of secondary extensional fractures occur on either side of the shear zones. A set of pinnate (feather) joints intersects the fault surfaces perpendicular to the slip vector. Microscopically, the shear zones consist of two pinnate joint sets that exhibit cataclastic joint fillings; quartz grains display intense intragranular fracturing. Secondary, intergranular extension fractures are associated with the pinnate joints. Extensional deformation is also the cause of the breccia fill of the pinnate joints. The initial deformation experienced by this zone is brittle and tensile, and is related to stresses induced by mining. This deformation has been masked by later changes in the stress field, which resulted in shearing. This deformation zone does not appear to be controlled by pre-existing geological features and, thus, represents a 'burst fracture', which is believed to be related to a seismic event of magnitude ML=2.1 recorded in July 1998, the epicentre of which was located to within 50 m of the study locality.

Transformation of a cadaver population: Analysis of a South African cadaver program, 1921-2013.

PubMed

Kramer, Beverley; Hutchinson, Erin F

2015-01-01

Anatomy has served as a cornerstone in the training of various allied and clinical disciplines and has traditionally been based on dissection of the human body. Thus, to pursue this method of teaching and learning, access to cadavers is of continuing importance. Over a significant period of time unclaimed cadavers have performed an essential role in the teaching of anatomy in South Africa and in Africa. As recent cadaver numbers were declining at the School of Anatomical Sciences, University of the Witwatersrand, Johannesburg and difficulty in procurement was being experienced, the purpose of this study was to critically evaluate the composition of our cadaver population over time so as to provide possible strategies to arrest the decline. A retrospective, quantitative analysis of cadaver records from the School of Anatomical Sciences between 1921 and 2013 was undertaken. Analysis included a comparison of Poisson counts and Fischer's exact test. A significant decrease in the number of cadavers received during the period 2000-2013 and a slow bequest program over the same period of time has led to concerns about the sustainability of teaching anatomy through dissection. Decreases in the numbers of males and cadavers of the black population group occurred between 1990 and 2013, and of bequests from 2000 to 2013. An influence on the cadaver population from a changing political climate and change in socioeconomic status of part of the population was perceived. Changes in sex and population group of the cadavers may have a long-term effect on teaching and research. © 2014 American Association of Anatomists.

An oligotrophic deep-subsurface community dependent on syntrophy is dominated by sulfur-driven autotrophic denitrifiers

PubMed Central

Kieft, Thomas L.; Kuloyo, Olukayode; Linage-Alvarez, Borja; van Heerden, Esta; Lindsay, Melody R.; Magnabosco, Cara; Wang, Wei; Wiggins, Jessica B.; Guo, Ling; Perlman, David H.; Kyin, Saw; Shwe, Henry H.; Harris, Rachel L.; Oh, Youmi; Yi, Min Joo; Purtschert, Roland; Slater, Greg F.; Ono, Shuhei; Wei, Siwen; Li, Long; Sherwood Lollar, Barbara; Onstott, Tullis C.

2016-01-01

Subsurface lithoautotrophic microbial ecosystems (SLiMEs) under oligotrophic conditions are typically supported by H2. Methanogens and sulfate reducers, and the respective energy processes, are thought to be the dominant players and have been the research foci. Recent investigations showed that, in some deep, fluid-filled fractures in the Witwatersrand Basin, South Africa, methanogens contribute <5% of the total DNA and appear to produce sufficient CH4 to support the rest of the diverse community. This paradoxical situation reflects our lack of knowledge about the in situ metabolic diversity and the overall ecological trophic structure of SLiMEs. Here, we show the active metabolic processes and interactions in one of these communities by combining metatranscriptomic assemblies, metaproteomic and stable isotopic data, and thermodynamic modeling. Dominating the active community are four autotrophic β-proteobacterial genera that are capable of oxidizing sulfur by denitrification, a process that was previously unnoticed in the deep subsurface. They co-occur with sulfate reducers, anaerobic methane oxidizers, and methanogens, which each comprise <5% of the total community. Syntrophic interactions between these microbial groups remove thermodynamic bottlenecks and enable diverse metabolic reactions to occur under the oligotrophic conditions that dominate in the subsurface. The dominance of sulfur oxidizers is explained by the availability of electron donors and acceptors to these microorganisms and the ability of sulfur-oxidizing denitrifiers to gain energy through concomitant S and H2 oxidation. We demonstrate that SLiMEs support taxonomically and metabolically diverse microorganisms, which, through developing syntrophic partnerships, overcome thermodynamic barriers imposed by the environmental conditions in the deep subsurface. PMID:27872277

Microbial Abundance and Diversity at 0.8 to 3.6 Kilometers Beneath the Surface in the Witwatersrand Basin, South Africa

NASA Astrophysics Data System (ADS)

Hall, J.; Rowley, A.; Davidson, M.; Lin, L.; Lippmann, J.; Ward, J.; Slater, G.; Boice, E.; McCuddy, S.; Moser, D.; Onstott, t; Onstott, t

2001-12-01

Access to the Au mines of South Africa has provided us with an unparalleled opportunity to investigate the diversity and abundance of microbes from hydrologically restricted environments at depths up to 3.2 kilometers beneath the surface (kmbls.). Samples of highly pressurized, anaerobic water collected from freshly drilled bore holes into fault or dyke structures ranged in temperature from 32o to 60oC, in salinity from 0.2% to 2.5% and in pH from 7.2 to 10. Flow cytometry analyses of 21 samples amended with a fluorescent DNA stain yielded microbial concentrations ranging from <5{x}103 (detection limit) to 5{x}105 cellsml. The cell concentrations for half of these samples were below the detection limit and those of all the samples collected at 3.2 kmbls. were below detection. Fluorescent, forward and side scatter intensities indicate that the remaining samples contain one or two morphotypes. These values contrast with water samples from subsurface, dammed water pockets or service water where the cell concentrations range from 5{x}104 to 2.5{x}106 cellsml and as many as three morphotypes can be readily distinguished. Thermophilic enrichments suggest that some of these morphotypes are cultivable under conditions that are comparable to the environment. The apparent lack of cells in some of the water samples may reflect a combination of the thermal history of the basin, the origin of the fluid and the isolation of some of the fractures.

Kriging: Understanding allays intimidation

USGS Publications Warehouse

Olea, R.A.

1996-01-01

In 1938 Daniel Gerhardus "Danie" Krige obtained an undergraduate degree in mining engineering and started a brilliant career centered on analyzing the gold and uranium mines in the Witwatersrand conglomerates of South Africa. He became interested in the disharmony between the poor reliability of reserve estimation reports and the magnitude of the economic decisions that were based on these studies. Back at the University of Witwatersrand, he wrote a master's thesis that began a revolution in mining evaluation methods. Krige was not alone in his research. Another mining engineer, Georges Matheron, a Frenchman, thought space data analysis belonged in a separate discipline, just as geophysics is a separate branch from physics. He named the new field geostatistics. Kriging is the name given in geostatistics to a collection of generalized linear regression techniques for the estimation of spatial phenomena. Pierre Carlier, another Frenchman, coined the term krigeage in the late 1950s to honor Krige's seminal work. Matheron anglicized the term to kriging when he published a paper for English-speaking readers. France dominated the development and application of geostatistics for several years. However, geostatistics in general, and kriging in particular, are employed by few and are regarded with apprehension by many. One of the possible applications of kriging is in computer mapping. Computer contouring methods can be grouped into two families: triangulation and gridding. The former is a direct procedure in which the contour lines are computed straight from the data by partitioning the sampling area into triangles with one observation per vertex. Kriging belongs in the gridding family. A grid is a regular arrangement of locations or nodes. In the gridding method the isolines are determined from interpolated values at the nodes. The difference between kriging and other weighting methods is in the calculation of the weights. Even for the simplest form of kriging, the calculations are more demanding. The kriging system of equations differs from classical regression in that the observations are allowed to be correlated and that neither the estimate nor the observations are necessarily points - they may have a volume, shape, and orientation. The mean square error is the average of the squares of the differences between the true and the estimated values. Simple kriging, the most basic form of kriging in that the system of equations has the fewest terms, requires the phenomena to have a constant and known mean. The next step up, ordinary kriging, does not require knowledge of the population mean. The external drift method, universal kriging, and intrinsic kriging go even further by allowing fluctuations in the mean. In practice, estimation by kriging is not as difficult to handle as it may look at first glance. In these days of high technology, all the details in the procedure are coded into computer programs. When properly used, kriging has several appealing attributes, the most important being that it does the work more accurately. By design, kriging provides the weights that result in the minimum mean square error. And yes, there have been people who have tested its superiority with real data. Practice has consistently confirmed theory. Kriging is also robust. Within reasonable limits, kriging tends to persist in yielding correct estimates even when the user selects the wrong model, misspecifies parameters, or both. This property should be an incentive for the novice to try the method. Gross misuse of kriging, though, can lead to poor results, worse even than those produced by alternative methods. Kriging has evolved and continues to expand to accommodate the estimation of increasingly demanding realities. Conclusions Theory and practice show that computer contour maps generated using kriging have the least mean square estimation error. In addition, the method provides information to assess the reliability of the maps.

Optimization of a bioremediation system of soluble uranium based on the biostimulation of an indigenous bacterial community.

PubMed

Maleke, Maleke; Williams, Peter; Castillo, Julio; Botes, Elsabe; Ojo, Abidemi; DeFlaun, Mary; van Heerden, Esta

2015-06-01

High concentrations of uranium(VI) in the Witwatersrand Basin, South Africa from mining leachate is a serious environmental concern. Treatment systems are often ineffective. Therefore, optimization of a bioremediation system that facilitates the bioreduction of U(VI) based on biostimulation of indigenous bacterial communities can be a viable alternative. Tolerance of the indigenous bacteria to high concentrations of U and the amount of citric acid required for U removal was optimized. Two bioreactor studies which showed effective U(VI) removal more than 99 % from low (0.0037 mg L(-1)) and high (10 mg L(-1)) concentrations of U to below the limit allowed by South African National Standards for drinking water (0.0015 mg L(-1)). The second bioreactor was able to successfully adapt even with increasing levels of U(VI) feed water up to 10 mg L(-1), provided that enough electron donor was available. Molecular biology analyses identified Desulfovibrio sp. and Geobacter sp. among known species, which are known to reduce U(VI). The mineralogical analysis determined that part of the uranium precipitated intracellularly, which meant that the remaining U(VI) was precipitated as U(IV) oxides and TEM-EDS also confirmed this analysis. This was predicted with the geochemical model from the chemical data, which demonstrated that the treated drainage was supersaturated with respect to uraninite > U4O9 > U3O8 > UO2(am). Therefore, the tolerance of the indigenous bacterial community could be optimized to remediate up to 10 mg L(-1), and the system can thus be upscaled and employed for remediation of U(VI) impacted sites.

Costs of a school-based dental mobile service in South Africa.

PubMed

Molete, M P; Chola, L; Hofman, K J

2016-10-19

The burden of untreated tooth decay remains high and oral healthcare utilisation is low for the majority of children in South Africa. There is need for alternative methods of improving access to low cost oral healthcare. The mobile dental unit of the University of the Witwatersrand (Wits) has been operational for over 25 years, providing alternative oral healthcare to children and adults who otherwise would not have access. The aim of this study was to conduct a cost-analysis of a school based oral healthcare program in the Wits mobile dental unit. The objectives were to estimate the general costs of the school based program, costs of oral healthcare per patient and the economic implications of providing services at scale. In 2012, the Wits mobile dental unit embarked on a 5 month project to provide oral healthcare in four schools located around Johannesburg. Cost and service use data were retrospectively collected from the program records for the cost analysis, which was undertaken from a provider perspective. The costs considered included both financial and economic costs. Capital costs were annualised and discounted at 6 %. One way sensitivity tests were conducted for uncertain parameters. The total economic costs were R813.701 (US$76,048). The cost of screening and treatment per patient were R331 (US$31) and R743 (US$69) respectively. Furthermore, fissure sealants cost the least out of the treatments provided. The sensitivity analysis indicated that the Wits mobile dental unit was cost efficient at 25 % allocation of staff time and that a Dental Therapy led service could save costs by 9.1 %. Expanding the services to a wider population of children and utilising Dental Therapists as key personnel could improve the efficiency of mobile dental healthcare provision.

Hydrogeologic controls on episodic H2 release from precambrian fractured rocks--energy for deep subsurface life on earth and mars.

