@article{HoehnFrimmelDebailleetal.2021, author = {H{\"o}hn, Stefan and Frimmel, Hartwig E. and Debaille, Vinciane and Price, Westley}, title = {Pre-Klondikean oxidation prepared the ground for Broken Hill-type mineralization in South Africa}, series = {Terra Nova}, volume = {33}, journal = {Terra Nova}, number = {2}, doi = {10.1111/ter.12502}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218545}, pages = {168 -- 173}, year = {2021}, abstract = {New Cu isotope data obtained on chalcopyrite from the Black Mountain and the Broken Hill deposits in the medium- to high-grade metamorphic Aggeneys-Gamsberg ore district (South Africa) require a revision of our understanding of the genesis of metamorphic Broken Hill-type massive sulphide deposits. Chalcopyrite from both deposits revealed unusually wide ranges in δ\(^{65}\)Cu (-2.41 to 2.84 per mille NIST 976 standard) in combination with distinctly positive mean values (0.27 and 0.94 per mille, respectively). This is interpreted to reflect derivation from various silicate and oxide precursor minerals in which Cu occurred in higher oxidation states. Together with the observation of a typical supergene base metal distribution within the deposits and their spatial association with an unconformity only meters above the ore horizon, our new data are best explained by supergene oxidation of originally possibly SEDEX deposits prior to metamorphic sulphide formation, between the Okiepian (1,210-1,180 Ma) and Klondikean (1,040-1,020 Ma) orogenic events.}, language = {en} } @article{Ibebuchi2021, author = {Ibebuchi, Chibuike Chiedozie}, title = {Revisiting the 1992 severe drought episode in South Africa: the role of El Ni{\~n}o in the anomalies of atmospheric circulation types in Africa south of the equator}, series = {Theoretical and Applied Climatology}, volume = {146}, journal = {Theoretical and Applied Climatology}, number = {1-2}, issn = {1434-4483}, doi = {10.1007/s00704-021-03741-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-268569}, pages = {723-740}, year = {2021}, abstract = {During strong El Ni{\~n}o events, below-average rainfall is expected in large parts of southern Africa. The 1992 El Ni{\~n}o season was associated with one of the worst drought episodes in large parts of South Africa. Using reanalysis data set from NCEP-NCAR, this study examined circulation types (CTs) in Africa south of the equator that are statistically related to the El Ni{\~n}o signal in the southwest Indian Ocean and the implication of this relationship during the 1992 drought episode in South Africa. A statistically significant correlation was found between the above-average Nino 3.4 index and a CT that features widespread cyclonic activity in the tropical southwest Indian Ocean, coupled with a weaker state of the south Indian Ocean high-pressure. During the analysis period, it was found that the El Ni{\~n}o signal enhanced the amplitude of the aforementioned CT. The impacts of the El Ni{\~n}o signal on CTs in southern Africa, which could have contributed to the 1992 severe drought episode in South Africa, were reflected in (i) robust decrease in the frequency of occurrence of the austral summer climatology pattern of atmospheric circulation that favors southeasterly moisture fluxes, advected by the South Indian Ocean high-pressure; (ii) modulation of easterly moisture fluxes, advected by the South Atlantic Ocean high-pressure, ridging south of South Africa; (iii) and enhancement of the amplitude of CTs that both enhances subsidence over South Africa, and associated with the dominance of westerlies across the Agulhas current. Under the ssp585 scenario, the analyzed climate models suggested that the impact of radiative heating on the CT significantly related to El Ni{\~n}o might result in an anomalous increase in surface pressure at the eastern parts of South Africa.}, language = {en} } @article{Ibebuchi2021, author = {Ibebuchi, Chibuike Chiedozie}, title = {Circulation pattern controls of wet days and dry days in Free State, South Africa}, series = {Meteorology and Atmospheric Physics}, volume = {133}, journal = {Meteorology and Atmospheric Physics}, number = {5}, issn = {1436-5065}, doi = {10.1007/s00703-021-00822-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-268552}, pages = {1469-1480}, year = {2021}, abstract = {Atmospheric circulation is a vital process in the transport of heat, moisture, and pollutants around the globe. The variability of rainfall depends to some extent on the atmospheric circulation. This paper investigates synoptic situations in southern Africa that can be associated with wet days and dry days in Free State, South Africa, in addition to the underlying dynamics. Principal component analysis was applied to the T-mode matrix (variable is time series and observation is grid points at which the field was observed) of daily mean sea level pressure field from 1979 to 2018 in classifying the circulation patterns in southern Africa. 