Predators of aerial insects and riparian cross-boundary trophic dynamics: web-building spiders, dragonflies and damselflies
- Authors: Chari, Lenin Dzibakwe
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55791 , vital:26734
- Description: This thesis characterises the cross-boundary trophic interactions of a relatively small model ecosystem, the Kowie River (Eastern Cape of South Africa), to explore their epistemic implications for systems ecology. Using web-building spiders and odonates (dragonflies and damselflies) as model organisms, I sought to investigate whether the diets of predators of aerial insects could be used to assess the strength of the trophic connectivity between freshwater and terrestrial systems in relation to variables such as stream width, distance from the river and aquatic insect emergence rates and abundances. Predator diet composition was determined by using a combination of diet analysis tools: direct observations of cross-subsidies, naturally-abundant stable (carbon and nitrogen) isotope analysis and fatty acid analysis. I also sought to reveal feeding niches and guilds among riparian aerial predators and investigate how the environment influenced predators’ access to aquatic prey subsidies. As emergent aquatic insect abundances decreased with an increase in distance from the river, and increased with stream width and seasonal changes from winter to summer, stable isotope and fatty acid analyses revealed distinct changes in web-building spider diet composition. Examination of the fatty acid eicosapentaenoic acid, a component commonly used as an indicator of consumer reliance on aquatic nutritional subsidies, showed that aquatic subsidies extended further inland at the wider sections of the river. Spiders and odonates at the wider sections of the Kowie River generally received more subsidies (56 – 70%) than those at the narrower sections (25 – 60%). When terrestrial insect biomass was distinctly low in winter, the benefit of aquatic subsidisation to spiders was relatively lower at the narrower sections of the Kowie River relative to the wide sections. As such, riparian areas adjacent to wide parts of the river were more likely to support larger populations of aerial predators than those at the narrow sections. Apart from the diet changes across time and space, there was evidence of inter-specific niche partitioning in both spiders and odonates, but no differences were observed between males and females of the same species. Results showed odonates of different sizes and hunting strategies had separate dietary niches, hence varied access to aquatic nutritional subsidies. The larger odonate taxa that frequently foraged mid-air had more varied diets and relied less on aquatic emergent insects than the smaller odonates that foraged from perches near the river. There was also evidence of niche partitioning amongst the spiders, as those that built horizontal webs captured more aquatic insects (40 – 78%) than the vertical orb-web builders (20 – 66%). This study showed that the nature and extent of trophic cross-boundary linkages in riparian areas largely depended on the availability of subsidies that varied seasonally and spatially. The width of the stream and seasonal variability emerged as important predictors of emergent insect abundances/biomasses that influenced predator feeding niches. The high mobility of odonates made their reliance on aquatic nutritional subsidies different from the less mobile spiders. The link between the width of the river and the extent of trophic connectivity has implications for riparian area management and definition of riparian buffer zones. However, the variation in diet niches amongst terrestrial consumers makes the results area-specific, and more studies are required that incorporate additional terrestrial predators in other fluvial systems so that we can make some generalizations on the dynamics of riparian trophic cross-boundary links.
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Preference for C4 shade grasses increases hatchling performance in the butterfly, Bicyclus safitza
- Authors: Nokelainen, Ossi , Ripley, Bradford Sherman , Van Bergen, Erik , Osborne, Colin P , Brakefield, Paul M
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61424 , vital:28025 , http://onlinelibrary.wiley.com/doi/10.1002/ece3.2235/full
- Description: The Miocene radiation of C4 grasses under high-temperature and low ambient CO2 levels occurred alongside the transformation of a largely forested landscape into savanna. This inevitably changed the host plant regime of herbivores, and the simultaneous diversification of many consumer lineages, including Bicyclus butterflies in Africa, suggests that the radiations of grasses and grazers may be evolutionary linked. We examined mechanisms for this plant–herbivore interaction with the grass-feeding Bicyclus safitza in South Africa. In a controlled environment, we tested oviposition preference and hatchling performance on local grasses with C3 or C4 photosynthetic pathways that grow either in open or shaded habitats. We predicted preference for C3 plants due to a hypothesized lower processing cost and higher palatability to herbivores. In contrast, we found that females preferred C4 shade grasses rather than either C4 grasses from open habitats or C3 grasses. The oviposition preference broadly followed hatchling performance, although hatchling survival was equally good on C4 or C3 shade grasses. This finding was explained by leaf toughness; shade grasses were softer than grasses from open habitats. Field monitoring revealed a preference of adults for shaded habitats, and stable isotope analysis of field-sampled individuals confirmed their preference for C4 grasses as host plants. Our findings suggest that plant–herbivore interactions can influence the direction of selection in a grass-feeding butterfly. Based on this work, we postulate future research to test whether these interactions more generally contribute to radiations in herbivorous insects via expansions into new, unexploited ecological niches.
