493 research outputs found

    The COVID-19 pandemic: a catalyst for creativity and collaboration for online learning and work-based higher education systems and processes

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    PURPOSE: The purpose of this research is to focus on work-based problems catalysed by the COVID-19 global pandemic, based on a case study of a multi-continental, multi-campus university distributed across Kenya, Tanzania, Uganda and Pakistan. Higher education institutions (HEIs) in developing countries lacked pre-existing infrastructure to support online education and/or policy and regulatory frameworks during the pandemic. The university's programmes in Pakistan and East Africa provide lessons to other developing countries' HEIs. The university's focus on teaching and learning and staff development has had a transformational organisational effect. FINDINGS: Systems and processes developed across the university in the effort to ensure educational continuity. From the disruption to all educational programmes and the disarray of regulatory bodies' responses, collaboration emerged as a key driver of positive change. The findings reiterate the value of trust and provision of opportunities for those with the requisite competencies to lead in a participatory and distributive manner whilst addressing limited human and financial resources. The findings reflect on previous work respecting organisational change recast in the digital age. ORIGINALITY/VALUE: This paper reflects the authors' work in real-time as they led and managed changes encountered during the COVID-19 pandemic. The paper will be of value to management and leadership cadres, particularly in developing contexts, responsible for recovery and sustainability of the higher education sector

    An Imaging Fabry-Perot System for the Robert Stobie Spectrograph on the Southern African Large Telescope

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    We present the design of the Fabry-Perot system of the Robert Stobie Spectrograph on the 10-meter class Southern African Large Telescope and its characterization as measured in the laboratory. This system provides spectroscopic imaging at any desired wavelength spanning a bandpass 430 - 860 nm, at four different spectral resolving powers ranging from 300 to 9000. Our laboratory tests revealed a wavelength dependence of the etalon gap and parallelism with a maximum variation between 600 - 720 nm that arises because of the complex structure of the broadband multi-layer dielectric coatings. We also report an unanticipated optical effect of this multi-layer coating structure that produces a significant, and wavelength dependent, change in the apparent shape of the etalon plates. This change is caused by two effects: the physical non-uniformities or thickness variations in the coating layers, and the wavelength dependence of the phase change upon refection that can amplify these non-uniformities. We discuss the impact of these coating effects on the resolving power, finesse, and throughput of the system. This Fabry-Perot system will provide a powerful tool for imaging spectroscopy on one of the world's largest telescopes.Comment: 17 pages, 14 figures, accepted for publication in The Astronomical Journa

    Fabry-Perot Absorption Line Spectroscopy of the Galactic Bar. II. Stellar Metallicities

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    We measure the Ca II 8542 line strength in 3360 stars along three lines-of-sight in the Galactic bar: (l,b) ~ (+/-5.0,-3.5) and Baade's Window, using Fabry-Perot (FP) absorption line spectroscopy. This is the first attempt to show that reliable absorption line strengths can be measured using FP spectroscopy. The Ca II 8542 line is a good indicator of metallicity and its calibration to [Fe/H] is determined for globular cluster red giants in previous investigations. We derive such a calibration for the bulge giants and use it to infer metallicities for our full red clump sample (2488 stars) at all three lines-of-sight. We present the stellar metallicity distributions along the major axis of the bar. We find the mean [Fe/H] = -0.09 +/- 0.04 dex in Baade's Window, and find the distribution in this field to agree well with previous works. We find gradients in the mean metallicity and its dispersion w.r.t Baade's WIndow of -0.45 and -0.20 dex respectively at l = +5.5, and of -0.10 dex and -0.20 dex at l = -5.0. We detect a signature of a possible tidal stream at l = +5.5, in both our velocity and metallicity distributions. Its radial velocity indicates that it is not associated with the Sagittarius stream. We also measure the metallicity of a bulge globular cluster NGC 6522 in our Baade's Window field to be -0.90 +/- 0.10 dex, in agreement with recent measurements of Zoccali et al. (2008). This agreement demonstrates the reliability of our metallicity measurements.Comment: accepted for publication in the Astrophysical Journal, 15 pages, 12 figure

