Age and Correlation of the Moorefield Shale (Upper Mississippian) in its Type Area, Northeastern Arkansas

The name Moorefield was proposed by Adams and Ulrich (1904) for exposures of gray to brown, phosphatic shale with a basal limestone, overlying the Lower Mississippian Boone Formation, and underlying the Upper Mississippian Batesville Sandstone, in the vicinity of Moorefield, Independence County, northeastern Arkansas. Gordon (1944) 1) restricted the name Moorefield to the lower limestone-bearing interval, 2) applied a new name, Ruddell, to the succeeding shale section that comprises the bulk of the interval, with a type area near Moorefield, and 3) interpreted the interval contacts as unconformities. The name Ruddell was used for the revised Geological Map of Arkansas (1993), but later publications by the Arkansas Geological Survey and other sources refer the entire interval to the Moorefield Shale, and report a maximum thickness of 91.44 m. (300 feet). Age assignments for the Moorefield Shale are based almost entirely on ammonoid cephalopods (e.g. Gordon 1965, Saunders et al. 1977, Korn and Titus 2011). Brachiopods (e.g. Girty 1911) have provided a supporting role, but never to the precision of the ammonoids. Initially, Gordon (1965) recognized two ammonoid zones and four subzones through all the Moorefield, except the base. Korn and Titus (2011) reexamined Gordon’s published ammonoid assemblages, and made additional collections from the type Moorefield. They recognized only two Moorefield ammonoid zones: the lower Goniatites eganensis - Girtyoceras welleri zone, succeeded by the upper Goniatites multiliratus zone concentrated near the middle of the interval. The best age assignment for these abundant, middle Moorefield ammonoid assemblages is to the lower Chesterian Series (Korn and Titus 2011). The unfossiliferous lower Moorefield Shale spans the Meramecian-Chesterian boundary. The upper section, above the ammonoid occurrences, but also barren of ammonoids, and other biostratigraphically useful fossils, likely extends to at least the middle Chesterian. Thus, the bulk of the Moorefield formation represents the Chesterian, not the Meramecian Series. This age assignment is complicated further by the reduction of the lithostratigraphic units comprising the type Meramecian Series (Lane and Brenckle 2005), and a lack of ammonoid assemblages in its type area, St. Louis County, Missouri

<i>WhatsApp</i> use among African international distance education (IDE) students: transferring, translating and transforming educational experiences

Much of the research on how social media is embedded into the educational practices of higher education students has a Western orientation. In concentrating on a case study of the varied ways in which African International Distance Education (IDE) students actively use social media to shape their learning experiences, we discuss an under-researched group. The paper draws on analysis of 1295 online questionnaires and 165 in-depth interviews with IDE students at UNISA, South Africa, one of the largest providers of IDE globally. WhatsApp emerges as ‘the’ key social media tool that opens up opportunities for IDE students to transfer, translate and transform their educational journey when studying ‘at a distance’. Although WhatsApp does provide a ‘space of opportunity’ for some students, this is framed through socio-technical marginalisation, itself a reflection of demographic legacies of inequality. Exploring social media practices though the case of African IDE students places these students centre stage and adds to the awareness of the multiple centres from which international education is practiced

In vitro anti-malarial interaction and gametocytocidal activity of cryptolepine

YesBackground: Discovery of novel gametocytocidal molecules is a major pharmacological strategy in the elimination and eradication of malaria. The high patronage of the aqueous root extract of the popular West African anti-malarial plant Cryptolepis sanguinolenta (Periplocaceae) in traditional and hospital settings in Ghana has directed this study investigating the gametocytocidal activity of the plant and its major alkaloid, cryptolepine. This study also investigates the anti-malarial interaction of cryptolepine with standard anti-malarials, as the search for new anti-malarial combinations continues. Methods: The resazurin-based assay was employed in evaluating the gametocytocidal properties of C. sanguinolenta and cryptolepine against the late stage (IV/V) gametocytes of Plasmodium falciparum (NF54). A fixed ratio method based on the SYBR Green I fluorescence-based assay was used to build isobolograms from a combination of cryptolepine with four standard anti-malarial drugs in vitro using the chloroquine sensitive strain 3D7. Results: Cryptolepis sanguinolenta ( IC50 = 49.65 nM) and its major alkaloid, cryptolepine ( IC50 = 1965 nM), showed high inhibitory activity against the late stage gametocytes of P. falciparum (NF54). In the interaction assays in asexual stage, cryptolepine showed an additive effect with both lumefantrine and chloroquine with mean ΣFIC50s of 1.017 ± 0.06 and 1.465 ± 0.17, respectively. Cryptolepine combination with amodiaquine at therapeutically relevant concentration ratios showed a synergistic effect (mean ΣFIC50 = 0.287 ± 0.10) whereas an antagonistic activity (mean ΣFIC50 = 4.182 ± 0.99) was seen with mefloquine. Conclusions: The findings of this study shed light on the high gametocytocidal properties of C. sanguinolenta and cryptolepine attributing their potent anti-malarial activity mainly to their effect on both the sexual and asexual stages of the parasite. Amodiaquine is a potential drug partner for cryptolepine in the development of novel fixed dose combinations

