41 research outputs found
Information from 2006, 2010 and 2011 for the Karnmelkspruit Cape Vulture Gyps coprotheres colony, Lady Grey district, Eastern Cape Province, South Africa
No full textThe Cape Vulture (Gyps coprotheres), a southern African endemic, is listed asa threatened species (‘Vulnerable’) in southern Africa (Barnes 2000) and globally (IUCN 2012). Information relating to the structure, size, breeding status and conservation of a Cape Vulture colony (at 30° 50´S; 27° 14´E) in the Karnmelkspruit Gorge in the Lady Grey district in the north-eastern region of South Africa’s Eastern Cape Province, is available in the literature (Boshoff & Vernon 1979, 1980; Vernon et al. 1983; Vernon 1984, Boshoff & Vernon 1987; Boshoff 1990). This note provides additional information, obtained during three visits to the colony by the author
Internationally linked authors in Uganda, East Africa : an example of author-level bibliometrics for a developing country
No full textCITATION: Boshoff, N., Basaza-Ejiri, H. A. D. & Tise, E. R. 2018. Internationally linked authors in Uganda, East Africa : an example of author-level bibliometrics for a developing country. In STI 2018 Conference Proceedings, 23rd International Conference on Science and Technology Indicators, 12-14 September 2018, Leiden, Netherlands.The original publication is available at http://sti2018.cwts.nl/proceedingsIn developing countries, researchers with strong international links potentially act as a double-edge sword. On the one hand, local researchers with international links could strengthen the research base of an institution or country while, on the other hand, they could leave the research base vulnerable should they migrate. The study identified internationally linked authors in Uganda, East Africa, by applying individual-level bibliometrics to a dataset of 3,948 Ugandan authors from the Web of Science, for the period 2011–2015. The focus was on four overlapping groups of internationally linked authors: (1) Ugandan authors with an international co-author, (2) Uganda authors with a joint international affiliation, (3) Ugandan authors affiliated with an international organisation that has a local address, and (4) Ugandan authors affiliated with an international research partnership. The study showed that without the identified forms of international linkages, the Ugandan scholarly workforce would reduce to 14% of its current size. Moreover, 74% of Ugandan authors without any international links had co-authored articles with Ugandan authors who are linked internationally. Although the extent of both international and national mobility associated with internationally linked authors seem low, benchmarking against comparative figures for other countries in sub-Saharan Africa is required.http://sti2018.cwts.nl/proceedingsPublisher's versio
X-Ray Micro Tomography of Water Absorption by Superabsorbent Polymers in Mortar
No full textSuperabsorbent Polymers (SAP) have been recently subject of investigation as smart admixtures for cement-based materials. The properties of these polymers enable their use for internal curing, increasing freeze/thaw resistance, boosting autogenous self-healing and providing a crack self-sealing effect in cementitious composites. Except for the earliest application, the functioning of these beneficial effects invloves the absorption by the polymers of ingress water in the hardened cementitious matrix and later release, as well as their capacity to complete multiple absorption/desorption cycles. In this work, the absorption of water in mortar with superabsorbent polymers is monitored during the first 60 min of absorption through micro-CT. The experimental series included the presence of cracks. The registration and differentiation of sub-minute (18 s) scans enabled the individuation of bulk water content distribution in the mortar with a resolution of 55 μm. The swollen volume of SAP could also be quantified and studied in time. The results point out that although embedded SAP absorb water from the matrix, this absorption is slow and reduced with respect to water absorption during mixing for the used SAP. Same effect is observed for SAP in the cracks.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Materials and Environmen
Selective anticancer activity of a hexapeptide with sequence homology to a non-kinase domain of Cyclin Dependent Kinase 4
No full textBackground: cyclin-dependent kinases 2, 4 and 6 (Cdk2, Cdk4, Cdk6) are closely structurally homologous proteins which are classically understood to control the transition from the G1 to the S-phases of the cell cycle by combining with their appropriate cyclin D or cyclin E partners to form kinase-active holoenzymes. Deregulation of Cdk4 is widespread in human cancer, CDK4 gene knockout is highly protective against chemical and oncogene-mediated epithelial carcinogenesis, despite the continued presence of CDK2 and CDK6; and overexpresssion of Cdk4 promotes skin carcinogenesis. Surprisingly, however, Cdk4 kinase inhibitors have not yet fulfilled their expectation as 'blockbuster' anticancer agents. Resistance to inhibition of Cdk4 kinase in some cases could potentially be due to a non-kinase activity, as recently reported with epidermal growth factor receptor. Results: a search for a potential functional site of non-kinase activity present in Cdk4 but not Cdk2 or Cdk6 revealed a previously-unidentified loop on the outside of the C'-terminal non-kinase domain of Cdk4, containing a central amino-acid sequence, Pro-Arg-Gly-Pro-Arg-Pro (PRGPRP). An isolated hexapeptide with this sequence and its cyclic amphiphilic congeners are selectively lethal at high doses to a wide range of human cancer cell lines whilst sparing normal diploid keratinocytes and fibroblasts. Treated cancer cells do not exhibit the wide variability of dose response typically seen with other anticancer agents. Cancer cell killing by PRGPRP, in a cyclic amphiphilic cassette, requires cells to be in cycle but does not perturb cell cycle distribution and is accompanied by altered relative Cdk4/Cdk1 expression and selective decrease in ATP levels. Morphological features of apoptosis are absent and cancer cell death does not appear to involve autophagy. Conclusion: these findings suggest a potential new paradigm for the development of broad-spectrum cancer specific therapeutics with a companion diagnostic biomarker and a putative functional site for kinase-unrelated activities of Cdk4
Stenting the neonatal arterial duct in duct-dependent pulmonary circulation: new techniques, better results
No full textAbstractObjectivesThe goal of this study was to assess a new approach to stent the arterial duct in neonates with a duct-dependent pulmonary circulation.BackgroundPrevious attempts to stent the neonatal arterial duct were unsatisfactory. Learning from these failures, we speculated that covering the complete length of the duct with current low-profile stents might avoid previous problems.MethodsTen neonates with duct-dependent pulmonary circulations through a short straight duct were treated with stent implantation. The duct was crossed with an atraumatic 0.014-inch wire. A low-profile premounted coronary stent (outer diameter <4F, length 13 to 24 mm, diameter 3.0 to 4.0 mm) was positioned within the duct, not protected by a sheath; care was taken to cover the complete length of the duct from the aortaductal junction until well within the pulmonary trunk.ResultsAll stents could safely be deployed with adequate pulmonary flow at early- and medium-term follow-up. There were no procedure-related complications; one patient died early from sepsis. All patients had adequate relief of cyanosis for at least three to four months. During follow-up, the pulmonary vasculature bed had grown without distortion. Acute occlusion of a stented duct was not observed. Ductal flow progressively decreased slowly over several months by luminal narrowing, until the stented duct had either become redundant or was dilated/restented or until elective staged surgery was performed.ConclusionsWith current technology, complete stenting of a short straight duct is a safe and effective palliation, allowing adequate growth of the pulmonary arteries
