Transformation of Nicotiana tabacum cv. Samsun with melanin and indigo genes

Please read the abstract in Chapter 6: Summary, of this documentDissertation (MSc (Genetics))--University of Pretoria, 2005.Geneticsunrestricte

Measuring monopole and dipole polarizability of acoustic meta-atoms

We present a method to extract monopole and dipole polarizability from experimental measurements of two-dimensional acoustic meta-atoms. In contrast to extraction from numerical results, this enables all second-order effects and uncertainties in material properties to be accounted for. We apply the technique to 3D-printed labyrinthine meta-atoms of a variety of geometries. We show that the polarizability of structures with shorter acoustic path length agrees well with numerical results. However, those with longer path lengths suffer strong additional damping, which we attribute to the strong viscous and thermal losses in narrow channels

Transient gene expression assays in rose tissues using a Bio-Rad Helios® hand-held gene gun

Rose tissues of different varieties were transformed using a Bio-Rad Helios® hand-held biolistic gun. Parameters for optimum transient expression were optimized and included rose variety, flower age, tissue, gold particle size, DNA loading ratio. Smooth flowers without thick waxy layers and young unopened actively growing flowers were found to be better suited for the transient expression assays. The DNA amounts, gold particle amounts and size etc were not found to influence the efficiency of the transient transformation in these tissues. These studies indicate that biolistic transformation using hand-held guns can be used for successful transient expression assays in rose flower tissues. This is especially useful for a quick and easy analysis of genes and their expression before attempting stable transformation.http://www.elsevier.com/locate/saj

Transient gene expression assays in rose tissues using a Bio-Rad Helios® hand-held gene gun

Rose tissues of different varieties were transformed using a Bio-Rad Helios® hand-held biolistic gun. Parameters for optimum transient expression were optimized and included rose variety, flower age, tissue, gold particle size, DNA loading ratio. Smooth flowers without thick waxy layers and young unopened actively growing flowers were found to be better suited for the transient expression assays. The DNA amounts, gold particle amounts and size etc were not found to influence the efficiency of the transient transformation in these tissues. These studies indicate that biolistic transformation using hand-held guns can be used for successful transient expression assays in rose flower tissues. This is especially useful for a quick and easy analysis of genes and their expression before attempting stable transformation.http://www.elsevier.com/locate/saj

Development and testing of a transcatheter heart valve with reduced calcification potential

IntroductionPatients from developing countries who require heart valve surgery are younger and have less access to open heart surgery than those from developed countries. Transcatheter heart valves (THVs) may be an alternative but are currently unsuitable for young patients because of their inadequate durability. We developed and tested a THV utilizing two new types of decellularized bovine pericardial leaflets in an ovine model.MethodsThe two decellularized tissues [one with a very low dose (0.05%) of monomeric glutaraldehyde (GA) fixation and detoxification (DF) and the other without glutaraldehyde (DE)] were compared to an industry standard [Glycar—fixed with the standard dose (0.625%) of glutaraldehyde]. THVs were manufactured with the three tissue types and implanted in the pulmonary position of nine juvenile sheep for 180 days. Baseline and post-explantation evaluations were performed to determine the hemodynamic performance of the valves and their dynamic strength, structure, biological interaction, and calcification.ResultsHeart failure occurred in one animal due to incompetence of its Glycar valve, and the animal was euthanized at 158 days. The gradients over the Glycar valves were higher at the explant than at the implant, but the DE and DF valves maintained normal hemodynamic performance throughout the study. The DF and DE tissues performed well during the mechanical testing of explanted leaflets. Glycar tissue developed thick pannus and calcification. Compared to Glycar, the DF tissue exhibited reduced pannus overgrowth and calcification and the DE tissue exhibited no pannus formation and calcification. All tissues were endothelialized adequately. There was a striking absence of host ingrowth in the DE tissue leaflets, yet these leaflets maintained integrity and mechanical function.ConclusionIn the juvenile sheep THV model, Glycar tissue developed significant pannus, calcification, and hemodynamic deterioration. Using a very low dose of monomeric GA to fix the decellularized bovine pericardium yielded less pannus formation, less calcification, and better hemodynamic function. We postulate that the limited pannus formation in the DF group results from GA. Bovine pericardium decellularized with our proprietary method resulted in inert tissue, which is a unique finding. These results justify further development and evaluation of the two decellularized tissue types in THVs for use in younger patients

