Volume 2

Permanent URI for this community

http://hdl.handle.net/11070/942

Browse

Browsing Volume 2 by Title

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Analytical evaluation of eight-cell cow embryos structure, outwards water and inwards cryo-protectants to ensure successful cryopreservation
    (University of Namibia, 2013) Mausse, Francisco; Bezugly, N.
    Modern reproductive techniques use cow embryos at different stages of development. Eight-cell embryos feature a layer comprising seven cells (blastomeres), surrounding the inner cell, making a total of eight. This article analyses outwards water paths and inwards cryo-protectants, within the eight-cell cow embryos and effectiveness of their cryopreservation. Reproductive cycles and superovulation in cows were triggered through reproductive hormones injection. After slaughter, oocytes were harvested and eight-cell embryos were produced in vitro fertilization and through embryo culture. The study included morphological observations to visualize embryo structure, distribution of blastomeres, cell-layers and analytical evaluation as well, to assess distribution of penetrating cryoprotectants within the inner-cell mass. Findings based on the eight-cell embryo structure suggest that the quantity of outwards water and inwards cryo-protectants is symmetrically distributed. Although, the characteristic of water and cryo-protectants movement is expected to be much better in eight-cell embryos, cryo-protectants properties and the modality of cryo-protectants should differ from procedures applied in other class of embryos. Survival rate of cryopreserved eight cell embryos was lower (6.3%) as compared to the results for 7–8 days embryos. Obviously, a successful cryopreservation of eight-cell cow embryos can only be achieved through a combination of both technical and biological parameters.
  • Thumbnail Image
    Item
    A Classification of Fuzzy Subgroups of Finite Abelian Groups
    (University of Namibia, 2013) Gideon, Frednard
    The knowledge of fuzzy sets and systems has become a considerable aspect to apply in various mathematical systems. In this paper, we apply a knowledge of fuzzy sets to group structures. We consider a fuzzy subgroups of finite abelian groups, denoted by G = Zpn +Zqm , where Z is an integer, p and q are distinct primes and m;n are natural numbers. The fuzzy subgroups are classified using the notion of equivalence classes. In essence the equivalence relations of fuzzy subsets X is extended to equivalence relations of fuzzy subgroups of a group G. We then use the notion of flags and keychains as tools to enumerate fuzzy subgroups of G. In this way, we characterized the properties of the fuzzy subgroups of G. Finally, we use maximal chains to construct a fuzzy subgroups-lattice diagram for these groups of G.
  • Thumbnail Image
    Item
    A distributed water balance model to estimate direct groundwater recharge: A case study from the nhoma and khaudum catchments, Namibia
    (University of Namibia, 2013) Wanke, Heike; Dunkeloh, Armin; Udluft, Peter; Wanke, Ansgar
    The most important water resource in drylands such as Namibia is groundwater and its recharge including temporal and spatial variations need to be assessed reliably for sustainable water management. In this paper, a grid-based conceptual water balance model with a simplification at the catchment scale level is used to assess groundwater recharge. The reliability of the model predictions are verified by the independent chloride mass balance method. The distributed, process-oriented, physically based water balance model MODBIL used in this study considers the major water balance components and calculates a spatially differentiated water balance by simulating water fluxes and storages at temporal and spatial resolutions based on meteorological, topographic, soil physical, land cover and geological input parameters. In this study it is set up for the upper Khaudum and Nhoma catchments in the Kalahari of north-eastern Namibia and northwestern Botswana at a spatial resolution of 500 x 500 m, calculated daily for a period of 22 years. A mean annual area groundwater recharge of 11.5 mm a􀀀1 is calculated for the catchments, but spatial variations between 0 and 17.5 mm a􀀀1 occur depending on the variability of vegetation, soil and geomorphology. Groundwater recharge only occurred on a few days during the simulation period.
  • Thumbnail Image
    Item
    Evaluation of bamboo (bambusa vulgaris (schrad)) culm for drip irrigation
    (University of Namibia, 2013) Ogedengbe, Kola
    Pipes used for irrigation are expensive for small holder farmers. Therefore, bamboo with its pipe-like aerial stem (culm) may be a promising substitute for irrigation pipes. However, there is a dearth of information on the Bamboo Pipe (BP) for this application. The potential of bamboo for agricultural land irrigation was therefore investigated. Medical infusion tubes were forced fixed on the prepared bamboo pipes irrigation unit to act as emitters and Amaranthus hybridus (vegetable) was irrigated as the test crop. Emitters Coefficient of discharge (CVq) and Christiansen Uniformity Coefficient (CUC) were determined during its use for the drip irrigation of Amaranthus hybridus. The results obtained were analysed using Pearson’s correlation coefficient and t-test. The BPs were effective in carrying out drip irrigation (flow rate 0.042 - 0.117 L/hr) of the Amaranthus hybridus. The CVq and CUC varied between 1.82–2.38 and 96.20–98.86 % respectively, which were within acceptable limits. There was negative correlation between CVq and the discharge rate. The maximum yield of Amarathus hybridus obtained was 4.6 kg/m2 (4600 kg/ha) with the medi-emitters discharging at 20 drops/min, a high yield per hectare for an irrigated vegetable.
