Browsing Faculty of Science by Title
-
Gatsinzi, J-B. (International Press; http://www.intlpress.com/HHA/, NaN, 2004)[more][less]
Abstract: In this paper, we show that the rational homotopy Lie algebra of classifying spaces for certain types of hyperbolic coformal 2-cones is not nilpotent. Description: Copyright of International Press. http://www.intlpress.com/ URI: http://hdl.handle.net/10311/183 Files in this item: 2
license.txt (1.998Kb)Microsoft Word - Gatsinzi 2004.pdf (611.5Kb) -
Onibere, E.A.; Morgan, S.; Busang, E.M.; Mpoeleng, D. (Elsevier Science Ltd, www.elsevier.com/locate/intcom, NaN, 2001)[more][less]
Abstract: This paper reports on research carried out to determine whether a localised interface is preferred by users in a multi-cultural and multi-lingual country where a non-local language is nationally used,. We attempted to discover whether local symbols are more acceptable to users as icons and also whether the current phrases used in menus and icon descriptions are clearly understood by the various communities. A survey was conducted nation-wide among computer end-users in Botswana. The results indicate an overwhelming desire from users for a localised interface. However, there appears to be little need for localised icons and no agreement as to which language to use for text-based interfaces. URI: http://hdl.handle.net/10311/887 Files in this item: 1
Mpoeleng_IC_2001.pdf (1.247Mb) -
Nkoane, B.B.M.; Sawula, G.M.; Wibetoe, G.; Lund, W. (Elsevier www.elsevier.com/locate/jgeoexp, NaN, 2005)[more][less]
Abstract: Plant species that accumulate high levels of metals in proportion to the metal content in the soil are of considerable interest in biogeochemical and biogeobotanical prospecting. This study was aimed at investigating copper and nickel accumulation in the plants Helichrysum candolleanum and Blepharis diversispina, to assess their potential use as mineral indicators in biogeochemical prospecting. Soils and plants were collected from copper–nickel mineralised areas in Botswana. Analyses of the soils and the respective plant parts (roots, stem, leaves and flowers) were carried out using ultrasonic slurry sampling electrothermal atomic absorption spectrometry (ETAAS), which allowed rapid determination of copper and nickel in small amounts of the samples. The metal concentration in the soil was in the range c40 Ag/g–4% (w/w) for Cu and c60 Ag/g–0.3% (w/w) for Ni. The concentration ranges of the elements in the plant parts were c6 Ag/g–0.2% Cu and c3–210 Ag/g Ni. At high soil metal content (greater than 2.5% (w/w) Cu and 0.1% (w/w) Ni), high levels of both nickel and copper were found in the shoots (leaves and flowers) of H. candolleanum. Concentrations as high as 0.2% (w/w) Cu were found in the leaves and flowers of H. candolleanum, indicating hyperaccumulation for this plant. For B. diversispina, the metal concentrations did not exceed 100 Ag/ g for any plant part, for both metals. Both plant species tolerate high concentrations of metals and should therefore be categorized as metallophytes. In order to evaluate metal translocation from the soil to the shoots, metal leaf transfer coefficients (ratio of metal concentration in the leaf to metal concentration in the soil) were calculated. Our data suggest that the two plant species have different metal uptake and transport mechanisms, which needs to be investigated further. The present work also suggests that H. candolleanum may be used as a copper/nickel indicator plant in biogeochemical or biogeobotanical prospecting. URI: http://hdl.handle.net/10311/527 Files in this item: 1
NKOANE2005Indicatorplants.pdf (1.835Mb) -
Ali, M.M.; Kaelo, P. (Elsevier Ltd. www.elevier.com/locate/amc, NaN, 2008)[more][less]
Abstract: Particle swarm optimization algorithm has recently gained much attention in the global optimization research community. As a result, a few variants of the algorithm have been suggested. In this paper, we study the efficiency and robustness of a number of particle swarm optimization algorithms and identify the cause for their slow convergence. We then propose some modifications in the position update rule of particle swarm optimization algorithm in order to make the convergence faster. These modifications result in two new versions of the particle swarm optimization algorithm. A numerical study is carried out using a set of 54 test problems some of which are inspired by practical applications. Results show that the new algorithms are much more robust and efficient than some existing particle swarm optimization algorithms. A comparison of the new algorithms with the differential evolution algorithm is also made. URI: http://hdl.handle.net/10311/178 Files in this item: 2
Ali_Kaelo_AMC_2008.pdf (3.814Mb)license.txt (1.998Kb) -
