This thesis is made of three self-contained essays on the agricultural sector of Tanzania, each of them focusing on an aspect of direct policy relevance. In the first essay, I study whether an inverse relationship exists between cultivated area and physical productivity (yield per acre) for a set of important annual crops. I define size as the area of a plot on which a crop is grown, thus introducing a more disaggregated level of analysis than the common plot or crop levels of analysis. I control for the existing hypotheses in the literature potentially explaining this inverse relationship and propose to control for two new hypotheses which are only testable at this level of analysis. In the second essay, I look at output marketing for a set of important crops. I stress the links between the market failure theoretical narrative and empirical applications, and argue this has resulted in less attention being paid to the reasons why farmers may enter -or not- the market for a particular crop. I estimate participation and supply equations for a set of important crops and show that the rationale for entry differs across crops. This calls for a more flexible conception of `the market'. The first two essays use the Tanzanian National Panel Surveys to conduct econometric analysis. The third essay is based on primary data collected in 2016 in order to carry analysis of the Bambara nut, an underutilised crop. Because underutilised crops hardly feature in national datasets, primary data is needed to understand their socio-economic dynamics. Focusing on the Mtwara region of Tanzania, I study the importance of Bambara for local livelihoods using a mixed-methods study based on both quantitative and qualitative data. This study contributes to the growing interest on underutilised crops and their importance in designing more sustainable agricultural strategies.

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M.Tech. / Haemostasis is an internal mechanism to stop bleeding from a damaged blood vessel. Conceptually this process occurs in a number of essential steps following tissue injury. Although the herbal preparation of Arnica montana has been well documented for its tendency to prolong bleeding, according to the Law of Similars, homeopathically prepared Arnica montana 6C is well indicated for traumatic injuries and post surgical bruising. Arnica montana 6C can be used when there is mechanical trauma that causes wounds, haemorrhages, haematomas, sore-bruised bone and muscular pains, inflammations, fractures, muscular strains and sprains. The remedy is often prescribed before and immediately after surgery to reduce post-operative pain and to speed up recuperation. Three in vitro studies conducted at the Technikon Witwatersrand (now the University of Johannesburg) on various potencies of homeopathically prepared Arnica montana showed lowered overall coagubility of blood, but no significant difference between the experimental and control groups. Bengsch (2000), Hohl (2005), Vermeulen (2000) and van Tonder (2005) recommended that studies on the effect of homeopathically prepared Arnica montana on blood coagulability be repeated in vivo. This study formed part of a three part in vivo study to determine the effect of Arnica montana homeopathic preparations on blood coagulation by measuring the Bleeding Time (BT), activated Partial Thromboplastin Time (aP'TT) and Prothrombin Time (PT). This study investigated the effect of Arnica montana 6C on these measurements. Eighty participants were allocated a participant number and randomised by the research supervisor into four groups of twenty participants. Twenty participants were in the placebo group that was shared by all three studies. Twenty participants were allocated to the experimental group for this study. The study was conducted over a period of two weeks at the University of Johannesburg (UJ) Doomfontein Campus Homeopathy Health Centre. Consenting participants were screened by means of a questionnaire (Appendix D) regarding relevant medical history and other background information. A case history was taken and a physical examination was performed. Any prospective participants that were diagnosed with and/or suffer from hypertension, hypotension, heart disease, a iii bleeding disorder, anaemia, iron or any vitamin deficiency, liver disease, malaria or are currently on aspirin or anticoagulants (Appendix D) were excluded from the study. The bleeding time was measured by a trained medical technologist using a standardised bleeding time technique. Blood samples drawn by a phlebotomist went for coagulation tests comprising of aPTT and PT at the NHLS Main Haematology laboratory of the Johannesburg Hospital. Twenty participants were given a 25mL bottle of Arnica montana 6C in 20% ethanol. Twenty participants received an identical bottle containing only 20% ethanol. All participants were requested to take ten drops twice a day for two weeks. All three coagulation test measurements were performed again at the end of the second week. The BT, PT and aPTT results were analysed by using ordinary descriptive statistics such as mean and standard deviation. Changes over time in blood coagulation were ascertained utilising ANOVA (analysis of variance). The results showed that there is no statistically significant difference between the experimental and control group in BT, aPTT and PT. There was also no statistically significant difference between the first BT, PT and aPTT before medication and the second BT, PT and aPTT after two weeks of medication. The results of the study support the hypothesis that Arnica montana 6C would have no effect on the bleeding or coagulation times in vivo. These results support the view that prescribing the remedy before surgery is not likely to increase the post surgical risk of haemorrhage

