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Modelling the sustainable harvest of Sclerocarya birrea subsp. caffra fruits in the South African lowveld

  • Authors: Emanuel, P L , Shackleton, Charlie M , Baxter, Jeremy
  • Date: 2005
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/181312 , vital:43718 , xlink:href="https://doi.org/10.1016/j.foreco.2005.03.066"
  • Description: Levels of commercialization, size class profile and fruit production of Sclerocarya birrea (marula) trees were studied in the Bushbuckridge region of South Africa. A stage-based population matrix model was used to estimate the sustainable yield for S. birrea fruit. The trees begin to bear fruit at an average size of 42.8 cm in circumference and this relates to an approximate age of 19 years. For a stable size class profile, the population growth rate, λ, was 1.1828758. The observed size class profile did not conform to the stable stage size class profile, obtained from the model. Thus, it was not possible to predict the state of the observed population. Using the model, it was estimated that 92% of fruit could be removed without impacting the current population profile. The management of other more destructive forms of S. birrea resource use (such as bark or firewood harvesting), however, do need to be monitored to limit negative impacts on the population that may reduce fruit availability for regeneration or cropping.
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  • Date Issued: 2005

Monetary valuation of livelihoods for understanding the composition and complexity of rural households

  • Authors: Dovie, Delali B K , Witkowski, Ed T F , Shackleton, Charlie M
  • Date: 2005
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/181346 , vital:43721 , xlink:href="https://doi.org/10.1007/s10460-004-7233-0"
  • Description: There is, at present, little precise understanding of the relative contributions of the various income streams used by impoverished rural households in southern Africa. The impact of household profiles on overall income also is not well understood. There is, therefore, little consideration of these factors in national economic accounting. This paper is an attempt to reduce this gap in knowledge by reflecting on the relative contribution of agro-pastoralism, secondary woodland resources, and formal and informal cash income streams to households in the semi-arid rural village of Thorndale, Limpopo Province, South Africa. In the absence of jobs and confronted with high migrant labor, households with open access to natural resources derived more benefits from land-based livelihoods than cash income streams (i.e., 57.5 % vs. 42.5 %). Total livelihood income was valued at US$2887 per household per annum. A significant correlation between monetary values derived from crops and formal wages was established, and it was found that households with high cash incomes tended to invest more in crop production. Over 80 of households were male-headed. Of these heads of household, more than 60 were long-term migrants to urban areas, leaving household decision-making to the women. The low literacy rates of women have deprived them of paid jobs outside the area and, therefore, have increased their dependence on crops (62%) and secondary woodlands resources (60%). This was further reflected in the proportion of households in which females were the main contributors of cash income (9.7%), or joint contributors with men (24.4%). Various positive correlations were established between the number of women per household and the three land-based livelihoods. This implied that women’s total control over such activities was mostly a result of the absence of men and not a typical phenomenon. In spite of this control, it was not positively reflected in the lives of majority of the women. Households differed in their participation in livelihood activities. Household size influenced the level of production and was positively correlated with the value of secondary woodland resources and crops. The study shows the interdependence of land-based livelihood sources and the impact of household features on production and consumption. Policies that focus on livelihood options need to recognize and accommodate associated household dynamics.
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  • Date Issued: 2005

Monitoring the oceanic flow between Africa and Antarctica: report of the first Good Hope cruise

  • Authors: Ansorge, Isabelle J , Speich, S , Lutjeharms, Johan R E , Goni, G J , Rautenbach, C J de W , Froneman, P William , Rouault, M , Garzoli, S
  • Date: 2005
  • Language: English
  • Type: Article
  • Identifier: vital:6832 , http://hdl.handle.net/10962/d1007568
  • Description: The Southern Ocean plays a major role in the global oceanic circulation, as a component of the Meridional Overturning Circulation, and it is postulated that it has a great influence on present-day climate. However, our understanding of its complex three-dimensional dynamics and of the impact of its variability on the climate system is rudimentary. The newly constituted, international GoodHope research venture aims to address this knowledge gap by establishing a programme of regular observations across the Southern Ocean between the African and Antarctic continents. The objectives of this programme are fivefold: (1) to improve understanding of Indo-Atlantic inter-ocean exchanges and their impact on the global thermohaline circulation and thus on global climate change; (2) to understand in more detail the influence these exchanges have on the climate variability of the southern African subcontinent; (3) to monitor the variability of the main Southern Ocean frontal systems associated with the Antarctic Circumpolar Current; (4) to study air-sea exchanges and their role on the global heat budget, with particular emphasis on the intense exchanges occurring within the Agulhas Retroflection region south of South Africa, and (5) to examine the role of major frontal systems as areas of elevated biological activity and as biogeographical barriers to the distribution of plankton. We present here preliminary results on the physical and biological structure of the frontal systems using the first GoodHope transect that was completed during February-March 2004.
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  • Date Issued: 2005