Ogwu, F.J.; Talib, M.; Aderounmu, G.A. (Science Publications, http://www.scipub.org/scipub/c4p.php?j_id=JCS, NaN, 2007)[more][less]
Abstract: This study presents a technique for improving the quality of service (QoS) guarantee in an ATM network. In the proposed model, it was assumed that high priority traffic have been allocated a switch resource to guarantee a given QoS and low priority cells are allowed to enter the buffer, to improve the exploitation of reserved resources. The proposed technique was backed up with an exact analytical model for evaluating the cell loss probability of high and low priority cells. The performance of the proposed model was evaluated using C++ programming language. The results of the simulation shows that the loss probability of both high and low cells reduces as the buffer capacity increase and that the performance of high priority cell is better than that of low priority cell. URI: http://hdl.handle.net/10311/818 Files in this item: 1
Ogwu_JCS11_2007.pdf (556.8Kb) -
Banda, A.; Mubyana-John, T.; Taylor, J.E. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: The influence of burning on soil microbial dehydrogenase activity, nitrogen content and fungal population along the Boro route in the Okavango Delta was assessed in the flood and dry seasons. Soil samples from the burnt plots and the adjacent control un-burnt plots were cultured on agar plates using dilution methods. Fusarium spp. were dominant while Aspergillus species were low in burnt plots. The other fungi such as Drechslera sp., Exophiala jeanselmmei, Penicillium compactum and Chrysosporium merdarium were only in the burnt plots as compared to unburnt control plots. However, fungal diversity and soil dehydrogenase activity reduced after 6 months of burning showing significant increase in Chrysosporium merdarium in almost all the burnt plots. The influence of burning on soil nitrogen was insignificant instead flooding had a stronger influence on nitrogen content than burning. The results indicate that burning increased fungal diversity and biomass, however, reduces overall microbial enzyme activity after burning without influencing soil nitrogen and pH. URI: http://hdl.handle.net/10311/919 Files in this item: 1
Mbuyana_AJPSB_2011.pdf (220.0Kb) -
Mubyana, T.; Krah, M.; Totolo, O.; Bonyongo, M. (Journal of Arid Environments. http://www.elsevier.com/wps/find/journaldescription.cws_home/622855/description#description, NaN, 2003)[more][less]
Abstract: The effect of flooding on soil total nitrogen, phosphorus and microbial population in different vegetation zones (floodplain, island and woodland) and profile depth (0?1, 0?5, 2?0, 3?0, 4?0 and 5?0m) of the Okavango Delta was studied from February to July 1999. Total nitrogen significantly differed with soil profile depth, moisture regime and months. In the woodlands, insignificant total nitrogen was detected at all depths except at 0?1m, where 0?03% and 1?17% were detected in February and March, respectively. In the island samples, only 0?05% was detected at 4m in February. Nitrogen in the floodplain samples was concentrated in the A1 horizon where 0?12%, 0?61% and 0?03% were detected in February, March, and May, respectively. Organic phosphorus significantly differed with vegetation zone but not with months and depth. Although organic phosphorus was low (0?02–0?52%) at all sites, it was liberally distributed throughout the profiles. On the island, actinomycetes were only detected up to 2m in February and up to 3m in July. Fungi concentrated in the top 0?5m (103–105). In both the floodplain and island samples, bacteria concentrated in the upper 3m. However, after May, populations decreased significantly. In the floodplain, significant actinomycetes populations were only detected in the upper 0?5m. Generally, organic phosphorus showed positive correlations with fungal populations. This study indicates that these soils are low in total nitrogen and phosphorus. URI: http://hdl.handle.net/10311/293 Files in this item: 1
Influence of seasonal flooding.pdf (3.953Mb) -
Dikinya, O.; Hinz, C.; Aylmore, L.G. (Csiro, http://www.publish.csiro.au/nid/84.htm, NaN, 2007)[more][less]
