Different Populations of Gold Particles as Outlined by Their Silver Content: A Regional Investigation in the Precambrian Kimberley Reef Placer of the East Rand Goldfield/Witwatersrand/South Africa

1984 ◽  
pp. 247-259 ◽  
Author(s):  
W. Hirdes
Keyword(s):  
South Africa ◽  
Silver Content ◽  
Gold Particles ◽  
Different Populations

scholarly journals Metabolomic Analysis of The Chemical Diversity of South Africa Leaf Litter Fungal Species Using an Epigenetic Culture-Based Approach

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4262
Author(s):  
Rachel Serrano ◽  
Víctor González-Menéndez ◽  
Germán Martínez ◽  
Clara Toro ◽  
Jesús Martín ◽  
...  
Keyword(s):  
South Africa ◽  
Genome Mining ◽  
Fungal Species ◽  
Chemical Diversity ◽  
Fermentation Conditions ◽  
Metabolite Profiles ◽  
Different Populations ◽  
Fungal Genomes ◽  
Microbial Natural Products ◽  
Fermentation Media

Microbial natural products are an invaluable resource for the biotechnological industry. Genome mining studies have highlighted the huge biosynthetic potential of fungi, which is underexploited by standard fermentation conditions. Epigenetic effectors and/or cultivation-based approaches have successfully been applied to activate cryptic biosynthetic pathways in order to produce the chemical diversity suggested in available fungal genomes. The addition of Suberoylanilide Hydroxamic Acid to fermentation processes was evaluated to assess its effect on the metabolomic diversity of a taxonomically diverse fungal population. Here, metabolomic methodologies were implemented to identify changes in secondary metabolite profiles to determine the best fermentation conditions. The results confirmed previously described effects of the epigenetic modifier on the metabolism of a population of 232 wide diverse South Africa fungal strains cultured in different fermentation media where the induction of differential metabolites was observed. Furthermore, one solid-state fermentation (BRFT medium), two classic successful liquid fermentation media (LSFM and YES) and two new liquid media formulations (MCKX and SMK-II) were compared to identify the most productive conditions for the different populations of taxonomic subgroups.

Standing Out and Blending In: Contact-Based Research, Ethics, and Positionality

2021 ◽  
pp. 1-5
Author(s):  
Carolyn E. Holmes
Keyword(s):  
South Africa ◽  
Research Ethics ◽  
Political Science ◽  
Ethical Training ◽  
Research Outcomes ◽  
Different Populations ◽  
The Way

ABSTRACT This article explores the ethical difficulties that arise because of the interaction between fieldwork practitioners and their sites, in terms of the positionality of the researcher. What are the ethics of blending in or of standing out? This question stems from my experience of 12 months of fieldwork in South Africa in two distinct locales and among two different populations, one in which I could “pass” and another in which I was marked as various degrees of “outsider.” Drawing on this fieldwork, as well as an overview of the literature in political science on positionality, I argue that our discipline—because of the way it shapes interactions and research outcomes—must take positionality seriously in ethical training and practice.

Limited population differentiation in the bearded limpet Patella barbara (Gatropoda: Patellidae) along the coast of South Africa

1999 ◽  
Vol 79 (4) ◽  
pp. 639-651 ◽  
Author(s):  
Tyrone M. Ridgway ◽  
Barbara A. Stewart ◽  
George M. Branch
Keyword(s):  
South Africa ◽  
Gene Flow ◽  
Morphological Plasticity ◽  
Electrophoretic Analysis ◽  
Good Evidence ◽  
Shell Morphology ◽  
Discriminant Functions ◽  
The West ◽  
A Value ◽  
Different Populations

Patterns of genetic and morphological variation among eight populations of Patella barbara along the coast of South Africa were examined to see whether reported differences in shell morphology and behaviour between the west and east coasts were mirrored by other morphological and/or genetic differences. Morphological analyses of radular structure, gut-loop coiling and sperm microstructure revealed no differences between the populations. Discriminant functions analysis based on shell morphometrics showed major overlap between populations and failed to separate them. Electrophoretic analysis of 17 enzyme loci gave an overall genetic identity (Nei) value of 0.995, a value which lies within the generally accepted range for conspecific populations. In two of the populations, at Dwesa and Arniston, individuals were found to be ‘gardening’ algal resources. At Clovelly, a ‘normal’ form of P. barbara was found on the rocks, whereas a reduced and tall-shelled form occurred on the ascidian Pyura stolonifera, demonstrating phenotypic morphological plasticity. It was concluded that different populations of Patella barbara are both morphologically indistinguishable and genetically homogenous along the coast of South Africa, thus providing good evidence for widespread gene flow.

scholarly journals Iodine deficiency and thyroid nodular pathology - epidemiological and cancer characteristics in different populations: Portugal and South Africa

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
José Eduardo Carvalho Santos ◽  
William John Kalk ◽  
Miguel Freitas ◽  
Isabel Marques Carreira ◽  
Miguel Castelo Branco
Keyword(s):  
South Africa ◽  
Iodine Deficiency ◽  
Different Populations

