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Information And Knowledge Management And Access To Information
No full textPaper presented at the Zimbabwe University Libraries Consortium International Conference held at the Crowne Plaza Monomatapa Hotel, Harare, Zimbabwe from April 24 to 26,2006
On a New 4-Vector Cosmological Field Theory.
No full textThe original Dirac Equation is modified in the simplest imaginable and
most trivial manner to include a universal 4-Vector Cosmological Field term in the space and
time dimensions. This cosmological field leads to a modified Dirac Equation capable of
explaining why the Universe appears to be made up chiefly of matter. It is seen that
this 4-Vector Cosmological Field is actually a particle field and this particle field can possibly
be identified with the darkmatter and darkenergy field. Further, this 4-Vector Cosmological
Field is seen to give spacetime the desired quantum mechanical properties of randomness.
Furthermore, it is seen that in the emergent Universe, the position coordinates of a particle
in space ? contrary to the widely accepted belief that the position of a particle in space
has no physical significance, we see that that opposite is true ? namely that the position
of a particle has physical significance. We further note that the 4-Vector Cosmological Field
modification to the Dirac Equation leads us to a vacuum model redolent but differrent
from that of Quantum Electrodynamics (QED). This new vacuum model is without virtual
particles but darkparticles. We dare to make the suggestion that these darkparticles may
possibly explain the current mystery of what really is darkmatter and darkenergy.North-West University -Potchefstroom Campus,
School of Physics - Unit for Space Research
Nutritive value of Acacia tree foliages growing in the Limpopo Province of South Africa
No full textAcacia trees form the third largest woody plant family in southern Africa and are an important ecological component of the bushveld vegetation that is prevalent in the Limpopo Province of South Africa. The purpose of the study was to determine types and amounts of tannins and also to evaluate the nutritive value of tree foliages, Acacia karroo, Acacia nilotica, Acacia tortilis, Acacia galpinii, Acacia sieberiana, Acacia hebeclada and Acacia rhemniana, grown in the Limpopo Province and also to determine types and amounts of tannins occurring in them. Young leaves with petioles from seven tree foliages were collected from five different trees per species at the University of the North (now University of Limpopo) in April 2003, in a completely randomized design. Packed volume ranged from 1.50 mL/g for A. karroo to 3.00 mL/g for A. hebeclada whilst water retention ranged from 3.71 g/g for A. galpinii to 4.98 g/g for A. sieberiana. These results suggest that all the tree leaves have a high intake potential. All the Acacia species had crude protein levels above 100 g/kg dry matter (DM), ranging from 103 g/kg DM for A. rhemniana to 183 g/kg DM for A. sieberiana. Crude protein levels of this magnitude in a diet are adequate to support the maintenance requirements of cattle, sheep and goats at low to medium production levels. The Acacias contained medium to high levels of neutral and acid detergent fibres with ranges of 488 to 622 and 415 to 545 g/kg DM, respectively. In vitro DM and organic matter degradabilities varied from 345 to 534 and 254 to 474 g/kg DM, respectively. Acacia hebeclada, A. sieberiana and A. galpinii contained traces of total phenolics whilst A. tortilis contained approximately 90 g/kg DM of total phenolics and A. karroo, A. nilotica and A. rhemniana contained intermediate concentrations. Extract condensed tannin (CT) content ranged from 1.1 g/kg in A. hebeclada to 80.7 g/kg in A. karroo. At level above 50 g/kg, CT tends to negatively affect intake and digestibility in ruminants. Consequently, reduced intakes of A. galpinii, A. karroo and A. tortilis could be expected because they contained CT values above 50 g/kg. Only A. nilotica showed a sharp curve in the potassium iodate test, reflecting its considerable content of hydrolysable tannins (HT). All the other species had flat curves reflecting low levels of HT in them. The results showed that all the species except for A. galpinii, A. karroo and A. tortilis are of good nutritive value and have a potential for integration into livestock feeding systems in the Limpopo Province
Optimal Control of Combined Therapy in a Single Strain HIV-1 Model
No full textHighly active antiretroviral therapy (HAART) is administered to symptomatic human immunodeficiency virus (HIV) infected individuals to improve their health. Various administration schemes are used to improve patients?lives and at the same time suppressing development of drug resistance,
reduce evolution of new viral strains, minimize serious side effects, improve patient adherence and also reduce the costs of drugs. We deduce an optimal drug
administration scheme useful in improving patients? health especially in poor
resourced settings. In this paper we use the Pontryagin?s Maximum Principle to derive optimal drug dosages based on a mathematical dynamical model. We use methods of optimal control to determine optimal controls analytically, and then use the Runge-Kutta scheme of order four to numerically simulate
different therapy effects. We simulate the different effects of a drug regimen
composed of a protease inhibitor and a nucleoside reverse transcriptase inhibitor.
