1834 research outputs found
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The Arabidopsis GolS1 promotor as a potential biosensor for heat stress and fungal infection?
No full textGalactinol (Gol) has classically been considered to serve as a galactose donor during the biosynthesis of raffinose family oligosaccharides (RFOs). These sucrosyl oligosaccharides have been well characterised in their roles in carbon translocation and storage and, abiotic stress protection in plants. However, recent findings have demonstrated Gol to be an efficient free radical scavenger and it has also been suggested to act as signalling molecule during induced systemic resistance (ISR), upon pathogen infection. Collectively, these findings centres to the involvement of only a single galactinol synthase gene (GolS, synthesising Gol) in Arabidopsis (AtGolS1, At2g47180). The AtGolS1 isoform has been shown to be transcriptionally up-regulated during heat stress and Botrytis cinerea infection. Further, it is also responsive to jasmonic acid, a key component of the ISR pathway. Here we targeted the AtGolS1 promotor containing well defined heat shock transcription factor elements and a single putative jasmonate binding element, to develop a dual-functional biosensor with the ability to detect both heat stress and Botrytis cinerea infection. We created transgenic Arabidopsis lines where the reporter genes β-glucuronidase (GUS) and the green florescent protein (GFP) were under the control of the AtGolS1 promotor. Using the native AtGolS1 gene as a point of reference, we confirmed that the reporter genes were transcriptionally responsive to both heat stress and methyl jasmonate treatment in transgenic Arabidopsis. Under the same experimental conditions, both GUS assays and GFP imaging correlated with these transcriptional responses. Finally, we infected the transgenic lines with Botrytis cinerea infections to analyse reporter activity. Transcript analysis of transgenic lines clearly showed an increase in transcript abundance for both the native AtGolS1 and the reporter genes in reponse to B. cinerea infection. Similarly, reporter assays revealed a distinct difference in activity between infected and uninfected plants from 24h to 96h after Botrytis cinerea infection. These results provide sufficient proof-of-concept for the AtGolS1 promotor to be used as a dual functional biosensor for both heat stress and fungal infection.National Research Foundatio
Elliptic curve cryptography
No full textIn this thesis we present a selection of Diffie-Hellman cryptosystems, which
were classically formulated using the multiplicative group of a finite field, but
which may be generalised to use other group varieties such as elliptic curves.
We also describe known attacks on special cases of such cryptosystems, which
manifest as solutions to the discrete logarithm problem for group varieties,
and the elliptic curve discrete logarithm problem in particular. We pursue
a computational approach throughout, with a focus on the development of
practical algorithms.National Research Foundatio
Extended information processing of technology education learners during the early phases of the design process
No full textThe purpose of my study was to describe the manner in which Grade 9 technology learners typically
accessed and used information sources during the early phases of their design processes. I did this
by using an Extended Cognition framework to study the internal and external information sources
that learners typically accessed and used in a technology learning environment. Theoretically, my
study aimed to develop the application of the Extended Cognition Theory in an educational
context. In this manner, my study adds to the scarce literature on design cognition in technology
education. The methodological purpose of this study was to adapt conventional Think Aloud
Protocol methods (TAPS) to investigate groups of learners in their natural technology learning
environment. This methodology enabled me to understand the link between theoretical and
empirical approaches of design cognition. As such, I was able to conceptualise practical guidelines
that could be used by technology lecturers and teachers for the effective facilitation of the early
phases of design processes.
The conceptual framework of my study was adapted from empirical studies of expert designers, and
is underpinned by the Information Processing and Embodiment theories. I followed a concurrent
mixed methods approach and employed a case study design applying pragmatic assumptions. The
target population for this study comprised Grade 9 learners based in a low socio-economic region.
Eight female participants were purposefully selected and conveniently clustered into three groups:
two groups of three participants, and one group of two participants. Data collection therefore
consisted of three separately video recorded protocol studies. I was able to elicit the information
access and usage activities of the participants by providing them with a design task that I adapted
from a prescribed textbook, as suggested for technology by the Department of Basic Education.
During the video recordings of the participants’ design processes, I was able to collect concurrent
verbal, visual and temporal data types. I analysed the data according to a five-level framework,
also adapted from the empirical investigations of expert designers.
During my quantitative data analysis, I identified the occurrences of each group of participants’
cognitive phases, as well as the occurrences of their information access and use activities during
each cognitive phase. On the one hand, problem structuring did not occur regularly. However,
during their problem structuring activities, the participants mainly accessed and used instructions
contained in the design task and pictures. On the other hand, the participants predominantly
exhibited problem solving cognitive phases in which they mainly accessed and used external
information sources including pictures and sketches. During my qualitative data analysis, I traced how the participants transformed their understanding of
the design problem and possible design solutions. During problem structuring, the participants
accessed information about the users’ needs, the design context and design objectives by
perceiving and recognising useful information in their design task instructions and pictures.
Information use during problem structuring was evidenced when the participants transformed
information that they accessed to propose design objectives, constraints and requirements.
Accessed information was typically transformed when the participants: (1) Read/evaluated
information from the design task; (2) Evaluated the problem/context; (3) Evaluated/Elaborated
information about the design objective; (4) Justified a design requirement; (5) Proposed/justified a
design constraint; (6) Evaluated/Elaborated available resources in the environment; (7) Elaborated
on the design context. During problem solving, the participants accessed information about the
function, behaviour and structure of possible design solutions by perceiving and recognising useful
information, primarily in their sketches, 3D models and pictures. Information use during problem
solving was evidenced when the participants transformed accessed information to propose design
specifications and limitations. Accessed information was typically transformed when the
participants: (1) Evaluated existing solutions; (2) Proposed design limitations; (3) Modified existing
solutions; (4) Proposed/evaluated a design idea; (5) Elaborated on a design idea; (6) Justified ideas;
(7) Qualified ideas; (8) Modified previous design ideas.
