Brucellosis is a zoonosis global importance.Brucella abortus and Brucella melitensis are the main species responsible for this disease in humans and production losses in domestic ruminants.Unpasteurized milk,home-made...Brucellosis is a zoonosis global importance.Brucella abortus and Brucella melitensis are the main species responsible for this disease in humans and production losses in domestic ruminants.Unpasteurized milk,home-made cheese and ice cream,and meat present a risk for human infection[1].展开更多
The present study focused on the isolation, identification and antimicrobial profile of the dominant lactic acid bacteria from three traditional fermented milk products namely: Omashikwa, Mabisi and Mashini Ghamushikw...The present study focused on the isolation, identification and antimicrobial profile of the dominant lactic acid bacteria from three traditional fermented milk products namely: Omashikwa, Mabisi and Mashini Ghamushikwa from the north-central and north-eastern parts of Namibia. The microbiological and antimicrobial activities of these products fluctuate from one region to another depending on the local indigenous microflora. Omashikwa and Mashini Ghamushikwa fermentation processes involves the addition of Boscia albitrunca root (Omunkuzi) and butter churning. The root contributes to the flavor of the product, increasing the milk fermentation rate and churning. Mabisi is produced by letting the milk to ferment naturally until the water is separated from the whey. The water is then decanted, and the whey is shaken until it is smooth without removal of fat. A total of 180 isolates of Lactic acid bacteria (LAB) were obtained and identified based on their phenotypical characterization. Cell free supernatants (CFS) of the 180 LAB isolates were evaluated for antimicrobial activities against selected food borne pathogens;Escherichia coli ATCC 25,922, Staphylococcus aureus ATCC 25,923, Bacillus cereus ATTC 10,876, Candida famata and Geotrichum klebahnii using the well diffusion assay. Twenty LAB isolates having the highest inhibitory effects were selected for biochemical identification using API 50 kit and these were identified as being;Lactobacillus plantarum (53%), Lactobacillus rhamnosus (29%), Pediococcus pentosaceus (6%), Lactobacillus paracasei ssp. paracasei (6%) and Lactococcus lactic ssp. lactis (6%). Pediococcus pentosaceus showed the highest inhibitory effect on all the indicator strains. This study provides an insight into LAB diversity of unstudied Namibian fermented milk products and reports a potential production of antimicrobial compounds which is significant in the standardization of protective starter cultures which can be used to control fermentation process and shelf life extension of dairy products in Namibia.展开更多
Namibia has been affected by the Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) pandemic with infected and affected persons experiencing stigma at different levels. Despite the high ...Namibia has been affected by the Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) pandemic with infected and affected persons experiencing stigma at different levels. Despite the high level of knowledge?on HIV/AIDS, stigma remains a challenge. It was for this reason that this paper describes and measures the level of HIV/AIDS stigma in a rural community in Namibia. Mixed methods were used to collect data from 224 participants consisting of 93 people living with HIV/AIDS (PLWHA) who were recruited voluntarily from their support groups, 77 family members nominated by PLWHA participants, 31 community members who were recruited through simple random sampling and 19 opinion leaders who were purposefully selected and four health care workers from an Antiretroviral clinic who were available at the time of this study. Three measurement instruments namely HIV/AIDS Stigma Instrument-PLWHA (HASI-P), Family & Community Stigma Instrument (F&C-SI) and HIV/AIDS Stigma Instrument-Nurse (HASI- N) were used. In-depth interviews were conducted to complement the quantitative results. The study found that stigma manifests in different ways and results revealed that verbal abuse (55%, n = 50, PLWHA), social isolation (73%, n = 67), negative self-perception (33%, n = 30), and household stigma (26% n = 19, family members) were the most common form of stigma experienced by PLWHA. Furthermore health care workers reported stigma of association (50%, n = 2) as care providers for people living with HIV/AIDS. The study concluded that stigma exists although some scores such as fear of contagion and workplace stigma were low. Therefore, interventions in knowledge on basic facts of HIV transmission need to be strengthened. Nonetheless the majority of participants confirmed their willingness to care for sick relatives with HIV and AIDS. This study did not explore stigma of association against caregivers with other participants other than the four health care workers from the antiretroviral clinic. Future researchers can take this further.展开更多
As the sole obligate symbiotic birds in Africa,oxpeckers offer a unique model for studying symbiotic relationships.Due to the multitrophic level they occupy and the context dependent foraging behavior they exhibit,the...As the sole obligate symbiotic birds in Africa,oxpeckers offer a unique model for studying symbiotic relationships.Due to the multitrophic level they occupy and the context dependent foraging behavior they exhibit,the type of symbiotic relationship can be variable.In addition to providing a cleaning service to the host by removing ticks,oxpeckers frequently feed on blood,mucus,and saliva,inflicting potential damage on the host.Here,we used DNA metabarcoding on faecal samples to analyze the taxonomic composition of the trophic interactions of the Yellow-billed Oxpecker(Buphagus africanus)and Red-billed Oxpecker(B.erythrorhynchus)in northeastern Namibia.In contrast to conventional methods,DNA metabarcoding allows for a detailed identification of dietary resources encompassing both mammal hosts and consumed arthropods within the same samples.With this information,we examined differences in the diet composition between oxpecker species and localities,as well as the co-occurrence between host and arthropod species.Our findings revealed that oxpeckers predominantly source their diet from mammals,ticks,and flies;however,ticks and flies rarely co-occur in the diet of an individual.We observed variability among individuals in their feeding ecology,which is strongly correlated with locality and,to a lesser extent,with the mammal host.We noted a high degree of mobility between hosts within relatively short periods,with 32%of the samples showing traces of at least two mammal hosts.This study illustrates the dynamic foraging behavior of these specialized symbiotic birds,shedding light on their potential role in pest control services and disease transmission.展开更多