PubMed

Sherwood Lollar, B; Voglesonger, K; Lin, L-H; Lacrampe-Couloume, G; Telling, J; Abrajano, T A; Onstott, T C; Pratt, L M

2007-12-01

Dissolved H(2) concentrations up to the mM range and H(2) levels up to 9-58% by volume in the free gas phase are reported for groundwaters at sites in the Precambrian shields of Canada and Finland. Along with previously reported dissolved H(2) concentrations up to 7.4 mM for groundwaters from the Witwatersrand Basin, South Africa, these findings indicate that deep Precambrian Shield fracture waters contain some of the highest levels of dissolved H(2) ever reported and represent a potentially important energy-rich environment for subsurface microbial life. The delta (2)H isotope signatures of H(2) gas from Canada, Finland, and South Africa are consistent with a range of H(2)-producing water-rock reactions, depending on the geologic setting, which include both serpentinization and radiolysis. In Canada and Finland, several of the sites are in Archean greenstone belts characterized by ultramafic rocks that have under-gone serpentinization and may be ancient analogues for serpentinite-hosted gases recently reported at the Lost City Hydrothermal Field and other hydrothermal seafloor deposits. The hydrogeologically isolated nature of these fracture-controlled groundwater systems provides a mechanism whereby the products of water-rock interaction accumulate over geologic timescales, which produces correlations between high H(2) levels, abiogenic hydrocarbon signatures, and the high salinities and highly altered delta (18)O and delta (2)H values of these groundwaters. A conceptual model is presented that demonstrates how periodic opening of fractures and resultant mixing control the distribution and supply of H(2) and support a microbial community of H(2)-utilizing sulfate reducers and methanogens.

Head and neck lymphomas: A 20-year review in an Oral Pathology Unit, Johannesburg, South Africa, a country with the highest global incidence of HIV/AIDS.

PubMed

Alli, Nasreen; Meer, Shabnum

2017-04-01

Non-Hodgkin lymphoma occurs with increasing frequency in HIV/AIDS. As South Africa has the highest incidence of HIV/AIDS worldwide, an epidemiologic study of this nature provides insight into head and neck lymphomas in a defined South African population. This retrospective review evaluated frequency and clinico-pathologic characteristics of patients diagnosed with head and neck lymphoma at the Oral Pathology Department, University of Witwatersrand between 1993 and 2012. Histopathology reports of patients with head and neck lymphomas (n=504) were reviewed. Demographic (age, gender), clinical (site and size of tumour), laboratory and histological parameters were recorded. There were 504 patients with head and neck lymphomas. The mean age was 40.4years. The male:female ratio was 1.1:1. The cervical lymph node was the most common anatomic site (115 cases) and the maxilla (60 cases) the most common extranodal site. Plasmablastic lymphoma (159 cases) was the most common histologic subtype, seen more frequently as a result of its strong association with HIV/AIDS. The most common Hodgkin's lymphoma was the nodular sclerosing variant (21 cases). Of the head and neck lymphomas in patients with a known HIV status, 56% had plasmablastic lymphoma, 43.9% diffuse large B cell lymphoma and 25% Burkitt lymphoma. There is an increase in head and neck lymphoma frequency, contrary to that found in Western countries. The high HIV prevalence in certain lymphomas provides strong indication of the role of HIV/AIDS in pathogenesis of lymphomas. This study serves as a baseline for future studies, especially in South Africa. Copyright © 2017 Elsevier Ltd. All rights reserved.

Social Justice and Environmental Awareness Developed through a Citizens' Jury

NASA Astrophysics Data System (ADS)

Knight, J.

2014-12-01

A Citizens' Jury (CJ) is a discussion forum in which managers, policymakers or politicians are able to present their case to the general public ('citizens') to whom they are accountable, and for these citizens to critically ask questions of the managers/policymakers/politicians in order to better understand issues surrounding local development, planning and policy, impacts and adaptive measures, and to highlight their concerns. A CJ can be useful with respect to developing social justice and environmental awareness issues because it can empower community action and present different viewpoints. A practical CJ exercise is used in a second-year undergraduate course entitled Climate Change and Society, at University of the Witwatersrand, Johannesburg, South Africa. The CJ is used to consider some of the impacts of management policies used for climate change and sustainable development adaption, based on a hypothetical scenario. This scenario is that a major energy company wants to build a dam with hydroelectric power station in a developing country. This will provide low-carbon renewable energy to the country, investment in electricity infrastructure, and the company is committed to help economic development in the country, including in jobs and education. However, building and flooding of the dam will involve displacing 10,000 people from rural communities, flooding agricultural areas and areas of high biodiversity, and archaeological sites. The exercise is based on students, in groups, assuming different 'identities' which may include a local business person, resident, politician, member of an NGO, tourist, engineer, farmer etc, from which viewpoint they must argue for/against the proposal and to question other peoples' viewpoints. This exercise is useful because it allows students to develop understandings of different viewpoints, evaluate risk and impacts on different communities, and highlights the complexity of real-world decision-making.

Impact of socio-economic factors on quality of life in patients on continuous ambulatory peritoneal dialysis in an African setting.

PubMed

Okaka, E I; Davies, M; Ahmed, M; Naidoo, S; Naicker, S

2014-01-01

Quality of life (QOL) is an important outcome following the treatment of disease. It is influenced by physical, psychological, social and economic factors. We proposed to determine the effect of some socioeconomic factors on QOL of patients on CAPD. A cross sectional study in which all patients on CAPD attending three clinics attached to the University of the Witwatersrand, Johannesburg were recruited excluding those with intercurrent illness. The WHO quality of life instrument, WHOQOL-Bref, was used to measure QOL. The patients were grouped according to marital status, highest level of education attained, income, employment, and QOL domain scores were compared using ANOVA and Student t test. A total of 140 patients comprising 80 males and 40 females were assessed. The mean age of patients was 41.9 ± 11.5 years, 95%of patients were black, 44.3% married, 69.3% had secondary education, 22% were employed and 51.4% had a monthly income of less than five thousand Rand (500 US dollars). Single patients scored better in the social relationships domain compared to separated patients (p=0.02, CI: 5.6-32.9). The group with secondary education scored low in the psychological domain compared with those with primary education (p=0.02, CI: 1.35-15.8) and those with tertiary education (p=0.02, CI: 1.72-18.07).The highest income group had best scores in all domains except the physical domain. Those in employment had better scores in the physical domain (p=0.04, CI: 0.356-12.549). Income had the most impact on QOL in study participants.

Indigenous and Contaminant Microbes in Ultradeep Mines

NASA Technical Reports Server (NTRS)

Onstott, T. C.; Moser, D. P.; Pfiffner, S. M.; Fredrickson, J. K.; Brockman, F. J.; Phelps, T. J.; White, D. C.; Peacock, A.; Balkwill, D.; Hoover, R. B.;

Indigenous and Contaminant Microbes in Ultradeep Mines

NASA Technical Reports Server (NTRS)

Onstott, T. C.; Moser, D. P.; Pfiffner, S. M.; Fredrickson, J. F.; Brockman, F. J.; Phelps, T. J.; White, D. C.; Peacock, A.; Balkwill, D.; Hoover, R.;

An Outbreak of Lymphocutaneous Sporotrichosis among Mine-Workers in South Africa.

PubMed

Govender, Nelesh P; Maphanga, Tsidiso G; Zulu, Thokozile G; Patel, Jaymati; Walaza, Sibongile; Jacobs, Charlene; Ebonwu, Joy I; Ntuli, Sindile; Naicker, Serisha D; Thomas, Juno

2015-09-01

The largest outbreak of sporotrichosis occurred between 1938 and 1947 in the gold mines of Witwatersrand in South Africa. Here, we describe an outbreak of lymphocutaneous sporotrichosis that was investigated in a South African gold mine in 2011. Employees working at a reopened section of the mine were recruited for a descriptive cross-sectional study. Informed consent was sought for interview, clinical examination and medical record review. Specimens were collected from participants with active or partially-healed lymphocutaneous lesions. Environmental samples were collected from underground mine levels. Sporothrix isolates were identified by sequencing of the internal transcribed spacer region of the ribosomal gene and the nuclear calmodulin gene. Of 87 male miners, 81 (93%) were interviewed and examined, of whom 29 (36%) had skin lesions; specimens were collected from 17 (59%). Sporotrichosis was laboratory-confirmed among 10 patients and seven had clinically-compatible lesions. Of 42 miners with known HIV status, 11 (26%) were HIV-infected. No cases of disseminated disease were detected. Participants with ≤ 3 years' mining experience had a four times greater odds of developing sporotrichosis than those who had been employed for >3 years (adjusted OR 4.0, 95% CI 1.2-13.1). Isolates from 8 patients were identified as Sporothrix schenckii sensu stricto by calmodulin gene sequencing while environmental isolates were identified as Sporothrix mexicana. S. schenckii sensu stricto was identified as the causative pathogen. Although genetically distinct species were isolated from clinical and environmental sources, it is likely that the source was contaminated soil and untreated wood underground. No cases occurred following recommendations to close sections of the mine, treat timber and encourage consistent use of personal protective equipment. Sporotrichosis is a potentially re-emerging disease where traditional, rather than heavily mechanised, mining techniques are used. Surveillance should be instituted at sentinel locations.

Teleducation : Linking Continents Across Time and Space Through Live, Real-Time Interactive Classes

NASA Astrophysics Data System (ADS)

Macko, S. A.; Szuba, T.; Swap, R.; Annegarn, H.; Marjanovic, B.; Vieira, F.; Brito, R.

2005-12-01

International education is a natural extension of global economies, global environmental concerns, and global science. While faculty and student exchanges between geographic areas permit for educational experiences and cultural exchanges for the privileged few, distance learning offers opportunities for educational exchanges under any circumstance where time, expense, or location otherwise inhibit offering or taking a particular course of study. However, there are severe pedagogical limitations to traditional Web-based courses that suffer from a lack of personalized, spontaneous exchange between instructor and student. The technology to establish a real time, interactive teleducation program exists, but to our knowledge is relatively untested in a science classroom situation, especially internationally over great distances. In a project to evaluate this type of linkage, we offered a real-time, interactive class at three separate universities, which communicated instantaneously across an ocean at a distance of greater than 8,000 miles and seven time zones. The course, 'Seminar on the Ecology of African Savannas', consisted of a series of 11 lectures originating in either Mozambique (University of Eduardo Mondlane), South Africa (University of the Witwatersrand) or the United States (University of Virginia). We combined ISDN, internet and satellite linkages to facilitate the lectures and real time discussions between instructors and approximately 200 university students in the three countries. Although numerous technical, logistical, and pedagogical issues - both expected and unexpected - arose throughout the pilot year, the project can be viewed as overwhelmingly successful and certainly serves as proof-of-concept for future initiatives, both internationally and locally. This review of our experience will help to prepare other students, faculty, and institutions interested in establishing or developing international education initiatives

Increasing diversity in the geosciences through the AfricaArray geophysics field course

NASA Astrophysics Data System (ADS)

Vallejo, G.; Emry, E.; Galindo, B. L.; Carranza, V.; Gomez, C. D.; Ortiz, K.; Castro, J. G.; Guandique, J.; Falzone, C.; Webb, S. J.; Manzi, M.; Mngadi, S. B.; Stephens, K.; Chinamora, B.; Whitehead, R.; de Villiers, D. P.; Tshitlho, K.; Delhaye, R. P.; Smith, J. A.; Nyblade, A.

2014-12-01

For the past nine years, the AfricaArray diversity program, sponsored by industry, the National Science Foundation, and several partnering universities have supported outstanding U.S. STEM underrepresented minority undergraduates to gain field experience in near-surface geophysical techniques during an 8-week summer program at Penn State University and the University of Witwatersrand (Wits). The AfricaArray geophysics field school, which is run by Wits, has been teaching field-based geophysics to African students for over a decade. In the first 2-3 weeks of the program, the U.S. students are given basic instruction in near-surface geophysics, South African geology, and South African history and culture. The students then join the Wits AfricaArray geophysics field school - working alongside Wits students and students from several other African universities to map the shallow subsurface in prospective areas of South Africa for platinum mining. In addition to the primary goals of collecting and interpreting gravity, magnetic, resistivity, seismic refraction, seismic reflection, and EM data, students spend time mapping geologic units and gathering information on the physical properties of the rocks in the region (i.e. seismic velocity, density, and magnetic susceptibility). Subsurface targets include mafic dikes, faults, the water table, and overburden thickness. Upon returning to the U.S., students spend 2-3 weeks finalizing their project reports and presentations. The program has been effective at not only providing students with fundamental skills in applied geophysics, but also in fostering multicultural relationships, preparing students for graduate work in the geosciences, and attracting STEM students into the geosciences. Student presenters will discuss their experiences gained through the field school and give their impressions about how the program works towards the goal of increasing diversity in the geosciences in the U.S.