The variation of silver content in native gold particles as revealed by ESCA

1982 ◽  
Vol 8 (5) ◽  
pp. 193-196 ◽  
Author(s):  
V. I. Nefedov ◽  
N. M. Zhavoronkov ◽  
G. V. Machavariani ◽  
Ya. V. Salyn ◽  
V. A. Makeev ◽  
...  
Keyword(s):  
Native Gold ◽  
Silver Content ◽  
Gold Particles

scholarly journals One tree, many colonies: colony structure, breeding system and colonization events of host trees in tunneling Melissotarsus ants

2020 ◽  
Author(s):  
Pierre-André Eyer ◽  
Edward L. Vargo ◽  
Christian Peeters
Keyword(s):  
South Africa ◽  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Breeding System ◽  
Scale Insects ◽  
Colony Structure ◽  
Slow Process ◽  
Host Trees ◽  
Different Populations ◽  
African Genus

AbstractAnts exhibit a striking variety of lifestyles, including highly specialist or mutualist species. The minute blind workers of the African genus Melissotarsus chew tunnels in live trees to accommodate their obligate partner scale insects. Their modified legs are adapted for tunneling, but are unsuited for walking outside, confining these ants to their initial host tree. Here, we investigated whether this unique lifestyle results in complex patterns of genetic diversity at different scales, from the same tree to different populations. Using 19 microsatellite markers, we assessed their mating strategy and colony structure among and across populations in South Africa. We showed that only one queen reproduces within a colony, mated with up to three males. Yet, several inseminated dealate queens are present in colonies; one probably replaces the older queen as colonies age. The reproduction of a single queen per colony at a given time results in genetic differentiation between colonies, even those located on the same tree. Overall, we discussed how the slow process of colony digging under the bark and the lack of worker patrolling above the bark might result in reduced competition between colonies and allow several secluded colonies to cohabit in a cramped space on a tree.

Measurement of organisational inertia: portability of a South African scale in an Australian context

2001 ◽  
Vol 27 (2) ◽  
Author(s):  
Gert Roodt ◽  
Carli Kinnear ◽  
Ronel Erwee ◽  
Don Smith ◽  
Bernadette Lynch ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Cross Cultural ◽  
Measuring Instruments ◽  
Single Factor ◽  
The South ◽  
Australian Context ◽  
Two Factors ◽  
High Internal Consistency ◽  
Different Populations

This research investigates whether the metric qualities of the South African Organisational Inertia Scale have cross-cultural equivalence in the Australian context. The underlying theoretical model and research in South Africa is discussed and problems associated with assuming cross-cultural equivalence of measuring instruments are noted. A sample of convenience of 340 participants, constituted from different populations, participated in this investigation. A single factor with a high internal consistency was extracted in contrast to the South African results of two factors with high internal consistencies. Opsomming Hierdie navorsing is daarop gerig om vas te stel of die metriese eienskappe van die Suid-Afrikaanse Organisational Inertia Scale kruiskulturele ekwivalensie in die Australiese konteks het. Die onderliggende teoretiese model en navorsing in Suid-Afrika word bespreek en probleme wat met die aanvaarding van kruis-kulturele ekwivalensie gepaard gaan, word aangedui.n Geleentheidsteekproefvan 340 deelnemers, saamgestel uit verskeie populasies, het aan die ondersoek deelgeneem.'n Enkele faktor met hoe interne konstantheid is onttrek in teenstelling met die Suid-Afrikaanse resultate waar twee faktore met hoe interne konstanthede verkry is.

scholarly journals Witwatersrand composite paleoplacers

2021 ◽  
Vol 63 (4) ◽  
pp. 8-22
Author(s):  
V. A. Stepanov
Keyword(s):  
South Africa ◽  
Heavy Fraction ◽  
Igneous Rocks ◽  
Ore Formation ◽  
Gold Particles ◽  
Useful Components ◽  
Gold Silver ◽  
The World ◽  
Factual Data ◽  
Alluvial Formation

Background. The Witwatersrand gold province located in South Africa is the richest in the world. The Witwatersrand deposits are composite, where osmirids and diamonds are mined along with gold, silver and uranium. The genesis of the Witwatersrand deposits is controversial. Most local geologists support the hypothesis of the presence of paleoplacer deposits with subsequent metamorphic transformation of ore-bearing conglomerates. In addition, there are aeolian, hydrothermal-sedimentary, hydrothermal-sedimentary-metamorphic and magmatic models of ore formation.Aim. To establish the genesis of the Witwatersrand deposits.Materials and methods. Analysis of published literature and factual data.Results. Osmirids and diamonds are mined along with gold, silver and uranium from the composite Witwatersrand deposits. Such a set of useful components is not known in any of the deposits of magmatic or hydrothermal genesis. Considering the confinement of useful components to conglomerates, the detrital nature of most of the gold grains and the presence of various accompanying minerals in the heavy fraction, characteristic of igneous rocks of felsic, basic and ultrabasic composition, the hypothesis of the primary alluvial nature of the deposits of the Witwatersrand province looks the most reasonable.Conclusions. The factual material indicates an alluvial origin of the Witwatersrand deposits with subsequent metamorphic transformation of ore-bearing reefs. The primary alluvial formation of ore-bearing conglomerates is indicated by the confinement of gold and uranium to channel facies with a tendency to accumulate in the basal horizons of the reefs, the presence of rounded gold particles bearing the traces of transportation in alluvial flows, as well as a set of minerals in the heavy fraction of concentrate, characteristic of placers.

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