Abstract: The paper examines the effects of electrolyte concentration and sodium adsorption ration (SAR) on the relative saturated hydraulic conductivity (RHC) and the ionic behaviour of calcium (Ca) and sodium (Na) ions in the Na-Ca echange complex. Batch binary exchange and saturated column transport experiments were carried out to quantify these effects using agricultural Balkuling soil and mining residue. Generally, RHC has been found to decrease with time, with increasing SAR and with decreasing electrolyte concentration. The more rapid decrease in RHC in the mining residue, particularly at the lowest concentration (1 mmol/L), was consistent at all SAR values. The decreases in RHC were likely to be caused by partial blocking of pores by dispersed clay particles, as evidenced by the appearance of suspended clay particles in the effluent during leaching. Significant differences in RHC were abserved in the passage of fronts of decreasing electrolyte concentration for CaCl2 and SAR 15 solutions through the soil columns. These differences were attributable to structural alterations (slaking) of the media and the nature of the particles released and mobilised within the porous structure at a given point in the column. Measurements at the critical threshold concentration and turbidity increase in SAR to 15 is initially accompained by erractic RHC, presumably due to the break up of soilaggregates under the increased swelling forces. The less coherent mining residue soil was substantially more vulnerable to blockage of pores than the Balkuling soil in which clay particles are likely to be more readily mobilised, and hence available to re-deposit and occlude the matrix pores. URI: http://hdl.handle.net/10311/312 Files in this item: 1
-
Nijegorodov, N.; Winkoun, D.P.; Nkoma, J.S. (Elsevier Science Ltd http:www.elsevier.com/locate/saa, NaN, 2003)[more][less]
Abstract: Please refer to the attached article for an ABSTRACT. The abstract was not uploaded here due to formula appearance problem in UBRISA. URI: http://hdl.handle.net/10311/403 Files in this item: 1
Nijegorodov_SAa60_2004.pdf (1.056Mb) -
Nijegorodov, N.; Winkoun, D.P.; Nkoma, J.S. (Elsevier Science Ltd. www.elsevier.com/locate/saa, NaN, 2004)[more][less]
Abstract: The fluorescence and laser properties of seven specially chosen aromatic compounds are studied at 293 ◦C. The quantum yield of fluorescence, γ, decay times, τf , of the deaerated and non-deaerated solutions are measured. The oscillator strength, fe, fluorescence rate constants, kf , natural lifetimes, τT 0 , and intersystem crossing rate constants, kST, are calculated. Some laser parameters are calculated or measured experimentally. It is found that the position of the T level plays an important role in the fluorescence and laser properties of aromatic compounds. If the T level is situated below the Sp level, it decreases the quantum yield of fluorescence and the decay time and increases the threshold of laser action. If, due to some structural changes of a molecule, the T level is situated higher than the Sp level, then the quantum yield of fluorescence and the decay times are increasing and the threshold of laser action is decreasing. Such influence of the position of the T level upon fluorescence and laser properties of aromatic compound is explained by the fact that the Sp level mixes with the T level more readily than with other τ ∗ levels. URI: http://hdl.handle.net/10311/366 Files in this item: 1
Nijegorodov_SAa60_2004.pdf (1.056Mb) -
Nijegorodov, N.; Mabbs, R.; Winkoun, D.P. (Elsevier Science Ltd. www.elsevier.com/locate/saa, NaN, 2003)[more][less]
Abstract: Please refer to the attached article for an ABSTRACT. The abstract was not uploaded here due to formula appearance problem in UBRISA. URI: http://hdl.handle.net/10311/402 Files in this item: 1
Nijegorodov_SAa59-2003.pdf (1.367Mb) -
Chaturvedi, P. (Oxford University Press, Oxford Journals; http://ecam.oxfordjournals.org/, March NaN, 2008)[more][less]
Abstract: In the present study, inhibitory effect of the methanol extract of Raphanus sativus root on lipid peroxidation has been carried out in normal rats. Graded doses of methanol extract of root of the plant (40, 80 and 120 mg kg 1 body weight) were administered orally for 15 days to experimental treated rats. Distilled water was administered to experimental control rats. At the end of experiment, rats were killed by decapitation after ether anesthesia. Blood and liver were collected to measure thiobarbituric acid reactive substance, reduced glutathione and activity of catalase. Results indicated that the extract of R. sativus root reduced the levels of thiobarbituric acid reactive substance significantly in all experimental treated groups (P50.05) as compared to the experimental control group. It also increased the levels of reduced glutathione and increased the activity of catalase. In vitro experiments with the liver of experimental control and experimental treated rats were also carried out against cumene hydroperoxide induced lipid peroxidation. The extract inhibited in vitro cumene hydroperoxide induced lipid peroxidation. R. sativus inhibits lipid peroxidation in vivo and in vitro. It provides protection by strengthening the antioxidants like glutathione and catalase. Inclusion of this plant in every day diet would be beneficial. Description: eCAM Advance Access originally published online on February 20, 2007 eCAM 2008 5(1):55-59; doi:10.1093/ecam/nel077 Version available here is the 2007 version. URI: http://hdl.handle.net/10311/182 Files in this item: 2
