Impacts of a trophy hunting ban on private land conservation in South African biodiversity hotspots:
- Authors: Parker, Kim , de Vos, Alta , Clements, Hayley S , Biggs, Duan , Biggs, Reinette
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158219 , vital:40163 , https://0-doi.org.wam.seals.ac.za/10.1111/csp2.214
- Description: Private land conservation areas (PLCAs) have become critical for achieving global conservation goals, but we lack understanding of how and when these areas respond to global pressures and opportunities. In southern Africa, where many PLCAs rely on trophy hunting as an income‐generating strategy, a potential ban on trophy hunting locally or abroad holds unknown consequences for the future conservation of these lands. In this study, we investigate the consequences of a potential trophy hunting ban in PLCAs in two biodiversity hotspots in South Africa's Eastern and Western Cape provinces. We used semistructured interviews with PLCA managers and owners to elicit perceived impacts of an internationally imposed trophy hunting ban on conservation activities in PLCAs, and to probe alternative viable land uses.
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Nutrient release dynamics associated with native and invasive leaf litter decomposition: a Mesocosm Experiment
- Authors: Mutshekwa, Thendo , Cuthbert, Ross N , Wasserman, Ryan J , Murungweni, Florence M , Dalu, Tatenda
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160467 , vital:40448 , https://doi.org/10.3390/w12092350
- Description: Leaf litter contributes to the functioning of aquatic ecosystems through allochthonous inputs of carbon, nitrogen, and other elements. Here, we examine leaf litter nutrient inputs and decomposition associated with four plant species using a mesocosm approach. Native sycamore fig Ficus sycomorus L., and silver cluster–leaf Terminalia sericea Burch. ex DC. decomposition dynamics were compared to invasive tickberry Lantana camara L. and guava Psidium guajava L., whereby phosphate, nitrate, nitrite, silicate, and ammonium releases were quantified over time. Leaf inputs significantly reduced pH, with reductions most marked by invasive L. camara. Conductivity was heightened by all leaf input treatments, except native T. sericea.
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Occurrence of selected endocrine disrupting compounds in the Eastern Cape province of South Africa:
- Authors: Farounbi, Adebayo I , Ngqwala, Nosiphiwe P
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148447 , vital:38740 , DOI: 10.1007/s11356-020-08082-y
- Description: Endocrine-disrupting compounds are attracting attention worldwide because of their effects on living things in the environment. Ten endocrine disrupting compounds: 4-nonylphenol, 2,4-dichlorophenol, estrone, 17β-estradiol, bisphenol A, 4-tertoctylphenol, triclosan, atrazine, imidazole and 1,2,4-triazole were investigated in four rivers and wastewater treatment plants in this study. Rivers were sampled at upstream, midstream and downstream reaches, while the influent and effluent samples of wastewater were collected from treatment plants near the receiving rivers. Sample waters were freeze-dried followed by extraction of the organic content and purification by solid-phase extraction. Concentrations of the compounds in the samples were determined with ultra-high performance liquid chromatography-tandem mass spectrometry. The instrument was operated in the positive electrospray ionization (ESI) mode.
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Retracted COVID-19 Papers and the level of 'citation pollution': a preliminary analysis and directions for future research
- Authors: Van der Walt, Wynand , Willems, Kris A , Friedrich, Wernher , Hatsu, Sylvester , Krauss, Kirstin
- Date: 2020
- Subjects: Retraction watch , Research -- Evaluation , Bibliographical citations -- Evaluation , Science publishing -- Corrupt practices , Scholarly publishing -- Corrupt practices , Learning and scholarship -- Corrupt practices , Medical publishing -- Corrupt practices , COVID-19 (Disease) -- Publishing
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/167732 , vital:41508 , https://www.abd-bvd.be/nl/bladen-voor-documentatie/2020-3-4/