A quantitative research was conducted at Tschudi mine, Tsumeb, Namibia with its main drive being to determine the influence that density and blast parameters has on the performance of a blast. The factors that are mos...A quantitative research was conducted at Tschudi mine, Tsumeb, Namibia with its main drive being to determine the influence that density and blast parameters has on the performance of a blast. The factors that are most vital to the fragmentation process are classified into three namely: explosive parameters, rock parameters and blast geometry. Rock fragmentation is dependent on two main factors, the rock properties which are uncontrollable and the blasting parameters that can be manipulated to give maximum efficiency. The selected variable quantities, density, charge length, volume of blast and mass of charge per hole were recorded after observation, determined via laboratory testing or calculated from their known equations. The main objective is to develop a model to predict blasting performance, and this will be achieved with the use of the Kuz-Ram model. The proposed equation related mean expected fragmentation size (calculated using the Kuz-Ram fragmentation model) to the actual fragmentation. Blasting parameters namely: burden, spacing, and charge quantity that are not included in this study were measured or calculated on site to facilitate the inputs of the Kuz-Ram model. A specialized software package SPLIT Desktop was used to estimate the actual mean fragmentation by analyzing scaled images from the post blast muck pile. The Microsoft Excel regression analysis correlated the two intact rock properties with the blasting efficiency. The expected mean fragmentation and the actual fragmentation were then used to determine the blast performance, defined as the percentage ratio of the actual mean to the expected mean. The blast performance showed a good relationship with density (R2 = 0.81971), with performance of the blast reducing with an increase in density. The performance also dropped with increase in charge length. The blast performance and mass of charge/explosives per hole relationship showed a correlation of (R2 = 0.56195), but the results were disregarded. Lastly the volume of the blast had a direct relation to the blast performance (R2 = 0.80897) and it would be logical to state that, the two are directly proportional to each other.展开更多
The Cuvelai Basin of north-central Namibia consists of unique seasonal wetlands made up of shallow pans locally known as Iishana （Oshana, singular） which form ephemeral network systems. The basin has relatively fert...The Cuvelai Basin of north-central Namibia consists of unique seasonal wetlands made up of shallow pans locally known as Iishana （Oshana, singular） which form ephemeral network systems. The basin has relatively fertile soils encouraging human settlements. More than 40% of the country＇s population resides in the basin. Early settlers in the basin utilized indigenous knowledge to develop land use systems that were in harmony with biophysical characteristics of the area. Over the years, there has been a departure from these indigenous land use systems resulting in land management problems. A desktop study coupled with field observations was conducted to describe the indigenous land use systems of the Owambo people living in the basin, and to determine factors behind the departure and consequential impacts of this departure on sustainability of land uses. Possible ways of preventing erosion of this indigenous knowledge were given attention. The paper recommends that the Owamboindigenous land management system needs to be embedded within government policies and regulations and should be strictly enforced. There is also a need for designing strategic basin management plans that are a combination of both scientific and indigenous knowledge.展开更多
The Cuvelai Etosha Basin of Namibia is characterised by complex aquifer systems with multi-layered aquifers and various water qualities. Some parts of the basin have been covered with a pipeline system that supplies p...The Cuvelai Etosha Basin of Namibia is characterised by complex aquifer systems with multi-layered aquifers and various water qualities. Some parts of the basin have been covered with a pipeline system that supplies purified surface water from the Kunene River. Locations that lack a pipeline system utilise hand-dug wells as a source of drinking water. These wells draw water from shallow perched aquifers and are not protected from surface contamination nor is the water quality monitored. Sanitised water supply is relevant for the growth and development of societies and is a priority of the United Nations Millennium Development Goals. A bacteriological water quality study aimed at investigating the presence and seasonal variation of;Citrobacter, Escherichia, Klebsiella, Enterobacter, Proteus, Salmonella, Shigella, and Pseudomonas species was conducted on 44 hand-dug wells in the Ohangwena and Omusati regions of the Cuvelai Etosha Basin. Samples were collected from both the wet and dry seasons. Results disclosed the presence of Salmonella, Shigella, Citrobacter, Escherichia, Klebsiella, Enterobacter, Proteus, and Pseudomonas species. Chi-square confirmed a significant seasonal variation in Salmonella (P Shigella (P Citrobacter (P > 0.05), Escherichia (P > 0.05), Klebsiella (P > 0.05), Entero-bacter (P > 0.05), Proteus (P > 0.05) and Pseudomonas (P > 0.05) species. Water from these hand-dug wells is not safe for drinking unless it is subjected to appropriate treatment. It is recommended that hand-dug wells should be properly constructed at safe distances from contaminating structures such as pit latrines and routinely assessed for pathogens, and the water should be sanitized prior to consumption.展开更多
Water samples from Daan Viljoen dam, Avis dam and Goreangab dam were collected and filtered with burlap, cotton and polyester. The water samples were analyzed for the presence of total coliform, Escherichia coli, hete...Water samples from Daan Viljoen dam, Avis dam and Goreangab dam were collected and filtered with burlap, cotton and polyester. The water samples were analyzed for the presence of total coliform, Escherichia coli, heterotrophic plate count (HPC), somatic coliphage, Clostridium perfringens, turbidity and conductivity. The bacteriological analysis was carried out by membrane filtration and pour plate techniques. The water from the three dams was found to contain high levels of microorganisms which indicated that it was not safe for human consumption. Turbidity was improved after filtration. Cotton filtered out the most microorganisms (p < 0.05) in all dams compared with the other two types of cloths.展开更多
In many instances, care for the elderly, especially in long-term care institutions, is provided under minimal supervision by caregivers who are lay people. This can lead to poor quality care or neglect of the elderly....In many instances, care for the elderly, especially in long-term care institutions, is provided under minimal supervision by caregivers who are lay people. This can lead to poor quality care or neglect of the elderly. The research question was: “How competent are lay caregivers for the elderly in old age homes, who often lack the opportunity for training to improve their knowledge and skills, in delivering care to the elderly? The aims of the study were to explore and describe the experiences of both the caregivers and the elderly in respect of caring for the elderly in old age homes. The objectives of the study were to explore and describe the experiences of the caregivers and the elderly with respect to caring for the elderly and in respect of nursing care they received. A qualitative, explorative, descriptive, contextual and phenomenology design was used to perform this study. In the situational analysis, the experiences and needs of the caregivers were described. Themes in terms of interpersonal relationships that could be positive or negative regarding the elderly were identified. These included lack of regular in-service training sessions for caregivers. Likewise, sub-themes like communication, support and caring for elderly people were revealed. Inadequate knowledge of caregivers in caring procedures, a shortage of staff, equipment and absence of policies which should support and guide the work of caregivers impacts negatively on the care of the elderly. From the experiences of the elderly and caregivers, the competencies under scrutiny emerged and were measured qualitatively by the perceptions of the elderly, in respect of the caring they were exposed to.展开更多