The contribution of the Precambrian continental lithosphere to global H2 production.

PubMed

Lollar, Barbara Sherwood; Onstott, T C; Lacrampe-Couloume, G; Ballentine, C J

2014-12-18

Microbial ecosystems can be sustained by hydrogen gas (H2)-producing water-rock interactions in the Earth's subsurface and at deep ocean vents. Current estimates of global H2 production from the marine lithosphere by water-rock reactions (hydration) are in the range of 10(11) moles per year. Recent explorations of saline fracture waters in the Precambrian continental subsurface have identified environments as rich in H2 as hydrothermal vents and seafloor-spreading centres and have suggested a link between dissolved H2 and the radiolytic dissociation of water. However, extrapolation of a regional H2 flux based on the deep gold mines of the Witwatersrand basin in South Africa yields a contribution of the Precambrian lithosphere to global H2 production that was thought to be negligible (0.009 × 10(11) moles per year). Here we present a global compilation of published and new H2 concentration data obtained from Precambrian rocks and find that the H2 production potential of the Precambrian continental lithosphere has been underestimated. We suggest that this can be explained by a lack of consideration of additional H2-producing reactions, such as serpentinization, and the absence of appropriate scaling of H2 measurements from these environments to account for the fact that Precambrian crust represents over 70 per cent of global continental crust surface area. If H2 production via both radiolysis and hydration reactions is taken into account, our estimate of H2 production rates from the Precambrian continental lithosphere of 0.36-2.27 × 10(11) moles per year is comparable to estimates from marine systems.

The process of installing REDCap, a web based database supporting biomedical research: the first year.

PubMed

Klipin, M; Mare, I; Hazelhurst, S; Kramer, B

2014-01-01

Clinical and research data are essential for patient care, research and healthcare system planning. REDCapTM is a web-based tool for research data curatorship developed at Vanderbilt University in Nashville, USA. The Faculty of Health Sciences at the University of the Witwatersrand, Johannesburg South Africa identified the need for a cost effective data management instrument. REDCap was installed as per the user agreement with Vanderbilt University in August 2012. In order to assist other institutions that may lack the in-house Information Technology capacity, this paper describes the installation and support of REDCap and incorporates an analysis of user uptake over the first year of use. We reviewed the staffing requirements, costs of installation, process of installation and necessary infrastructure and end-user requests following the introduction of REDCap at Wits. The University Legal Office and Human Research Ethics Committee were consulted regarding the REDCap end-user agreement. Bi-monthly user meetings resulted in a training workshop in August 2013. We compared our REDCap software user numbers and records before and after the first training workshop. Human resources were recruited from existing staff. Installation costs were limited to servers and security certificates. The total costs to provide a functional REDCap platform was less than $9000. Eighty-one (81) users were registered in the first year. After the first training workshop the user numbers increased by 59 in one month and the total number of active users to 140 by the end of August 2013. Custom software applications for REDCap were created by collaboration between clinicians and software developers. REDCap was installed and maintained at limited cost. A small number of people with defined skills can support multiple REDCap users in two to four hours a week. End user training increased in the number of users, number of projects created and the number of projects moved to production.

The value of the WIRHE Scholarship Programme in training health professionals for rural areas: Views of participants

PubMed Central

2017-01-01

Introduction Rural hospitals in South Africa, as elsewhere, face enduring shortages of, and challenges in attracting and retaining, suitably qualified staff. The Wits Initiative for Rural Health Education (WIRHE), based at the University of the Witwatersrand but covering three universities, is a rural scholarship programme established to find local solutions to these challenges in the North West and Mpumalanga provinces. The purpose of this evaluation was to ascertain whether the WIRHE project was achieving its objectives. Methods This article draws from an evaluation commissioned by the Swiss-South African Cooperative Initiative, a major funder of the programme when WIRHE was launched in 2003. Qualitative interviews were conducted either as face-to-face meetings or telephonically with 21 WIRHE students and graduates. Content analysis was undertaken to identify common themes. Results There was a consistency in the findings as the students and graduates reported similar experiences. Many of the participants were overwhelmed by their initial challenges of having to adapt to a different language, an institutional culture and resources that they previously did not have access to. The participants acknowledged the role of WIRHE staff in facilitating the transition from home to university and, in particular, the value of the financial and academic support. The geographic distance to Wits presented a challenge for the Pretoria- and Sefako Makgatho-based students. The holiday work affirmed clinical advantages for WIRHE students and heightened students’ interest in becoming healthcare workers. Conclusion WIRHE’s key success factors are the financial, academic and emotional support offered to students. WIRHE achieved its objectives based on a principled strategic approach and an understanding that students from rural backgrounds are more likely to return to rural areas. The study supports the value of structured support programmes for students of rural origin as they pursue their studies. PMID:29041799

Control of strong ground motion of mining-induced earthquakes by the strength of the seismogenic rock mass

USGS Publications Warehouse

McGarr, A.

2002-01-01

The shear stress ?? that can be sustained by the rock mass in the environs of a mining-induced earthquake controls the near-fault peak ground velocity v of that event according to v???0.25(??/G) ??, where ?? is the shear wave speed and G is the modulus of rigidity. To estimate ?? at mining depths, I review the results of four studies involving Witwatersrand tremors that relate to the bulk shear strength. The first and most general analysis uses the common assumptions that the seismogenic crust is pervasively faulted, has hydrostatic pore pressure before mining, and an extensional stress state that is close to failure. Mining operations reduce the pore pressure to zero within the mine and redistribute the stresses such that, in localized regions, the state of stress is again at the point of failure. Laboratory friction experiments can be used to estimate ?? in the zero-pore-pressure regime. Second, model calculations of states of stress in the vicinity of milling at about 3 km depth indicated the shear stress available to cause faulting near the centre of a distribution of induced earthquakes. Third, laboratory experiments combined with microscopic analyses of fault gouge from the rupture zone of a mining-induced event provided an estimate of the average shear stress acting on the fault to cause this earthquake at a depth of 2 km. Fourth, moment tensors determined for mining- induced earthquakes usually show substantial implosive components, from which it is straightforward to estimate ??. These four different analyses yield estimates of ?? that fall in the range 30 to 61 MPa which implies that near-fault particle velocities could he as high as about 1.5 m/s. To the extent that the causative fault ruptures previously intact rock, both ?? and v, in localized regions, could be several times higher than 61 MPa and 1.5 m/s.

The Process of Installing REDCap, a Web Based Database Supporting Biomedical Research

PubMed Central

Mare, I.; Hazelhurst, S.; Kramer, B.

2014-01-01

Summary Background Clinical and research data are essential for patient care, research and healthcare system planning. REDCapTM is a web-based tool for research data curatorship developed at Vanderbilt University in Nashville, USA. The Faculty of Health Sciences at the University of the Witwatersrand, Johannesburg South Africa identified the need for a cost effective data management instrument. REDCap was installed as per the user agreement with Vanderbilt University in August 2012. Objectives In order to assist other institutions that may lack the in-house Information Technology capacity, this paper describes the installation and support of REDCap and incorporates an analysis of user uptake over the first year of use. Methods We reviewed the staffing requirements, costs of installation, process of installation and necessary infrastructure and end-user requests following the introduction of REDCap at Wits. The University Legal Office and Human Research Ethics Committee were consulted regarding the REDCap end-user agreement. Bi-monthly user meetings resulted in a training workshop in August 2013. We compared our REDCap software user numbers and records before and after the first training workshop. Results Human resources were recruited from existing staff. Installation costs were limited to servers and security certificates. The total costs to provide a functional REDCap platform was less than $9000. Eighty-one (81) users were registered in the first year. After the first training workshop the user numbers increased by 59 in one month and the total number of active users to 140 by the end of August 2013. Custom software applications for REDCap were created by collaboration between clinicians and software developers. Conclusion REDCap was installed and maintained at limited cost. A small number of people with defined skills can support multiple REDCap users in two to four hours a week. End user training increased in the number of users, number of projects created and the number of projects moved to production. PMID:25589907

Microbial Ecosystems from the Deepest Regions of the Terrestrial Deep Biosphere

NASA Astrophysics Data System (ADS)

Moser, D. P.

2011-12-01

Although recent discoveries from four continents support the existence of microbial ecosystems across vast regions of our planet's inner space, very little is known about the abundance, distribution, diversity, or ultimate depth limit of subsurface microbial life. These deep lithospheric inhabitants must contend with a variety of potential challenges including high temperature, pressure and salinity, extreme isolation, and low energy flux. Interestingly, although deep microbial ecosystems are assumed to be energy and nutrient limited, it is often difficult to identify any one limiting substrate and the energy for deep life is often present in relative abundance (e.g. as geologically-produced hydrogen or other reduced gases). Recently, the concept of radiation-supported deep microbial ecosystems has gained traction in the literature. In particular, one bacterium, a Firmicute denoted Candidatus Desulforudis audaxviator, has been shown to be prominent, and in cases dominate, in deep fracture fluids from across the Witwatersrand basin of South Africa, where it appears to persist by utilizing H2 and SO42- derived from radiochemical reactions in U-rich host rock. Until recently, these mines were thought to define the geographic limit of this genus and species; however, our recent North American detection of D. audaxviator in radioactive subsurface water resulting from underground nuclear tests both supports earlier assertions concerning the radiochemical lifestyle of D. audaxviator and greatly expands its range. Results such as these suggest that novel modes of life operating without inputs from the photosphere are possible, and thus may have implications for the likelihood of detecting life off the Earth (e.g. in the Martian subsurface). In addition to underground nuclear detonation cavities, this talk will consider insights gained from ongoing microbial ecology assessments from several to date unexplored deep ecosystems accessed via deep mines in the Black Hills (USA) and Canadian Shield (Canada) and exploratory boreholes in the Southern Great Basin (USA). The tantalizing possibility that several of these new potential habitats have exceeded some limit for life will be also be explored.

Early-phase dental students' motivations and expectations concerning the study and profession of dentistry.

PubMed

Lalloo, R; Ayo-Yusuf, O A; Yengopal, V

2008-05-01

This study investigated the career choice and aspirations of early phase dental students in the four dental schools in South Africa, namely the University of the Western Cape (UWC), University of the Witwatersrand (Wits), University of Limpopo (Medunsa) and University of Pretoria (UP). Willing participants completed a self-administered questionnaire (n=184). Motivations for entering a dentistry programme were similar across race and university, with wanting a secure job most often stated as an important factor. For a third of respondents, dentistry was not a first choice. Amongst the White students, it was a first choice for 82% compared with 59% amongst Black Africans. Expected income five-years after graduation also differed significantly across race and university, with White and UP students expecting to earn considerably higher than the others. About 36% of students were concerned about the levels of personal debt related to studying, with the White and Asian students less concerned. Those who expected lower levels of income from the profession were more concerned about personal debts. Most students planned to enter general dental practice (GDP) after community service, almost all White and Wits students expressed this intention, compared with only 35% of Black Africans and 39% of Medunsa students. Orthodontics and Maxillofacial & Oral Surgery were the most popular specialities of choice. The professional attribute "Has a friendly manner and good relationship with patients" was ranked high most often. In conclusion, career advice may not need to be tailored differently for the different racial groups. There is however a need for further investigations on how to address the concerns of financial security which may be realised by the practice of dentistry, and in particular the racial disparities observed in expectations of the profession. This study further highlights the need for government financial assistance for students from under-represented groups.

Economic evaluation of a shortened standardised treatment regimen of antituberculosis drugs for patients with multidrug-resistant tuberculosis (STREAM): study protocol.