From the findings of my study, I could develop practical guidelines for current and future technology
teachers. These guidelines should help technology teachers to effectively facilitate information rich
design thinking during the early phases of learners’ design processes. I conclude this study by
reiterating that the participants’ design cognition was enhanced by the availability of various
information sources. This implies that technology teachers play a central role as information providers
and mediators. Failure to provide adequate information sources during design tasks might inhibit
learners’ development of the proficient design skills intended by the technology Curriculum and
Assessment Policy Statement (CAPS) document.National Research Foundatio
Power series expansion of the Jost function on the complex angular momentum plane
No full textThe aim of this research is to develop a method for expanding the Jost functions
as a Taylor-type power series on the complex angular momentum plane.
From this method in conjunction with the Watson transformation, we were
able to express the scattering amplitude as a sum of the background and pole
terms, furthermore, this method propose a way of evaluating, numerically,
the pole term. To demonstrate how this method may be applied, we considered
the Born approximation. We found out that the developed method
improved the Born approximation at large scattering angles. Therefore, this
method is useful when the di fferential cross section of the background term
fails to converge to that of the exact diff erential cross section at large scattering
angles.National Research Foundatio
The collaborative workshop: insights into best practices between institutions and into the NRF policies and procedures
No full textThe Grants Management and Systems Administration (GMSA) Directorate hosted its 7th annual Research Administrators Workshop (RAW) from 4 to 6 October 2016 in Polokwane. The workshop aimed to bring together key stakeholders from universities and science councils across South Africa, including international delegates, to share experiences and best practices in research administration and management
Supporting research and innovation in a limited resource setting: the case of national coomission for science and technology (Malawi)
No full textThe Grants Management and Systems Administration (GMSA) Directorate hosted its 7th annual Research Administrators Workshop (RAW) from 4 to 6 October 2016 in Polokwane. The workshop aimed to bring together key stakeholders from universities and science councils across South Africa, including international delegates, to share experiences and best practices in research administration and management
The salva rei substantia requirement in personal servitudes
No full textThe research question addressed in this dissertation is whether sufficient reasons exist for embracing a flexible approach to the salva rei substantia requirement in usufruct law. In South African law the requirement is generally approached in a rigid way, although there seems to be indications that an equitable outcome would be favoured where a usufructuary is vulnerable and subject to unreasonable treatment. A shift towards a flexible approach finds some support from comparative, policy, theoretical and constitutional considerations. Comparative law indicates that the nature of and conceptions regarding family wealth have changed to promote support of the surviving spouse. Additionally, pragmatic considerations require empowering the usufructuary to allow for the development of usufructuary property to maintain or increase its value. Theoretical arguments also support a shift to flexible rules for the sake of efficiency and sharing. As an example of governance property, usufructuary property requires flexible governance norms and coordination devices. Finally, non-property constitutional provisions require a mandatory shift to a flexible approach in certain circumstances. This shift would entail enlarging exceptions to the obligations of the usufructuary or not enforcing those obligations strictly, especially when it would result in termination of a usufruct. A shift towards greater flexibility would result in a deprivation of the bare owner’s property right, but this deprivation would not be arbitrary. Courts have the common law power to develop the law of usufruct to bring about the required shift.National Research Foundatio
Communicating your research to a non-expert audience
No full textPresentations SA PhD Project Conference: Gauteng Province 11 Otober 2016
The Desmond Tutu training programme
No full textPresentations SA PhD Project Conference: Gauteng Province 11 October 2016
An analysis of the occupational qualifications sub-framework in South Africa
No full textThe dissertation, An analysis of the Occupational Qualifications Sub-Framework in South Africa describes the South African Occupational Qualifications Sub-Framework (OQSF), one of the sub-frameworks of the South African National Qualifications Framework (NQF). The OQSF provides for occupationally-focused qualifications and serves to consolidate the South African Vocational Education and Training (VET) system within the context of the NQF. The study sets out to develop an analytical framework to guide decision makers in support of the VET system in South Africa. The Quality Council for Trades and Occupations (QCTO) is the Quality Council (QC) responsible for the OQSF and therefore much reference is given to this QC. The study examines the QCTO approach to occupational qualification development and the policy environment that the QCTO operates within that could enable the consolidation of the South African VET system. Seminal to this approach is the necessity of dialogue between the QCTO and other NQF entities including the South African Qualifications Authority (SAQA), the Council on Higher Education (CHE), the Quality Council for General and Further Education and Training (Umalusi), the Department of Higher Education and Training (DHET) and the Department of Basic Education (DBE). The primary focus of the study is the OQSF as the principal policy instrument to consolidate the South African VET system. The policy direction taken in order to ascertain whether the policies adopted in support of the OQSF does in fact lead to systemic coherence within the South African NQF and broader skills development landscape is examined. The National Skills Development Strategy (NSDS) III is the overarching strategy for skills development in South Africa and this study argues that the consolidation of the South African VET system can assist in the achievement of the goals enshrined in the NSDS III and ultimately the National Development Plan (NDP). The NSDS III focuses on the Sector Education and Training Authorities (21 SETAs currently) and the National Skills Fund (NSF). It emphasises partnerships between training institutions, SETAs and employers. The sectoral qualifications which are registered on the NQF and are utilised within the SETA landscape are on the OQSF which is the responsibility of the QCTO. The study asserts that the eight goals of the NSDS III are intrinsically linked to enabling South Africa to become a developmental state much like the East Asian states and that the consolidation of the South African VET system is an essential part of the achievement of this national objective.National Research Foundatio