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Principled, pragmatic revitalisation of catchment management forums in South Africa
- Authors: Munnik, Victor , Burt, Jane C , Price, Leigh , Barnes, Garth , Ashe, Bryan , Motloung, Sysman
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/436743 , vital:73298 , ISBN 978-1-4312-0831-9 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT%20682-17.pdf
- Description: There are many views on Catchment Management Forums (CMFs). They are seen as places for enthusiastic participation, communities of practice in the making, and crucial to the devo-lution of water management to local stakeholders. They are also seen as exhausted, toothless talk shops, unrepresenta-tive, undemocratic, haunts of the privileged, ignored by officials and a waste of time.
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Principles of Control Protocol Design and Implementation
- Authors: Eales, Andrew , Foss, Richard
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426801 , vital:72392 , https://www.aes.org/e-lib/online/browse.cfm?elib=18238
- Description: Control protocols are used within audio networks to manage both audio streams and networked audio devices. A number of control protocols for audio devices have been recently developed, including the AES standards AES64-2012 and AES70-2015. Despite these developments, an ontology of control protocol design and implementation does not exist. This paper proposes design and implementation heuristics for control protocols. Different categories of control protocol design and implementation heuristics are presented and the implications of individual heuristics are discussed. These heuristics allow the features provided by different control protocols to be compared and evaluated and provide guidelines for future control protocol development.
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Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars
- Authors: Pagonis, Vasilis , Ankjærgaard, Christina , Jain, Mayank , Chithambo, Makaiko L
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124616 , vital:35638 , DOI: 10.1016/j.physb.2016.06.013
- Description: Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IRSL signals, both during and after short infrared stimulation pulses. The equations are developed using a recently proposed kinetic model, which describes localized electronic recombination via tunneling between trapped electrons and recombination centers in luminescent materials. Recombination is assumed to take place from the excited state of the trapped electron to the nearest-neighbor center within a random distribution of luminescence recombination centers. Different possibilities are examined within the model, depending on the relative importance of electron de-excitation and recombination. The equations are applied to experimental TR-IRSL data of natural feldspars, and good agreement is found between experimental and modeling results.
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Recombinant expression, purification and in vitro interaction analysis of HOP and RhoC
- Authors: Vaaltyn, Michaelone Chantelle
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64523 , vital:28555
- Description: Expected release date-May 2019
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Recommendations for the future of recreational fisheries to prepare the social‐ecological system to cope with change
- Authors: Arlinghaus, Robert , Cooke, Steven J , Sutton, S G , Danylchuk, A J , Potts, Warren M , Freire, K D M , Alós, J , Da Silva, E T , Cowx, Ian G , Van Anrooy, R
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125810 , vital:35819 , https://doi.10.1111/fme.12191
- Description: This paper presents conclusions and recommendations that emerged from the 7th World Recreational Fishing Conference (WRFC) held in Campinas, Brazil in September 2014. Based on the recognition of the immense social and economic importance of recreational fisheries coupled with weaknesses in robust information about these fisheries in many areas of the world, particularly in many economies in transition, it is recommended to increase effort to build effective governance arrangements and improve monitoring and assessment frameworks in data-poor situations. Moreover, there is a need to increase interdisciplinary studies that will foster a systematic understanding of recreational fisheries as complex adaptive social-ecological systems. To promote sustainable recreational fisheries on a global scale, it is recommended the detailed suggestions for governance and management outlined in the United Nations Food and Agricultural Organization Technical Guidelines for Responsible Fisheries: Recreational Fisheries are followed.
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Reimagining curriculum through a Bernsteinian lens: rethinking the canon in Political Science
- Authors: Clarence, Sherran
- Date: 2016
- Language: English
- Type: text , conference publication
- Identifier: http://hdl.handle.net/10962/66961 , vital:29006
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Remastered:
- Authors: Ntombela, N
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146423 , vital:38524 , https://www.e-flux.com/announcements/49246/the-exhibitionist-journal-on-exhibition-making/
- Description: Exhibition abstract. Issue 12 scrutinizes our founding premise, that The Exhibitionist is a journal “by curators, for curators.” When we launched six years ago, this circuit of self-reflection seemed necessary, and enabled a conversation that was not available in other venues. But one effect of this focus, as we see it now, was a siloing-off of curatorial thinking from other parts of the field of exhibition making—which is, after all, based in collective forms of authorship.