Alcohol and mental health: co-occurring alcohol use and mental health disorders

There is a strong link between alcohol use and mental health, yet research often fails to provide a comprehensive understanding of the complex interaction between the two aspects. In relation to treatment, alcohol and mental health services often work in a disjointed manner; likewise, policies and guidelines for the two sectors are generally developed in isolation from one another. The result of this silo mentality is that the needs of individuals with comorbid alcohol and mental health disorders, commonly referred to as “Dual Diagnosis”, are often unmet, leading to serious harmful consequences for the affected individuals, their families and society as a whole. This generates further stigma and isolation for an already vulnerable and high-risk population. The present Chapter provides an overview of the epidemiology, and the main etiological theories of co-occurring Alcohol Use Disorders (AUD) and Mental Health Disorders (MHD). It is hoped that this chapter can inform treatment and policies for this population

Die heffing van indirekte belasting in Suid-Afrika

M.Com. (Business Management)This study examines the system of value-added tax as replacement for the retail sales tax which is currently in operation in South Africa. It furthermore sets out to provide an insight into the potential local application thereof. The following aspects were discussed: (a) The current state of indirect taxation in South Africa under the retail sales tax regime. (b) The origin and development of the value-added tax system worldwide. (c) The replacement of indirect taxes through a system of tax on value added. (d) The development of value-added tax subsequent to the initial recommendation by the Margo commission. (e) A number of problem areas specifically relating to the structure of the proposed tax, e.g. foodstuffs, farming activities and capital goods. (f) The establishment of a clearing mechanism for the BLS and TBCV countries in a Southern African Customs Union. (g) General administrative provisions under a value-added tax and a proposed audit under the system. The discussion indicates that the retail sales tax is not conforming to initial objectives (at least in theory) and the government is of the opinion that value-added tax will rectify this situation..

Entrepreneurial self-efficacy, intrinsic motivation, and entrepreneurial intention as antecedents of nascent necessity-entrepreneur business start-up behaviour in South Africa: a longitudinal study.

This research examines the inter-relationships among entrepreneurial self-efficacy, intrinsic motivation, and entrepreneurial intention as antecedents to entrepreneurial start-up behaviour. The research participants were South African nascent necessity-entrepreneurs. Theoretical foundations for the research are derived from Ajzen’s (1991) theory of planned behaviour. The research design involved a repeated measures longitudinal study over 4.5 years that included an entrepreneurship training, mentoring, and incubation intervention program. This was introduced during the first 12-months of the study. Repeated measures of the variables of interest were collected at T₁ (baseline), T₂ (immediately at the end of the 12-month entrepreneurship intervention program), and T₃ (end-of-study). A structural model comprised of the variables of interest was developed and structural equation modelling (SEM) was used to analyse the data. The research questions addressed centred upon the extent to which entrepreneurial self-efficacy, intrinsic motivation, and entrepreneurial intention were inter-related and the extent to which they contributed toward nascent necessity-entrepreneur entrepreneurial start-up behaviour. The longitudinal nature of the research allowed for an understanding of the dynamic nature of the variables of interest over the three points where measurements were taken. This was important since changes in the means of the three antecedent variables were observed to various degree immediately after the entrepreneurship training, mentoring, and incubation intervention program (T₂) and at the end-of-study (T₃) - compared to T₁ and T₂. These changes highlighted the shortcomings in cross-sectional studies where variables of interest are known to be unstable over time. While previous studies have examined the inter-relationships among entrepreneurial self-efficacy, entrepreneurial intention, and entrepreneurial start-up behaviour, this research adds to current theory by examining to what extent intrinsic motivation is an important antecedent contributor (along with entrepreneurial self-efficacy) to entrepreneurial behaviour. It also makes a contribution to theory by examining the variable interrelationships in a South African nascent necessity-entrepreneur context (other entrepreneurial intention studies have focused on opportunity-oriented entrepreneurs). The research makes a contribution to practice by providing insights into the design, development, and delivery of effective entrepreneurial training, mentoring, and incubation programs. The research also provides valuable insights for policy makers in the framing of policy aimed at stimulating the entrepreneurial training of nascent necessity-entrepreneurs as a means of assisting them in the new venture creation process.Thesis (Ph.D.) -- University of Adelaide, Entrepreneurship, Commercialisation and Innovation Centre (ECIC), 201

Indigenous nascent entrepreneur self-efficacy and perceived individual success

Considerable research has examined the relationship between entrepreneurial self-efficacy (ESE) and performance. ESE refers to the strength of the individuals' beliefs that they are capable of successfully performing the roles and tasks of entrepreneurs. Whereas prior ESE research has a non-Indigenous focus, this study addresses a gap in the literature by examining the relationship between ESE and perceived individual success in Indigenous nascent entrepreneurs. Whereas entrepreneurship from a non-Indigenous perspective is focused upon the commercialization of innovation and economic objectives, Indigenous entrepreneurship has both economic and non-economic objectives as desired outcomes. The research identified entrepreneurial experience- ESE and ESE-perceived individual success relationships. Education was inversely related to entrepreneurial experience