PubMed

Gama, Elvis; Madan, Jason; Langley, Ivor; Girma, Mamo; Evans, Denise; Rosen, Sydney; Squire, S Bertel

2016-10-17

Multidrug-resistant tuberculosis (MDR-TB) poses a serious financial challenge to health systems and patients. The current treatment for patients with MDR-TB takes up to 24 months to complete. Evidence for a shorter regimen which differs from the standard WHO recommended MDR-TB regimen and typically lasts between 9 and 12 months has been reported from Bangladesh. This evaluation aims to assess the economic impact of a shortened regimen on patients and health systems. This evaluation is innovative as it combines patient and health system costs, as well as operational modelling in assessing the impact. An economic evaluation nested in a clinical trial with 2 arms will be performed at 4 facilities. The primary outcome measure is incremental cost to the health system of the study regimen compared with the control regimen. Secondary outcome measures are mean incremental costs incurred by patients by treatment outcome; patient costs by category (direct medical costs, transport, food and accommodation costs, and cost of guardians/accompanying persons and lost time); health systems cost by category and drugs; and costs related to serious adverse events. The study has been evaluated and approved by the Ethics Advisory Group of the International Union Against Tuberculosis and Lung Disease; South African Medical Research Ethics Committee; Wits Health Consortium Protocol Review Committee; University of the Witwatersrand Human Research Ethics Committee; University of Kwazulu-Natal Biomedical Research Ethics Committee; St Peter TB Specialized Hospital Ethical Review Committee; AHRI-ALERT Ethical Review Committee, and all participants will provide written informed consent. The results of the economic evaluation will be published in a peer-reviewed journal. ISRCTN78372190. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Three-dimensionally derived interlandmark distances for sex estimation in intact and fragmentary crania.

PubMed

Small, Candice; Schepartz, Lynne; Hemingway, Jason; Brits, Desiré

2018-06-01

The skull is the element most frequently presented to forensic anthropologists for analysis yet weathering, corpse maiming, and scavenger activity often result in damage and fragmentation. This fragmentation results in a reduction in the number of traditional calliper derived measurements that can be obtained and subjected to discriminant based analyses for sex estimation. In this investigation, we employed three-dimensional geometric morphometric methods to derive novel interlandmark distance measures across six regions of the cranium including the basicranium, basipalate, zygoma, orbits and the cranium globally to create functions to discriminate sex with high efficacy, even in the event of fragmentation. Forty-five homologous landmarks were digitised across each of 227 (114 males and 113 females) South African crania of European descent (white) sampled from the Raymond A Dart Collection of Human Skeletons, housed in the School of Anatomical Sciences, University of the Witwatersrand, South Africa. A total of 990 interlandmark distances (ILDs) were mathematically derived using Pythagorean geometry. These ILDs were then filtered by region and subjected to both direct and stepwise discriminant function analyses. Discriminant equations where derived for each region and achieved the following average cross-validated sex estimation accuracies: basicranium-74%; basipalate-80.2%; zygomatic-82.4; orbits-71.8%; nasomaxilla-83.7%; global cranium-88.2%. A large number of the ILDs used to derive the discriminant functions are novel, demonstrating the efficacy of geometric morphometric methods and illustrating the need to reassess old methods of data collection using modern methods to determine whether they best capture biological differences. The results of this study provide an invaluable contribution to forensic anthropology in South Africa as it provides an accurate, practical means of assessing sex using fragmentary material that may otherwise have been disregarded. These will undeniable aid in accurate sex estimation and ultimately, victim identification. Copyright © 2018 Elsevier B.V. All rights reserved.

A cluster randomised controlled trial to determine the effect of community mobilisation and advocacy on men’s use of violence in periurban South Africa: study protocol

PubMed Central

Christofides, Nicola J; Hatcher, Abigail M; Pino, Angelica; Rebombo, Dumisani; McBride, Ruari Santiago; Anderson, Althea; Peacock, Dean

2018-01-01

Objective This paper describes the design and methods of a cluster randomised controlled trial (C-RCT) to determine the effectiveness of a community mobilisation intervention that is designed to reduce the perpetration of violence against women (VAW). Methods and analysis A C-RCT of nine intervention and nine control clusters is being carried out in a periurban, semiformal settlement near Johannesburg, South Africa, between 2016 and 2018. A community mobilisation and advocacy intervention, called Sonke CHANGE is being implemented over 18 months. It comprises local advocacy and group activities to engage community members to challenge harmful gender norms and reduce VAW. The intervention is hypothesised to improve equitable masculinities, reduce alcohol use and ultimately, to reduce VAW. Intervention effectiveness will be determined through an audio computer-assisted self-interview questionnaire with behavioural measures among 2600 men aged between 18 and 40 years at baseline, 12 months and 24 months. The primary trial outcome is men’s use of physical and/or sexual VAW. Secondary outcomes include harmful alcohol use, gender attitudes, controlling behaviours, transactional sex and social cohesion. The main analysis will be intention-to-treat based on the randomisation of clusters. A qualitative process evaluation is being conducted alongside the C-RCT. Implementers and men participating in the intervention will be interviewed longitudinally over the period of intervention implementation and observations of the workshops and other intervention activities are being carried out. Ethics and dissemination Ethical approval was obtained from the University of the Witwatersrand Human Research Ethics Committee and procedures comply with ethical recommendations of the United Nations Multi-Country Study on Men and Violence. Dissemination of research findings will take place with local stakeholders and through peer-reviewed publications, with data available on request or after 5 years of trial completion. Trial registration number NCT02823288; Pre-result. PMID:29574438

Geochemistry and mineralogy of sediments from the Ventersdorp and Transvaal Supergroups, South Africa: Cratonic evolution during the early Proterozoic

NASA Astrophysics Data System (ADS)

Wronkiewicz, David J.; Condie, Kent C.

1990-02-01

Approximately 100 pelite and 12 quartzite samples from the Ventersdorp (~2.7 Ga) and Transvaal Supergroups (~2.6-2.1 Ga) have been analyzed to monitor the early Proterozoic evolution of the Kaapvaal Craton, southern Africa. From oldest to youngest, pelites were sampled from the Ventersdorp-Bothaville (BOT), Transvaal-Selati (SEL), Black Reef (BR), Timeball Hill (TH), Strubenkop (STR), and Silverton (SIL) Formations. Paleocurrent measurements in Transvaal quartzites indicate sources lying predominantly to the north and east. Relative to the BOT-SEL-BR, pelites from the TH-STR-SIL are enriched in heavy-REE, LILE, Zr, Hf, Nb, and Ta, depleted in K 2O, MgO, Ni, and Cr, and have lower Cr/Zr, Sc/Th, K 2O/Na 2O, and K/ Rb ratios. Compared to SEL-BR, BOT-TH-STR-SIL pelites have higher light-REE contents and La/Yb ratios, and lower Eu/Eu∗ ratios (0.61-0.66). Relative to NASC (North American Shale Composite), THSTR-SIL pelites are enriched in light-REE, Th, U, Ta, Nb, Sc, Cs, have higher La/Yb ratios, and are depleted in K 2O and MgO. BOT-SEL-BR pelites are enriched in K 2O, MgO, Cr, and Ni, have higher K 2O/Na 2O, Sc/Th, and Eu/Eu∗ ratios, and are depleted in Th, U, heavy-REE, and High Field Strength Elements (HFSE) relative to NASC. Compositions of TH-STR-SIL pelites suggest a provenance similar to average Phanerozoic uppercontinental crust. This source is more evolved than that of BOT-SEL-BR pelites, indicating a transformation from primitive (mafic-rich) to evolved (felsic-rich) upper-crust at 2.2 Ga. This transition follows earlier primitive to evolved trends in Moodies-Pongola (3.3-3.0 Ga) and Witwatersrand (~2.8 Ga) successions. These data suggest that several cycles of changing upper-continental crust occurred in the Kaapvaal craton between 3.3-2.1 Ga.

An Outbreak of Lymphocutaneous Sporotrichosis among Mine-Workers in South Africa

PubMed Central

Govender, Nelesh P.; Maphanga, Tsidiso G.; Zulu, Thokozile G.; Patel, Jaymati; Walaza, Sibongile; Jacobs, Charlene; Ebonwu, Joy I.; Ntuli, Sindile; Naicker, Serisha D.; Thomas, Juno

2015-01-01

Background The largest outbreak of sporotrichosis occurred between 1938 and 1947 in the gold mines of Witwatersrand in South Africa. Here, we describe an outbreak of lymphocutaneous sporotrichosis that was investigated in a South African gold mine in 2011. Methodology Employees working at a reopened section of the mine were recruited for a descriptive cross-sectional study. Informed consent was sought for interview, clinical examination and medical record review. Specimens were collected from participants with active or partially-healed lymphocutaneous lesions. Environmental samples were collected from underground mine levels. Sporothrix isolates were identified by sequencing of the internal transcribed spacer region of the ribosomal gene and the nuclear calmodulin gene. Principal Findings Of 87 male miners, 81 (93%) were interviewed and examined, of whom 29 (36%) had skin lesions; specimens were collected from 17 (59%). Sporotrichosis was laboratory-confirmed among 10 patients and seven had clinically-compatible lesions. Of 42 miners with known HIV status, 11 (26%) were HIV-infected. No cases of disseminated disease were detected. Participants with ≤3 years’ mining experience had a four times greater odds of developing sporotrichosis than those who had been employed for >3 years (adjusted OR 4.0, 95% CI 1.2–13.1). Isolates from 8 patients were identified as Sporothrix schenckii sensu stricto by calmodulin gene sequencing while environmental isolates were identified as Sporothrix mexicana. Conclusions/Significance S. schenckii sensu stricto was identified as the causative pathogen. Although genetically distinct species were isolated from clinical and environmental sources, it is likely that the source was contaminated soil and untreated wood underground. No cases occurred following recommendations to close sections of the mine, treat timber and encourage consistent use of personal protective equipment. Sporotrichosis is a potentially re-emerging disease where traditional, rather than heavily mechanised, mining techniques are used. Surveillance should be instituted at sentinel locations. PMID:26407300

The Search for Life on Mars - Current Knowledge, Earth Analogues, and Principal Issues

NASA Technical Reports Server (NTRS)

Mumma, Michael J.

2012-01-01

For centuries, the planet Mars has been imagined as a possible abode for life. Serious searches for life's signatures began in the 19th century via ground-based visual astronomy that stimulated a vibrant fantasy literature but little lasting scientific knowledge. Modern scientific inquiry has emphasized the search for chemical signatures of life in the soil and rocks at the planet's surface, and via biomarker gases in the atmosphere. Today, investigations are based on high-resolution spectroscopy at Earth's largest telescopes along with planet orbiting and landed space missions. Methane has assumed central importance in these searches. Living systems produce more than 900/0 of Earth's atmospheric methane; the balance is of geochemical origin. Abundant methane is not expected in an oxidizing atmosphere such as Mars', and its presence would imply recent release - whether biological or geochemical. F or that reason, the quest for methane on Mars has been a continuing thread in the fabric of searches conducted since 1969. I will review aspects of the discovery and distribution of methane on Mars, and will mention ongoing extended searches for clues to its origin and destruction. On Earth, hydrogen (generated via serpentinization or radiolysis of water) provides an important 'fuel' for carbonate-reducing and sulphate-reducing biota (CH4 and H2S producers, respectively). Several such communities are known to reside at depth in continental domains (e.g., Lidy Hot Springs, Idaho; Witwatersrand Basin, S. Africa). If similar conditions exist in favourable locations on Mars, organisms similar to these could likely prosper there. Geologic (abiotic) production will also be mentioned, especially abiotic methane production associated with low-temperature serpentinization (e.g., terrestrial ophiolites). It is vitally important to pursue evidence for geochemical and biological production with equal vigour and intellectual weight lest unwanted and unintended bias contaminate the results. Finally, I will touch upon unresolved questions and issues posed by the methane detections.

