UNAM Open Access Journal University of Namibia
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Relationship between Dissolved Oxygen and the Vertical and Longitudinal Distribution of Zooplankton off the Namibian coast
Get PDFZooplankton play an important role in the marine food web and are abundant on the Namibian coast, which is part of the highly productive Benguela upwelling system. In the Benguela system zooplankton populations are dominated by copepods and euphausiids. The abundance and distribution of zooplankton are affected by various environmental factors such as temperature, light intensity and dissolved oxygen (DO). This study investigated the relationship between DO and the diversity of zooplankton at different depths in the water column on the continental shelf off the Namibian coast. There was a positive correlation between DO and diversity of zooplankton offshore (Pearson’s r =0.83), while there exists a very weak positive correlation between DO and zooplankton diversity onshore (r= 0.196). Diversity of zooplankton does not differ significantly with depth at both onshore and offshore stations (Shannon’s Index H0 < 1). However, Divesity of zooplankton between offshore (H0=2.8 to 3.6) and onshore (H0=0.8 to 0.9) stations differs significanty (p = 0:0271;d f = 4) in the top 90m, but is not significantly different below 90m (p = 0:406;d f = 4). Nevertheless, the onshore stations had higher species richness compared to the offshore stations. Dissolved oxygen does not have a direct effect on the diversity of zooplankton, but an indirect effect and it is the interplay and interaction between several biological and environmental factors that affects zooplankton assemblage composition
Phytochemical investigation on Namibian plants for anti-malaria compounds
No full textMalaria is on the decline in Namibia due to interventions by the Ministry of Health and Social Services (MoHSS) and the country is moving towards pre-elimination of the disease. However, barriers such as resistance of the uptake of interventions by "at risk" communities, e.g. lack of treatment seeking behavior for WHO recommended ACT's exist. Some communities in malaria-endemic areas do not accept Western medicine, preferring traditional medicines as prescribed by traditional healers. It is important to balance people's cultural beliefs and practices with the MoHSS's objective of malaria elimination by 2020. To facilitate integration of traditional treatments into mainstream malaria case management, documentation and validation of the treatments to allow their safe and effective use have to be carried out. This study was conducted to document and validate the use of seven plants native to Namibia, targeted on the basis of their indigenous uses which suggest their toxicity to Plasmodium parasites. Crude extracts were prepared using methanol-dichloromethane (1/1V/V) and distilled water at 60 C. The extracts were further Partitioned with chloroform-methanol water (12/6/lV/V). Preliminary phytochemical screening was performed to detect the presence of selected Antiplasmodial compounds. Phytochemical tests revealed the presence of anthraquinones, flavonoids, terpenoids, coumarines, and glycosides; alkaloids and steroids were not detected. Paradoxically, thin-layer chromatography analysis on the crude extracts of the same plants tested positive for all compounds. The presence of these phytochemicals and the data generated support the ethno-medicinal uses for these plant
A framework for setting up pastoral information services in Namibia
Get PDFThis paper is based on a study entitled “Information needs and information seeking behaviour of Namibian pastors”. The study aimed to establish the information required by pastors to carry out their work; how they seek information and the problems they encounter in doing so. One of the study’s objectives was to come up with a framework for setting up pastoral information services in Namibia. The study used a mixed methods research design employing both qualitative and quantitative methodologies. In this paper, the authors propose a framework for setting up pastoral information services for Namibian pastors. The framework is based on the premise that information service providers need to analyse the pastors’ contexts, motivating factors, prevailing circumstances, information seeking behaviours and information use
Evaluation of bamboo (bambusa vulgaris (schrad)) culm for drip irrigation
Get PDFPipes 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
Reconnaissance Survey of Radioisotopes in Soil and Possible Impact on Seasonal Anthrax Outbreak at Etosha National Park, Namibia
Get PDFRecent 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
Analytical evaluation of eight-cell cow embryos structure, outwards water and inwards cryo-protectants to ensure successful cryopreservation
Get PDFModern 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
Structures of salivary and pancreatic amylase hydrolysates from processed starches
