383 research outputs found
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The Effect of Cyclic Loading on the Wicking Performance of Nylon 6.6 Yarns and Woven Fabrics Used for Outdoor Performance Clothing
No full textThe effects of short interval dynamic
loading and unloading on yarn and fabric wicking performance were evaluated at different cyclic load ranges using the conventional extension recovery method on a modified Instron Tensile Tester. This was based on the principle that during use, the constituent yarns in a fabric are continuously stressed and relaxed as the garment shape changes. Results showed that the straining forces generated between the filaments of the yarns resulted in spasmodic pumping of the liquid which was dependent on the yarn and fabric construction,contact between the yarns, volume of liquid in yarns, and duration of the force applied
On the Radiation Problem of High Mass Stars.
No full textA massive star is defined to be one with a mass greater than 8 - 10M .
Central to the on-going debate on how these objects [massive stars] come into being is
the so-called Radiation Problem. For nearly forty years now, it has been argued that the
radiation field emanating from massive stars is high enough to cause a global reversal of
direct radial in-fall of material onto the nascent star. We argue that only in the case of
a non-spinning isolated star does the gravitational field of the nascent star overcome the
radiation field. An isolated non-spinning star is a non-spinning star without any circumstellar
material around it, the gravitational field beyond its surface is described exactly
by Newton?s inverse square law. The fact that massive stars should have their gravitational
field being much stronger than their radiation field is drawn from the analysis of
an isolated massive star, where in this case the gravitational field is much stronger than
the radiation field. This conclusion is erroneously extended to the case of massive stars
enshrouded in gas & dust. We find that, for the case of a non-spinning gravitating body
where we take into consideration the circumstellar material, that at 8 - 10M , the
radiation field will not reverse the radial in-fall of matter but a stalemate between the radiation
and gravitational field will be achieved ? i.e., in-fall is halted but not reversed. This
picture is very different from the common picture that is projected and accepted in the
popular literature that at 8 - 10M , all the circumstellar material ? from the surface
of the star, right up to the edge of the core; is expected to be swept away by the radiation
field. We argue that massive stars should be able to come into being if the molecular core
from which they form exhibit some rotation because a rotating core exhibits an ASGF
which causes there to be an equatorial accretion disk and along this equatorial disk, the
radiation field can not be much stronger than the gravitational field hence this equatorial
accretion disk becomes the channel via which the nascent massive star accretes all of its
material.Supported by the Republic of South Africa?s National Research Foundation and the North West University, and Germany?s
DAAD Programme via the University of K?oln
Substance abuse in the Western Cape Province of South Africa: insights through mathematical modelling
No full textEvaluation of the microbial quality of water supplies to municipal,mining and squatter communities in the Bindura urban area of Zimbabwe, in relation to incidences of specific enteric diseases.
No full textA survey of the microbiological and chemical quality of water supplies in the Bindura urban and peri-urban area was carried out over a three year period from January 2000 to July 2003. Bindura is the provincial city of Mashonaland Central, situated 88 km from the national capital, Harare. Large-scale farming and mining activities in the area predispose water bodies to eutrophication and chemical pollutants raising concerns about the safety of local water supplies . In this study , thermotolerant (faecal) coliform levels, total aerobic bacterial counts and physicochemical profiles were determined for municipal and borehole water as well as water supplies to mining and squatter communities. Although municipal and mining compound water supplies were of satisfactory microbial and chemical quality, borehole water supplies showed a seasonal fluctuation with higher coliform counts in the wet season from November to March. Stream water supplies to a squatter camp in the peri-urban area consistently recorded coliform levels greater than 1800 per 100 ml and total aerobic plate counts of up to 2.8 x 106 cfu/ml. All cholera incidents recorded in 1999 and 2000 at the Provincial hospital were from peri-urban settlements and surrounding commercial farms while 1045 to 2 632 cases of Dysentery were also reported each year at the Provincial Hospital during the period 1997- 2002
Research and Development capacity building at Higher Academic Institutions as an innovative solution to enhance economic growth: A case for NUST in Zimbabwe.