Inhibitory response of raphanus.pdf (861.5Kb)license.txt (1.998Kb) -
Kgathi, D.L.; Bolaane, B. (Sage http://wmr.sagepub.com/cgi/content/abstract/19/4/342, NaN, 2001)[more][less]
Abstract: Sustainable solid waste management is a strategy for achieving environmental quality in both the developed and the developing world. Environmental quality is a necessary condition for an increase in per capita welfare over time. The paper suggests alternative instruments for solid waste reduction, re-use and recycling. But to be able to apply the suggested economic instruments, the quantities and composition of the waste must be known. Having identified the current instruments of Botswana’s solid waste management (regulatory measures, environmental education, and economic instruments of property rates, service levy, and sanitation fees), the paper argues that these do not go far enough in enhancing environmental protection. Alternative instruments such as solid waste collection and disposal levies, deposit refund schemes, and product levies are suggested. It is also suggested that public environmental education and regulatory measures should be strengthened. URI: http://hdl.handle.net/10311/480 Files in this item: 1
Kgathi_WMR_2001.pdf (1.278Mb) -
Swatuk, L. A.; Rahm, D. (Elsevier, http://www.linkinghub.elsevier.com/retrieve/pii/S1474706504001834, NaN, 2004)[more][less]
Abstract: Botswana is generally regarded as an African success story. Nearly four decades of unabated economic growth, multi-party democracy, conservative decision-making and low-levels of corruption have made Botswana the darling of the international donor community. One consequence of rapid and sustained economic development is that water resources use and demands have risen dramatically in a primarily arid/semi-arid environment. Policy makers recognize that supply is limited and that deliberate steps must be taken to manage demand. To this end, and in line with other members of the Southern African Development Community (SADC), Botswana devised a National Water Master Plan (NWMP) and undertook a series of institutional and legal reforms throughout the 1990s so as to make water resources use more equitable, efficient and sustainable. In other words, the stated goal is to work toward Integrated Water Resources Management (IWRM) in both policy and practice. However, policy measures have had limited impact on de facto practice. This paper reflects our efforts to understand the disjuncture between policy and practice. The information presented here combines a review of primary and secondary literatures with key informant interviews. It is our view that a number of constraints—cultural, power political, managerial—combine to hinder efforts toward sustainable forms of water resources use. If IWRM is to be realized in the country, these constraints must be overcome. This, however, is no small task. URI: http://hdl.handle.net/10311/405 Files in this item: 1
Swatuk_PCE_2004.pdf (1.142Mb) -
Gwebu, T.D. (Taylor & Francis (Routledge), http://jir.ucsur.pitt.edu/, NaN, 2008)[more][less]
Abstract: Based on the intergenerational wealth flows conceptual framework, this paper investigates how the AIDS pandemic threatens to disrupt the transfer of resources between generations by using a typical low income urban area in sub-Saharan Africa as a case study. It explores the everyday living conditions of orphans, their guardians, and the primary home caregivers, with the intention of gaining a deeper insight into their current and future life chances, as a result of parental morbidity and mortality due to HIV/AIDS. The research employs a qualitative methodology and relies on documentary information from secondary sources. Short- and long-term recommendations on how to mitigate the negative impacts of HIV/AIDS on wealth transfers among the affected populations are suggested based on the study findings. URI: http://hdl.handle.net/10311/1019 Files in this item: 1
Gwebu_JIR_2008.pdf (1.160Mb) -
Ogunlusi, G.O.; Ige, J.; Oyetunji, O.A.; Ojo, J.F. (Springer Science+Business Media B.V., http://www.springer.com/chemistry/journal/11243, NaN, 2009)[more][less]