- Description: Retraction Watch maintains a "running list" of retracted papers on Covid-19 related research. By the end of September 2020, thirty-three retracted Covid-19 papers were listed. We analysed these retracted papers, focusing specifically on how they have been cited by review papers, and subsequently how they have penetrated and potentially distorted public discourse and legitimate research on Covid-19. The study demonstrates the need for more in-depth studies that focus on the phenomenon of citation pollution. We show that the "Covid-19 publication race", amplified by a pressure-to-publish research culture, distorted published science on Covid-19. We highlight the urgency to engage popular media and critical decision makers on how to distinguish between questionable and legitimate science. We also emphasise the importance of dealing with illegitimate research in a timely manner, both from a scholarly communications and research quality perspective. , Retraction Watch maintient une "liste courante" des articles rétractés sur les recherches liées au Covid-19. Fin septembre 2020, trente-trois articles rétractés sur le Covid-19 étaient répertoriés. Nous avons analysé ces articles rétractés, en nous concentrant spécifiquement sur la façon dont ils ont été cités par d'autres articles, et ensuite sur la façon dont ils ont pénétré et potentiellement faussé le discours public et la recherche légitime sur le Covid-19. L'étude démontre le besoin d'études plus approfondies qui se concentrent sur le phénomène de la pollution des citations. Nous montrons que la "course à la publication sur le Covid-19", amplifiée par une culture de la pression à la publication de la recherche, a déformé l'information scientifique publiée sur le Covid-19. Nous soulignons l'urgence d'engager les médias populaires et les décideurs critiques sur la manière de distinguer la science douteuse de la science légitime. Nous soulignons également l'importance de traiter rapidement les recherches illégitimes, tant du point de vue de la communication scientifique que de la qualité de la recherche. , Retraction Watch houdt een "lopende lijst" bij van ingetrokken papieren over Covid-19-gerelateerd onderzoek. Eind september 2020 waren drieëndertig ingetrokken Covid-19 papieren op de lijst geplaatst. We hebben deze ingetrokken papieren geanalyseerd, waarbij we ons specifiek hebben gericht op de manier waarop ze zijn geciteerd door review papers, en vervolgens op de manier waarop ze zijn doorgedrongen en mogelijk vervormd in het publieke discours en het legitieme onderzoek naar Covid-19. De studie toont aan dat er behoefte is aan meer diepgaande studies die zich richten op het fenomeen van de citatievervuiling. We tonen aan dat de "Covid-19-publicatierace", versterkt door een druk om te publiceren onderzoekscultuur, de gepubliceerde wetenschap over Covid-19 vertekend heeft. We benadrukken de urgentie om de populaire media en kritische besluitvormers te betrekken bij het maken van een onderscheid tussen twijfelachtige en legitieme wetenschap. We benadrukken ook het belang van het tijdig aanpakken van onrechtmatig onderzoek, zowel vanuit het oogpunt van wetenschappelijke communicatie als vanuit het oogpunt van de kwaliteit van het onderzoek.
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Simultaneous liposomal encapsulation of antibiotics and proteins: co-loading and characterization of rifampicin and Human Serum Albumin in soy-liposomes
- Authors: Bapolisi, Alain M , Nkanga, Christian I , Walker, Roderick B , Krause, Rui W M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148617 , vital:38755 , https://doi.org/10.1016/j.jddst.2020.101751
- Description: The recurrent development of resistance to antimicrobial agents threatens the ability for successful treatment of infectious diseases. Hydrophobic antibiotics such as rifampicin (Rif) are particularly affected due to poor bioavailability. On the other hand, proteins play important roles in drug delivery and release. Further, the combination of antimicrobials with therapeutic proteins and their encapsulation in liposomes seems a promising approach for improvement of antimicrobial efficacy. This study aimed to encapsulate Rif simultaneously with a large protein, Human Serum Albumin (HSA) in liposomes made from an inexpensive crude soy lecithin (CSL).
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Study of Star-Forming Regions in the Peculiar Galaxies NGC 660, NGC 1512, NGC 4395, and NGC 4618:
- Authors: Smirnova, K I , Wiebe, D S , Moiseev, A V , Jozsa, G I G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160456 , vital:40447 , https://0-doi.org.wam.seals.ac.za/10.1134/S199034132003013X
- Description: The star-forming regions (SFRs) in the peculiar galaxies NGC 660, NGC 1512, NGC 4395 and NGC 4618 are studied. The relationships between such characteristics of star forming regions as UV, near- and far-IR fluxes, as well as in the Hα and HI lines, surface brightness in these ranges, and the scatter of the radial velocities of ionized and neutral hydrogen are considered. It is shown that in all the galaxies considered, the IR fluxes from SFRs are less than in the “normal” galaxies, but for different reasons: in the galaxies with signs of recent interaction NGC 660 and NGC 1512, this is due to the low surface brightness of SFRs; in the lopsided galaxies NGC 4395 and NGC 4618, the low brightness of SFRs in the infrared range is due to their compact size. These differences indicate that the star formation process depends not only on the morphological type of a galaxy, but also on many other factors.
