The role of fossils in interpreting the development of the Karoo Basin

Main articleThe Permo-Carboniferous to Jurassic aged rocks off the main Karoo Basin of South Africa are world renowned for the wealth of synapsid reptile and early dinosaur fossils, which have allowed a ten-fold biostratigraphic subdivision of the Karoo Supergroup to be erected. The role of fossils in interpreting the development of the Karoo Basin is not, however, restricted to biostratigraphic studies. Recent integrated sedimentological and palaeontological studies have helped in more precisely defining a number of problematical formational contacts within the Karoo Supergroup, as well as enhancing palaeoenvironmental reconstructions, and basin development models.Non

Biostratigraphy of the lower Burgersdorp Formation (Beaufort Group; Karoo Supergroup) of South Africa – implications for the stratigraphic ranges of early Triassic tetrapods

The Beaufort Group (Karoo Supergroup) of South Africa comprises a thick sequence of fluvio-lacustrine sedimentary rocks that accumulated in a landlocked, intracratonic foreland basin in southwestern Gondwana during the Middle Permian to Middle Triassic. To the south this basin was bounded by the Cape Fold Belt, which acted as the major source of both sediment and discharge. Rocks of the Beaufort Group are renowned for their rich fossil record and eight tetrapod-based biozones are currently recognized. The uppermost two biozones of the Beaufort Group, the Lystrosaurus and Cynognathus assemblage zones, record terrestrial biotic recovery following the Permo-Triassic mass extinction event. Stratigraphic overlap between these biozones occurs in the proximal sector, but their separation by an unconformity in the distal sector reflects the incomplete preservation of the sequence in this part of the basin. Our results afford chronostratographic control that impacts on current theories on the development of the Karoo Basin, and on the relative age of the sequence.South African Council for Geoscience, the University of the Witwatersrand and the National Research Foundation

A taxonomic note concerning a dicynodont (Synapsida: Anomodontia) from the Middle Triassic of East Africa

Main articleThe complicated histories of the Indian dicynodont Rechnisaurus and the East African dicynodont Kannemeyeria cristarhynchus has led to the incorrect use of the name ‘cristarhynchus’ for the latter taxon. This paper therefore proposes a new species name and diagnosis.The National Research Foundation and University Research Committee of the University of the Witwatersran

A diverse diapsid tooth assemblage from the Early Triassic (Driefontein locality, South Africa) records the recovery of diapsids following the end-Permian mass extinction

Mass extinctions change the trajectory of evolution and restructure ecosystems. The largest mass extinction, the end-Permian, is a particularly interesting case due to the hypothesized delay in the recovery of global ecosystems, where total trophic level recovery is not thought to have occurred until 5–9 million years after the extinction event. Diapsids, especially archosauromorphs, play an important role in this recovery, filling niches left vacant by therapsids and anapsids. However, the nature of lineage and ecological diversification of diapsids is obscured by the limited number of continuous, well-dated stratigraphic sections at the Permian-Triassic boundary and continuing through the first half of the Triassic. The Karoo Basin of South Africa is one such record, and particularly the late Early Triassic (Olenekian) Driefontein locality fills this gap in the diapsid fossil record. We collected a total of 102 teeth of which 81 are identified as diapsids and the remaining 21 as identified as temnospondyls. From the sample, seven distinct tooth morphotypes of diapsids are recognized, six of which are new to the locality. We used a combination of linear measurements, 3D geomorphometrics, and nMDS ordination to compare these morphotypes and made inferences about their possible diets. Although the morphotypes are readily differentiated in nMDS, the overall morphological disparity is low, and we infer five morphotypes are faunivorous with the other two potentially omnivorous or piscivorous based on their morphological similarities with dentitions from extant diapsids, demonstrating an unsampled taxonomic and ecological diversity of diapsids in the Early Triassic based on teeth. Although ecological specialization at Driefontein may be low, it records a diversity of diapsid taxa, specifically of archosauromorph lineages

An Acheulean handaxe from Gladysvale Cave site, Gauteng, South Africa.