The objective of this study was to compare the field growth performance of Moringa oleifera and Moringa ovalifolia in semi-arid environment of central Namibia rangeland. This part of Namibia has both arid and semi-ari...The objective of this study was to compare the field growth performance of Moringa oleifera and Moringa ovalifolia in semi-arid environment of central Namibia rangeland. This part of Namibia has both arid and semi-arid climates. These climates require the growing of drought-resistant fodder trees to aid in the provision of animal feed or supplement. This is paramount to livestock farmers who are striving to meet the feed demand of their animals especially during winter and drought periods. It is upon this background that both Moringa species were grown to evaluate their field growth performances. Moringa oleifera grew faster with 224.9 cm and 281.45 cm heights than Moringa ovalifolia that had 77.025 cm and 113.2 cm heights in 2014/2015 summer season (October 2014 to April 2015) and 2015/2016 summer season (October 2015 to April 2016), respectively, although Moringa ovalifolia is native to Namibia. In Namibia, summer usually starts October and ends April the follow year after which winter follows. Moringa oleifera grew significantly higher (P Moringa ovalifolia, though they belong to the Moringaceae family and were grown under the parallel conditions. Therefore, Moringa oleifera would serve as a better alternative for improving rangelands’ productivity under these adverse climatic and environmental conditions since it can grow faster than Moringa ovalifolia, whose characteristic leads to the rapid establishment of trees and large quantity of leaf-biomass production.展开更多
The caring is a very important aspect for every child’s well-being and development. A child should be cared for by biological parents or extended family members when possible. In the absence of these two possibilitie...The caring is a very important aspect for every child’s well-being and development. A child should be cared for by biological parents or extended family members when possible. In the absence of these two possibilities, other options are in place such as Residential Child Care Facilities (RCCFs). However, RCCFs are generally regarded as last resorts, as it is noted that they have a negative impact on the well-being of the children. Caregivers in RCCFs should ensure that these children are being adequately cared for as they substitute their biological or extended families. It is also a child’s rights to be provided love, care and support coupled with a sense of belonging, recognition and independence. However, children without or inadequate parental care are likely to be vulnerable from all forms of violence. The aim of this qualitative, exploratory, descriptive, contextual and phenomenological study was to explore and describe the children’s experiences regarding the care received at the Residential Child Care Facilities and to provide recommendations regarding research findings. Data were collected through one on one in-depth interviews and Tech method was used to analyze data. The results of the study show that children in RCCFs have experienced both positive and negative care. The care is experienced through relationships with staff in the facilities, provision of their basic needs, knowledge of their cultural identity and their adult future preparation once they leave the facilities. Thus, it is recommended that a conducive environment that contributes to the quality of care for children in RCCFs be established, taking into consideration human resources capacity, policy guidelines and standards in place while providing care to those children.展开更多
A quantitative technique was conducted at Rosh Pinah Zinc mine, Namibia with its main purpose to determine airways resistance which is a function of the parameters;roughness of the airways and the friction factor. The...A quantitative technique was conducted at Rosh Pinah Zinc mine, Namibia with its main purpose to determine airways resistance which is a function of the parameters;roughness of the airways and the friction factor. The 32 branch points (<em>i.e.</em> a-ag) that stand for ventilation circuit have been selected. Data collected includes, length and width of airways, air velocity;air density, and roughness of the airways which were used to determine coefficient of frictions, friction factors and airway resistances. A ventilation model was developed. In order to improve the current ventilation model, airways resistance of the mine was determined and simulated in a modified model using VentSim<sup>TM</sup> software. An average total airways resistance of 0.32027 Ns<sup>2</sup>/m<sup>8</sup> has been achieved for Rosh Pinah mine. It should be pointed out that, as the mine advances its production faces deeper, this value would increases suddenly. Simulation revealed that as much as 34.4 m<sup>3</sup>/s of air can be received at the production faces, compared to the measured received amount of 19.3 m<sup>3</sup>/s. Therefore, volumetric efficiency of the mine was improved from 29.3% to 68.3%. It was also noticed that after importing the resistance values into the model together with other parameters, the model was greatly improved and no cause for concern.展开更多
This study re-evaluates the characteristics of Cu-Pb-Ag and Fe-Mn ore mineralization of the Kombat Mine and Gross Otavi Mine based on field geology, fluid inclusions, petrology, mineralogy, and geochemistry. This is t...This study re-evaluates the characteristics of Cu-Pb-Ag and Fe-Mn ore mineralization of the Kombat Mine and Gross Otavi Mine based on field geology, fluid inclusions, petrology, mineralogy, and geochemistry. This is to determine the genetic relationship between Fe-Mn and Cu-Pb-Ag mineralization. The study has established that the Cu-Pb-Ag ore at the Kombat Mine can be classified as a variant of MVT-type deposit, whereas the Fe-Mn ore can be classified as a stratiform-syn-sedimentary deposit. The formation of the MVT-type deposit is associated with a hydrothermal fluid system with a mean temperature of 183<span style="white-space:nowrap;">°C and mean salinity of 12.85 wt. % NaCl equivalent. The syn-sedimentary Fe-Mn ore, which is largely associated with calc-silicate lithologies, consists mainly of magnetite and hematite with minor pyrite, hausmannite and jacobsite, and was deposited by diagenetic and mixed diagenetic-hydrogenetic processes under changing oxic and anoxic conditions within the sedimentary basin. Acceptable geochemical exploration indicators of the existing mineralization include anomalous values above 0.5% Cu, 0.2% S;0.05% Pb;0.04% As;0.01% Zn;V, W, Mo, and Ag are 0.002%. Mineralogical indicators include chalcopyrite, bornite, covellite and galena with minor chalcocite, sphalerite, and tennantite for the Cu-Pb MVT-type ores at Kombat Mine.展开更多
Nasal colonization with Staphylococcus strains puts children at risk of developing difficult-to-treat staphylococcal infections. Antibiotic resistance data is limited in Namibia. Our study thus aimed to provide resist...Nasal colonization with Staphylococcus strains puts children at risk of developing difficult-to-treat staphylococcal infections. Antibiotic resistance data is limited in Namibia. Our study thus aimed to provide resistance trends for nasal staphylococci isolated from school children in the Mariental District. This is the first report on antibiotic resistance trends of staphylococci from Namibian school children. By Kirby-Bauer disk diffusion assay, 352 Staphylococcus aureus and 81 coagulase-negative staphylococci (CoNS) isolates from Namibian school children aged 6 - 14 years underwent susceptibility testing against seven antibiotics. Ninety-six percent S. aureus and 66.7% CoNS were resistant to ampicillin. Ampicillin resistance was significantly higher in S. aureus than in CoNS (P S. aureus. Ciprofloxacin was also the most effective drug against CoNS. Cefoxitin/methicillin resistance was seen in 14.5% S. aureus isolates and 8.6% of CoNS. Thirty-one antibiotic resistance patterns were observed, most frequently ampicillin (A), ampicillin-erythromycin (AP-E), and ampicillin-tetracycline (AP-T). Altogether 12.5% isolates (50 S. aureus and four CoNS) were multi-drug resistant. From the methicillin-resistant S. aureus (MRSA) isolates, 43.1% were multi-drug resistant. Methicillin-resistant CoNS were not multi-drug resistant, with the most common resistance pattern being ampicillin-rifampicin-cefoxitin (AP-RP-FOX). In conclusion, multi-drug resistance in our study was relatively low. However, some of the MRSA isolates were multi-drug resistant, which is of concern. Learners should be educated on the importance of handwashing and appropriate use of antibiotics to prevent spread of antibiotic-resistant bacteria within the community. Ciprofloxacin and gentamicin may effectively be used to treat staphylococcal infections in this study population.展开更多