Motopomo: the historical-theoretical background to contemporary graphic design practices

  • Authors: Economou, Inge
  • Date: 2005
  • Subjects: Graphic arts , Graphic arts -- 20th century , Modernism (Art)
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:10764 , http://hdl.handle.net/10948/179 , Graphic arts , Graphic arts -- 20th century , Modernism (Art)
  • Description: This study proposes to illustrate that the twentieth century passage from modernity to postmodernity, with its induction of socio-cultural development and attitudinal change, exists as a fundamental means of informing the character of contemporary graphic design practice1. Today, in contrast to the intentions of this study, many appraisals of graphic design work would seem to place too much emphasis on the analyses and evaluation of the stylistic character of creative practices and not enough on the theoretical, historical and attitudinal issues surrounding them. As such, this study attempts to reveal the meaning and moreover the relevance of philosophical, social, cultural and critical theory for contemporary, postmodern graphic design practices. This is done in order to provide graphic designers with a reflective awareness of the structure of the cultural context within which they work, and takes into account twentieth century cultural theory and twentieth century, western graphic design practice, within the framework of the passage from modernity to postmodernity.
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  • Date Issued: 2005

Msawawa

Multivariate analysis of honeybees, Apis mellifera Linnaeus (Hymenoptera: Apidae) of the northeastern and southern regions of Algeria.

  • Authors: Barour, C , Tahar, A , Radloff, Sarah E , Hepburn, H Randall
  • Date: 2005
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/451976 , vital:75092 , https://hdl.handle.net/10520/EJC32628
  • Description: Morphometric characters of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to characterize their populations in the northeastern and southern regions (ecological-climatological zones) of Algeria, from 36°55' to 32°25'N and 3°39' to 8°22'E. Three morphoclusters were identified by using principal components and linear discriminant analyses. The bees are identified as Apis mellifera intermissa Buttel-Reepen.
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  • Date Issued: 2005

Multivariate morphometric analysis of Apis cerana of southern mainland Asia

  • Authors: Hepburn, H Randall , Radloff, Sarah E , Hepburn, Colleen , Fuchs, S , Otis, G W , Sein, M M , Aung, H L , Pham, H T , Tam, D Q , Nuru, A M , Ken, T
  • Date: 2005
  • Language: English
  • Type: Article
  • Identifier: vital:6906 , http://hdl.handle.net/10962/d1011859
  • Description: Multivariate morphometric analyses were performed on a series of worker honeybees, Apis cerana, representing 557 colonies from all of southern mainland Asia extending from Afghanistan to Vietnam south of the Himalayas. Scores from the principal components analysis revealed five statistically separable but not entirely distinct morphoclusters of bees: (1) the Hindu Kush, Kashmir, N. Myanmar, N. Vietnam and S. China; (2) Himachal Pradesh region of N. India; (3) N. India, Nepal; (4) central and S. Myanmar and Vietnam, Cambodia, Thailand, S. China and peninsular Malaysia; (5) central and S. India. The major morphoclusters are distributed coherently with the different climatic zones of the region. While populations are definable, nomenclatural adjustments remain for the future.
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  • Date Issued: 2005

Ndihamba ndodwa

Ndiyahamba mna

Ndiyathakatha ngemfene katata

Ndiyathakatha ngemfene katata

Ndiyathakatha ngemfene katata

Ndiyawoyik' amapolisa

Nomathotholo

Nomutile ndikwenzeni

Not all J domains are created equal: implications for the specificity of Hsp40-Hsp70 interactions