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Zimbabwe's 2018 elections: funding, public resources and vote buying
- Authors: Ndakaripa, Musiwaro
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148988 , vital:38793 , DOI: 10.1080/03056244.2020.1735327
- Description: Using the concept of ‘competitive authoritarianism’, this briefing examines how the governing Zimbabwe African National Union – Patriotic Front (ZANU–PF) retained power in the July 2018 presidential, parliamentary and local government elections. It advances that, having come to power through military assistance in November 2017, the new ZANU–PF government instituted cosmetic political reforms to gain domestic and international legitimacy while maintaining financial networks and tentacles on public institutions. This briefing posits that, with a huge funding base, abuse of public resources and massive vote buying, materially, Zimbabwe's 2018 elections were heavily slanted in favour of ZANU–PF.
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31° South: the physiology of adaptation to arid conditions in a passerine bird.
- Authors: Ribeiro, Ângela M , Puetz, Lara , Pattinson, Nicholas B , Dalén, Love , Deng, Yuan , Zhang, Guojie , da Fonseca, Rute R , Smit, Ben , Gilbert, M. Thomas P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441508 , vital:73894 , https://doi.org/10.1111/mec.15176
- Description: Arid environments provide ideal ground for investigating the mechanisms of adaptive evolution. High temperatures and low water availability are relentless stressors for many endotherms, including birds; yet birds persist in deserts. While physiological adaptation probably involves metabolic phenotypes, the underlying mechanisms (plasticity, genetics) are largely uncharacterized. To explore this, we took an intraspecific approach that focused on a species that is resident over a mesic to arid gradient, the Karoo scrub‐robin (Cercotrichas coryphaeus). Specifically, we integrated environmental (climatic and primary productivity), physiological (metabolic rates: a measure of energy expenditure), genotypic (genetic variation underlying the machinery of energy production) and microbiome (involved in processing food from where energy is retrieved) data, to infer the mechanism of physiological adaptation. We that found the variation in energetic physiology phenotypes and gut microbiome composition are associated with environmental features as well as with variation in genes underlying energy metabolic pathways. Specifically, we identified a small list of candidate adaptive genes, some of them with known ties to relevant physiology phenotypes. Together our results suggest that selective pressures on energetic physiology mediated by genes related to energy homeostasis and possibly microbiota composition may facilitate adaptation to local conditions and provide an explanation to the high avian intraspecific divergence observed in harsh environments.
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Considering the links between non-timber forest products and poverty alleviation
- Authors: Shackleton, Charlie M , Pullanikkatil, Deepa
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433551 , vital:72983 , ISBN 978-3-319-75580-9 , https://link.springer.com/chapter/10.1007/978-3-319-75580-9_2
- Description: The debates around the value and importance of non-timber forest products (NTFPs) are complex and ongoing. The complexity is a result of many factors, including the wide variety of species, products and uses, as well as the variety of constituencies and disciplines each seeing advantage from ‘co-opting’ the importance of the contribution of NTFPs to their own areas of interest and concern. Conservationists are interested in NTFPs because their combined high value in many settings offers a potential alternative to the destruction of forests by either commercial logging or their widespread conversion to other land uses.
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Counter-memory and and–and: aesthetics and temporalities for living together
- Authors: Tello, Verónica
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146077 , vital:38493 , https://0-doi.org.wam.seals.ac.za/10.1177/1750698019876002
- Description: This essay traces a critical genealogy of counter-memory – spanning critical theory, film and contemporary art – bound to what Rosi Braidotti terms nomadic subjectivity. Engaging with the work of feminist and postcolonial theorists and artists, this essay charts the import of nomadic subjectivity as a method for staying with the many times and histories of global contemporaneity. It aims to move beyond thinking of counter-memory as simply a means to maintain or register erased and/or contested histories, or as a dialectical mnemonic system. It charts an alternative concept of counter-memory, one that is post-dialectical, not bound to the formulas of either/or, us/them or self/other, but which is instead committed to the endless accumulation and proximities of things – the and–and.