The way in which adolescents perceive themselves and interact with peers, teachers and caregivers could determine whether they would drink alcohol and smoke dagga or not. Without positive self-concept amongst adolescents and experiencing of positive communication with caregivers, it can be said, there is a likelihood of drinking alcohol and smoking of dagga by adolescents. A 52-item questionnaire was constructed on the basis of current international and South African research on the adolescents who drink alcohol and smoke dagga. The biographical data was used as independent variables in the questionnaire. These independent variables included questions on age, gender, grade and the person who takes care of adolescent. The questionnaire was completed by 443 adolescents in grade 9 and 11 from one secondary school in Soweto. Of this total, 48,1% were males (N=213) and 51,9% were females (N=230). A factor analysis of the questionnaire revealed two statistically significant constructs and they were termed “Experience of locus of control with respect to school” (Chronbach alpha of 0.900) and “Experience of communication with caregivers by adolescents (0.892). With respect to the bivariate analysis of the relationships between (1)the gender of adolescents (2)the age of adolescents and who is the caregiver to the adolescent and the (1)drinking of alcohol and the (2)smoking of dagga, the following was found: • adolescents who lived with stepparents are more inclined to drink alcohol than adolescents who lived with both mother and father, single parents and other. • a significantly higher proportion of males drink alcohol man females who drink alcohol. • a significantly higher proportion of older adolescents (17 years, 18 years and older) drink alcohol than younger adolescents (16 years, 15 years and younger). The impact of this research would indicate that adolescents with negative self-concept about themselves display a significantly greater inclination towards drinking alcohol and smoking of dagga. Also, adolescents who live with stepparents display a significantly more negative experience of drinking alcohol and smoking of dagga than adolescents who live with both mother and father, single parents and other. / Prof. C.P.H Myburgh

No description available.

A new and fast-growing group of computer users is appearing. These are professionals, managers and such like, who want to use computers in the course of their work. They have choice over their use of the computers unlike 'traditional' naive users. This discretion means that they can decide not to use a computer and this difference means that the research conducted into, and the design guidelines for, non-discretionary naive users may not be appropriate for the discretionary users.

This thesis describes a systematic investigation of the efficiency of misincorporation by Avian Myeloblastosis Virus reverse transcriptase with all possible combinations of dNTP substrate, template nucleotide, and the nucleotide at the 3' terminus of the primer. Each of a series of 16 synthetic oligonucleotide primers was annealed to single-stranded Ml3 DNA templates, and a single dNTP was misincorporated at the primer 3' end using AMV reverse transcriptase. The proportion and pattern of misincorporation and incorporation in all 64 situations were assayed using 5'-labelled primers, and the products were separated on denaturing polyacrylamide gels. Correct incorporations occurred more readily than misincorporations. The efficiency of misincorporation depended on the individual primer but, comparing primers, a clear dependence on the template nucleotide was observed for the preferential misincorporation of different dNTPs. The exact combination of template nucleotide and dNTP was important; although purine:pyrimidine (dNTP substrate: template nucleotide) and pyrimidine:purine misincorporations occurred comparatively readily, some pyrimidine:pyrimidine and purine:purine reactions were equally efficient and yet others were never seen to occur. Some misincorporations were facilitated by subsequent correct incorporations, but despite this the results suggest that the level of misincorporation is limited by the rate of reaction and enzyme inactivation rather than by exonuclease activity. The recovery of point mutants arising from reverse transcriptase-directed misincorporation of single dNTPs onto single oligonucleotide primers is described and discussed. Misincorporation of dNTPs is a form of in vitro mutagenesis which facilitates the generation of a library of point mutations spread throughout a gene. Conditions have been established in this study for the production of a bank of primers with 3' termini distributed over a region of a gene to be mutated. The misincorporation of single dNTPs onto the termini of such a bank of primers should allow the generation of a library of point mutants.