18 circulation types (CTs) were classified in the study region. From the linkage of the CTs to the observed rainfall data, from 11 stations in Free State, it was found that dominant austral winter and late austral autumn CTs have a higher probability of being associated with dry days in Free State. Dominant austral summer and late austral spring CTs were found to have a higher probability of being associated with wet days in Free State. Cyclonic/anti-cyclonic activity over the southwest Indian Ocean, explained to a good extent, the inter-seasonal variability of rainfall in Free State. The synoptic state associated with a stronger anti-cyclonic circulation at the western branch of the South Indian Ocean high-pressure, during austral summer, leading to enhanced low-level moisture transport by southeast winds was found to have the highest probability of being associated with above-average rainfall in most regions in Free State. On the other hand, the synoptic state associated with enhanced transport of cold dry air, by the extratropical westerlies, was found to have the highest probability of being associated with (winter) dryness in Free State.}, language = {en} } @article{DecloedtFreemanHowellsetal.2016, author = {Decloedt, Eric H. and Freeman, Carla and Howells, Fleur and Casson-Crook, Martine and Lesosky, Maia and Koutsilieri, Eleni and Lovestone, Simon and Maartens, Gary and Joska, John A.}, title = {Moderate to severe HIV-associated neurocognitive impairment : A randomized placebo-controlled trial of lithium}, series = {Medicine}, volume = {95}, journal = {Medicine}, number = {46}, doi = {10.1097/MD.0000000000005401}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165838}, pages = {e5401}, year = {2016}, abstract = {Background: HIV-associated neurocognitive disorder (HAND) remains highly prevalent despite effective anti-retroviral therapy (ART). A number of adjunctive pharmacotherapies for HAND have been studied with disappointing results, but preliminary data suggest that lithium may provide clinical benefit. In addition, the low cost of lithium would facilitate access in low- and middle-income countries which carry the greatest burden of HIV. Methods: Our objective was to evaluate the 24-week efficacy and safety of lithium in patients with moderate to severe HAND. Our primary efficacy endpoint was the change in Global Deficit Score (GDS) from baseline to 24 weeks, whereas our secondary endpoint was the change in proton magnetic resonance spectroscopy (1H-MRS) brain metabolite concentrations. We conducted a 24-week randomized placebo-controlled trial of lithium as adjunctive pharmacotherapy. We enrolled participants with moderate to severe HAND, on ART for at least 6 months, with suppressed viral loads and attending public sector primary care clinics in Cape Town, South Africa. We randomized 66 participants to lithium (n = 32) or placebo (n = 34). Lithium or placebo was dosed 12-hourly and titrated to achieve the maintenance target plasma concentration of 0.6 to 1.0 mmol/L. Sham lithium concentrations were generated for participants receiving placebo. Results: Totally 61 participants completed the study (lithium arm = 30; placebo arm = 31). Participants at enrolment had a mean age of 40 years and a median CD4+ T-cell count of 500 cells/μL. The median change in GDS between baseline and week 24 for the lithium and placebo arms were -0.57 (95\% confidence interval [CI] -0.77, -0.32) and -0.56 (-0.69, -0.34) respectively, with a mean difference of -0.054 (95\% CI -0.26, 0.15); P = 0.716. The improvement remained similar when analyzed according to age, severity of impairment, CD4+ count, time on ART, and ART regimen. Standard 1H-MRS metabolite concentrations were similar between the treatment arms. The study drug was well tolerated in both study arms. Six serious adverse events occurred, but none were considered related to the study drug. Conclusion: Adjunctive lithium pharmacotherapy in patients on ART with HAND was well tolerated but had no additional benefit on neurocognitive impairment.