Leveraging ongoing research to evaluate the health impacts of South Africa's salt reduction strategy: a prospective nested cohort within the WHO-SAGE multicountry, longitudinal study

PubMed Central

Charlton, Karen; Menyanu, Elias; Biritwum, Richard Berko; Naidoo, Nirmala; Pieterse, Chiné; Madurai, Savathree (Lorna); Baumgartner, Jeannine; Asare, George A; Thiele, Elizabeth; Schutte, Aletta E; Kowal, Paul

2016-01-01

Introduction Attempting to curb the rising epidemic of hypertension, South Africa implemented legislation in June 2016 mandating maximum sodium levels in a range of manufactured foods that contribute significantly to population salt intake. This natural experiment, comparing two African countries with and without salt legislation, will provide timely information on the impact of legislative approaches addressing the food supply to improve blood pressure in African populations. This article outlines the design of this ongoing prospective nested cohort study. Methods and analysis Baseline sodium intake was assessed in a nested cohort of the WHO Study on global AGEing and adult health (WHO-SAGE) wave 2 (2014–2015), a multinational longitudinal study on the health and well-being of adults and the ageing process. The South African cohort consisted of randomly selected households (n=4030) across the country. Spot and 24-hour urine samples are collected in a random subsample (n=1200) and sodium, potassium, creatinine and iodine analysed. Salt behaviour and sociodemographic data are captured using face-to-face interviews, alongside blood pressure and anthropometric measures. Ghana, the selected control country with no formal salt policy, provided a nested subsample (n=1200) contributing spot and 24-hour urine samples from the SAGE Ghana cohort (n=5000). Follow-up interviews and urine collection (wave 3) in both countries will take place in 2017 (postlegislation) to assess change in population-level sodium intake and blood pressure. Ethics and dissemination SAGE was approved by the WHO Ethics Review Committee (reference number RPC149) with local approval from the North-West University Human Research Ethics Committee and University of the Witwatersrand Human Research Ethics Committee (South Africa), and University of Ghana Medical School Ethics and Protocol Review Committee (Ghana). The results of the study will be published in peer-reviewed international journals, presented at national and international conferences, and summarised as research and policy briefs. PMID:27903563

Origins and ages of fracture fluids in the South African Crust

NASA Astrophysics Data System (ADS)

Heard, A. W.; Warr, O.; Borgonie, G.; Linage-Alvarez, B.; Kuloyo, O.; Magnabosco, C.; Lau, M.; Erasmus, M.; Cason, E. D.; van Heerden, E.; Kieft, T. L.; Mabry, J.; Onstott, T. C.; Sherwood Lollar, B.; Ballentine, C. J.

2017-12-01

Crustal fracture fluids can remain isolated for millions (Myr) to billions of years (Gyr), and contain information on paleohydrogeology, subsurface ecology, and conservative components that may elucidate the atmospheric evolution of the early Earth [1-3]. Stable isotope analyses of water combined with isotopic analyses of the dissolved noble gases provide insight into the history of aqueous fracture fluids. We report stable isotope and noble gas data for fracture fluids from 5 different sites in the Witwatersrand Basin and Bushveld Igneous Province, South Africa. We determine radiogenic noble gas residence times ranging from thousands of years to tens of millions of years. The oldest sample, from Masimong Mine, has a water stable isotopic composition close to the global meteoric water line (GMWL), indicating its preservation in the crust and making it one of the oldest recorded paleometeoric waters. The δ2H and δ18O of water in this sample and similar age samples from the same mining district [1,4] require isotopically depleted groundwater recharge compared to modern precipitation. This could reflect a recharge regime at a higher paleolatitude, elevation, or with higher rainfall, established up to tens of Myr ago, and perhaps similar to the recharge regime in the modern Lesotho Highlands [5]. These data suggest that groundwater isotopes may provide useful paleoclimatic information for many Myr. As hypothesized, such paleometeoric water samples lack 124-128Xe enrichments reported from Gyr age groundwaters discovered on the Canadian Shield [3] and in Archean fluid inclusions [6], providing an important control set and reaffirming that those samples record the evolution of ancient atmospheric Xe rather than subsurface alteration. [1] Lippmann, J. et al. (2003) GCA 67, 4597-4619. [2] Lin, L.-H. (2006) et al. Science 314, 479-482. [3] Holland, G. et al. (2013) Nature 497, 357-360. [4] Lippmann-Pipke, J. et al. (2011) Chem. Geol. 283, 287-296. [5] West, A. G. et al. (2014) J. Geochem. Explor. 145, 213-222. [6] Pujol, M. et al. (2011) EPSL 308,298-306.

Engaging Diverse Students Through International Collaboration and Professional Preparation

NASA Astrophysics Data System (ADS)

Feineman, M. D.; Nyblade, A.; Webb, S. J.

2016-12-01

The AfricaArray-Bushveld REU is a partnership between the Pennsylvania State University and the University of the Witwatersrand. The primary goal is to engage a diverse cohort of students in international scientific collaboration through a program of training, field work, and laboratory and/or computational analysis. At least 50% of the student participants each year are from under-represented minorities. Students spend 2-3 weeks at Penn State, then 3 weeks in South Africa, followed by another 2-3 weeks in the US. The introductory 2-3 week session at Penn State is devoted to ethics and safety training, the human history, culture, and geologic history of South Africa, and Earth Science Literacy. Upon arriving in South Africa, the students are placed into field groups with students, post-docs, and faculty from Wits and other African nations participating in the AfricaArray Geophysics Field School. Each disciplinary group includes at least 1 mentor from the US and 1 from South Africa. Students spend time collecting rock samples for geochemical analysis, installing and servicing seismometers, and/or collecting data from the shallow subsurface using a variety of geophysical techniques. All students attend lectures by faculty at Wits, receive training in proper use and maintenance of scientific instrumentation, and interact with industry representatives. The culmination of this part of the REU is a day of oral presentations, where all students (REU and AfricaArray Geophysics Field School) share their experiences and data. After returning to the US, students engage in geochemical analysis, processing of seismic data, and modeling geophysical data. In addition to faculty mentors, the students work closely with graduate students and post-docs. All participate in mentor-led discussions about future career paths and graduate school options. As a capstone to the REU, each student writes a conference abstract and gives a poster presentation of their research. Each abstract includes co-authors from the US and South Africa, and these have been presented by students at SACNAS, NABG, GSA, and AGU meetings. At the end of the REU, students participating in anonymous surveys report feeling more confident in their ability to contribute to an international scientific collaboration and to complete a graduate degree in geosciences.

A cluster randomised controlled trial to determine the effect of community mobilisation and advocacy on men's use of violence in periurban South Africa: study protocol.

PubMed

Christofides, Nicola J; Hatcher, Abigail M; Pino, Angelica; Rebombo, Dumisani; McBride, Ruari Santiago; Anderson, Althea; Peacock, Dean

2018-03-23

This paper describes the design and methods of a cluster randomised controlled trial (C-RCT) to determine the effectiveness of a community mobilisation intervention that is designed to reduce the perpetration of violence against women (VAW). A C-RCT of nine intervention and nine control clusters is being carried out in a periurban, semiformal settlement near Johannesburg, South Africa, between 2016 and 2018. A community mobilisation and advocacy intervention, called Sonke CHANGE is being implemented over 18 months. It comprises local advocacy and group activities to engage community members to challenge harmful gender norms and reduce VAW. The intervention is hypothesised to improve equitable masculinities, reduce alcohol use and ultimately, to reduce VAW. Intervention effectiveness will be determined through an audio computer-assisted self-interview questionnaire with behavioural measures among 2600 men aged between 18 and 40 years at baseline, 12 months and 24 months. The primary trial outcome is men's use of physical and/or sexual VAW. Secondary outcomes include harmful alcohol use, gender attitudes, controlling behaviours, transactional sex and social cohesion. The main analysis will be intention-to-treat based on the randomisation of clusters. A qualitative process evaluation is being conducted alongside the C-RCT. Implementers and men participating in the intervention will be interviewed longitudinally over the period of intervention implementation and observations of the workshops and other intervention activities are being carried out. Ethical approval was obtained from the University of the Witwatersrand Human Research Ethics Committee and procedures comply with ethical recommendations of the United Nations Multi-Country Study on Men and Violence. Dissemination of research findings will take place with local stakeholders and through peer-reviewed publications, with data available on request or after 5 years of trial completion. NCT02823288; Pre-result. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Some New Windows into Terrestrial Deep Subsurface Microbial Ecosystems

NASA Astrophysics Data System (ADS)

Moser, D. P.

2011-12-01

Over the past several years, our group has surveyed the microbial ecology and biogeochemistry of a range of fracture rock subsurface ecosystems via deep mine boreholes in South Africa, the United States, and Canada; and boreholes from surface or deeply-sourced natural springs of the U.S. Great Basin. Collectively, these mostly unexplored habitats represent a wide range of geologic provinces, host rock types, aquatic chemistries, and the vast potential for biogeographic isolation. Thus, patterns of microbial diversity are of interest from the perspective of filling a fundamental knowledge gap; and while not necessarily expected, the detection of closely related microorganisms from geographically isolated settings would be noteworthy. Across these sample sets, microbial communities were invariably very low in biomass (e.g. 10e3 - 10e4 cells per mL) and dominated by deeply-branching bacterial lineages, particularly from the phyla Firmicutes and Nitrospira. In several cases, the Firmicutes have shown very close phylogenetic affiliations to lineages detected at divergent locations. For example, one abundant lineage from a new artesian well drilled into the Furnace Creek Fault of Death Valley, CA bears a very close phylogenetic relatedness to environmental DNA sequences (SSU rRNA gene) detected in one of the world's deepest mines (Tau Tona of South Africa) and what was North America's deepest gold mine (Homestake of South Dakota). Several radioactive wells from the Nevada National Security Site have produced rRNA gene sequences very close (e.g. greater than 99% identity) to that of Desulforudis audaxviator, a rarely detected microorganism thought to subsist as a single species ecosystem on the products of radiochemical reactions in deep crustal rocks from the South African Witwatersrand Basin. These sequences, along with more distantly related sequences from the marine subsurface (ridge flank basalt and mud volcanoes) and groundwater in Europe, hint at a role in certain hydrogen-rich subsurface settings for this group. Likewise, patterns of archaeal diversity across many of our Great Basin sites suggest shared deep lineages, particularly with the phylum, Thaumarchaeota. Here we will explore the possible significance of these patterns of diversity and discuss future research plans involving high throughput molecular techniques.

Preferences for ARV-based HIV prevention methods among men and women, adolescent girls and female sex workers in Gauteng Province, South Africa: a protocol for a discrete choice experiment.

PubMed

Quaife, Matthew; Eakle, Robyn; Cabrera, Maria; Vickerman, Peter; Tsepe, Motlalepule; Cianci, Fiona; Delany-Moretlwe, Sinead; Terris-Prestholt, Fern

2016-06-27

For the past few decades, condoms have been the main method of HIV prevention. Recent advances in antiretroviral (ARV)-based prevention products have substantially changed the prevention landscape, yet little is known about how popular these products will be among potential users, or whether new methods might be used in conjunction with, or instead of, condoms. This study will use a discrete choice experiment (DCE) to (1) explore potential users' preferences regarding HIV prevention products, (2) quantify the importance of product attributes and (3) predict the uptake of products to inform estimates of their potential impact on the HIV epidemic in South Africa. We consider preferences for oral pre-exposure prophylaxis; a vaginal microbicide gel; a long-acting vaginal ring; a SILCS diaphragm used in concert with gel; and a long-acting ARV-based injectable. This study will gather data from 4 populations: 200 women, 200 men, 200 adolescent girls (aged 16-17 years) and 200 female sex workers. The DCE attributes and design will be developed through a literature review, supplemented by a thematic analysis of qualitative focus group discussions. Extensive piloting will be carried out in each population through semistructured interviews. The final survey will be conducted using computer tablets via a household sample (for women, men and adolescents) and respondent-driven sampling (for female sex workers), and DCE data analysed using a range of multinomial logit models. This study has been approved by the University of the Witwatersrand Human Research Ethics Committee and the Research Ethics Committee at the London School of Hygiene and Tropical Medicine. Findings will be presented to international conferences and peer-reviewed journals. Meetings will be held with opinion leaders in South Africa, while results will be disseminated to participants in Ekurhuleni through a public meeting or newsletter. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Building Geophysics Talent and Opportunity in Africa: Experience from the AfricaArray/Wits Geophysics Field School

NASA Astrophysics Data System (ADS)

Webb, S. J.; Manzi, M.; Scheiber-Enslin, S. E.; Durrheim, R. J.; Jones, M. Q. W.; Nyblade, A.

2015-12-01

There are many challenges faced by geophysics students and academic staff in Africa that make it difficult to develop effective field and research programs. Challenges to conducting field work that have been identified, and that can be tackled are: lack of training on geophysical equipment and lack of exposure to field program design and implementation. To address these challenges, the AfricaArray/Wits Geophysics field school is designed to expose participants to a wide variety of geophysical instruments and the entire workflow of a geophysical project. The AA field school was initially developed for the geophysics students at the University of the Witwatersrand. However, by increasing the number of participants, we are able to make more effective use of a large pool of equipment, while addressing challenging geophysical problems at a remote field site. These additional participants are selected partially based on the likely hood of being able start a field school at their home institution. A good candidate would have access to geophysical equipment, but may not have knowledge of how to use it or how to effectively design surveys. These are frequently junior staff members or graduate students in leadership roles. The three week program introduces participants to the full geophysical field workflow. The first week is spent designing a geophysical survey, including determining the cost. The second week is spent collecting data to address a real geophysical challenge, such as determining overburden thickness, loss of ground features due to dykes in a mine, or finding water. The third week is spent interpreting and integrating the various data sets culminating in a final presentation. Participants are given all lecture material and much of the software is open access; this is done to encourage using the material at the home institution. One innovation has been to use graduate students as instructors, thus building a pool of talent that has developed the logistic and training skills necessary to implement field programs. Several geophysics field schools are being developed in Madagascar, Zimbabwe, Nigeria, Kenya, Uganda, Tanzania and Cameroon. We hope to enable some of our graduate students to help with these budding programs.