Our results indicate that for highly toxic drugs, small dosage sizes and allowing drug holidays make a profound impact in both improving the quality of life and reducing economic costs of therapy. The results show that for drugs with less toxicity, continuous therapy is beneficial
Metabolic response of pigs supplemented with incremental levels of leguminous Acacia karroo, Acacia nilotica and Colophospermum mopane leaf meals
No full textThe nutritional effects of varying levels of leguminous leaf meal inclusion were investigated using 40 mixed weaner pigs of average weight 31?4 (s.d. 4?19) kg offered diets which included leguminous leaf meals (Acacia karroo, Acacia nilotica and Colophospermum mopane) over 18 days. The leaf meals were included at 100, 200 and 300 g/kg of dry matter. Leaf meals increased daily live-weight gain ( P > 0?05) at low inclusion levels. They were also shown to increase food intake and food conversion ratio. There was an increase in digestibility of dry matter and protein at low inclusion level of leaf meals ( P < 0?05), then a decrease in the digestibility as the level of leaf meals increased. Inclusion of leaf meals induced production of proline-rich proteins (molecular weights of 24 600, 54 000, 66 000 and 74 000 Da) in the parotid salivary glands of pigs but not in the mandibular glands ( P > 0?05). The activity of hepatic microsomal uridine diphosphate glucuronyl transferase increased significantly ( P < 0?05) for pigs offered diets supplemented with A. nilotica and C. mopane but not with A. karroo ( P < 0?05). Intestinal parameters (crypt depth, villus height and villus-crypt ratio) were not significantly affected by leaf meal inclusion ( P > 0?05) except crypt depth at the proximal position of the small intestine, which decreased with increasing leaf meal levels ( P < 0?05)
Openphone user engagement and requirements solicitation in low literacy users
No full textThe OpenPhone project aims to design an Interactive Voice Response (IVR)
health information system that enables people who are caregivers for
HIV/AIDS infected children to access relevant information by using a
telephone in their native language of Setswana in Botswana. The system
lowers accessibility barriers since it is accessible to illiterate users and the
community of the blind. The design utilizes usability engineering
methodology in order to ascertain that the end product is usable, efficient,
effective and satisfactory to the targeted users who are predominantly
females, ranging from semi-literate to illiterate adults but nevertheless
numerically literate. The paper describes the methodologies that were used
to obtain information from the target user population. The contribution that
was made by staff members of the clinic where the caregivers normally get
information services is also discussed. This stakeholder information has
design implications on the OpenPhone system. Based on the information
gathered, we are now able to begin the initial design of the OpenPhone
system
A Two-Strain HIV-1 Mathematical Model to Assess the Effects of Chemotherapy on Disease Parameters
No full textTreatment of human immunodeficiency virus type 1 (HIV-1) infection during the symptomatic phase has significantly improved patient survival. We present a two-strain HIV mathematical model that captures the dynamics of the immune system and two HIV-1 variants under antiretroviral therapy.