Ecosystem Approach to Fisheries(EAF)management is a concept aimed at the conservation and sustainable use of the entire ecosystem.While EAF is a noble approach,its implementation has been challenging.Although Namibia ...Ecosystem Approach to Fisheries(EAF)management is a concept aimed at the conservation and sustainable use of the entire ecosystem.While EAF is a noble approach,its implementation has been challenging.Although Namibia has committed to the implementation of EAF,only limited assessment has been done of Namibian fisheries management processes and instruments concerning EAF.A qualitative assesment was done to ascertain if the Namibian fisheries management processes and instruments conform to the EAF principles.Namibian fisheries management processes and instruments largely conform to the EAF principles,although there are notable areas needing improvements.The conformities were pronounced in the total allowable catch setting,rebuilding depleted stocks,minimizing bycatch,and fishing impact minimization.The polluter pays,and user pays principles were also applied.Areas that were found lacking in this study included setting the indicators for EAF and ecosystem integrity.The assessment also noted the absence of guidelines for the precautionary approach principle and a transparent policy for quota and right allocation processes.The strategies for managing transboundary fish species are also not formulated.Overall,this assessment showed the complexities and challenges that Namibia and other countries need to overcome to implement EAF successfully.展开更多
The distribution of the various organic and inorganic constituents and their influences on the combustion of coal has been comprehensively studied.However,the combustion characteristics of pulverized coal depend not o...The distribution of the various organic and inorganic constituents and their influences on the combustion of coal has been comprehensively studied.However,the combustion characteristics of pulverized coal depend not only on rank but also on the composition,distribution,and combination of the macerals.Unlike the proximate and ultimate analyses,determining the macerals in coal involves the use of sophisticated microscopic instrumentation and expertise.In this study,an attempt was made to predict the amount of macerals(vitrinite,inertinite,and liptinite)and total mineral matter from the Witbank Coalfields samples using the multiple input single output white-box artificial neural network(MISOWB-ANN),gene expression programming(GEP),multiple linear regression(MLR),and multiple nonlinear regression(MNLR).The predictive models obtained from the multiple soft computing models adopted are contrasted with one another using difference,efficiency,and composite statistical indicators to examine the appropriateness of the models.The MISOWB-ANN provides a more reliable predictive model than the other three models with the lowest difference and highest efficiency and composite statistical indicators.展开更多
The purpose of the study sought to assess and evaluate the contents and records of the emergency trolley in the maternity section of the state hospitals in Windhoek, Namibia. A quantitative and descriptive research de...The purpose of the study sought to assess and evaluate the contents and records of the emergency trolley in the maternity section of the state hospitals in Windhoek, Namibia. A quantitative and descriptive research design was used for the study to investigate emergency equipment, essential drugs and emergency trolleys. A convenient sample of 10 emergency trolleys in the Windhoek Central Hospital (Hospital A) and Katutura Intermediate Hospital (Hospital B) in Windhoek, Namibia were used. Data was collected using a checklist adapted and edited from the EMSSA. Data were analysed using Microsoft excel 2013. Essential paediatric equipment including bag valve mask devices, Magill’s forceps, oxygen masks were absent in many of the units and wards. Data described that checking of defibrillators, monitors and suction devices still remained a major problem in the units/wards that were fortunate enough to have the aforementioned equipment. A conclusion was that generally the units/wards performed well during the assessments and evaluations. There were still units without emergency trolleys, trolleys that were poorly assessed, and those that were obstructed and registered nurses that had a negative perception to the audit of the emergency trolley. Specialized units such as NICU and Hi-Care Hospital A and Prem Unit Hospital B performed very well in their assessments. Development of policy with regards to assessing, restocking and maintenance of emergency supplies can be used to guide the nurses on what to do. Resuscitation morbidity and mortality meetings in order to identify issues and outcomes surround resuscitation incidences within the unit or ward.展开更多
Water scarcity is a major problem for Namibia and South Africa as both countries are classified as ＂water stressed＂, based on their per capita water availability which is below the threshold of 1,000-1,666 ma-person...Water scarcity is a major problem for Namibia and South Africa as both countries are classified as ＂water stressed＂, based on their per capita water availability which is below the threshold of 1,000-1,666 ma-person^-1.year^-1. Water provision in both countries has traditionally relied on supply-side sources, and the potential for expansion is becoming dim, making efforts towards demand management approaches more feasible. Findings show that CBM （community based management） systems of water points offer an alternative in terms of ownership and self-reliance based on institutional arrangements at community level. However, the CBM system involves some forms of payment for water access, and affordability has become a main challenge, to the extent that some governments are considering the reintroduction of water subsidies for poor rural communities in the near future.展开更多
Experimental studies to demonstrate self healing potentials of Al-Mg-Si alloy were undertaken in this research work. Self healing exploring secondary precipitation in the Al-Mg-Si alloy and use of low melting metallic...Experimental studies to demonstrate self healing potentials of Al-Mg-Si alloy were undertaken in this research work. Self healing exploring secondary precipitation in the Al-Mg-Si alloy and use of low melting metallic alloy reinforcement (60Sn-40Pb alloy) were used as basis for the investigation. For the precipitation study, the Al-Mg-Si alloy was under-aged at temperature of 160oC for 10 minutes and then subjected to second step ageing treatment at four different temperatures within the range of 25oC and 70oC. In the 60Sn-40Pb alloy reinforced Al-Mg-Si alloy study, the samples were prepared in pre-cracked state and then subjected to healing heat-treatment at 250oC. For all cases tensile test and healing efficiency was used to analyze the results generated. It was observed that a second step thermal ageing at 50oC resulted in peak improvement in tensile strength, yield strength, toughness and percent elongation while ageing above this temperature lead to a drop in the tensile properties in comparison to that of the sample not subjected to a second ageing treatment. Also the use of 60Sn-40Pb alloy as reinforcement in the Al-Mg-Si alloy resulted in a healing efficiency of 91% after pre-cracking and heat-treatment. The satisfactory bonding between the 60Sn-40Pb alloy and the Al-Mg-Si alloy matrix contributed to the high healing efficiency observed.展开更多
文摘Brucellosis is a zoonosis global importance.Brucella abortus and Brucella melitensis are the main species responsible for this disease in humans and production losses in domestic ruminants.Unpasteurized milk,home-made cheese and ice cream,and meat present a risk for human infection[1].