Treatment of synthetic textile wastewater containing dye mixtures with microcosms

The aim was to assess the ability of microcosms (laboratory-scale shallow ponds) as a post polishing stage for the remediation of artificial textile wastewater comprising two commercial dyes (basic red 46 (BR46) and reactive blue 198 (RB198)) as a mixture. The objectives were to evaluate the impact of Lemna minor L. (common duckweed) on the water quality outflows; the elimination of dye mixtures, organic matter, and nutrients; and the impact of synthetic textile wastewater comprising dye mixtures on the L. minor plant growth. Three mixtures were prepared providing a total dye concentration of 10 mg/l. Findings showed that the planted simulated ponds possess a significant (p &lt; 0.05) potential for improving the outflow characteristics and eliminate dyes, ammonium-nitrogen (NH4-N), and nitrate-nitrogen (NO3-N) in all mixtures compared with the corresponding unplanted ponds. The removal of mixed dyes in planted ponds was mainly due to phyto-transformation and adsorption of BR46 with complete aromatic amine mineralisation. For ponds containing 2 mg/l of RB198 and 8 mg/l of BR46, removals were around 53%, which was significantly higher than those for other mixtures: 5 mg/l of RB198 and 5 mg/l of BR46 and 8 mg/l of RB198 and 2 mg/l of BR46 achieved only 41 and 26% removals, respectively. Dye mixtures stopped the growth of L. minor, and the presence of artificial wastewater reduced their development

Why Should We Preserve Fishless High Mountain Lakes?

High mountain lakes are originally fishless, although many have had introductions of non-native fish species, predominantly trout, and recently also minnows introduced by fishermen that use them as live bait. The extent of these introductions is general and substantial often involving many lakes over mountain ranges. Predation on native fauna by introduced fish involves profound ecological changes since fish occupy a higher trophic level that was previously inexistent. Fish predation produces a drastic reduction or elimination of autochthonous animal groups, such as amphibians and large macroinvertebrates in the littoral, and crustaceans in the plankton. These strong effects raise concerns for the conservation of high mountain lakes. In terms of individual species, those adapted to live in larger lakes have suffered a higher decrease in the size of their metapopulation. This ecological problem is discussed from a European perspective providing examples from two study areas: the Pyrenees and the Western Italian Alps. Species-specific studies are urgently needed to evaluate the conservation status of the more impacted species, together with conservation measures at continental and regional scales, through regulation, and at local scale, through restoration actions, aimed to stop further invasive species expansions and to restore the present situation. At different high mountain areas of the world, there have been restoration projects aiming to return lakes to their native fish-free status. In these areas autochthonous species that disappeared with the introduction of fish are progressively recovering their initial distribution when nearby fish-free lakes and ponds are available

The same course, different access: the digital divide between urban and rural distance education students in South Africa

Access to education is a significant determinant in future success, not only for a country but equally for individuals. Higher Education (HE) thus is an integral part of the Sustainable Development Goals and vital in supporting African development. Despite this, there is often a lack of access to HE in many parts of Africa, distance education can subsequently play an important role in increasing access to education by providing materials online. Even though institutions such as the University of South Africa, a provider of Open Distance Learning (ODL), can open access to HE for many marginalised and peripheral communities, we cannot separate access to ODL education from the debate of access to ICTs. Students in urban areas have a significantly different educational experience to students with poor ICT access in urban, peri-urban and rural areas. This paper explores the nature of access to ICT and how this affects students’ ability to access HE