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Differences in the use of surface water resources by desert birds are revealed using isotopic tracers
- Authors: Smit, Ben , Woodborne, Stephan , Wolf, Blair O , McKechnie, Andrew E
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440532 , vital:73790 , https://doi.org/10.1093/auk/uky005
- Description: The scarcity of free-standing water sources is a key determinant of animal and plant community structure in arid environments, and an understanding of the extent to which particular species use surface water is vital for modeling the effects of climate change on desert avifauna. We investigated interspecific variation in the use of artificial water sources among birds in the Kalahari Desert, South Africa, by (i) observations at waterholes and (ii) tracing spatial water-use patterns during summer by isotopically labeled water sources and blood sampling. More than 50% of the avian community (primarily insectivores and omnivores) were not observed to drink. The majority (53%) of species drinking at waterholes were granivorous, and their use of surface water was best predicted by their relative abundance in the community. Species representing the remaining dietary guilds drank significantly more on hot days. Blood samples revealed that only 11 of 42 species (mostly granivores and a few omnivores) showed evidence of drinking at a waterhole with enriched deuterium values; on average, in the latter birds, water from the enriched waterhole accounted for ~38% of their body water pool. These findings illustrate that 2 methods employed in this study provide different, but complementary data on the relative importance of a water source for an avian community. Although our results suggest that most avian species are independent of surface water, drinking patterns on the hottest days during our study period suggest that free-standing water might become more important for some of the non-drinking species under hotter climatic conditions.
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Ecological connectivity between the areas beyond national jurisdiction and coastal waters: Safeguarding interests of coastal communities in developing countries
- Authors: Popova, Ekaterina , Vousden, David , Sauer, Warwick H H , Mohammed, Essam Y , Allain, Valerie , Downey-Breedt, Nicola , Fletcher, Ruth , Gjerde, Kristina M , Halpin, Patrick , Kelly, Stephen , Obura, David , Pecl, Gretta T , Roberts, Michael , Raitsos, Dionysios E , Rogers, Alex , Samoilys, Melita , Sumaila , Ussif Rashid , Tracey, Sean , Yool, Andrew
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124331 , vital:35594 , https://doi.10.1016/j.marpol.2019.02.050
- Description: The UN General Assembly has made a unanimous decision to start negotiations to establish an international, legally-binding instrument for the conservation and sustainable use of marine biological diversity within Areas Beyond National Jurisdiction (ABNJ). However, there has of yet been little discussion on the importance of this move to the ecosystem services provided by coastal zones in their downstream zone of influence. Here, we identify the ecological connectivity between ABNJ and coastal zones as critically important in the negotiation process and apply several approaches to identify some priority areas for protection from the perspective of coastal populations of Least Developed Countries (LDCs). Initially, we review the scientific evidence that demonstrates ecological connectivity between ABNJ and the coastal zones with a focus on the LDCs. We then use ocean modelling to develop a number of metrics and spatial maps that serve to quantify the connectivity of the ABNJ to the coastal zone. We find that the level of exposure to the ABNJ influences varies strongly between countries. Similarly, not all areas of the ABNJ are equal in their impacts on the coastline. Using this method, we identify the areas of the ABNJ that are in the most urgent need of protection on the grounds of the strength of their potential downstream impacts on the coastal populations of LDCs. We argue that indirect negative impacts of the ABNJ fishing, industrialisation and pollution, communicated via oceanographic, cultural and ecological connectivity to the coastal waters of the developing countries should be of concern.
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Factors influencing the spatial patterns of vertebrate roadkill in South Africa: The Greater Mapungubwe Transfrontier Conservation Area as a case study
- Authors: Collinson, Wendy J , Parker, Daniel M , Bernard, Ric T F , Reilly, Brian K , Davies-Mostert, Harriet T
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158320 , vital:40172 , https://0-doi.org.wam.seals.ac.za/10.1111/aje.12628
- Description: Few studies have investigated the factors that influence roadkill occurrence in developing countries. In 2013, we monitored a 100‐km section of the road (comprising the R572 and R521 regional highways and the D2662) that pass through the Greater Mapungubwe Transfrontier Conservation Area in South Africa, to assess the possible factors influencing roadkill. Over a period of 120 days, and across the three ecological seasons, we recorded 981 roadkills (rate = 0.08 roadkill/km/day) from four vertebrate taxonomic groups. We generated predictive models of roadkill from one combined data set that considered eight variables identified from the literature as potential correlates of roadkill. The model that included the distance of the fence from the road, habitat type adjacent to the road, and the presence of a hill in the road (i.e., elevation) or a bank on the side of the road best explained roadkill occurrence.
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Measuring and modelling evapotranspiration in a South African grassland: Comparison of two improved Penman-Monteith formulations
- Authors: Gwate, Onalenna , Mantel, Sukhmani K , Palmer, Anthony R , Gibson, Lesley A , Munch, Zahn
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438167 , vital:73440 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/44_03_16_3530.pdf
- Description: Accurately measuring evapotranspiration (ET) is important in the con-text of global atmospheric changes and for use with climate models. Direct ET measurement is costly to apply widely and local calibration and validation of ET models developed elsewhere improves confidence in ET derived from such models. is study sought to compare the per-formance of the Penman-Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) ET models, over mesic grasslands in two study sites in South Africa. The study used routine meteorological data from a scientific-grade automatic weather station (AWS) to apply the PML and PMP models. The PML model was calibrated at one site and validated in both sites. On the other hand, the PMP model does not require cali-bration and hence it was validated in both sites.