Get PDFDigestion of starch in humans includes luminal and mucosal steps. Structures from the luminal phase of amylases hydrolysis can impact subsequent steps of digestion at the mucosa of the small intestine. However, structures of the starch digestion products along the gut from the mouth to the small intestines products that impact glucose homeostasis are not well understood. This submission focuses on the luminal step of starch digestion, i.e. impact of salivary and pancreatic amylases on the structure of hydrolysis products obtained from cooked starches from different botanical sources. Starch to water ratios of 1:0.7 (T0.7) or 1:2 (T2) were used to cook normal corn (NCS), wheat (NWS) and potato (NPS) starches. Comparatively, DMSO was used to disperse the starches to remove the effect of granular organisation. Cooked and dispersed starches were then subjected to salivary and pancreatic amylases hydrolysis for 20 min and 120 min. Extent of 20 min hydrolysis was lower at T0.7 compared to T2 and TD for all the starches. The molecular weight profiles of 20 min hydrolysates between the processing treatments were more different for NPS than for the other starches. Oligosaccharide composition of 120 min hydrolysates differed in amounts of DP 2, 3, 5, 6 and 7 between processing treatments and also between the starches. These differences, however, did not necessarily follow the intensity of cooking treatment. These differences in structures of hydrolysates, which are the substrate for mucosal hydrolysis in the small intestine, can potentially influence glucose homeostasis
Avian assemblages of urbanized habitats in north-central Namibia
Get PDFStudies were conducted by means of the line transect method in 4 towns (Ondangwa, Ongwediva, Oshakati, Outapi) and 12 larger villages in Ovamboland, north-central Namibia. In overall, 59 residential bird species were recorded. In particular across settlement, the number varied from 6 to 34 (x = 20:2;sd = 9:99). The Simpson’s Diversity Index varied from D = 0:61 to D = 0:93. Overall, dominants comprised 68.1% of all pairs recorded (N = 2105), with Passer domesticus accounted for 32.2% (eudominant). Other dominant species included: Uraeginthus angolensis, Cypsiurus parvus, Corvus albus, Streptopelia senegalensis and Urocolius indicus. Subdominants (5 species) comprised 14.2%. Bird assemblage in Ruacana proved to be fairly distant from that in other Ovambo settlements. Latitudinal trends have been shown for the proportion between Pycnonotis tricolor and P. nigricans and Passer diffusus and P. domesticus species. Passer domesticus almost totally replaced Passer diffusus, while Streptopelia senegalensis almost totally replaced Streptopelia capicola in the urbanized habitats of the northStudies were conducted by means of the line transect method in 4 towns (Ondangwa, Ongwediva, Oshakati, Outapi) and 12 larger villages in Ovamboland, north-central Namibia. In overall, 59 residential bird species were recorded. In particular across settlement, the number varied from 6 to 34 (x = 20:2;sd = 9:99). The Simpson’s Diversity Index varied from D = 0:61 to D = 0:93. Overall, dominants comprised 68.1% of all pairs recorded (N = 2105), with Passer domesticus accounted for 32.2% (eudominant). Other dominant species included: Uraeginthus angolensis, Cypsiurus parvus, Corvus albus, Streptopelia senegalensis and Urocolius indicus. Subdominants (5 species) comprised 14.2%. Bird assemblage in Ruacana proved to be fairly distant from that in other Ovambo settlements. Latitudinal trends have been shown for the proportion between Pycnonotis tricolor and P. nigricans and Passer diffusus and P. domesticus species. Passer domesticus almost totally replaced Passer diffusus, while Streptopelia senegalensis almost totally replaced Streptopelia capicola in the urbanized habitats of the north-central Namibia
Reconnaissance Survey of Radioisotopes in Soil and Possible Impact on Seasonal Anthrax Outbreak at Etosha National Park, Namibia
Get PDFRecent 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
Assessing virtual culture exchanges
Get PDFThe rapidly growing presence of old and new media in postcolonial Namibia, particularly from the decade after the turn of the Millennium, has signifi cance for cultural and lifestyle transformations in the country. Formerly entrenched social identities, shaped by restrictive colonialism and indigenous traditions, appear to be under pressure as shifts become apparent in the face of cultural globalisation. This article examines the characteristics of change from the perspective of young Windhoek adults’ experiences of Internet social networks. The research constitutes a cultural study that addresses the current knowledge gap regarding how the Internet is increasingly situated in youth identity and cultural lifestyle spaces. Social networks appear to be changing the cultural landscapes of Namibia, if the evidence is accepted, and youth are at the cutting edge of cultural transformations wrought by new media such as the Internet