}, language = {en} } @article{TabatabaiPrifertPfeiletal.2014, author = {Tabatabai, Julia and Prifert, Christiane and Pfeil, Johannes and Grulich-Henn, Juergen and Schnitzler, Paul}, title = {Novel Respiratory Syncytial Virus (RSV) Genotype ON1 Predominates in Germany during Winter Season 2012-13}, series = {PLOS ONE}, volume = {9}, journal = {PLOS ONE}, number = {10}, doi = {10.1371/journal.pone.0109191}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115229}, pages = {e109191}, year = {2014}, abstract = {Respiratory syncytial virus (RSV) is the leading cause of hospitalization especially in young children with respiratory tract infections (RTI). Patterns of circulating RSV genotypes can provide a better understanding of the molecular epidemiology of RSV infection. We retrospectively analyzed the genetic diversity of RSV infection in hospitalized children with acute RTI admitted to University Hospital Heidelberg/Germany between October 2012 and April 2013. Nasopharyngeal aspirates (NPA) were routinely obtained in 240 children younger than 2 years of age who presented with clinical symptoms of upper or lower RTI. We analyzed NPAs via PCR and sequence analysis of the second variable region of the RSV G gene coding for the attachment glycoprotein. We obtained medical records reviewing routine clinical data. RSV was detected in 134/240 children. In RSV-positive patients the most common diagnosis was bronchitis/bronchiolitis (75.4\%). The mean duration of hospitalization was longer in RSV-positive compared to RSV-negative patients (3.5 vs. 5.1 days; p < 0.01). RSV-A was detected in 82.1\%, RSV-B in 17.9\% of all samples. Phylogenetic analysis of 112 isolates revealed that the majority of RSV-A strains (65\%) belonged to the novel ON1 genotype containing a 72-nucleotide duplication. However, genotype ON1 was not associated with a more severe course of illness when taking basic clinical/laboratory parameters into account. Molecular characterization of RSV confirms the co-circulation of multiple genotypes of subtype RSV-A and RSV-B. The duplication in the G gene of genotype ON1 might have an effect on the rapid spread of this emerging RSV strain.}, language = {en} } @phdthesis{Schmidt2012, author = {Schmidt, Lisa Luise}, title = {Untersuchungen zum Einfluss der antiretroviralen Kombinationstherapie (HAART) auf das sexuelle Risikoverhalten von HIV-positiven Patienten in der Provinz Western Cape, S{\"u}dafrika}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-74799}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {Untersuchungen zum Einfluss der antiretroviralen Kombinationstherapie (HAART)auf das sexuelle Risikoverhalten von HIV-positiven Patienten in der Provinz Western Cape, S{\"u}dafrika}, subject = {HIV}, language = {de} } @article{NaidooDuPreezStuartHilletal.2012, author = {Naidoo, Robin and Du Preez, Pierre and Stuart-Hill, Greg and Jago, Mark and Wegmann, Martin}, title = {Home on the Range: Factors Explaining Partial Migration of African Buffalo in a Tropical Environment}, series = {PLoS One}, volume = {7}, journal = {PLoS One}, number = {5}, doi = {10.1371/journal.pone.0036527}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134935}, pages = {e36527}, year = {2012}, abstract = {Partial migration (when only some individuals in a population undertake seasonal migrations) is common in many species and geographical contexts. Despite the development of modern statistical methods for analyzing partial migration, there have been no studies on what influences partial migration in tropical environments. We present research on factors affecting partial migration in African buffalo (Syncerus caffer) in northeastern Namibia. Our dataset is derived from 32 satellite tracking collars, spans 4 years and contains over 35,000 locations. We used remotely sensed data to quantify various factors that buffalo experience in the dry season when making decisions on whether and how far to migrate, including potential man-made and natural barriers, as well as spatial and temporal heterogeneity in environmental conditions. Using an information-theoretic, non-linear regression approach, our analyses showed that buffalo in this area can be divided into 4 migratory classes: migrants, non-migrants, dispersers, and a new class that we call "expanders". Multimodel inference from least-squares regressions of wet season movements showed that environmental conditions (rainfall, fires, woodland cover, vegetation biomass), distance to the nearest barrier (river, fence, cultivated area) and social factors (age, size of herd at capture) were all important in explaining variation in migratory behaviour. The relative contributions of these variables to partial migration have not previously been assessed for ungulates in the tropics. Understanding the factors driving migratory decisions of wildlife will lead to better-informed conservation and land-use decisions in this area.