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Non-timber forest product use and market chains along a deforestation gradient in southwest Malawi
- Authors: Mahonya, Sophie , Shackleton, Charlie M , Schreckenberg, Kate
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/177465 , vital:42824 , https://doi.org/10.3389/ffgc.2019.00071
- Description: The importance of non-timber forest products (NTFPs) to rural livelihoods is widely acknowledged globally, as is the income generated from casual or fulltime trade on village and urban markets. However, there is less understanding of how the condition or status of the neighboring landscapes influence the use of and trade in NTFPs. Here we report on the use and trade in NTFPs in four villages situated along a gradient of decreasing forest cover in southwest Malawi using a mixed-methods approach. Data were sourced via a survey of 286 households, value chain analysis of the four most commonly traded NTFPs (thatch grass, edible orchids, mushrooms, and wild fruits), key informant interviews with NTFP traders and direct observations.
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Perspectives in coastal human ecology (CHE) for marine conservation
- Authors: Aswani, Shankar
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125576 , vital:35797 , https://doi.10.1016/j.biocon.2019.05.047
- Description: Coastal human ecology (CHE) is a mixture of different theoretical and thematic approaches straddling between the humanities and social and natural sciences which studies human and coastal/marine interactions at the local-scale and through intense fieldwork. Topics of interest include human coastal adaptations past and present; the historical ecology of fisheries and future implications; local forms of marine governance and economic systems; local food security and livelihoods, and indigenous/local ecological knowledge systems among many research themes. In this paper, I explore different strands of CHE in the study of tribal, artisanal, and small-scale industrial fisheries from the mid-90s onward that can contribute to the foundational knowledge necessary for designing and implementing successful coastal fisheries management and conservation programs. Marine conservation has often failed due to a lack of understanding of the fine grained marine human-environmental interactions at the local scale. In this context, I also examine developing and future research directions in CHE, and discuss their potential contribution for filling the gap in existing approaches to actionable scholarship in marine conservation. The strength of many CHE approaches lies in their potential for bridging humanism and natural science, and thus CHE approaches are well equipped to address many of the challenges faced by marine conservation practitioners today.
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Rethinking ICT4D Impact Assessments: reflections from the Siyakhula Living Lab in South Africa
- Authors: Mthoko, Hafeni , Khene, Caroline
- Date: 2019
- Language: English
- Type: text , conference paper
- Identifier: http://hdl.handle.net/10962/105286 , vital:32495 , https://doi.org/10.1007/978-3-030-11235-6_4
- Description: The approach to outcome and impact assessments of ICTD has often relied solely on identifying project effects in relation to project baseline data; however, such an approach limits the potential learning that could be occurring throughout a project’s lifecycle. Impact assessments should be conducted in a comprehensive manner, taking into account the evaluation data that has been captured from the initiation of the project through to its implementation, and beyond. This study sought to reflect on the implementation of an impact assessment framework that is based on a comprehensive approach to evaluation. The framework was implemented in the Siyakhula Living Lab to assess for its outcomes and impacts on the community. A pragmatic approach was applied through a reflective process, to assess the utility of the framework within this context. Semi-structured interviews with project stakeholders were conducted to further gain insight into the comprehensive approach to conducting impact assessments. It was found that a comprehensive approach to assessing impacts provided a meaningful way to understand the effects of the ICTD initiative, and provided an overview of project areas that required improvement. However, it was found that the proposed assessment framework required a customisation component in order to modify it to better suit the project context. The way in which future impact assessments are conducted can draw on the lessons gained from following a more comprehensive approach to evaluation, and thus improve learning over time.