文摘The present study focused on the isolation, identification and antimicrobial profile of the dominant lactic acid bacteria from three traditional fermented milk products namely: Omashikwa, Mabisi and Mashini Ghamushikwa from the north-central and north-eastern parts of Namibia. The microbiological and antimicrobial activities of these products fluctuate from one region to another depending on the local indigenous microflora. Omashikwa and Mashini Ghamushikwa fermentation processes involves the addition of Boscia albitrunca root (Omunkuzi) and butter churning. The root contributes to the flavor of the product, increasing the milk fermentation rate and churning. Mabisi is produced by letting the milk to ferment naturally until the water is separated from the whey. The water is then decanted, and the whey is shaken until it is smooth without removal of fat. A total of 180 isolates of Lactic acid bacteria (LAB) were obtained and identified based on their phenotypical characterization. Cell free supernatants (CFS) of the 180 LAB isolates were evaluated for antimicrobial activities against selected food borne pathogens;Escherichia coli ATCC 25,922, Staphylococcus aureus ATCC 25,923, Bacillus cereus ATTC 10,876, Candida famata and Geotrichum klebahnii using the well diffusion assay. Twenty LAB isolates having the highest inhibitory effects were selected for biochemical identification using API 50 kit and these were identified as being;Lactobacillus plantarum (53%), Lactobacillus rhamnosus (29%), Pediococcus pentosaceus (6%), Lactobacillus paracasei ssp. paracasei (6%) and Lactococcus lactic ssp. lactis (6%). Pediococcus pentosaceus showed the highest inhibitory effect on all the indicator strains. This study provides an insight into LAB diversity of unstudied Namibian fermented milk products and reports a potential production of antimicrobial compounds which is significant in the standardization of protective starter cultures which can be used to control fermentation process and shelf life extension of dairy products in Namibia.
文摘Namibia has been affected by the Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) pandemic with infected and affected persons experiencing stigma at different levels. Despite the high level of knowledge?on HIV/AIDS, stigma remains a challenge. It was for this reason that this paper describes and measures the level of HIV/AIDS stigma in a rural community in Namibia. Mixed methods were used to collect data from 224 participants consisting of 93 people living with HIV/AIDS (PLWHA) who were recruited voluntarily from their support groups, 77 family members nominated by PLWHA participants, 31 community members who were recruited through simple random sampling and 19 opinion leaders who were purposefully selected and four health care workers from an Antiretroviral clinic who were available at the time of this study. Three measurement instruments namely HIV/AIDS Stigma Instrument-PLWHA (HASI-P), Family & Community Stigma Instrument (F&C-SI) and HIV/AIDS Stigma Instrument-Nurse (HASI- N) were used. In-depth interviews were conducted to complement the quantitative results. The study found that stigma manifests in different ways and results revealed that verbal abuse (55%, n = 50, PLWHA), social isolation (73%, n = 67), negative self-perception (33%, n = 30), and household stigma (26% n = 19, family members) were the most common form of stigma experienced by PLWHA. Furthermore health care workers reported stigma of association (50%, n = 2) as care providers for people living with HIV/AIDS. The study concluded that stigma exists although some scores such as fear of contagion and workplace stigma were low. Therefore, interventions in knowledge on basic facts of HIV transmission need to be strengthened. Nonetheless the majority of participants confirmed their willingness to care for sick relatives with HIV and AIDS. This study did not explore stigma of association against caregivers with other participants other than the four health care workers from the antiretroviral clinic. Future researchers can take this further.
基金partially supported by the Namibia Students Financial Assistance Fund(NSFAF)Kreditanstalt für Wiederaufbau(KfW)-University of Namibia(UNAM,BMZ Ref.2015.67.015)+2 种基金funded by the project TROPIBIO NORTE-01-0145-FEDER-000046supported by Norte Portugal Regional Operational Programme(NORTE2020)developed in the framework of the“Twin Lab CIBIO/UNAM”(UNESCO Chair Life on Land)。
文摘As the sole obligate symbiotic birds in Africa,oxpeckers offer a unique model for studying symbiotic relationships.Due to the multitrophic level they occupy and the context dependent foraging behavior they exhibit,the type of symbiotic relationship can be variable.In addition to providing a cleaning service to the host by removing ticks,oxpeckers frequently feed on blood,mucus,and saliva,inflicting potential damage on the host.Here,we used DNA metabarcoding on faecal samples to analyze the taxonomic composition of the trophic interactions of the Yellow-billed Oxpecker(Buphagus africanus)and Red-billed Oxpecker(B.erythrorhynchus)in northeastern Namibia.In contrast to conventional methods,DNA metabarcoding allows for a detailed identification of dietary resources encompassing both mammal hosts and consumed arthropods within the same samples.With this information,we examined differences in the diet composition between oxpecker species and localities,as well as the co-occurrence between host and arthropod species.Our findings revealed that oxpeckers predominantly source their diet from mammals,ticks,and flies;however,ticks and flies rarely co-occur in the diet of an individual.We observed variability among individuals in their feeding ecology,which is strongly correlated with locality and,to a lesser extent,with the mammal host.We noted a high degree of mobility between hosts within relatively short periods,with 32%of the samples showing traces of at least two mammal hosts.This study illustrates the dynamic foraging behavior of these specialized symbiotic birds,shedding light on their potential role in pest control services and disease transmission.