}, language = {en} } @phdthesis{Jacobs2011, author = {Jacobs, Graeme Brendon}, title = {HIV-1 resistance analyses from therapy-na{\"i}ve patients in South Africa, Tanzania and the characterization of a new HIV-1 subtype C proviral molecular clone}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67319}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {The acquired immunodeficiency syndrome (AIDS) is currently the most infectious disease worldwide. It is caused by the human immunodeficiency virus (HIV). At the moment there are ~33.3 million people infected with HIV. Sub-Saharan Africa, with ~22.5 million people infected accounts for 68\% of the global burden. In most African countries antiretroviral therapy (ART) is administered in limited-resource settings with standardised first- and second-line ART regimens. During this study I analysed the therapy-na{\"i}ve population of Cape Town, South Africa and Mwanza, Tanzania for any resistance associated mutations (RAMs) against protease inhibitors, nucleoside reverse transcriptase inhibitors and non-nucleoside reverse transcriptase inhibitors. My results indicate that HIV-1 subtype C accounts for ~95\% of all circulating strains in Cape Town, South Africa. I could show that ~3.6\% of the patient derived viruses had RAMs, despite patients being therapy-na{\"i}ve. In Mwanza, Tanzania the HIV drug resistance (HIVDR) prevalence in the therapy-na{\"i}ve population was 14.8\% and significantly higher in the older population, >25 years. Therefore, the current WHO transmitted HIVDR (tHIVDR) survey that is solely focused on the transmission of HIVDR and that excludes patients over 25 years of age may result in substantial underestimation of the prevalence of HIVDR in the therapy-na{\"i}ve population. Based on the prevalence rates of tHIVDR in the study populations it is recommended that all HIV-1 positive individuals undergo a genotyping resistance test before starting ART. I also characterized vif sequences from HIV-1 infected patients from Cape Town, South Africa as the Vif protein has been shown to counteract the antiretroviral activity of the cellular APOBEC3G/F cytidine deaminases. There is no selective pressure on the HIV-1 Vif protein from current ART regimens and vif sequences was used as an evolutionary control. As the majority of phenotypic resistance assays are still based on HIV-1 subtype B, I wanted to design an infectious HIV-1 subtype C proviral molecular clone that can be used for in vitro assays based on circulating strains in South Africa. Therefore, I characterized an early primary HIV-1 subtype C isolate from Cape Town, South Africa and created a new infectious subtype C proviral molecular clone (pZAC). The new pZAC virus has a significantly higher transient viral titer after transfection and replication rate than the previously published HIV-1 subtype C virus from Botswana. The optimized proviral molecular clone, pZAC could be used in future cell culture and phenotypic HIV resistance assays regarding HIV-1 subtype C.}, subject = {HIV}, language = {en} } @phdthesis{Loewe2003, author = {L{\"o}we, Peter}, title = {Methoden der K{\"u}nstlichen Intelligenz in Radarmeteorologie und Bodenerosionsforschung}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-7594}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2003}, abstract = {Die Dissertation "Methoden der K{\"u}nstlichen Intelligenz in Radarmeteorologie und Bodenerosionsforschung" besch{\"a}ftigt sich mit der Erfassung des Parameters der potentiellen Erosivit{\"a}t vor dem Hintergrund der Bodenerosionsproblematik S{\"u}dafrikas. Basierend auf der Betrachtung der Erosivit{\"a}t einzelner Niederschlagsereignisse wird demonstriert, wie durch wissensbasierte Ans{\"a}tze aus Wetterradardatens{\"a}tzen fl{\"a}chendeckende Niederschlagsinformationen gewonnen werden k{\"o}nnen. Diese dienen als Eingangsdaten f{\"u}r ein Erosivit{\"a}tsmodell, das aus Zellul{\"a}ren Automaten aufgebaut wird. Die Ergebnisse des Erosivit{\"a}tsmodells werden vorgestellt und diskutiert.