  • Authors: Hennessy, Fritha , Nicoll, Willam S , Zimmerman, Richard , Cheetham, Michael E , Blatch, Gregory L
  • Date: 2005
  • Language: English
  • Type: Article
  • Identifier: vital:6487 , http://hdl.handle.net/10962/d1006270 , http://dx.doi.org/10.1110/ps.051406805
  • Description: Heat shock protein 40s (Hsp40s) and heat shock protein 70s (Hsp70s) form chaperone partnerships that are key components of cellular chaperone networks involved in facilitating the correct folding of a broad range of client proteins. While the Hsp40 family of proteins is highly diverse with multiple forms occurring in any particular cell or compartment, all its members are characterized by a J domain that directs their interaction with a partner Hsp70. Specific Hsp40-Hsp70 chaperone partnerships have been identified that are dedicated to the correct folding of distinct subsets of client proteins. The elucidation of the mechanism by which these specific Hsp40-Hsp70 partnerships are formed will greatly enhance our understanding of the way in which chaperone pathways are integrated into finely regulated protein folding networks. From in silico analyses, domain swapping and rational protein engineering experiments, evidence has accumulated that indicates that J domains contain key specificity determinants. This review will critically discuss the current understanding of the structural features of J domains that determine the specificity of interaction between Hsp40 proteins and their partner Hsp70s. We also propose a model in which the J domain is able to integrate specificity and chaperone activity.
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  • Date Issued: 2005

Nowinile uyathand' indoda

On the growth and characterisation of AIGaN alloys for optoelectronic applications

  • Authors: James, Grant Robert
  • Date: 2005
  • Subjects: Gallium nitride -- Electric properties , Photoluminescence
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/8824 , vital:26433
  • Description: In this study the growth and characterisation of undoped and Si-doped AlxGa1-xN has been performed. The layers were grown using low-pressure metalorganic vapour phase deposition (MOCVD) on sapphire substrates. The optical and electrical properties of the AlxGa1-xN layers were studied using variable temperature Hall effect and photoluminescence measurements. AlxGa1-xN layers were grown over the entire composition range. Room temperature ultraviolet (UV) transmission measurements showed that the material quality was very good for layers with an Al content, x, of 0 _ x _ 0.5. However, the quality of layers of higher composition was seen to rapidly decrease with increasing x. The electrical and optical properties of AlxGa1-xN with x < 0.5 were also good, comparable to those reported on in literature. The study of the Si-doping of AlxGa1-xN was performed in two parts; firstly a series of Al0.23Ga0.77N samples was grown in which the doping level was increased from zero to n _ 3 × 1018 cm-3. A similar, albeit a less rigorous, study was performed for Al0.41Ga0.59N and Al0.5Ga0.5N. A second series of samples was then grown in which the doping level was kept constant, while the Al content was incrementally increased. Room temperature Hall effect measurements performed on Si-doped Al0.23Ga0.77N showed that the electron concentration did not scale linearly with the silane flow, as was the case in GaN. It was also seen that the electron mobility of the layers increased with slight Si-doping, possibly due to an improvement in the crystalline quality and/or a change in the conduction mechanism. It was also found that at higher compositions (x = 0.41 and 0.50) an increase in the doping level resulted in an increase in the mobility. Variable temperature Hall effect and photoluminescence measurements, performed on the Al0.23Ga0.77N samples, revealed a good correlation between the first PL activation energy E1 and the donor activation energy ED, prompting the conclusion that the first PL recombination channel in AlxGa1-xN is due to the delocalisation of excitons bound at neutral Si donors. Furthermore, E1 and ED were seen to decrease with n1/3, as is the case for GaN and other semiconductor materials. It was also observed that strong exciton localisation occurs in slightly Si-doped material, with the amount of localization becoming less at higher doping levels. Possible mechanisms responsible for the second PL recombination channel of activation energy E2 were also proposed. The electrical and optical properties of the second set of AlxGa1-xN samples was then studied. The PL properties of undoped AlxGa1-xN were typical of a homogeneous alloy system, with the increase in the PL FWHM and exciton localisation energies with x following the trend predicted by alloy disorder theory. The variation of the band gap energy with the Al content could not, however, be fitted over the entire composition range using a single bowing parameter. It was proposed that this was due either to an effect of the 9 7 valence band crossover, or due to exciton localisation at alloy disorder and/or impurities. As was the case for GaN and Al0.23Ga0.77N, all undoped material was highly resistive. As was mentioned earlier, the exciton localisation energies increased according to alloy disorder theory in undoped AlxGa1-xN. In the doped samples, however, a large increase in the donor localisation energy was measured for x > 0.3. The possibility that Si could become a DX-centre in AlxGa1-xN was then investigated. However, Hall effect measurements showed that the Si activation energy increased in good agreement with the model of a shallow effective mass state donor, with no sudden increase in ED being observed up to x = 0.4. It was then suggested that the increase in the E1 and E2 activation energies, as well as the exciton localisation energies, could be due to the 9 7 valence band crossover, which occurs at roughly the same composition. However, due to the scarcity of reports on the valence band structure in AlxGa1-xN no conclusions could be made at this stage as to the effect of the 9 7 valence band crossover on the PL properties of AlxGa1-xN.
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  • Date Issued: 2005