文摘A quantitative research was conducted at Tschudi mine, Tsumeb, Namibia with its main drive being to determine the influence that density and blast parameters has on the performance of a blast. The factors that are most vital to the fragmentation process are classified into three namely: explosive parameters, rock parameters and blast geometry. Rock fragmentation is dependent on two main factors, the rock properties which are uncontrollable and the blasting parameters that can be manipulated to give maximum efficiency. The selected variable quantities, density, charge length, volume of blast and mass of charge per hole were recorded after observation, determined via laboratory testing or calculated from their known equations. The main objective is to develop a model to predict blasting performance, and this will be achieved with the use of the Kuz-Ram model. The proposed equation related mean expected fragmentation size (calculated using the Kuz-Ram fragmentation model) to the actual fragmentation. Blasting parameters namely: burden, spacing, and charge quantity that are not included in this study were measured or calculated on site to facilitate the inputs of the Kuz-Ram model. A specialized software package SPLIT Desktop was used to estimate the actual mean fragmentation by analyzing scaled images from the post blast muck pile. The Microsoft Excel regression analysis correlated the two intact rock properties with the blasting efficiency. The expected mean fragmentation and the actual fragmentation were then used to determine the blast performance, defined as the percentage ratio of the actual mean to the expected mean. The blast performance showed a good relationship with density (R2 = 0.81971), with performance of the blast reducing with an increase in density. The performance also dropped with increase in charge length. The blast performance and mass of charge/explosives per hole relationship showed a correlation of (R2 = 0.56195), but the results were disregarded. Lastly the volume of the blast had a direct relation to the blast performance (R2 = 0.80897) and it would be logical to state that, the two are directly proportional to each other.
文摘The Cuvelai Basin of north-central Namibia consists of unique seasonal wetlands made up of shallow pans locally known as Iishana （Oshana, singular） which form ephemeral network systems. The basin has relatively fertile soils encouraging human settlements. More than 40% of the country＇s population resides in the basin. Early settlers in the basin utilized indigenous knowledge to develop land use systems that were in harmony with biophysical characteristics of the area. Over the years, there has been a departure from these indigenous land use systems resulting in land management problems. A desktop study coupled with field observations was conducted to describe the indigenous land use systems of the Owambo people living in the basin, and to determine factors behind the departure and consequential impacts of this departure on sustainability of land uses. Possible ways of preventing erosion of this indigenous knowledge were given attention. The paper recommends that the Owamboindigenous land management system needs to be embedded within government policies and regulations and should be strictly enforced. There is also a need for designing strategic basin management plans that are a combination of both scientific and indigenous knowledge.
文摘The Cuvelai Etosha Basin of Namibia is characterised by complex aquifer systems with multi-layered aquifers and various water qualities. Some parts of the basin have been covered with a pipeline system that supplies purified surface water from the Kunene River. Locations that lack a pipeline system utilise hand-dug wells as a source of drinking water. These wells draw water from shallow perched aquifers and are not protected from surface contamination nor is the water quality monitored. Sanitised water supply is relevant for the growth and development of societies and is a priority of the United Nations Millennium Development Goals. A bacteriological water quality study aimed at investigating the presence and seasonal variation of;Citrobacter, Escherichia, Klebsiella, Enterobacter, Proteus, Salmonella, Shigella, and Pseudomonas species was conducted on 44 hand-dug wells in the Ohangwena and Omusati regions of the Cuvelai Etosha Basin. Samples were collected from both the wet and dry seasons. Results disclosed the presence of Salmonella, Shigella, Citrobacter, Escherichia, Klebsiella, Enterobacter, Proteus, and Pseudomonas species. Chi-square confirmed a significant seasonal variation in Salmonella (P Shigella (P Citrobacter (P > 0.05), Escherichia (P > 0.05), Klebsiella (P > 0.05), Entero-bacter (P > 0.05), Proteus (P > 0.05) and Pseudomonas (P > 0.05) species. Water from these hand-dug wells is not safe for drinking unless it is subjected to appropriate treatment. It is recommended that hand-dug wells should be properly constructed at safe distances from contaminating structures such as pit latrines and routinely assessed for pathogens, and the water should be sanitized prior to consumption.
文摘Water samples from Daan Viljoen dam, Avis dam and Goreangab dam were collected and filtered with burlap, cotton and polyester. The water samples were analyzed for the presence of total coliform, Escherichia coli, heterotrophic plate count (HPC), somatic coliphage, Clostridium perfringens, turbidity and conductivity. The bacteriological analysis was carried out by membrane filtration and pour plate techniques. The water from the three dams was found to contain high levels of microorganisms which indicated that it was not safe for human consumption. Turbidity was improved after filtration. Cotton filtered out the most microorganisms (p < 0.05) in all dams compared with the other two types of cloths.
文摘In many instances, care for the elderly, especially in long-term care institutions, is provided under minimal supervision by caregivers who are lay people. This can lead to poor quality care or neglect of the elderly. The research question was: “How competent are lay caregivers for the elderly in old age homes, who often lack the opportunity for training to improve their knowledge and skills, in delivering care to the elderly? The aims of the study were to explore and describe the experiences of both the caregivers and the elderly in respect of caring for the elderly in old age homes. The objectives of the study were to explore and describe the experiences of the caregivers and the elderly with respect to caring for the elderly and in respect of nursing care they received. A qualitative, explorative, descriptive, contextual and phenomenology design was used to perform this study. In the situational analysis, the experiences and needs of the caregivers were described. Themes in terms of interpersonal relationships that could be positive or negative regarding the elderly were identified. These included lack of regular in-service training sessions for caregivers. Likewise, sub-themes like communication, support and caring for elderly people were revealed. Inadequate knowledge of caregivers in caring procedures, a shortage of staff, equipment and absence of policies which should support and guide the work of caregivers impacts negatively on the care of the elderly. From the experiences of the elderly and caregivers, the competencies under scrutiny emerged and were measured qualitatively by the perceptions of the elderly, in respect of the caring they were exposed to.