}, subject = {S{\"u}dafrika}, language = {de} } @phdthesis{Bangert2000, author = {Bangert, Berthold}, title = {Tephrostratigraphy, petrography, geochemistry, age and fossil record of the Ganigobis Shale Member and associated glaciomarine deposits of the Dwyka Group, Late Carboniferous, southern Africa}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-2233}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2000}, abstract = {Thin, pyroclastic marker beds are preserved in argillaceous units of the Dwyka Group in southern Nambia and South Africa which are the earliest witnesses of volcanism in Karoo-equivalent strata of southern Africa. The aim of this study is to present the field appearance of these marker beds, to characterise their mineralogy, geochemistry and heavy mineral contents and to present new radiometric age data from their juvenile zircons. Carboniferous-Permian Karoo deposits in the Aranos Basin of southern Namibia include the glacially dominated, Carboniferous Dwyka Group and the shelf sediments of the overlying Permian Ecca Group. The Dwyka Group can be subdivided into four upward-fining deglaciation sequences, each capped by relatively fine-grained glaciolacustrine or glaciomarine deposits. The uppermost part of the second deglaciation sequence comprises a thick fossiliferous mudstone unit, referred to as the "Ganigobis Shale Member". An abundance of marine macro- and ichnofossils as well as extrabasinally derived ashfall tuff beds characterise the more than 40 m thick mudstones and provide the basis for an integrated high-resolution biostratigraphic and tephrostratigraphic framework. The Ganigobis Shale Member contains remains of paleoniscoid fishes, bivalves, gastropods, scyphozoa, crinoid stalks, sponges and sponge spicules, radiolaria, coprolites and permineralised wood. These mostly marine body and trace fossils record the extent of the first of a series of marine incursions into the disintegrating Gondwanan interior as early as the Carboniferous. Within the Ganigobis Shale Member 21 bentonitic tuff beds displaying a thickness of 0.1 and 2.0 cm were determined which in part can be traced laterally over tens of kilometres indicating an ashfall derivation. Further bentonitic tuff beds of the Dwyka Group were detected in cut banks of the Orange River near Zwartbas in the Karasburg Basin (southern Namibia). The 65 tuff beds vary between 0.1 and 4.0 cm in thickness. Due to a similar fossil content and age of the background deposits, the tuff beds are thought to have originated from the same source area as those from the Aranos Basin. Thin-sections reveal the derivation of the tuff beds as distal fallout ashes produced by explosive volcanic eruptions. The matrix consists of a micro- to cryptocrystalline clay mineral-quartz mixture. Rare fragments of splinter quartz, completely recrystallized ash-sized particles of former volcanic glass and few apatite and zircon grains are the only juvenile components. The tuff beds contain as non-opaque, juvenile heavy minerals mostly zircon, apatite, monazite and sphene but also biotite, garnet, hornblende and tourmaline. Geochemical analyses point to an original, intermediate to acid composition of the tuff samples. LREE enrichment and Eu-anomalies show that the parent magma of the tuff beds was a highly evolved calc-alkaline magma. Tectonomagmatic discrimination diagrams point to a volcanic arc setting. Bedding characteristics and the lack of any Carboniferous-Permian volcanic successions onshore Namibia makes an aeolian transport of the ash particles over larger distances likely. Siliceous ashes could thus have been transported by prevailing south-westerly winds from arc-related vents in South America to southern Africa. A second, more local source area could have been located in an intracontinental rift zone along the western margin of southern Africa which is indicated by north-south directed ice-flow directions in the Late Carboniferous. SHRIMP-based age determinations of juvenile magmatic zircons separated from the tuff beds allow a new time calibration of Dwyka Group deglaciation sequences II - IV and the Dwyka/Ecca boundary. Zircons of the Ganigobis Shale Member yield SHRIMP-ages of 302-300 Ma. This dates the uppermost part of the second deglaciation sequence in southern Namibia to the Late Carboniferous (Gzelian) and provides a minimum age for the onset of Karoo-equivalent marine deposition. The age of the uppermost argillaceous part of the third deglaciation sequence (297 Ma) was determined from zircons of a tuffaceous bed sampled in a roadcut in the Western Cape Province, South Africa. The deposits correlate with the Hardap Shale Member in the Aranos Basin of southern Namibia which are part of much more widespread Eurydesma transgression. The age of the Dwyka/Ecca boundary was determined by SHRIMP-measurements of juvenile zircons from two tuff beds of the basal Prince Albert Formation sampled in the Western Cape Province (South Africa). The zircons revealed ages of 289 - 288 Ma which date the Dwyka/Ecca boundary at about 290 Ma. According to these ages, deglaciation sequences II-IV lasted for 5 Ma on average.}, subject = {S{\"u}dafrika}, language = {en} }