Socioeconomic differences in mortality in the antiretroviral therapy era in Agincourt, rural South Africa, 2001-13: a population surveillance analysis.

PubMed

Kabudula, Chodziwadziwa W; Houle, Brian; Collinson, Mark A; Kahn, Kathleen; Gómez-Olivé, Francesc Xavier; Tollman, Stephen; Clark, Samuel J

2017-09-01

Understanding the effects of socioeconomic disparities in health outcomes is important to implement specific preventive actions. We assessed socioeconomic disparities in mortality indicators in a rural South African population over the period 2001-13. We used data from 21 villages of the Agincourt Health and socio-Demographic Surveillance System (HDSS). We calculated the probabilities of death from birth to age 5 years and from age 15 to 60 years, life expectancy at birth, and cause-specific and age-specific mortality by sex (not in children <5 years), time period, and socioeconomic status (household wealth) quintile for HIV/AIDS and tuberculosis, other communicable diseases (excluding HIV/AIDS and tuberculosis) and maternal, perinatal, and nutritional causes, non-communicable diseases, and injury. We also quantified differences with relative risk ratios and relative and slope indices of inequality. Between 2001 and 2013, 10 414 deaths were registered over 1 058 538 person-years of follow-up, meaning the overall crude mortality was 9·8 deaths per 1000 person-years. We found significant socioecomonic status gradients for mortality and life expectancy at birth, with outcomes improving with increasing socioeconomic status. An inverse relation was seen for HIV/AIDS and tuberculosis mortality and socioeconomic status that persisted from 2001 to 2013. Deaths from non-communicable diseases increased over time in both sexes, and injury was an important cause of death in men and boys. Neither of these causes of death, however, showed consistent significant associations with household socioeconomic status. The poorest people in the population continue to bear a high burden of HIV/AIDS and tuberculosis mortality, despite free antiretroviral therapy being made available from public health facilities. Associations between socioeconomic status and increasing burden of mortality from non-communicable diseases is likely to become prominent. Integrated strategies are needed to improve access to and uptake of HIV testing, care, and treatment, and management of non-communicable diseases in the poorest populations. Wellcome Trust, South African Medical Research Council, and University of the Witwatersrand, South Africa. Copyright © 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.

The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits

NASA Astrophysics Data System (ADS)

Deditius, Artur P.; Reich, Martin; Kesler, Stephen E.; Utsunomiya, Satoshi; Chryssoulis, Stephen L.; Walshe, John; Ewing, Rodney C.

2014-09-01

The ubiquity of Au-bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of Au and As in this sulfide occurs under a wide range of physico-chemical conditions. Despite significant advances in the last 20 years, fundamental factors controlling Au and As ratios in pyrite from ore deposits remain poorly known. Here we explore these constraints using new and previously published EMPA, LA-ICP-MS, SIMS, and μ-PIXE analyses of As and Au in pyrite from Carlin-type Au, epithermal Au, porphyry Cu, Cu-Au, and orogenic Au deposits, volcanogenic massive sulfide (VHMS), Witwatersrand Au, iron oxide copper gold (IOCG), and coal deposits. Pyrite included in the data compilation formed under temperatures from ∼30 to ∼600 °C and in a wide variety of geological environments. The pyrite Au-As data form a wedge-shaped zone in compositional space, and the fact that most data points plot below the solid solubility limit defined by Reich et al. (2005) indicate that Au1+ is the dominant form of Au in arsenian pyrite and that Au-bearing ore fluids that deposit this sulfide are mostly undersaturated with respect to native Au. The analytical data also show that the solid solubility limit of Au in arsenian pyrite defined by an Au/As ratio of 0.02 is independent of the geochemical environment of pyrite formation and rather depends on the crystal-chemical properties of pyrite and post-depositional alteration. Compilation of Au-As concentrations and formation temperatures for pyrite indicates that Au and As solubility in pyrite is retrograde; Au and As contents decrease as a function of increasing temperature from ∼200 to ∼500 °C. Based on these results, two major Au-As trends for Au-bearing arsenian pyrite from ore deposits are defined. One trend is formed by pyrites from Carlin-type and orogenic Au deposits where compositions are largely controlled by fluid-rock interactions and/or can be highly perturbed by changes in temperature and alteration by hydrothermal fluids. The second trend consists of pyrites from porphyry Cu and epithermal Au deposits, which are characterised by compositions that preserve the Au/As signature of mineralizing magmatic-hydrothermal fluids, confirming the role of this sulfide in controlling metal ratios in ore systems.

Mortality of white South African gold miners.

PubMed Central

Reid, P J; Sluis-Cremer, G K

1996-01-01

OBJECTIVES--This two part study aimed to determine whether there was an excess mortality generally or for some diseases among middle aged white South African gold miners on the Witwatersrand and whether the underground dust exposure of these miners contributed to the development of lung cancer, chronic obstructive pulmonary disease (COPD), or ischaemic heart disease (IHD). METHODS--A cohort of 4925 white miners in South Africa, born between 1 January 1916 and 31 December 1930 who were alive and working in the vicinity of Johannesburg on 1 January 1970, then aged between 39 and 54, was followed up for 20 years by which time 2032 had died. Most were gold miners (about 87% had worked 85% or more of their shifts in gold mines). Standardised mortality ratios (SMRs) were calculated as percentages of the number of deaths observed in the cohort for a condition as stated on the death certificate divided by the number expected on the basis of concurrent mortality in the reference population (the total age specific white male population of South Africa). A case-control analysis was performed for three diseases (lung cancer, COPD, and IHD), the results of which are presented for those miners in the cohort who had spent at least 85% of their service on gold mines and had worked at least 15% of their shifts underground. RESULTS--The SMR for all causes of death was 129.6%, raised because of excess mortality due to the following causes: lung cancer (SMR = 139.8%), IHD (124.1%), COPD (189%) and cirrhosis of the liver (155.3%). Smoking was confirmed to be the main risk factor for lung cancer and COPD although cumulative dust exposure was found to increase the risk of COPD in conjunction with smoking. No significant risk of lung cancer resulted from exposure to dust. High blood pressure and smoking were found to increase the risk of IHD, but no association between IHD and the quetelet index (weight/height2) was found. CONCLUSIONS--The most significant and unexpected finding was the 30% increase in the SMR for all causes. Very little of this increase could be attributed to mining and the main factor for this was probably the adoption of an unhealthy lifestyle by these men (compared with other South African white men) particularly smoking (86% were smokers) and alcohol consumption. PMID:8563852

The neonatal resuscitation training project in rural South Africa.

PubMed

Couper, I D; Thurley, J D; Hugo, J F M

2005-01-01

A paediatrician trainer from Australia (JT) spent 3 months in South Africa to assist with the development of neonatal resuscitation training in rural areas, particularly in district hospitals. The project was initiated by the Rural Health Unit at the University of the Witwatersrand and coordinated through the Family Medicine Education Consortium (FaMEC). The Rural Workforce Agency of Victoria together with General Practice and Primary Health Care Northern Territory covered the salary and international travel costs of the trainer, while local costs were funded by provincial departments of health, participants and a Belgian funded FaMEC project. The trainer developed an appropriate one-day skills training course in neonatal resuscitation (NNR), using the South African Paediatric Association Manual of Resuscitation of the Newborn as pre-reading, and a course to train trainers in neonatal resuscitation. From July to October 2004 he moved around the country running the neonatal resuscitation course, and, more importantly, training and accrediting trainers to run their own courses on an ongoing basis. The neonatal resuscitation course involved pre- and post-course multiple-choice question tests to assess knowledge and application, and, later, pre- and post-course skills tests to assess competence. A total of 415 people, including 215 nurses and 192 doctors, attended the neonatal resuscitation courses in 28 different sites in eight provinces. In addition, 97 trainers were trained, in nine sites. The participants rated the course highly. Pre- and post-course tests showed a high level of learning and improved confidence. The logistical arrangements, through the departments of family medicine, worked well, but the programme was very demanding of the trainer. Lessons and experiences were not shared between provinces, leading to repetition of some problems. A clear issue around the country was a lack of adequate equipment in hospitals for neonatal resuscitation, which needs to be addressed by health authorities. A process of ongoing training has been established, with provincial coordinators taking responsibility for standards and the roll-out of training. A formal evaluation of the project is planned. The project serves as a model for skills training in rural areas in South Africa, and for collaboration between organisations. A number of specific recommendations are made for the future of this NNR training project, which offer lessons for similar programmes.

Mineralogy and geochemistry of efflorescent minerals on mine tailings and their potential impact on water chemistry.

PubMed

Grover, B P C; Johnson, R H; Billing, D G; Weiersbye, I M G; Tutu, H

2016-04-01

In the gold mining Witwatersrand Basin of South Africa, efflorescent mineral crusts are a common occurrence on and nearby tailings dumps during the dry season. The crusts are readily soluble and generate acidic, metal- and sulphate-rich solutions on dissolution. In this study, the metal content of efflorescent crusts at an abandoned gold mine tailings dump was used to characterise surface and groundwater discharges from the site. Geochemical modelling of the pH of the solution resulting from the dissolution of the crusts was used to better understand the crusts' potential impact on water chemistry. The study involved two approaches: (i) conducting leaching experiments on oxidised and unoxidised tailings using artificial rainwater and dilute sulphuric acid and correlating the composition of crusts to these leachates and (ii) modelling the dissolution of the crusts in order to gain insight into their mineralogy and their potential impact on receiving waters. The findings suggested that there were two chemically distinct discharges from the site, namely an aluminium- and magnesium-rich surface water plume and an iron-rich groundwater plume. The first plume was observed to originate from the oxidised tailings following leaching with rainwater while the second plume originated from the underlying unoxidised tailings with leaching by sulphuric acid. Both groups of minerals forming from the respective plumes were found to significantly lower the pH of the receiving water with simulations of their dissolution found to be within 0.2 pH units of experimental values. It was observed that metals in a low abundance within the crust (for example, iron) had a stronger influence on the pH of the resulting solutions than metals in a greater abundance (aluminium or magnesium). Techniques such as powder X-ray diffraction (PXRD) and in situ mineral determination techniques such as remote sensing can effectively determine the dominant mineralogy. However, the minerals or metals incorporated through solid solution into bulk mineralogy that dominates the chemistry of the solutions upon their dissolution may occur in minor quantities that can only be predicted using chemical analysis. Their mineralogy can be predicted using geochemical modelling and can provide a set of hypothetical minerals that upon dissolution yield a solution similar to that of the actual crusts. This realisation has a bearing on decision-making such as in risk assessment and designing pollutant mitigation strategies.

Mass Independent Fractionation of Sulphur Isotopes in Precambrian Sedimentary Rocks: Indicator for Changes in Atmospheric Composition and the Operation of the Global Sulphur Cycle

NASA Astrophysics Data System (ADS)

Peters, M.; Farquhar, J.; Strauss, H.