文摘The objective of this study was to compare the field growth performance of Moringa oleifera and Moringa ovalifolia in semi-arid environment of central Namibia rangeland. This part of Namibia has both arid and semi-arid climates. These climates require the growing of drought-resistant fodder trees to aid in the provision of animal feed or supplement. This is paramount to livestock farmers who are striving to meet the feed demand of their animals especially during winter and drought periods. It is upon this background that both Moringa species were grown to evaluate their field growth performances. Moringa oleifera grew faster with 224.9 cm and 281.45 cm heights than Moringa ovalifolia that had 77.025 cm and 113.2 cm heights in 2014/2015 summer season (October 2014 to April 2015) and 2015/2016 summer season (October 2015 to April 2016), respectively, although Moringa ovalifolia is native to Namibia. In Namibia, summer usually starts October and ends April the follow year after which winter follows. Moringa oleifera grew significantly higher (P Moringa ovalifolia, though they belong to the Moringaceae family and were grown under the parallel conditions. Therefore, Moringa oleifera would serve as a better alternative for improving rangelands’ productivity under these adverse climatic and environmental conditions since it can grow faster than Moringa ovalifolia, whose characteristic leads to the rapid establishment of trees and large quantity of leaf-biomass production.
文摘The caring is a very important aspect for every child’s well-being and development. A child should be cared for by biological parents or extended family members when possible. In the absence of these two possibilities, other options are in place such as Residential Child Care Facilities (RCCFs). However, RCCFs are generally regarded as last resorts, as it is noted that they have a negative impact on the well-being of the children. Caregivers in RCCFs should ensure that these children are being adequately cared for as they substitute their biological or extended families. It is also a child’s rights to be provided love, care and support coupled with a sense of belonging, recognition and independence. However, children without or inadequate parental care are likely to be vulnerable from all forms of violence. The aim of this qualitative, exploratory, descriptive, contextual and phenomenological study was to explore and describe the children’s experiences regarding the care received at the Residential Child Care Facilities and to provide recommendations regarding research findings. Data were collected through one on one in-depth interviews and Tech method was used to analyze data. The results of the study show that children in RCCFs have experienced both positive and negative care. The care is experienced through relationships with staff in the facilities, provision of their basic needs, knowledge of their cultural identity and their adult future preparation once they leave the facilities. Thus, it is recommended that a conducive environment that contributes to the quality of care for children in RCCFs be established, taking into consideration human resources capacity, policy guidelines and standards in place while providing care to those children.
文摘A quantitative technique was conducted at Rosh Pinah Zinc mine, Namibia with its main purpose to determine airways resistance which is a function of the parameters;roughness of the airways and the friction factor. The 32 branch points (<em>i.e.</em> a-ag) that stand for ventilation circuit have been selected. Data collected includes, length and width of airways, air velocity;air density, and roughness of the airways which were used to determine coefficient of frictions, friction factors and airway resistances. A ventilation model was developed. In order to improve the current ventilation model, airways resistance of the mine was determined and simulated in a modified model using VentSim<sup>TM</sup> software. An average total airways resistance of 0.32027 Ns<sup>2</sup>/m<sup>8</sup> has been achieved for Rosh Pinah mine. It should be pointed out that, as the mine advances its production faces deeper, this value would increases suddenly. Simulation revealed that as much as 34.4 m<sup>3</sup>/s of air can be received at the production faces, compared to the measured received amount of 19.3 m<sup>3</sup>/s. Therefore, volumetric efficiency of the mine was improved from 29.3% to 68.3%. It was also noticed that after importing the resistance values into the model together with other parameters, the model was greatly improved and no cause for concern.
文摘This study re-evaluates the characteristics of Cu-Pb-Ag and Fe-Mn ore mineralization of the Kombat Mine and Gross Otavi Mine based on field geology, fluid inclusions, petrology, mineralogy, and geochemistry. This is to determine the genetic relationship between Fe-Mn and Cu-Pb-Ag mineralization. The study has established that the Cu-Pb-Ag ore at the Kombat Mine can be classified as a variant of MVT-type deposit, whereas the Fe-Mn ore can be classified as a stratiform-syn-sedimentary deposit. The formation of the MVT-type deposit is associated with a hydrothermal fluid system with a mean temperature of 183<span style="white-space:nowrap;">°C and mean salinity of 12.85 wt. % NaCl equivalent. The syn-sedimentary Fe-Mn ore, which is largely associated with calc-silicate lithologies, consists mainly of magnetite and hematite with minor pyrite, hausmannite and jacobsite, and was deposited by diagenetic and mixed diagenetic-hydrogenetic processes under changing oxic and anoxic conditions within the sedimentary basin. Acceptable geochemical exploration indicators of the existing mineralization include anomalous values above 0.5% Cu, 0.2% S;0.05% Pb;0.04% As;0.01% Zn;V, W, Mo, and Ag are 0.002%. Mineralogical indicators include chalcopyrite, bornite, covellite and galena with minor chalcocite, sphalerite, and tennantite for the Cu-Pb MVT-type ores at Kombat Mine.