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Report containing learning, reflection and evaluation based on social learning:
- Authors: Burt, Jane C , Wilson, Jessica , Copteros, Athina , Lotz-Sisitka, Heila , Pereira, Taryn , Mokoena, Samson , Munnik, Victor , Ngcozela, Thabang , Lusithi, Thabo
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/142005 , vital:38023 , ISBN WRC Report no K5/2313 Deliverable 7
- Description: This report forms the seventh deliverable in the NWRS2 citizen monitoring project and builds on the previous 6 deliverables, which include methodology for the project (Del 1), an assessment of civil society involvement in water policy (Del 2), an overview of the social learning approach and introduction to the case studies (Del 3), draft citizen monitoring guidelines (Del 4), an update on social learning to-date, including action plans (Del 5) and a report on a description and assessment of the case studies (Del 6). This report describes the last social learning module of the ‘Changing Practice’ course and highlights preliminary reflections on the learning that has taken place during this course. The report also describes the plans that were taken at the follow up research meeting. Finally we present the approach towards evaluating the role of social learning in the project as a whole.
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Responding to poverty in the light of the post-development debate: Some insights from the NGO Enda Graf Sahel
- Authors: Matthews, Sally
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142487 , vital:38084 , https://www.ajol.info/index.php/ad/article/view/135799
- Description: How can we take on board the many valuable insights of post-development theory without seeming to advocate indifference and inaction in the face of the misery that many people in the world experience daily? In this paper, I provide a partial response to this question. I begin by looking at some of the alternative strategies offered in post-development literature and set out to show that while there are several problems with these alternatives, to read post-development theory as advocating indifference or inaction is to read it uncharitably. Secondly, I draw on the experiences of the non-governmental organisation (NGO) Enda Graf Sahel in Dakar, Senegal to suggest some ways in which the insights of post-development theory, or some versions of post-development theory, can be taken into consideration without leading to inaction or indifference in the face of the suffering of those who occupy a less advantaged position in contemporary relations of power and privilege.
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Reviewing strategies in/for ESD policy engagement: Agency reclaimed
- Authors: Lotz-Sisitka, Heila
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182483 , vital:43834 , xlink:href="https://doi.org/10.1080/00958964.2015.1113915"
- Description: In this response article, I draw on critical realist perspectives to engage with the argument put forward in Bengtsson's study, which sees agency as an ontological necessity for Education for Sustainable Development (ESD) policy engagement. Bengtsson supports a notion of the logic of contingent action over the logic of power as dominance, suggesting possibilities for agency and resistance. Although I do not in principle disagree with the agentive possibilities embedded in this aspect of the Bengtsson argument, it is the scope of the conceptualization thereof that I consider in this response. I start with considering the limitations of a Westphalian analysis of policy appropriations and agency for ESD, and argue that the Westphalian frame for policy analysis may be inadequate for capturing the significance of non-state actors and wider generative mechanisms such as informal normative structures, and private, economic power in the global political economy. Drawing on Fraser's (2008) concept of the transnational public sphere, I explore other potential possibilities for agency-centered appropriations or negations of, and/or resistance to ESD policy discourses, potentially expanding the agency-centered perspective referred to in Bengtsson's analysis and critique of policy making for ESD, or, at the very least, by offering a wider view of possibility for what he refers to as the ‘ineradicable moment of conflict, or antagonism.’ In particular, I broaden the notion of the transnational public sphere to be inclusive of Dussel's (1998) three concerns of transformation, namely; poverty and wealth inequality, environmental degradation, and narrow rationalities involving ongoing colonization of people, territories and resources. In doing this, I concur with Fraser, who suggests that the concept of the public sphere may well be “so thoroughly Westphalian in its deep conceptual structure as to be unsalvageable as a critical tool for theorizing the present” and suggest that public sphere thinking and associated conceptions of agency require expansion, which I offer from postcolonial and decolonization literature, critical realism, ontological experiences, and reflection on Environmental Education (EE) /ESD policy in the southern African region. Ultimately, I propose need for a more radical framework for EE/ ESD policy research that reaches beyond analyses of appropriations of policy within the Wesphalian state framework, and that moves beyond critiquing or seeking out resistance moments associated with the assumptions of trickle down effects from UN level policy, or analysis that is centered on the EE versus ESD debate. Such a framework requires a revitalized notion of agency involving commitment to collective, relational (including the socio-materially relational) and transgressive forms of agency for deep societal transformations all round. Overall, it seems that environmental education policy and praxis research conceptualized within a decolonizing transnational sphere frame appears to still be an open and as yet under-explored terrain.