    Intershell-correlation-induced time delay in atomic photoionization

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    We predict an observable Wigner time delay in outer atomic shell photoionization near inner shell thresholds. The near-threshold increase of time delay is caused by intershell correlation and serves as a sensitive probe of this effect. The time delay increase is present even when the inner and outer shell thresholds are hundreds of electron volts apart. We illustrate this observation by several prototypical examples in noble gas atoms from Ne to Kr. In our study, we employ the random phase approximation with exchange and its relativistic generalization. We also support our findings by a simplified, yet quite insightful, treatment within the lowest-order perturbation theory.S.T.M. acknowledges the support of the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Department of Energy, under Grant No. DE-FG02-03ER15428

    BeetleAtlas: an ontogenetic and tissue-specific transcriptomic atlas of the red flour beetle Tribolium castaneum

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    The red flour beetle Tribolium castaneum has emerged as a powerful model in insect functional genomics. However, a major limitation in the field is the lack of a detailed spatio-temporal view of the genetic signatures underpinning the function of distinct tissues and life stages. Here, we present an ontogenetic and tissue-specific web-based resource for Tribolium transcriptomics: BeetleAtlas (https://www.beetleatlas.org). This web application provides access to a database populated with quantitative expression data for nine adult and seven larval tissues, as well as for four embryonic stages of Tribolium. BeetleAtlas allows one to search for individual Tribolium genes to obtain values of both total gene expression and enrichment in different tissues, together with data for individual isoforms. To facilitate cross-species studies, one can also use Drosophila melanogaster gene identifiers to search for related Tribolium genes. For retrieved genes there are options to identify and display the tissue expression of related Tribolium genes or homologous Drosophila genes. Five additional search modes are available to find genes conforming to any of the following criteria: exhibiting high expression in a particular tissue; showing significant differences in expression between larva and adult; having a peak of expression at a specific stage of embryonic development; belonging to a particular functional category; and displaying a pattern of tissue expression similar to that of a query gene. We illustrate how the different feaures of BeetleAtlas can be used to illuminate our understanding of the genetic mechanisms underpinning the biology of what is the largest animal group on earth

    Development and Validation of Novel PCR Assays for the Diagnosis of Bovine Stephanofilariasis and Detection of Stephanofilaria sp. Nematodes in Vector Flies

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    Background: Stephanofilaria spp. nematodes are associated with cutaneous lesions in cattle and other livestock and mammalian wildlife species. In Australia, Haematobia irritans exigua, commonly known as buffalo fly (BF) transmits a well-described but presently unnamed species of Stephanofilaria, which has been speculatively implicated in the aetiology of BF lesions. The sensitivity of current techniques for detecting Stephanofilaria spp. in skin lesions and vector species is low, and there is no genomic sequence for any member of the genus Stephanofilaria currently available in sequence databases. Methods: To develop molecular assays for the detection of the Australian Stephanofilaria sp., skin biopsies were collected from freshly slaughtered cattle with typical lesions near the medial canthus. Adult nematodes and microfilariae were isolated from the biopsies using a saline recovery technique. The nematodes were morphologically identified as Stephanofilaria sp. by scanning electron microscopy. DNA was extracted and the internal transcribed spacer 2 (ITS2) region of rDNA, and the cytochrome c oxidase subunit 1 (cox1) region of mtDNA was amplified and sequenced. Stephanofilaria sp. specific polymerase chain reaction (PCR) and qPCR assays (SYBR Green® and TaqMan™) were developed and optimised from the novel ITS2 sequence obtained. The specificity of each assay was confirmed by testing against nematode species Onchocerca gibsoni and Dirofilaria immitis, as well as host (bovine) and BF DNA. Results: Scanning electron microscopy of the anterior and posterior ends of isolated nematodes confirmed Stephanofilaria sp. A phylogenetic analysis of the cox1 sequence demonstrated that this species is most closely related to Thelazia callipaeda, a parasitic nematode that is a common cause of thelaziasis (or eyeworm infestation) in humans, dogs, and cats. Both conventional and qPCR assays specifically amplified DNA from Stephanofilaria sp. Conventional PCR, TaqMan™, and SYBR Green® assays were shown to detect 1 ng, 1 pg, and 100 fg of Stephanofilaria DNA, respectively. Both qPCR assays detected DNA from single Stephanofilaria microfilaria. Conclusion: Molecular diagnostic assays developed in this study showed high specificity and sensitivity for Stephanofilaria sp. DNA. The availability of an accurate and sensitive PCR assay for Stephanofilaria will assist in determining its role in the pathogenesis of cattle skin lesions, as well as in understanding its epidemiological dynamics. This assay may also have application for use in epidemiological studies with other species of Stephanofilaria, most particularly closely related S. stilesi, but this will require confirmation