  • Thumbnail Image
    Item
    Phytochemical analysis and in vitro anti-plasmodial activity of selected ethnomedicinal plants used to treat malaria associated symptoms in northern Namibia
    (University of Namibia, 2013) Nafuka, Sylvia N.; Mumbengegwi, Davis R.
    The search for biologically active compounds from plants is of importance for discovery of novel medicine against infectious diseases such as malaria. The aims of this study were to identify ethno-medicinal plants that are used to treat malaria-associated symptoms in traditional settings in northern Namibia; to detect and quantify the presence of major anti-plasmodial phytochemicals to evaluate the anti-plasmodial activity against Plasmodium falciparum 3D7A strain of the extracts of lead plants. Ten plants were identified through a survey conducted by the Multidisciplinary Research Centre at the University of Namibia. Nineteen methanolic extracts from 10 selected ethnomedicinal plants were prepared and analyzed using Thin Layer Chromatography (TLC) to detect classes of anti-plasmodial phytochemical compounds. Furthermore, total phenolic and alkaloids were also quantified. Furthermore, in vitro anti-plasmodial activity of crude methanol and aqueous extracts at 5, 10 and 50 mg/ml was evaluated against P. falciparum 3D7A strain at 1% parasitaemia and 2% hematocrit after 48 hours. The study revealed the presence of at least one of the major anti-plasmodial classes of compounds such as terpenoids, alkaloids, anthraquinones, flavonoids and coumarins in all the plant extracts analyzed. Out of 10 plant species, Mundulea sericea’s shoots indicated the presence of all five major anti-plasmodial phytochemical. The plants species studied show a high estimate of total alkaloids (0.37- 21.21 mg/1g of extracts) and phenolics (99. 58 - 444.07 GA/E mg/ml). Methanol extracts of M. sericea, D. mespiliformis and Cyphostemma spp showed the best anti-plasmodial activity with range of IC50 values from 3.179 to 3.523 mg/ml. The presence of anti-plasmodial phytochemical classes of compounds and high in vitro anti-plasmodial activity of selected plants extracts support the further investigation of these plants, as potential sources of novel anti-plasmodial compounds for malaria drug discovery.
  • Thumbnail Image
    Item
    Reconnaissance survey of radioisotopes in soil and possible impact on seasonal Anthrax outbreak at Etosha National Park, Namibia
    (University of Namibia, 2013) Hipondoka, Martin; Mauz, B.; Nande, E.M.; Bezuidenhout, J.
    Recent discovery of elevated concentrations of uranium and thorium in sediments of the Etosha Pan prompted this reconnaissance study to survey radionuclides for their possible impact on seasonal anthrax outbreaks in habitats adjacent to the pan. Plausible explanation about how animals contract anthrax is yet to be established. Because anthrax spores are non-invasive, one of the preconditions suggested for the initiation of infection is a lesion, which serves as entry point into tissue of the organism. Five samples taken from sediments at waterholes/depressions situated downwind of the pan, where the highest density of anthrax-related deaths occurs, were analysed in the laboratory using a gamma spectrometry. All sites sampled contain concentration of radionuclides higher than the crustal average, and the highest activity concentration of 93 Bq/kg 214Bi and 214Pb, for example, was recorded closest to the Etosha Pan. This suggests that the pan is the source of uranium, and thus possible that radionuclides are redistributed from the pan by prevailing wind, mobilized seasonally by running water and collected in pools in which animals drink. Alpha-emitting radionuclides can damage the renal, gastrointestinal and/or respiratory systems of exposed animals. Incurred damage is hypothesized as a likely mechanism under which spores are aided to enter the host for infection.
  • Thumbnail Image
    Item
    Seasonal changes in avian assemblages in kaokoland (mopane) savanna in the ogongo game reserve, north-central Namibia
    (University of Namibia, 2013) Kopij, Grzegorz
    Studies were conducted at UNAM Game Reserve (c. 1000 ha) in the BIOTA Observatory ’Ogongo’, which is located c. 50 km NW of Oshakati, north-central Namibia (17 700S, 15 310E). The natural vegetation of this area is the Koakoland (Mopane) Savanna. In 2011-2012, the line transect method has been employed to assess the species composition, dominance structure, and relative abundance of all bird species, and their seasonal changes in the late rainy season (March), middle of dry season (July), and beginning of rainy season (November). In total, 66 resident (46 in late rainy season, only 35 in the middle of dry season and 39 at the beginning of rainy season) and 19 non-resident species were recorded. Only two resident species have been classified as dominants in all three seasons: Plocepasser mahali and Uraeginthus angolensis; five species were dominants in two, and four species in one season. The avian assemblage undergoes significant seasonal changes, mostly related to the water regime in oshanas. Although the number and proportion of dominant species changed only slightly from season to season (6-7 species; 58.8-62.4% of contribution), highly significant seasonal differences in abundance were recorded for 18 resident species. Clear seasonal changes were also found in the proportions of main feeding guilds, i.e. granivores and insectivores. In comparison with other habitats in Namibia, Ogongo Game Reserve has a rich and diverse avifauna. For many bird species the reserve constitutes a safe breeding habitat, and a rich feeding area. It is fully justified to retain its status as nature sanctuary in Cuvelai Drainage ecosystem.