The taxonomic history of 17 British and N. W. European taxa of the Festuca ovina aggregate was reviewed. The morphology, anatomy, ecology, geographical distribution and typification of F. ovina, F. guestfalica, F. vivipara, F. lemanii, F. trachyphylla and F. brevipila was also discussed. Anatomical characters were taken from leaf-blade transverse sections and from leaf-blade epidermises and proved useful at all taxonomic ranks investigated. Gross morphological characters were generally slightly less useful although floral morphology was of great use at and below specific rank. Reliability of these characters has been assessed in cultivatio-n experiments. On the basis of morphological, anatomical, cytological, chemical and geographical evidence and with the aid of multivariant analysis and extensive hybridization studies it is concluded that the taxa studied fall into 3 species groups: the F. ovina group; the F. valesiaca group and the F. longifolia group. Hybridization at the hexaploid level more frequently produced more mature FI hybrids than did hybridizations at the tetraploid level. Hybridizations between diploid species produced the lowest numbers of mature FI hybrids. Furthermore diploid taxa were found to be more discrete morphologically than tetraploid taxa which were in turn more discrete than hexaploid taxa. It was concluded from this that the F. ovina aggregate is a polyploid pillar complex. On the basis of a wide body of evidence it was concluded that F. vivipara undoubtedly belongs to the F. ovina species group. The evolutionary relationship between this taxon with its close seminiferous relatives was also discussed.

This work examines the history of industrial fabrics and investigates how certain of these fabrics have developed to meet the changing demands of their end-uses. It also examines how woven textile fabrics are increasingly competing with the traditional engineering materials as new fibres and filaments allow an ever increasing range of properties; improved fabric engineering techniques are also ensuring that industrial fabrics are more suited to their end-uses. To aid fabric engineering a greater knowledge is required of fabric structure and mechanics, so developments in this field are examined. To help improve fabric research of this type, realistic physical testing methods are required both to test the usefulness of mathematical models, and to simulate conditions experienced in use. Due to certain restrictions of this type of testing, a suitable selective fabric extension measuring device is required so that problem areas such as clamping effects can be avoided. The. lack ofa suitable device to help overcome problems such as this has been a long standing difficulty, so the development of a new fabric extension gauge was one of the main objects of this work. Before such a device could be developed research first involved a survey of many of the previous extension measuring devices, however, as expected nothing suitable emerged. After considering many ideas for possible new devices, it was decided to try and develop a gauge using the relatively new material PVDF piezo polymer film. This is a thin, low modulus film which develops an electrical charge proportional to a CHANGE in mechanical stress, and which can be easily cut to any desired dimensions. Initial attempts to develop a suitable extension measuring device were not completely successful, but when suitable following circuitry was found, and a proper mounting procedure determined, the new gauge appeared very promising. When it was considered that a suitable extension measuring device was available, the next task involved the design of a biaxial tensile and shear testing machine for the new Clothworkers' Textile Hechanics and Structures Laboratory. It was considered that the availability of a suitable selective extension measuring device was of paramount importance before the design of the new tester could be considered. This apparatus was based essentially on, the proven principles of Yendell's and Bassett's testers, but a number of unique features were to be added, such as independently controlled clamps, and the ability to cycle in shear. The principles involved in the design of the mechanical hardware are described, as also are certain original recommendations which have been suggested for the second stage of the project in which the sophisticated control, measurement and analysis techniques will be developed.

With a multi-method research approach that involves retrospective reflection, concurrent screen-capturing (Camtasia), and key-stroke logging (Translog), this study probed Chinese-English translation processes and investigated the strategy use and pause patterns of 20 translators with different professional designations (i.e., novice, paraprofessional, and professional translators). Through the application of the Translation Competence Model (PACTE, 2007) from the Translation Studies field and of the Language Ability Model (Bachman & Palmer, 1996) from the field of Language Learner Strategies research, this study is the first of its kind to compare the differences in translators’ pause patterns in the three different translation phases (i.e., orientation, drafting, and revising phases) and strategy use, and to analyze the relationship of translators’ strategy use and pause vis-à-vis translation performance. The three types of data provided a fuller picture of translators’ translation processes, and the use of the two models served to triangulate and cross-validate the multiple sources of data on translators’ reported and observed strategy use, which amounted to 97 individual strategies and 3,464 instances. The data examined quantitatively and qualitatively showed that translators of higher professional designations or the high performance level had higher percentages in professional, psycho-physiological, bilingual, and affective strategies, and paused longer and more often and spent more time in the revising phase. However, translators of lower professional designations or the low performance level showed higher percentages in instrumental and extralinguistic strategies, and paused longer and allocated more time in the drafting phase. The analysis revealed no significant correlation between overall strategy use or pauses and translation performance. The findings inform researchers, trainers, and trainees in the professions of both translation and additional-language teaching about translation strategy use and pause patterns. / Graduate