WE DESCRIBE A SINGLE HANDAXE FROM fossiliferous breccias at Gladysvale Cave, South Africa. The artefact is the only known tool so far discovered during the controlled excavations conducted at this site over the last decade, and was recovered from decalcified sediments near the stratigraphic interface of two breccia units, making it difficult to assign it with confidence to either. The morphology of the handaxe indicates a middle-late Acheulean industry, and preliminary electron spin resonance and palaeomagnetic dating suggest an age of greater than 780 000 years.NCS2016http://hdl.handle.net/10520/EJC9652

Psychosocial interventions for improving quality of life outcomes in adults undergoing strabismus surgery (Protocol)

This is the protocol for a review and there is no abstract. The objectives are as follows: To investigate the effects of psychosocial interventions versus no intervention on quality of life and psychosocial outcomes in adults undergoing strabismus surgery. The primary objective is to assess whether patients who have taken part in a sychosocial intervention prior to their strabismus surgery report significantly improved quality of life compared to those who receive standard care,i.e. strabismus surgery alone. The secondary outcome measures will include anxiety, depression, social anxiety and social avoidance, as well as degree of success in terms of surgical outcome

What do patients with strabismus expect post surgery? The development and validation a questionnaire

Aims: To develop and validate a short questionnaire to assess patients’ expectations about outcomes post strabismus surgery. Methods: Questionnaire items were extracted from previous literature and reviewed by a multidisciplinary team. A cross-sectional study was then undertaken with 220 adult patients due to undergo strabismus surgery. Participants completed the 17-item questionnaire. Scale structure was explored using principal component analysis (PCA), and the subscales analysed in relation to demographic and clinical characteristics and psychosocial well-being in order to establish validity. Results: PCA revealed a 3-factor solution for the Expectations of Strabismus Surgery Questionnaire (ESSQ): (a) intimacy and appearance-related issues, (b) visual functioning, (c) social relationships. This 3-factor solution explained 59.30% of the overall variance in the ESSQ. Internal consistency, content and nomological and concurrent validity were considered acceptable. Conclusions: Patients with strabismus have high expectations about their postsurgical outcomes. This questionnaire provides a useful tool to assess the expectations patients have about their surgery, whether these expectations change over time and how they impact on postsurgical outcomes

Optimization of a high work function solution processed vanadium oxide hole-extracting layer for small molecule and polymer organic photovoltaic cells

We report a method of fabricating a high work function, solution processable vanadium oxide (V2Ox(sol)) hole-extracting layer. The atmospheric processing conditions of film preparation have a critical influence on the electronic structure and stoichiometry of the V2Ox(sol), with a direct impact on organic photovoltaic (OPV) cell performance. Combined Kelvin probe (KP) and ultraviolet photoemission spectroscopy (UPS) measurements reveal a high work function, n-type character for the thin films, analogous to previously reported thermally evaporated transition metal oxides. Additional states within the band gap of V2Ox(sol) are observed in the UPS spectra and are demonstrated using X-ray photoelectron spectroscopy (XPS) to be due to the substoichiometric nature of V2Ox(sol). The optimized V2Ox(sol) layer performance is compared directly to bare indium–tin oxide (ITO), poly(ethyleneoxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and thermally evaporated molybdenum oxide (MoOx) interfaces in both small molecule/fullerene and polymer/fullerene structures. OPV cells incorporating V2Ox(sol) are reported to achieve favorable initial cell performance and cell stability attributes

Arrhythmogenic late Ca2+sparks in failing heart cells and their control by action potential configuration

Sudden death in heart failure patients is a major clinical problem worldwide, but it is unclear how arrhythmogenic early afterdepolarizations (EADs) are triggered in failing heart cells. To examine EAD initiation, high-sensitivity intracellular Ca2+ measurements were combined with action potential voltage clamp techniques in a physiologically relevant heart failure model. In failing cells, the loss of Ca2+ release synchrony at the start of the action potential leads to an increase in number of microscopic intracellular Ca2+ release events (“late” Ca2+ sparks) during phase 2–3 of the action potential. These late Ca2+ sparks prolong the Ca2+ transient that activates contraction and can trigger propagating microscopic Ca2+ ripples, larger macroscopic Ca2+ waves, and EADs. Modification of the action potential to include steps to different potentials revealed the amount of current generated by these late Ca2+ sparks and their (subsequent) spatiotemporal summation into Ca2+ ripples/waves. Comparison of this current to the net current that causes action potential repolarization shows that late Ca2+ sparks provide a mechanism for EAD initiation. Computer simulations confirmed that this forms the basis of a strong oscillatory positive feedback system that can act in parallel with other purely voltage-dependent ionic mechanisms for EAD initiation. In failing heart cells, restoration of the action potential to a nonfailing phase 1 configuration improved the synchrony of excitation–contraction coupling, increased Ca2+ transient amplitude, and suppressed late Ca2+ sparks. Therapeutic control of late Ca2+ spark activity may provide an additional approach for treating heart failure and reduce the risk for sudden cardiac death