2005-12-01

Large mass independent fractionation (MIF) of sulphur isotopes in sedimentary rocks older than 2.3 Ga and the absence of this isotopic anomaly in younger rocks seem to be the consequence of a change in Earth's atmospheric composition from essentially oxygen-free or to oxygen-rich conditions. MIF is produced by photochemical reactions of volcanogenic sulphur dioxide with UV radiation in the absence of an ozone shield. The products of such processes are elemental sulphur with positive and sulphate with negative Δ33S values. Here we present isotope data (32S, 33S, 34S) for sedimentary pyrites from Archaean and Palaeoproterozoic rocks of the Kaapvaal Craton (South Africa), the Pilbara Craton (Australia) and the Greenland Shield (Isua Supercrustal Belt). Their ages range from 3.85 to 2.47 Ga. Large positive Δ33S values up to +9.13 ‰ in several Archaean units from the Kapvaal and Pilbara Cratons are attributed to low atmospheric oxygen at that time. Interestingly, very low Δ33S values between -0.28 and +0.57 ‰ appear to characterize the Witwatersrand succession of South Africa (3.0 Ga). This rather small MIF signature was previously detected in rocks of the same age in Western Australia (OHMOTO et al., 2005). The signature is interpreted as a global signal, which could be the consequence of a shielding effect induced by one or more atmospheric components. The most probable chemical compounds for this process are methane and carbon dioxide. Rocks of the Kameeldoorns Fm. (2.71 Ga), Kaapvaal Craton, display also low values between -0.46 and +0.33 ‰, which are consistent with the small (absent) MIF signal in rocks of the Hardey Fm. (2.76 Ga) of Western Australia (OHMOTO et al., 2005). Very low carbon isotope values between -51 and -40 ‰ in late Archaean kerogens (2.6 - 2.8 Ga) indicate a high concentration of methane in the atmosphere (PAVLOV et al., 2001). This high methane level could produce an organic haze, which absorbed most of the UV radiation and prevented mass independent fractionation of sulphur isotopes. In Palaeoproterozoic sediments of the Brockman Iron Fm., just prior to the proposed Great Oxidation Event, we determined predominantly negative Δ33S values between -1.07 and +0.08 ‰, which is atypical for sulphides. We interpret this negative MIF signal as a product of microbial reduction of atmospheric sulphate with an original negative MIF signature. This observation may indicate a higher concentration of sulphate in the ocean. Mass independent sulphur isotope data presented here provide a deeper insight into the major steps in atmospheric evolution and the Precambrian sulfur cycle. Ohmoto, H., Watanabe, Y., Ikemi, H. (2005) Geochim. Cosmochim. Acta 69, A 450 (abstr.). Pavlov, A.A., Kasting, J.F., Brown, L.L. (2001) JGR 106, 23267-23287.

Ammonium stability and nitrogen isotope fractionations for NH4+-NH3(aq)-NH3(gas) systems at 20-70 °C and pH of 2-13: Applications to habitability and nitrogen cycling in low-temperature hydrothermal systems

NASA Astrophysics Data System (ADS)

Li, Long; Lollar, Barbara Sherwood; Li, Hong; Wortmann, Ulrich G.; Lacrampe-Couloume, Georges

2012-05-01

Ammonium/ammonia is an essential nutrient and energy source to support life in oceanic and terrestrial hydrothermal systems. Thus the stability of ammonium is crucial to determine the habitability or ecological structure in hydrothermal environments, but still not well understood. To date, the lack of constraints on nitrogen isotope fractionations between ammonium and ammonia has limited the application of nitrogen isotopes to trace (bio)geochemical processes in such environments. In this study, we carried out laboratory experiments to (1) examine the stability of ammonium in an ammonium sulfate solution under temperature conditions from 20 to 70 °C and pH from 2.1 to 12.6 and (2) determine nitrogen isotope fractionation between ammonium and ammonia. Our experimental results show that ammonium is stable under the experimental temperatures when pH is less than 6. In experiments with starting pH greater than 8, significant ammonium was lost as a result of dissociation of ammonium and degassing of ammonia product. Nitrogen concentrations in the fluids decreased by more than 50% in the first two hours, indicating extremely fast effusion rates of ammonia. This implies that ammonium at high pH fluids (e.g., Lost City Hydrothermal Vents, Oman ophiolite hyperalkaline springs) may not be stable. Habitable environments may be more favorable at the leading edge of a pH gradient toward more acidic conditions, where the fluid can efficiently trap any ammonia transferred from a high pH vent. Although modeling shows that high temperature, low pH hydrothermal vents (e.g., Rainbow hydrothermal vent) may have the capability to retain ammonium, their high temperatures may limit habitability. The habitable zone associated with such a hydrothermal vent is likely at the lower front of a temperature gradient. In contrast, modeling of ammonium in deep terrestrial systems, suggests that saline fracture waters in crystalline rocks such as described in the Canadian Shield and in the Witwatersrand Basin, South Africa may also provide habitable environments for life. The nitrogen isotope results of remaining ammonium from the partial dissociation experiments fit well with a batch equilibrium model, indicating equilibrium nitrogen isotope fractionations have been reached between ammonium and its dissociation product aqueous ammonia. Modeling yielded nitrogen isotope fractionations between ammonium and aqueous ammonia were 45.4‰ at 23 °C, 37.7‰ at 50 °C, and 33.5‰ at 70 °C, respectively. A relationship between nitrogen equilibrium isotope fractionation and temperature is determined for the experimental temperature range as: 103·lnα(aq)=25.94×{103}/{T}-42.25 Integrated with three previous theoretical estimates on nitrogen isotope equilibrium fractionations between ammonium and gaseous ammonia, we achieved three possible temperature-dependent nitrogen isotope equilibrium fractionation between aqueous ammonia and gaseous ammonia:

Initial report on drilling into seismogenic zones of M2.0 - M5.5 earthquakes from deep South African gold mines (DSeis)

NASA Astrophysics Data System (ADS)

Ogasawara, Hiroshi; Durrheim, Raymond; Yabe, Yasuo; Ito, Takatoshi; van Aswegen, Gerrie; Grobbelaar, Michelle; Funato, Akio; Ishida, Akimasa; Ogasawara, Hiroyuki; Mngadi, Siyanda; Manzi, Musa; Ziegler, Martin; Ward, Tony; Moyer, Pamela; Boettcher, Margaret; Ellsworth, Bill; Liebenberg, Bennie; Wechsler, Neta; Onstott, Tullis; Berset, Nicolas

2017-04-01

The International Continental Scientific Drilling Program (ICDP) approved our proposal (Ogasawara et al., EGU 2016) to drill into and around seismogenic zones where critically stressed faults initiated ruptures at depth. The drilling targets include four ruptures equivalent to M2.0, 2.8, 3.5, and 5.5 that dynamically and quasi-statically evolved in 2.9 Ga hard rock in the Witwatersrand basin, South Africa. Major advantages of our drilling locations are the large quantity and high-quality of existing data from dense seismic arrays both on surface and near-field underground in three deep South African gold mines. Additionally, the great depths (1.0 to 3.3 km from surface) to collar holes reduce drilling costs significantly and enable a larger number of holes to be drilled. Flexibility in drilling direction will also allow us to minimize damage in borehole or drilled cores. With the ICDP funds, we will conduct full-core drilling of 16 holes with drilling ranges from 50 to 750 m to recover both materials and fractures in and around the seismogenic zones, followed by core and borehole logging. Additional in-hole monitoring at close proximity will be supported by co-mingled funds and will follow the ICDP drilling. Expected magnitudes of maximum shear stress are several tens of MPa. We have established an overcoring procedure to measure 3D-stress state for adverse underground working conditions so as not to interfere with mining operations. This procedure was optimized based on the Compact Conic-ended Borehole Overcoring (CCBO) technique (ISRM suggested; Sugawara and Obara, 1999). Funato and Ito (2016 IJRMMS) developed a diametrical core deformation analysis (DCDA) method to measure differential stress using only drilled core by assuming diametrical change with roll angles caused by elastic in-axisymmetrical expansion during drilling. A gold mine has already drilled a hole to intersect the hypocenter of a 2016 M3.5 earthquake and carried out the CCBO stress measurement in other holes at the M3.5 seismogenic zone. As we successfully conducted DCDA with the above-mentioned drilled core, we look forward to shedding light on spatial variations of stress in the seismogenic zones following our ICDP DSeis drilling. A M5.5 earthquake which took place near Orkney, South Africa on 5 August 2014, offers a special opportunity to compare seismically inverted spatio-temporal evolution of both the main rupture and the aftershock activity with the information directly probed by the ICDP DSeis project. Moyer et al. (2016 Seismol. Res. Lett. submitted) calls for comparing seismic source models as part of a workshop proposed to the Southern California Earthquake Center for Fall 2017. In addition, the upper edge of the M5.5 rupture is located hundreds of meters below the mining horizon, sufficiently away from anthropogenic activity. This allows geomicrobiologists to investigate deep microbiological activity fueled by H2 from seismic rupture to address questions about Earth's early life. Drilling machines are being rigged underground soon to kick off our ICDP DSeis drilling in early 2017.

Highlights from Johannesburg, Gauteng Province, South Africa

NASA Technical Reports Server (NTRS)

2002-01-01

Although the extraction of mineral wealth has been the major influence in the history of Johannesburg and the surrounding Witwatersrand regions (with about 45% of all gold ever mined coming from there), the discovery of now-famous hominid fossils at the Sterkfontein Caves, and the convening of the world's largest-ever conference on environment and development, are setting a new stage for the future. The United Nations began the second Development and Environment Conference in Johannesburg on August 26, 2002. This meeting addresses the implementation of international goals to fight poverty and protect the global environment that were established at the first such conference held in Rio de Janeiro in 1992. The Johannesburg summit involves about forty thousand participants, and perhaps 100 world leaders. One of several official opening ceremonies for the conference was held at the Sterkfontein Caves to recognize the outstanding universal value of the paleo-anthropological fossils found there.

These views from the Multi-angle Imaging SpectroRadiometer (MISR) highlight a number of the land use, vegetation, and geological features found within Gauteng Province (including the urban center of Johannesburg and the capital city Pretoria) and parts of the North West and Free State Provinces. The image on the right displays vegetation in red hues and is a false-color view utilizing data from MISR's near-infrared, red and blue bands. Both the natural-color view (left) and the false-color version were acquired by MISR's nadir camera on June 16, 2002. The urban areas appear as gray-colored pixels in the natural-color view, and exhibit colors corresponding with the relative abundance of vegetation found in the urban parts of this arid region.

The mountains trending east-west near the center of the images extend from Pretoria in the east to Rustenberg in the west. These ranges, the Magaliesberg and Witwatersberg, separate the low-lying, hotter bushveld to the north from the cooler highveld to the south. The large round feature near the north-west corner indicates an ancient volcanic crater in the Pilanesberg National Park. Many bright, buff-colored rectangular patches around Johannesburg are associated with mining activities, and at least two of these areas (situated 40 kilometers southeast of the city) hold large amounts of water. The Sterkfontein Caves (now included within the recently created 'Cradle of Humankind' World Heritage Site) are located about 35 kilometers northwest of Johannesburg. In the southern portion of the images, a section of the Vredefort Hills are apparent to the west, and to the east the Vaal River and a large water body contained by the Vaal Dam delineate the border between the Gauteng and Free State provinces.

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and views almost the entire globe every 9 days. This image is a portion of the data acquired during Terra orbit 13266, and covers an area of about 190 kilometers x 221 kilometers. It utilizes data from blocks 111 to 112 within World Reference System-2 path 170.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

Tectonic evolution of the Oudalan-Gorouol greenstone belt in NE Burkina Faso and Niger, West African craton.

NASA Astrophysics Data System (ADS)

Tshibubudze, Asinne; Hein, Kim A. A.