No full textProceedings of the 4th Engineers Without Borders International Conference, Victoria Falls, Zimbabwe, 10th ? 14th November 2010.Countries that are innovative and engage in massive Research and Development (R&D)
activities are emerging as super economies. The purpose of this paper is to highlight the
great untapped potential contribution to economic growth through R&D by departments at
universities. Literature review on R&D was undertaken and used as a basis for introducing summary of examples of research case studies that have been done. There is need for organizations to be innovative, to research and to develop new products, processes and systems. What worked for us 20 years ago will not work for us today and in the future. ?Products are born; they live, and they die?. The challenge is to have products that are always alive and fetching money for the organization besides negative influence by factors such as economical, sociological, technological and political changes. This paper outlines an opportunity for breaking away from the traditional way of doing things through fully utilizing
the potential that lies within institutions of higher learning. It highlights one such
involvement by the Department of Industrial and Manufacturing Engineering at the National
University of Science and Technology (NUST) in Zimbabwe through students, lecturers and
research staff. Organizations lack the ingredients for catching up with the pace of technology advancement because they do not have dedicated resources for R&D. New product
development and process improvements are not being done through ?focused teams? but are
embedded in other operations functions. The many universities and colleges in Zimbabwe
have unutilized capacity for innovation, research and development but face a multitude of challenges. The paper concludes with an R&D proposed model for universities, industry and commerce that can enhance utilization of universities in R&D
Integrating Information Ethics in Library and Information Science Curricula in Zimbabwe
No full textCountry Report presented at a Teaching Information Ethics in Africa Conference held at the University of Botswana, 6 ? 7 September 201
Using Mathematics to Understand Malaria Infection During Erythrocytic Stages
No full textWe review the basic intra-host model of malaria, without immunity. The model describes the Erythrocytic stage in a malaria infected human, which involves the interaction between malaria parasites and red blood cells. These two populations interact on a dynamic landscape, in which a population of replicating parasites depletes a population of replenishing red blood cells. This paper shows how concepts from nonlinear dynamics can be used to unravel the underlying dynamical features of the model. The intra-host basic reproductive number R0, crucial to calculations concerning control of the infection is
calculated. Using mathematical analysis of stability, conditions necessary for reducing
and/or clearing parasites in the host are determined. Numerical simulations are also
performed to verify analytic results and illustrate possible behaviour of the model
Oxidative stress associated with nematode infections in sheep: a preliminary study
No full textA hundred and seven sheep slaughtered at the Cold Storage Company (CSC) in Bulawayo, were
examined for nematode parasite infections using coporological methods. Direct smear and salt floatation methods were used to observe nematode parasite eggs. Nine sheep were found to be infested with nematode eggs only. Nine uninfected sheep were used as controls. Liver samples collected from the infected and noninfected sheep were used for assays of the antioxidant enzymes, glutathione peroxidase (GPX) and diphosphotriphosho-diaphorase (DTD) as well as the intermediary metabolic enzyme,succinate dehydrogenase (SDH). Lipid peroxidation was assayed by determining malondialdehyde (MDA) levels.
Significantly higher GPX activities were observed in infected sheep when compared with non- infected sheep (p < 001). No difference in the activity of DTD was observed in both infected and non-infected sheep (p>0.05). Parasitic infection resulted in significant reduction in SDH activity (p <0.05) and significantly higher MDA levels (p < 0.01). This study suggests that parasitic infections induce oxidative stress
The Role of Foods of Animal Origin in Human Nutrition and Health
No full textBook Chapter from the book:The Role of Livestock in Developing Communities: Enhancing Multifunctionality by Frans Swanepoel, Aldo Stroebel and Siboniso MoyoIn poor developing communities, livestock serve many functions including supply of food, fibre and draught power, income generation and enhancement of social status. The relationship among animal-source foods and human nutrition and health is complex and involves both positive and negative trade-offs and outcomes. The positive outcomes are mostly through their addressing malnutrition by supplying the essential nutrients that are lacking in plant-source foods. Among these are micronutrients such iron, zinc, vitamin B-12, riboflavin and conjugated linoleic acids. In addition, supplementing the diet of pregnant women and children with foods of animal origin has resulted in improved maternal, foetal and child health outcomes such as successful births, reduced maternal mortality, increased prenatal growth rates and improved cognitive functions. There are potential risks associated with (over) consumption of foods of animal origin such as increased risks of cardiovascular diseases, diabetes and obesity. However, at moderate levels of intake, foods of animal origin do not pose such threats and recent research indicates that they may actually be beneficial in reducing these diseases. Livestock?s potential contribution to environmental pollution and to total greenhouse gas emissions is recognised, but it is limited in the production systems available to poor communities where the nutritional and health benefits that accrue from consumption of foods of animal origin greatly outweigh the danger posed by livestock. Increasing the production of foods of animal origin at household level and linking this increased production to nutrition and the health of mothers and children is thus recommended for developing communities
High Temperature Creep Measuring Apparatus
No full textA high temperature creep measuring apparatus capable of operating over a wide range of
temperatures, humidities and stress levels was developed. To assess its reliability, the
apparatus was used to measure the creep behaviour of nylon6.6 tyre materials, under
different temperature and humidity operating modes. At all operating conditions, cords
exhibited instantaneous extensions on loading followed by steady creep over time with an eventual failure. The results obtained using the apparatus tallied well with results by other researchers, and this indicates that the apparatus can be used as a reliable measuring instrument