    Ticagrelor inverse agonist activity at the P2Y12 receptor is non-reversible versus its endogenous agonist adenosine 5´-diphosphate

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    Background Ticagrelor is labelled as a reversible, direct-acting platelet P2Y12 receptor (P2Y12R) antagonist that is indicated clinically for the prevention of thrombotic events in patients with acute coronary syndrome (ACS). As with many antiplatelet drugs, ticagrelor therapy increases bleeding risk in patients which in emergency situations requires platelet transfusion although there is ongoing debate on its effectiveness following ticagrelor therapy. The aim of this study was to further examine the reversibility of ticagrelor at the P2Y12R. Methods Studies were performed in human platelets with both P2Y12R-stimulated GTPase activity and platelet aggregation assessed. Cell-based bioluminescence resonance energy transfer (BRET) assays were also undertaken to assess G protein subunit activation downstream of P2Y12R activation. Results Initial studies revealed a range of P2Y12R ligands including ticagrelor displayed inverse agonist activity at the P2Y12R. Of these only ticagrelor was resistant to wash-out. In both human platelets and cell-based assays, washing failed to reverse ticagrelor-dependent inhibition of ADP-stimulated P2Y12R function in contrast to other P2Y12R antagonists. The P2Y12R agonist 2MeSADP, which was also resistant to wash-out, was able to effectively compete with ticagrelor. In silico docking revealed that ticagrelor and 2MeSADP penetrated more deeply into the orthosteric binding pocket of the P2Y12R than other P2Y12R ligands. Conclusion Ticagrelor binding to the P2Y12R is prolonged and more akin to that of an irreversible antagonist especially versus the endogenous P2Y12R agonist ADP. This study highlights the potential clinical need for novel ticagrelor reversal strategies in patients with spontaneous major bleeding and bleeding associated with urgent invasive procedures

    Platelet function following induced hypoglycaemia in type 2 diabetes

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    Aim: Strict glycaemic control has been associated with an increased mortality rate in subjects with type 2 diabetes (T2DM). Here we examined platelet function immediately and 24 hours following induced hypoglycaemia in people with type 2 diabetes compared to healthy age-matched controls. Methods: Hyperinsulinaemic clamps reduced blood glucose to 2.8 mmol/L (50 mg/dl) for 1 hour. Sampling at baseline; euglycaemia 5 mmol/L (90 mg/dl); hypoglycaemia; and at 24 post clamp were undertaken. Platelet function was measured by whole blood flow cytometry. Results: 10 subjects with T2DM and 8 controls were recruited. Platelets from people with T2DM showed reduced sensitivity to prostacyclin (PGI2, 1 nM) following hypoglycaemia. The ability of PGI2 to inhibit platelet activation was significantly impaired at 24 hours compared to baseline in the T2DM group. Here, inhibition of fibrinogen binding was 29.5% (10.3–43.8) compared to 50.8% (36.8–61.1), (P < 0.05), while inhibition of P-selectin expression was 32% (16.1–47.6) vs. 54.4% (42.5–67.5) (P < 0.05). No significant changes in platelet function were noted in controls. Conclusion: Induced hypoglycaemia in T2DM enhances platelet hyperactivity through impaired sensitivity to prostacyclin at 24 hours
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