Operationally defining sexual orientation : towards the development of a fundamental measure of adolescent sexual responsiveness variations

  • Authors: Heath, Lance Julian
  • Date: 2005
  • Subjects: Sexual orientation Homosexuality Psychometrics Teenagers--Sexual behavior
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:1681 , http://hdl.handle.net/10962/d1003564
  • Description: Much published work has pointed to the need for the development of a sound operational definition of sexual orientation in order to enable the research in this area to progress. To contribute to this process the current research set out to develop two measures of sexual orientation and examine their psychometric properties. In order to develop relevant tools historical, conceptual and operational definitions of sexual orientation were critically examined and standard questionnaire development techniques applied. The first scale consisted of 32 items and was administered to a total of 835 adolescents, comprising three sub-groups (189 Grade 11 Scholars, 547 First Year and 99 Third Year Psychology Students). A Cronbach alpha coefficient of 0.85 was calculated indicating that this instrument had very good internal consistency reliability. Similar factors emerged in each of the sample sub-groups when factor analyses were performed suggesting that this instrument has good external and construct validities. These factors each had respectable Cronbach alpha coefficients indicating their own internal consistency. The four factors which consistently emerged were Same Sex Responsiveness, Opposite Sex Responsiveness, Previous Month’s Same Sex Responsiveness and Previous Month’s Opposite Sex Responsiveness. The second scale consisted of 16 items and was administered to 646 adolescents, comprising the latter two sub-groups referred to above. A Cronbach alpha coefficient of 0.82 was calculated indicating that this instrument also had very good internal consistency reliability. Once again similar factors with generally good internal consistency emerged in factor analysis suggesting that this too was a valid instrument. The factors that emerged from the second scale were Same Sex Responsiveness, Unattractive Opposite Sex Responsiveness, Attractive Opposite Sex Responsiveness and Attraction. Future developments, adjustments and applications of the instruments as well as implications for the arena of sexual orientation research are discussed. In the light of the dearth of information with regard to the sexual orientations of South African adolescents the current study also briefly explored and presented the sample’s responses in terms of the dimensions of each questionnaire as well as how each emerging factor related to the demographics (education level, gender, sexual orientation self-label and age) of the sample.
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  • Date Issued: 2005

Optimising the material distribution process for the southern region of Telkom SA

  • Authors: Naicker, Kosalin Ganasen
  • Date: 2005
  • Subjects: Business logistics -- South Africa , Telecommunication -- South Africa
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: vital:8547 , http://hdl.handle.net/10948/407 , Business logistics -- South Africa , Telecommunication -- South Africa
  • Description: Most government owned telecommunication operators across the world have to deal with a number of regulatory, technology and service challenges, as the industry is liberalised in co-ordinance with worldwide trends. Telkom SA will be facing a number of strategic challenges that will test its ability to survive as a telecommunications company over the next number of years. To remain competitive, Telkom must develop strategies to assure survival in a competitive environment. To assure the long-term survival of Telkom SA when moving into a competitive environment, the organisation must build a sustainable competitive advantage. In the face of increasingly fierce competition, the adoption of collaborative alliances between firms is becoming more and more common and the adoption of a world-class supply chain will be an ideal scenario for Telkom SA. A worldclass supply chain goes beyond the scope of the internal operations of an organisation, therefore the material distribution process was chosen for this study, which involved the internal operations in the organisation. The study included the availability of material up to the transportation of the material to the staging areas. The aim of this research was to identify the inefficiencies of the material distribution process of the Southern Region of Telkom SA to become worldclass. A quantitative technique was used to identify the inefficiencies. It was found that the availability and transportation of material were the inefficient categories, preventing the customer to receive the product or service on time. Communication, inaccurate forecasting and inefficient transportation of material were some of the reasons for not delivering material on time. Some of the recommendations included developing a model that could overcome the current inefficiencies in transportation, improving the communication channels, training and the development of employees at all levels.
  • Full Text:
  • Date Issued: 2005
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