We explore the effects of chemotherapy on the dynamics of two viral strains and T lymphocytes with one mutant strain phenotypically resistant to drug effects. Model calculations show that there is a common pattern for CD4+ T cell count increase. There is a drastic increase of CD4+ T cells during the first few weeks of treatment, followed by a gradual increase, and these increases are strictly by clonal expansion of preexisting CD4+ T cells. Plasma HIV RNA dramatically decline to zero levels during the first week of drug administration. If drug efficacy is equal to or above a threshold efficacy, viral load remains at zero levels and if drug e?cacy is less than the threshold e?cacy, viral load
gradually increases until it stabilizes. Viral rebound during treatment is entirely due to the recovery of CD4+ T cells. The results also reveal that there is a dynamic equilibrium between viral load and cytotoxic T lymphocyte (CTL) response in an infected individual during drug administration
Extracellular cellulase production by tropical isolates of Aureobasidium pullulans
No full textExtracellular cellulase production by tropical
isolates of Aureobasidium pullulans. Can. J. Microbiol. Vol. 51, 2005Cellulase production by Aureobasidium pullulans from the temperate regions has remained speculative,
with most studies reporting no activity at all. In the current study, tropical isolates from diverse sources were
screened for cellulase production. Isolates were grown on a synthetic medium containing cell walls of Msasa tree
(Brachystegia sp.) as the sole carbon source, and their cellulolytic activities were measured using carboxymethyl
cellulose and ?-cellulose as substrates. All isolates studied produced carboxymethyl cellulase (endoglucanase) and
alpha-cellulase (exoglucanase) activity. Endoglucanase-specific activities of ten selected isolates ranged from 2.375
to 12.884 ?mol glucose?(mg protein)?1?h?1, while activities on ?-cellulose (exoglucanase activity) ranged from 0.293
to 22.442 ?mol glucose?(mg protein)?1?day?1. Carboxymethyl cellulose induced the highest cellulase activity in the
selected isolates, while the isolates showed variable responses to nitrogen sources. The current study indicates that
some isolates of A. pullulans of tropical origin produce significant extracellular cellulolytic activity and that crude
cell walls may be good inducers of cellulolytic activity in A. pullulans
Paramphistome species infecting cattle in Matabeleland North province in Zimbabwe
No full textA journal article published in UNZA Journal of Science and Technology in 2005 Vol. 9 No. 2: pages 21-29.Two thousand five hundred and eighty three cattle originating fromvarious localities in Matabeleland North province were examined for adult paramphistomes in wet season and two thousand two hundred and twenty in dry season. On slaughter, the rumen and reticulum of each amimal were cut open and inner walls examined for attached paramphistomes. About 37% were infected by paramphistomes in the wet season and 39% in the dry season. Applying t-test showed no significant differences at p<0.05 between infected cattle in the dry and wet seasons. In the wet season proximity to the dry season did not significantly influence the prevalence at p<0.05. Morphological structures and measurement of diagnostic features were me i median sagittal sections. Analysis of the structures of acetabulum, pharnyx, and genital atrium revealed the following parasites in the area: paramphistomum microbothrium, paramphostomum clavula, calicophoron calicophorum, calicophoron raja, and Gigantocolye symmeri in 20%, 2%, 10%, 2% and 5% of cattle examined respectively. The visible damage by adult parasites on the host's tissue was a result of sucking the rumen and reticulum mucosa into the acetabulum, which eventually nipped off, leading to slightly hardened areas devoid of ruga due to necrosis. In a few severe casesthe papillae was damaged and catarrhal pus like exudate was noticed on the mucosa
Decontamination of aflatoxin-contaminated maize by dehulling
No full textDehulling of maize grains as an aflatoxin decontamination method was investigated. Sixty kilograms of maize (whose average moisture content was 110 g kg?1) were thoroughly mixed and divided into two samples. The kernel moisture content of one sample was adjusted to 200 g kg?1 while the other (control) was left at 110 g kg?1. The two samples were kept at ambient temperature (25?30 ?C) for 21 days. Twenty sub-samples, ten from each, were further divided into two so that one lot was dehulled while the other was not dehulled. These sub-samples were then milled to pass through a 1mm screen and the meal was evaluated for aflatoxin contamination. It was found that there was a 92% decrease in aflatoxin levels in dehulled maize meal compared with undehulled maize meal. We therefore suggest that dehulling the grain can be used to reduce aflatoxin levels in maize