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Reflections on Teaching Africa in South Africa:
- Authors: Matthews, Sally
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142235 , vital:38061 , DOI: 10.1111/1467-9256.12107
- Description: This article draws on the author’s experience of teaching African Studies to undergraduate South African students in order to reflect on some of the key challenges facing teachers of African Studies, both in South Africa and beyond. In particular, it discusses challenges relating to teaching a field as contested as African Studies, looking at whether teaching African alternatives to mainstream African politics is helpful and at whether and how one can teach Africa in a way that encourages and develops critical thinking. The article also explores how the racial politics of the context in which one teaches African Studies inevitably affects the way in which students engage with the content of the course. While the article discusses these issues in relation to the South African higher education context in particular, implications for other contexts are also highlighted.
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Rhodes University Graduation Ceremony 2016
- Authors: Rhodes University
- Date: 2016
- Language: English
- Type: text
- Identifier: vital:8150 , http://hdl.handle.net/10962/d1021288
- Description: Rhodes University Graduation Ceremonies 2016 [at] 1820 Settlers National Monument Thursday, 31 March at 10.00 & 17:00 [and] Friday, 1 April at 10:00; 14:30 & 18:30 [and] Saturday, 2 April at 10:00
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Russian wheat aphids: Breakfast, lunch, and supper. Feasting on small grains in South Africa
- Authors: Botha, Christiaan E J , Sacranie, S , Gallagher, Sean , Hill, Jaclyn M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69031 , vital:29374 , https://doi.org/10.1016/j.sajb.2016.12.006
- Description: The Russian Wheat Aphid (Diuraphis noxia, RWA) negatively impacts commercially grown barley and wheat in South Africa. Climate change, the attendant rise in [CO2], and the appearance of new RWA biotypes have the potential to induce severe crop yield loss in agriculturally important wheat and barley cultivars. This study presents data showing changes in relative aphid population numbers, concurrently with assessments of plant damage under controlled environmental conditions, under ambient and elevated (450 ppm) [CO2]. Extensive structural damage to the vascular tissue and disruption to the transport systems were revealed using light, fluorescence and electron microscopy. This, coupled with biotype population studies, demonstrated that RWA has the capacity to inflict severe, potentially permanent damage to vegetative small grain plants. Furthermore, some currently ‘resistant’ cultivars may well lose resistance as a direct result of increasing atmospheric [CO2]. A small (50 ppm) increase in atmospheric [CO2] may result in increased aphid population numbers, potentially serious plant damage and, by implication, a potentially negative impact on yield, as increased aphid density per plant leads to an accelerated disruption of the assimilate and transpiration transport pathways. These outcomes pose a direct threat to the commercial small grain industry of South Africa and by extension, to other small grain production areas elsewhere.
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Schools performing against the odds
- Authors: Niacker, Inbanathan , Grant, Carolyn , Pillay, Sivanandani
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281126 , vital:55694 , xlink:href="https://doi.org/10.15700/saje.v36n4a1321"
- Description: There are many schools in developing countries which, despite the challenges they face, defy the odds and continue to perform at exceptionally high levels. We cast our gaze on one of these resilient schools in South Africa, and sought to learn about the leadership practices prevalent in this school and the enablements and constraints to the school leadership practice. Underpinned by a critical realist lens, and drawing on social realist theory, this case study of one school generated data through interviews, observation, document analysis and transect walks. The school principal, one head of department and two teachers, were selected as participants. The findings indicate that the school embraced an expansive form of teacher leadership comprising leadership within and beyond the classroom. Further, the structural, cultural and agential climate was receptive to the expansive leadership. We conclude that the professional capital of teachers, together with teachers serving as social actors rather than remaining primary agents, are key resources to change and transformation in an emerging economy.