Abstract: The kinetics of the reactions between azidopentacyanocobaltate(III), Co(CN)5N3 3-, and iron(II) polypyridyl complexes, Fe(LL)3 2? (LL = bipy, phen), have been studied in both neutral and acidic aqueous solutions at I = 0.1 mol dm-3 NaCl. The reactions were carried out under pseudo-first-order conditions in which the concentration of Fe(LL)32+ was kept constant, and the second-order rate constants obtained for the reactions at 35 C were within the range of 0.156–0.219 dm3 mol-1 s-1 for LL = bipy and 0.090–0.118 dm3 mol-1 s-1 for LL = phen. Activation parameters were measured for these systems. The dependence of reaction rates on acid was studied in the range [H+] = 0.001–0.008 mol dm-3. The reaction in acid medium shows interesting kinetics. Two reactive species were identified in acid medium, namely, the protonated cobalt complex and the azido-bridged binuclear complex. The electron-transfer process is proposed to go by mixed outerand inner-sphere mechanisms in acid medium, in which electron transfer through the bridged inner-sphere complex (k5) is slower than through the outer-sphere path (k4). Description: Symbols may not appear as they are in the original abstracts. URI: http://hdl.handle.net/10311/1035 Files in this item: 1
Ogunlusi_TMC_2009.pdf (948.9Kb) -
Mpoloka, S.W. (American-Eurasian Network for Scientific Information. http://www.aensi.org/aeb_online.html, NaN, 2008)[more][less]
Abstract: The nuclear 18S rDNA and chloroplast encoded rbcL gene sequences were used to investigate the evidence of residual UV-B induced mutagenesis in Dimorphotheca sinuata plants. The probes were generated by the polymerase chain reaction and labelled with a non-radioactive Digoxigenin label and used in Southern hybridization studies. High levels of variability in the 18S rDNA gene were found, pointing to genome rearrangements and possibly genome instability due to UV-B effects. URI: http://hdl.handle.net/10311/484 Files in this item: 1
Investigating evidence.pdf (1.233Mb) -
Alemaw, B.F.; Chaoka, T.R.; Totolo, O. (Elsevier Ltd. http://www.elsevier.com/wps/find/journaldescription.cws_home/413/description#description, NaN, 2006)[more][less]
Abstract: The agricultural economic sector of Botswana is limited mainly to range resources-based livestock and pockets of arable farming based on rainfall and limited irrigated agriculture at several places. In this study agricultural sustainability of rain-fed agriculture is investigated in Botswana by considering the Pandamatenga plains as a case study. Daily soil moisture regimes with respect to crop growth cycle were modelled using a water balance model based on 42 years of daily hydroclimatic inputs and corresponding simulated components of soil moisture, evaporation, surface runoff, and deep percolation. Using a sustainability criterion on crop water requirement and soil moisture availability during the cropping periods, it was found that rain-fed agriculture of maize, sunflower, and sorghum crops is sustainable. The relative sensitivity to drought of these crops was also found to conform to the Agromisa recommendations. In the pursuit to explore more IWRM opportunities, through the simulation of the corresponding direct runoff, we have also explored that more water harvesting opportunities exist in order to manage rainfall excesses effectively. URI: http://hdl.handle.net/10311/155 Files in this item: 4
alemaw_chaoka_totolo_06.pdf (2.112Mb)license.txt (1.998Kb)license.txt (1.998Kb)license.txt (1.998Kb) -
Moseki, B.; Buru, J.C. (Academic Journals, http://www.academicjournals.org/, NaN, 2010)[more][less]
Abstract: The aim of this study was to assess the growth response of Sesuvium portulacastrum (L.) (a halophyte) to various NaCl concentrations and hence determine how it is adapted to grow optimally under saline conditions. S. portulacastrum was grown hydroponically in various NaCl concentrations (that is, 0, 100, 200, 400 and 600 mol m-3 NaCl). It was found to exhibit a growth pattern typical of dicotyledonous halophytes. It attained maximal growth at 200 mol m-3 NaCl concentration in hydroponic cultures. It accumulated large concentrations of Na+ and Cl- with the leaves having the highest ion content. These ions are believed to be sequestered in the vacuole. S. portulacastrum also accumulated proline in high concentrations and this proline appeared to adjust the cytoplasmic ion concentration to balance that of the vacuole. URI: http://hdl.handle.net/10311/961 Files in this item: 1
Moseki_SRE_2010.pdf (102.5Kb) -
Ngamga, D.; Yankep, E.; Tane, P.; Bezabih, M.; Ngadjui, B.T.; Fomum, Z.T.; Abegaz, B.M. (Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com, NaN, 2005)[more][less]
Abstract: Three new isoflavonoids, griffonianone F, G and H were isolated from the seeds of Millettia griffoniana, along with the known prebarbigerone, pseudobaptigenin, pseudobaptigenin methyl ether, tephrosin, dipterixine, odorantine, 7,4’,5’-tetramethoxyisoflavone and isojamaicin. Their structures were assigned on the basis of spectroscopic data and chemical transformations. URI: http://hdl.handle.net/10311/274 Files in this item: 1
Isoflavonoids from Seeds.pdf (1.353Mb)