基金Southern African BiochemistryInformatics for Natural Products (SABINA)the Regional Initiative inScience and Education (RISE)
文摘Nasal colonization with Staphylococcus strains puts children at risk of developing difficult-to-treat staphylococcal infections. Antibiotic resistance data is limited in Namibia. Our study thus aimed to provide resistance trends for nasal staphylococci isolated from school children in the Mariental District. This is the first report on antibiotic resistance trends of staphylococci from Namibian school children. By Kirby-Bauer disk diffusion assay, 352 Staphylococcus aureus and 81 coagulase-negative staphylococci (CoNS) isolates from Namibian school children aged 6 - 14 years underwent susceptibility testing against seven antibiotics. Ninety-six percent S. aureus and 66.7% CoNS were resistant to ampicillin. Ampicillin resistance was significantly higher in S. aureus than in CoNS (P S. aureus. Ciprofloxacin was also the most effective drug against CoNS. Cefoxitin/methicillin resistance was seen in 14.5% S. aureus isolates and 8.6% of CoNS. Thirty-one antibiotic resistance patterns were observed, most frequently ampicillin (A), ampicillin-erythromycin (AP-E), and ampicillin-tetracycline (AP-T). Altogether 12.5% isolates (50 S. aureus and four CoNS) were multi-drug resistant. From the methicillin-resistant S. aureus (MRSA) isolates, 43.1% were multi-drug resistant. Methicillin-resistant CoNS were not multi-drug resistant, with the most common resistance pattern being ampicillin-rifampicin-cefoxitin (AP-RP-FOX). In conclusion, multi-drug resistance in our study was relatively low. However, some of the MRSA isolates were multi-drug resistant, which is of concern. Learners should be educated on the importance of handwashing and appropriate use of antibiotics to prevent spread of antibiotic-resistant bacteria within the community. Ciprofloxacin and gentamicin may effectively be used to treat staphylococcal infections in this study population.
文摘Ecosystem Approach to Fisheries(EAF)management is a concept aimed at the conservation and sustainable use of the entire ecosystem.While EAF is a noble approach,its implementation has been challenging.Although Namibia has committed to the implementation of EAF,only limited assessment has been done of Namibian fisheries management processes and instruments concerning EAF.A qualitative assesment was done to ascertain if the Namibian fisheries management processes and instruments conform to the EAF principles.Namibian fisheries management processes and instruments largely conform to the EAF principles,although there are notable areas needing improvements.The conformities were pronounced in the total allowable catch setting,rebuilding depleted stocks,minimizing bycatch,and fishing impact minimization.The polluter pays,and user pays principles were also applied.Areas that were found lacking in this study included setting the indicators for EAF and ecosystem integrity.The assessment also noted the absence of guidelines for the precautionary approach principle and a transparent policy for quota and right allocation processes.The strategies for managing transboundary fish species are also not formulated.Overall,this assessment showed the complexities and challenges that Namibia and other countries need to overcome to implement EAF successfully.
文摘The distribution of the various organic and inorganic constituents and their influences on the combustion of coal has been comprehensively studied.However,the combustion characteristics of pulverized coal depend not only on rank but also on the composition,distribution,and combination of the macerals.Unlike the proximate and ultimate analyses,determining the macerals in coal involves the use of sophisticated microscopic instrumentation and expertise.In this study,an attempt was made to predict the amount of macerals(vitrinite,inertinite,and liptinite)and total mineral matter from the Witbank Coalfields samples using the multiple input single output white-box artificial neural network(MISOWB-ANN),gene expression programming(GEP),multiple linear regression(MLR),and multiple nonlinear regression(MNLR).The predictive models obtained from the multiple soft computing models adopted are contrasted with one another using difference,efficiency,and composite statistical indicators to examine the appropriateness of the models.The MISOWB-ANN provides a more reliable predictive model than the other three models with the lowest difference and highest efficiency and composite statistical indicators.
文摘The purpose of the study sought to assess and evaluate the contents and records of the emergency trolley in the maternity section of the state hospitals in Windhoek, Namibia. A quantitative and descriptive research design was used for the study to investigate emergency equipment, essential drugs and emergency trolleys. A convenient sample of 10 emergency trolleys in the Windhoek Central Hospital (Hospital A) and Katutura Intermediate Hospital (Hospital B) in Windhoek, Namibia were used. Data was collected using a checklist adapted and edited from the EMSSA. Data were analysed using Microsoft excel 2013. Essential paediatric equipment including bag valve mask devices, Magill’s forceps, oxygen masks were absent in many of the units and wards. Data described that checking of defibrillators, monitors and suction devices still remained a major problem in the units/wards that were fortunate enough to have the aforementioned equipment. A conclusion was that generally the units/wards performed well during the assessments and evaluations. There were still units without emergency trolleys, trolleys that were poorly assessed, and those that were obstructed and registered nurses that had a negative perception to the audit of the emergency trolley. Specialized units such as NICU and Hi-Care Hospital A and Prem Unit Hospital B performed very well in their assessments. Development of policy with regards to assessing, restocking and maintenance of emergency supplies can be used to guide the nurses on what to do. Resuscitation morbidity and mortality meetings in order to identify issues and outcomes surround resuscitation incidences within the unit or ward.
文摘Water scarcity is a major problem for Namibia and South Africa as both countries are classified as ＂water stressed＂, based on their per capita water availability which is below the threshold of 1,000-1,666 ma-person^-1.year^-1. Water provision in both countries has traditionally relied on supply-side sources, and the potential for expansion is becoming dim, making efforts towards demand management approaches more feasible. Findings show that CBM （community based management） systems of water points offer an alternative in terms of ownership and self-reliance based on institutional arrangements at community level. However, the CBM system involves some forms of payment for water access, and affordability has become a main challenge, to the extent that some governments are considering the reintroduction of water subsidies for poor rural communities in the near future.
文摘Experimental studies to demonstrate self healing potentials of Al-Mg-Si alloy were undertaken in this research work. Self healing exploring secondary precipitation in the Al-Mg-Si alloy and use of low melting metallic alloy reinforcement (60Sn-40Pb alloy) were used as basis for the investigation. For the precipitation study, the Al-Mg-Si alloy was under-aged at temperature of 160oC for 10 minutes and then subjected to second step ageing treatment at four different temperatures within the range of 25oC and 70oC. In the 60Sn-40Pb alloy reinforced Al-Mg-Si alloy study, the samples were prepared in pre-cracked state and then subjected to healing heat-treatment at 250oC. For all cases tensile test and healing efficiency was used to analyze the results generated. It was observed that a second step thermal ageing at 50oC resulted in peak improvement in tensile strength, yield strength, toughness and percent elongation while ageing above this temperature lead to a drop in the tensile properties in comparison to that of the sample not subjected to a second ageing treatment. Also the use of 60Sn-40Pb alloy as reinforcement in the Al-Mg-Si alloy resulted in a healing efficiency of 91% after pre-cracking and heat-treatment. The satisfactory bonding between the 60Sn-40Pb alloy and the Al-Mg-Si alloy matrix contributed to the high healing efficiency observed.