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Screening of entomopathogenic fungi against citrus mealybug, Plannococcus citri (Hemiptera: Pseudococcidae)
- Authors: Chartier FitzGerald, Veronique C , Hill, Martin P , Moore, Sean D , Dames, Joanna F
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407059 , vital:70333 , xlink:href="https://hdl.handle.net/10520/EJC195093"
- Description: Planococcus citri (citrus mealybug) is a common and damaging citrus crop pest which has proven difficult to control using conventional methods, such as chemical pesticides and insect growth regulators, particularly late in the citrus growing season. The virulence of two entomopathogenic fungal species was studied in laboratory bioassays against the crawlers and adults of P. citri. Isolates of Metarhizium anisopliae and Beauveria bassiana, collected from citrus orchards in the Eastern Cape Province in South Africa, were verified using and molecular techniques. Mealybug bioassays were performed in 24-well plates. Beauveria bassiana (GAR 17 B3) and M. anisopliae (FCM AR 23 B3) isolates both resulted in 67.5 % mortality of mealybug crawlers and B. bassiana (GB AR 23 13 3) resulted in 64 % crawler mortality with concentrations of 1 x 107 conidia/ml. These three isolates were further tested in multipledose bioassays to determine the median lethal concentration (LC50), which were 5.29 x 105conidia/ml for the M. anisopliae isolate (FCM AR 23 B3), 4.25 x 106 conidia/ml for B. bassiana (GAR 17 B3), and 6.65 x 107 conidia/ml B. bassiana (GB AR 23 13 3) for crawlers, respectively. The results of this study suggested that two isolates (M. anisopliae FCM AR 23 B3 and B. bassiana GAR 17 B3) showed potential for further development as biological control agents against citrus mealybug. Further research would be required to determine their ability to perform under field conditions.
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SEAmester – South Africa’s first class afloat
- Authors: Ansorge, Isabelle J , Brundrit, Geoff , Brundrit, Jean , Dorrington, Rosemary A , Fawcett, Sarah , Gammon, David , Henry, Tahlia , Hermes, Juliet , Hölscher, Beate , d’Hotman, Jethan , Meiklejohn, Ian , Morris, Tammy , Pinto, Izidine , Du Plessis, Marcel , Roman, Raymond , Saunders, Clinton , Shabangu, Fannie W , De Vos, Marc , Walker, David R , Louw, Gavin
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/65539 , vital:28808 , https://doi.org/10.17159/sajs.2016/a0171
- Description: publisher version , From Introduction: Marine science is a highly competitive environment. The need to improve the cohort of South African postgraduates, who would be recognised both nationally and internationally for their scientific excellence, is crucial. It is possible to attract students early on in their careers to this discipline via cutting-edge science, technology and unique field experiences. Through the engagement of students with real-life experiences such as SEAmester, universities supporting marine science postgraduate degree programmes can attract a sustainable throughput of numerically proficient students. By achieving a more quantitative and experienced input into our postgraduate degree programmes, we will, as a scientific community, greatly improve our long-term capabilities to accurately measure, model and predict the impacts of current climate change scenarios. The short-term goal is to attract and establish a cohort of proficient marine and atmospheric science graduates who will contribute to filling the capacity needs of South African marine science as a whole. The SEAmester programme, by involving researchers from across all the relevant disciplines and tertiary institutions, provides an opportunity to build a network of collaborative teaching within the marine field. In doing so, these researchers will foster and strengthen new and current collaborations between historically white and black universities (Figure 1). The long-term objective of SEAmester is to build critical mass within the marine sciences to ensure sustained growth of human capacity in marine science in South Africa – aligning closely with the current DST Research and Development strategies and the Operation Phakisa Oceans Economy initiative.
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Sentential negation in South African Sign Language: A case study
- Authors: De Barros, Courtney , Siebörger, Ian
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/385377 , vital:68013 , xlink:href=" https://hdl.handle.net/10520/EJC-4acb542a9"
- Description: As with other sign languages, South African Sign Language (SASL) expresses negation using both manual and non-manual features. In this case study, naturalistic data provided by two native signers of SASL are analysed to show the syntactic relationship between these two sets of features. Using a Principles and Parameters approach and Government and Binding Theory, we investigate the syntactic scope of negation in our SASL data. We observe that side-to-side headshake, as a non-manual feature, appears to be the chief clausal negator in SASL, with a clause-final manual negative particle, NOT, playing a secondary role. We describe the negative headshake as a featural affix which is base-generated in the head of NegP and triggers V-to- Neg raising. The negative particle NOT appears to be base-generated in the Specifier of NegP. Suggestions for further syntactic research on SASL are provided.
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Sex and Loneliness: Banele Khoza’s 'Temporary Feelings'
- Authors: Lila, Philiswa
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147149 , vital:38597 , https://artthrob.co.za/2016/07/28/sex-and-loneliness-banele-khozas-temporary-feelings/
- Description: Banele Khoza grapples with short sharp emotions in his solo exhibition at the Pretoria Art Museum. Entitled ‘Temporary Feelings,’ the exhibition is very personal, yet critically engaging with issues of relationships, communication, social media and sexuality. He brings his vulnerability into the gallery space: what it means to be lonely, even though surrounded by people.
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