2010-05-01

The Oudalan-Gorouol Greenstone Belt (OGGB) forms part of the Palaeoproterozoic as the Baoulé-Mossi domain of the West African Craton (WAC) and hosts gold deposits at Essakane, Gossey, Korizena, and Falagountou in NE Burkina Faso, and Kossa goldfield in Niger. The Birimian supracrustal sequences in the OGGB are dominated by meta-volcanoclastic greywacke intercalated meta-conglomerate, siltstone and shale, carbonate (dolomite) and volcanic units pillow basalts). The belt is surrounded by plutonic rocks including granite, TTG suite granitoids and granite gneiss. The sequences where subjected to two phases of deformation, and several phases of contact metamorphosed to hornblende-hornfels facies during emplacement of pyroxenite-gabbro-norite, granodiorite-tonalite and gabbro dykes and porphyritic sills. The OGGB is bounded and/or crosscut by several major NNE to NE-trending shear zones including the steeply east-dipping Markoye Shear Zone (western margin of the OGGB), Tin Takanet-Bellekcire Shear Zone, Dori Shear Zone, Kargouna Shear Zone, Takabougou Shear Zone, and Bom Kodjelé Shear Zone (transects the centre of the OGGB). The structures were readily identified using LANDSAT, Aster, aeromagnetic and RTP magnetic data, with follow-up strategic mapping, highlighting the value of interpreting geophysical and remotely sensed data in regional mapping in Burkina Faso and Niger. Structural studies completed in 2007 adjacent to the Essakane gold mine indicated that the NE-trending, first-order crustal-scale Markoye Shear Zone (MSZ) has undergone at least two phases of reactivation concomitant to two phases of regional deformation (Tshibubudze et al., 2009). The first phase of deformation, D1, resulted in the formation of NNW-NW trending folds and thrusts during dextral-reverse displacement on the MSZ. The deformation predates the Eburnean Orogeny is termed the Tangaean Event (meaning low hills in the Moré language of Burkina Faso) and is tentatively dated at ca. 2170-2130 Ma (Hein, 2009). D2 involved a period of SE-NW crustal shortening and sinistral-reverse displacement on the MSZ, and is correlated to the Eburnean Orogeny ~2.1 Ga of Feybesse et al. (2006). Deformation in D2 is characterised by NE-trending regional folds (F2) and a pervasive NE-trending foliation (S2-C to S2). Since 2007 an identical tectonic history has been established for a number of shear zones in the OGGB including the north-trending Kargouna Shear Zone, which is subtended by NW- and NE-trending shears. However the metamorphic grade and mineral assemblages vary from one shear zone to the next. Structural studies completed adjacent to the Dori batholith have indicated that the MSZ forms a shear complex that was active during pluton emplacement. However, the MSZ has two main branches that join at the location of a mylonite zone located north west of Essakane. Southwest of Essakane, a NW-trending mylonite zone crosscuts the Dori batholith and near the village of Kargouna, which is situated southeast of Essakane, the Kargouna shear crosscuts and deforms the Dori batholith. It is thus likely that the Dori batholith was emplacement prior to D1 in the OGGB. Gold mineralization in the OGGB is generally hosted in the hanging-wall of NE-trending faults and or NW-trending folds in metasiltstone-sandstone-shale sequences. Nkuna (2009) concluded that the deposits can be classified as orogenic gold deposits under the sub-class of "intrusion related" due to their proximity to plutonic masses, which concurs with geophysical studies for the OGGB. References: Feybesse, J.L., Billa, M., Guerrot, C., Duguey, E., Lescuyer, J.L., Milési, J.P., Bouchot, V., 2006. The Palaeoproterozoic Ghanaian province: Geodynamic model and ore controls, including regional stress modelling. Precambrian Research 149, 149-196. Hein, K.A.A., 2009 (In press). Structural chronologies in the Goren Greenstone belt (Burkina Faso); Implications for West African tectonics. Journal of African Earth Sciences. Tshibubudze, A., Hein, K.A.A., Marquis, P. 2009. The Markoye Shear Zone in NE Burkina Faso. Journal of African Earth Sciences 55, 245-256. Nkuna, B., 2009 Ore genesis of the Essakane, Falagountou and Sokadie Au deposits: Oudalan-Gorouol Greenstone Belt (OGGB), Burkina Faso, West African Craton (WAC). Unpublished Honours thesis, University of the Witwatersrand Johannesburg, 60p.

Geomechanical analysis applied to geological carbon dioxide sequestration, induced seismicity in deep mines, and detection of stress-induced velocity anisotropy in sub-salt environments

NASA Astrophysics Data System (ADS)

Lucier, Amie Marie

The role of geomechanical analysis in characterizing the feasibility of CO2 sequestration in deep saline aquifers is addressed in two investigations. The first investigation was completed as part of the Ohio River Valley CO2 Storage Project. We completed a geomechanical analysis of the Rose Run Sandstone, a potential injection zone, and its adjacent formations at the American Electric Power's 1.3 GW Mountaineer Power Plant in New Haven, West Virginia. The results of this analysis were then used to evaluate the feasibility of anthropogenic CO2 sequestration in the potential injection zone. First, we incorporated the results of the geomechanical analysis with a geostatistical aquifer model in CO2 injection flow simulations to test the effects of introducing a hydraulic fracture to increase injectivity. Then, we determined that horizontal injection wells at the Mountaineer site are feasible because the high rock strength ensures that such wells would be stable in the local stress state. Finally, we evaluated the potential for injection-induced seismicity. The second investigation concerning CO2 sequestration was motivated by the modeling and fluid flow simulation results from the first study. The geomechanics-based assessment workflow follows a bottom-up approach for evaluating regional deep saline aquifer CO2 injection and storage feasibility. The CO2 storage capacity of an aquifer is a function of its porous volume as well as its CO2 injectivity. For a saline aquifer to be considered feasible in this assessment it must be able to store a specified amount of CO2 at a reasonable cost per ton of CO 2. The proposed assessment workflow has seven steps. The workflow was applied to a case study of the Rose Run sandstone in the eastern Ohio River Valley. We found that it is feasible in this region to inject and store 113 Mt CO2/yr for 30 years at an associated well cost of less than 1.31 US$/t CO2, but only if injectivity enhancement techniques such as hydraulic fracturing and injection induced micro-seismicity are implemented. The second issue to which we apply geomechanical analysis in this thesis is mining-induced stress perturbations and induced seismicity in the TauTona gold mine, which is located in the Witwatersrand Basin of South Africa and is one of the deepest underground mines in the world. In the first investigation, we developed and tested a new technique for determining the virgin stress state near the TauTona gold mine. This technique follows an iterative forward modeling approach that combines observations of drilling induced borehole failures in borehole images, boundary element modeling of the mining-induced stress perturbations, and forward modeling of borehole failures based on the results of the boundary element modeling. The final result was a well constrained range of principal stress orientations and magnitudes that are consistent with all the observed failures and other stress indicators. In the second investigation, we used this constrained stress state to examine the likelihood of faulting to occur both on pre-existing fault planes that are optimally oriented to the virgin stress state and on faults affected by the mining-perturbed stress field, the latter of which is calculated with boundary element modeling. We made several recommendations that could potentially increase safety in deep South African mines as development continues. Finally, the third issue addressed in this thesis is the detection of stress-induced shear wave velocity anisotropy in a sub-salt environment. In this study, we tested a technique proposed by Boness and Zoback (2006) to identify structure-induced velocity anisotropy and isolate possible stress-induced velocity anisotropy. The investigation used cross-dipole sonic data from three deep water sub-salt wells in the Gulf of Mexico. First, we determined the parameters necessary to ensure the quality of the fast azimuth data used in our analysis. We then characterized the quality controlled measured fast directions as either structure-induced or stress-induced based on the results of the Boness and Zoback (2006) technique. We found that this technique supplements the use of dispersion curve analysis for characterizing anisotropy mechanisms. We also find that this technique has the potential to provide information on the stresses that can be used to validate numerical models of salt-related stress perturbations. (Abstract shortened by UMI.)

FOREWORD: International Conference on Planetary Boundary Layer and Climate Change

NASA Astrophysics Data System (ADS)

Djolov, G.; Esau, I.

2010-05-01

One of the greatest achievements of climate science has been the establisment of the concept of climate change on a multitude of time scales. The Earth's complex climate system does not allow a straightforward interpretation of dependences between the external parameter perturbation, internal stochastic system dynamics and the long-term system response. The latter is usually referred to as climate change in a narrow sense (IPCC, 2007). The focused international conference "Planetary Boundary Layers and Climate Change" has addressed only time scales and dynamical aspects of climate change with possible links to the turbulent processes in the Planetary Boundary Layer (PBL). Although limited, the conference topic is by no means singular. One should clearly understand that the PBL is the layer where 99% of biosphere and human activity are concentrated. The PBL is the layer where the energy fluxes, which are followed by changes in cryosphere and other known feedbacks, are maximized. At the same time, the PBL processes are of a naturally small scale. What is the averaged long-term effect of the small-scale processes on the long-term climate dynamics? Can this effect be recognized in existing long-term paleo-climate data records? Can it be modeled? What is the current status of our theoretical understanding of this effect? What is the sensitivity of the climate model projections to the representation of small-scale processes? Are there significant indirect effects, e.g. through transport of chemical components, of the PBL processes on climate? These and other linked questions have been addressed during the conference. The Earth's climate has changed many times during the planet's history, with events ranging from ice ages to long periods of warmth. Historically, natural factors such as the amount of energy released from the Sun, volcanic eruptions and changes in the Earth's orbit have affected the Earth's climate. Beginning late in the 18th century, human activities associated with the Industrial Revolution such as the addition of greenhouse gases and aerosols has changed the composition of the atmosphere. These changes are likely to have influenced temperature, precipitation, storms and sea level (IPCC, 2007). However, these features of the climate also vary naturally, so determining what fraction of climate changes are due to natural variability versus human activities is challenging and not yet a solved problem. Africa is vulnerable to climate change as its ability to adaptat and mitigate is considerably dampened (IPCC, 2007). Climate change may impede a nations ability to achieve sustainable development and the Millennium Development Goals, and because of that Africa (particularly sub-tropical Africa) will experience increased levels of water stress and reduced agricultural yields of up to 50% by 2020. An example of the scale of the region's vulnerability was demonstrated during the last very dry year (1991/92) when 30% of the southern African population was put on food aid and more than one million people were displaced. Climate change in Africa is essentially dependent on our understanding of the PBL processes both due to the indispensible role of the atmospheric convection in the African climate and due to its tele-connections to other regions, e.g. the tropical Pacific and Indian monsoon regions. Although numerous publications attribute the observed changes to one or another modification of the convective patterns, further progress is impeded by imperfections of the small-scale process parameterizations in the models. The uncertainties include parameter uncertainties of known physical processes, which could be reduced through better observations/modelling, as well as uncertainties in our knowledge of physical processes themselves (or structural uncertainties), which could be reduced only through theoretical development and design of new, original observations/experiments (Oppenheimer et al., Science, 2007). Arguably, the structural uncertainties is hard to reduce and this could be one of the reasons determining slow progress in narrowing the climate model uncertainty range over the last 30 years (Knutti and Hagerl, Nature Geoscience, 2008). One of the most prominent structural uncertainties in the ongoing transient climate change is related to poor understanding and hence incorrect modelling of the turbulent physics and dynamics processes in the planetary boundary layer. Nevertheless, the climate models continue to rely on physically incorrect boundary layer parameterizations (Cuxart et al., BLM, 2006), whose erroneous dynamical response in the climate models may lead to significant abnormalities in simulated climate. At present, international efforts in theoretical understanding of the turbulent mixing have resulted in significant progress in turbulence simulation, measurements and parameterizations. However, this understanding has not yet found its way to the climate research community. Vice versa, climate research is not usually addressed by the boundary layer research community. The gap needs to be closed in order to crucially complete the scientific basis of climate change studies. The focus of the proposed forum could be formulated as follows: The planetary boundary layer determines several key parameters controlling the Earth's climate system but being a dynamic sub-system, just a layer of turbulent mixing in the atmosphere/ocean, it is also controlled by the climate system and its changes. Such a dynamic relationship causes a planetary boundary layer feedback (PBL-feedback) which could be defined as the response of the surface air temperature on changes in the vertical turbulent mixing. The forum participants have discussed both climatological and fluid dynamic aspects of this response, in order to quantify their role in the Earth's transient heat uptake and its representation in climate models. The choice of the forum location and dates are motivated by the role of tropical oceans and convection in the climate system and the prominent demonstration of the climate sensitivity to the ocean heat uptake observed off Cape Town. The international conference responded to the urgent need of advancing our understanding of the complex climate system and development of adequate measures for saving the planet from environmental disaster. It also fits well with the Republic of South African government's major political decision to include the responses to global change/climate change at the very top of science and technology policy. The conference participants are grateful to the Norway Research Council and the National Research Foundation (NRF) RSA who supported the Conference through the project "Analysis and Possibility for Control of Atmospheric Boundary Layer Processes to Facilitate Adaptation to Environmental Changes" realized in the framework of the Programme for Research and Co-operation Phase II between the two countries. Kirstenbosh Biodiversity Institute and Botanical Gardens, Cape Town contribution of securing one of the most beautiful Conference venues in the world and technical support is also highly appreciated. G. Djolov and I. Esau Editors Conference_Photo Conference Organising Comittee Djolov, G.South AfricaUniversity of Pretoria Esau, I.NorwayNansen Environmental and Remote Sensing Center Hewitson, B.South AfricaUniversity of Cape Town McGregor, J.AustraliaCSIRO Marine and Atmospheric Research Midgley, G.South AfricaSouth African National Botanical Institute Mphepya, J.South AfricaSouth African Weather Service Piketh, S.South AfricaUniversity of the Witwatersrand Pielke, R.USAUniversity of Colorado, Boulder Pienaar, K.South AfricaUniversity of the North West Rautenbach, H.South AfricaUniversity of Pretoria Zilitinkevich, S.FinlandUniversity of Helsinki The conference was organized by: University of Pretoria Nansen Environmental and Remote Sensing Center With support and sponsorship from: Norwegian Research Council (grant N 197649) Kirstenbosh Biodiversity Institute and Botanical Gardens