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Speaking to power through newspaper editorials in Zimbabwe:
- Authors: Nyaungwa, Mathew , Garman, Anthea
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158438 , vital:40186 , https://0-doi.org.wam.seals.ac.za/10.1386/jams.11.1.51_1
- Description: This article seeks to provide an insight into the complex role that editorials – a newspaper’s institutional voice – play in highly polarised political contexts. It focuses on how the editorials of two Zimbabwean daily newspapers – The Herald, a progovernment newspaper, and NewsDay, a perceived pro-opposition newspaper – spoke to those in power at a time of transition from a government of national unity to majoritarian rule in 2013. The study also sets out to understand how both the newspapers’ editorials over this time responded to a contested political domain. Qualitative content analysis, rhetorical analysis and in-depth interviews were used to consider the tactics employed in the editorials to question and challenge the decisions and behaviours of those in positions of authority. The research findings contradict the common view in Zimbabwe that the privately–owned media blindly support the opposition while the state-owned media do the same with ZANU-PF. The findings show that in the period in question both newspapers exploited the editorial as a space to urge politicians to think of the national common good.
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Adsorptive removal of ciprofloxacin and isoniazid from aqueous solution
- Authors: Dube, Cyril S , Tandlich, Roman , Wilhelmi, Brendan S
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76846 , vital:30629 , https://doi.org/10.2478/nbec-2018-0002
- Description: This paper describes study of ciprofloxacin and isoniazid removal from aqueous solutions using coal fly ash (FA), kaolinite, perlite, talc and vermiculite. The adsorptive features of the adsorbents were evaluated for ciprofloxacin and isoniazid with regards to the effects of contact time, pH, the solid/liquid ratio and antibiotic concentration. All adsorbents were sterilised by dry heat before use to avoid the proliferation of antimicrobial resistance by the bacteria present on the adsorbents during experiments. The regression correlation coefficients indicate that the Langmuir model gives the best fit for the sorption of both antibiotics onto FA and talc, ciprofloxacin onto kaolinite, and isoniazid onto perlite and vermiculite with R2 values ranging from 0.908 – 0.999. The Freundlich isotherm best describes the sorption of ciprofloxacin onto vermiculite and isoniazid onto kaolinite with R2 values of 0.999 for both. The Tempkin model best describes the sorption of ciprofloxacin onto perlite with an R2 = 0.997. The values of the Freundlich exponent, 1/n, range from 0.221 – 0.998, indicating a favourable adsorption of ciprofloxacin and isoniazid onto the adsorbents. The heat of sorption, B, calculated from the Temkin plots has values ranging from 0.018 – 10.460 J/mol, indicating a physical adsorption process (physisorption). Adsorption equilibrium was achieved after 30 min for both antibiotics and the kinetic data obtained conforms best to the pseudo-second order equation with R2 values ranging from 0.998 – 0.999. The removal of ciprofloxacin and isoniazid by all adsorbents except FA was strongly influenced by the pH suggesting that electrostatic interactions play a major role in the adsorption processes.
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Developmental and reproductive performance of a specialist herbivore depend on seasonality of, and light conditions experienced by, the host plant
- Authors: Zachariades, Uyi O O, , Heshula, L U P , Hill, Martin P
- Date: 2018
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59845 , vital:27667 , https://doi.org/10.1371/journal.pone.0190700
- Description: Host plant phenology (as influenced by seasonality) and light-mediated changes in the phenotypic and phytochemical properties of leaves have been hypothesised to equivocally influence insect herbivore performance. Here, we examined the effects of seasonality, through host plant phenology (late growth-season = autumn vs flowering-season = winter) and light environment (shade vs full-sun habitat) on the leaf characteristics of the invasive alien plant, Chromolaena odorata. In addition, the performance of a specialist folivore, Pareuchaetes insulata, feeding on leaves obtained from both shaded and full-sun habitats during autumn and winter, was evaluated over two generations. Foliar nitrogen and magnesium contents were generally higher in shaded plants with much higher levels during winter. Leaf water content was higher in shaded and in autumn plants. Total non-structural carbohydrate (TNC) and phosphorus contents did not differ as a function of season, but were higher in shaded foliage compared to full-sun leaves. Leaf toughness was noticeably higher on plants growing in full-sun during winter. With the exception of shaded leaves in autumn that supported the best performance [fastest development, heaviest pupal mass, and highest growth rate and Host Suitability Index (HSI) score], full-sun foliage in autumn surprisingly also supported an improved performance of the moth compared to shaded or full-sun leaves in winter. Our findings suggest that shaded and autumn foliage are nutritionally more suitable for the growth and reproduction of P. insulata. However, the heavier pupal mass, increased number of eggs and higher HSI score in individuals that fed on full-sun foliage in autumn compared to their counterparts that fed on shaded or full-sun foliage in winter suggest that full-sun foliage during autumn is also a suitable food source for larvae of the moth. In sum, our study demonstrates that seasonal and light-modulated changes in leaf characteristics can affect insect folivore performance in ways that are not linear.
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