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Application of vehicle routing in a bread delivery system at Bakers Inn 15th Avenue Factory in Bulawayo
No full textA Monthly Double-Blind Peer Reviewed Refereed Open Access International e-Journal - Included in the International Serial DirectoriesThis study involves designing a vehicle routing and scheduling system to improve the utilization of a fleet of delivery trucks at the same time reducing delivery costs in bread delivery. Data was collected from Bakers Inn 15th Avenue Bulawayo Bakery and the deliveries it made to 20 outlets around the city. A savings algorithm, co-joined with a neighborhood search, was adopted to solve the problem and LINDO software program was used to accelerate the computation of the costs and the routes with ease. The results were then compared with the current manual system at the company and it was found that the software-based vehicle routes improved performance and reduced cost indicating a major need for the manufacturing company to manage its supply chain well. Recommendations include immediate adaption of the software-based bread delivery system because the importance of vehicle routing was recognized
Potential Use of Esterases As Markers of Aquatic Pollution By Organophosphate and Carbamate Pesticides
No full textPresented at the Southern African Society of Aquatic Scientists Conference 2004Potential Use of Esterases As Markers of Aquatic Pollution By Organophosphate and Carbamate Pesticides Pesticides are used to widely in agriculture in Southern Africa. Many of these pesticides fall into the category of either organochlorines, pyrethroids, organophosphates or carbamates. We have been interested in the possible use of esterase is as biomarkers of environmental water pollution. Amongst the compounds we have studied are dimethoate, pirirniphos, malathione and monocrotophos. We have studied the effects of these pesticides on the esterase of aquatic molluscan species such as Lymnaea natalensis and Helisoma duryi and Physa acuta. The esterases studied include choline and non-choline esterases and activity was measured using different substrates namely, a-naphthyl acetate, phenyl acetate, 4-nitrophenyl acetate, acetyl thiocholine and S-butyryl
thiocholine. Our data indicates that there is a marked species difference in the response to these pesticides. In addition we have found that carbamate pesticides inhibit esterase activity to a lesser extent than do organophosphates and that this inhibition is time and dose dependent. In general esterase activity has been shown to be inhibited by as little as one ppm within eight hours of exposure. Our date supports the results of studies conducted elsewhere in freshwater, estuarine, as well as marine organisms that suggest inhibition of esterase activity in aquatic organisms is a potential biomarker of water pollution. A review of the literature will be provided in addition to data generated in our laboratory.SETAC Afric
Strain Dependant Variation In The Response Of Hepatic Drug Metabolizing Enzymes To Infection With Schistosoma Mansoni.
No full textPresented at the 8th International Symposium on Microsomes and Drug Oxidations in June 1990Introduction: Infection with S.mansoni has been shown to alter hepatic drug metabolising enzyme levels in mice although we have shown that hepatic drug metabolising enzymes of male hamsters are not significantly affected as a result of infection. Considerable specie and strain dependent variations do exist, however,' in the pathology of and immune response to S.mansoni infection in animals. It is not known if animals of the same specie but of different strains respond similarly to S.mansoni infection in terms
of their hepatic drug metabolising enzymes. This study was therefore performed to assess the effect of S.mansoni infection on hepatic drug metabolism in vitro in male BALB/c and CBA/H mice.
Results and Discussion: The results in Table 1 show that alterations in hepatic drug metabolism in vitro due to infection with S.mansoni vary between male BALB/c and CBA/H mice. Infected BALB/c and CBA/H mice both showed decreased concentrations of cytochromes P-450 and b5, and a decreased rate of ethoxyresorufin metabolism. Only infected BALB/c mice, however, showed decreases in their NADPHcytochrome c reduce activity and in the rate of ethoxycoumarin metabolism, and an increase in the rate of 4-nitroanisole metabolism. While the microsomal uridine diphosphate glucuronyl transferase
activities were decreased in infected BALB/c and CBA/H mice, the cytosolic glutathione-S-transferase activities were decreased only in BALB/c mice as a result of infection. The reasons for the strain
dependent difference observed here is not known. It is possible that various factors released in the circulation of animals infected with S.mansoni, such as interferons, interleukin-l, histamines etc, affect the activities of hepatic drug metabolising enzymes. Strain dependent alterations in microsomal drug metabolism have also been reported for animals pretreated with inducers of interferon synthesis. Interstrain differences among infected animals in the release of immune modulators such as those described above may be responsible for the varying effects on the hepatic drug metabolizing enzymes and their isozymes.
Conclusions: It is concluded that the disposition of xenobiotics in experimental S.mansoni infected mice will vary depending on the mouse strain being used. Choice of an animal model for studies on the effect of schistosomiasis on drug metabolism should therefore be made carefully especially if extrapolation to humans is intended.International Symposium on Microsomes and Drug Oxidation
Biomarkers of Environmental Pollution
No full textPresented at the Biochemistry and Molecular Biology Society Conference held at the University of Zimbabwe in October 2002The threat to our environment due to human activity continues as the need for increased agricultural and industrial output continues. Agrochemicals currently used include pesticides such as organochlorines, organophosphates (OP's), neonicotinoids and pyrethroids. Industrial activity continues to generate an increasing diversity and volume of chemicals, such as PCB's and dioxins, that find their way into our natural and manmade water bodies. Metals such as lead, chromium and cadmium are either mined or are discharged as by-products of human activity. When used safely or disposed of properly these compounds are not always hazardous. However, their improper disposal or use poses a hazard to the health of humans, wildlife and the ecosystem as a whole. They are known to cause a variety of toxic effects such as genetic damage, organ toxicity and several physiological changes such as endocrine disruption. There is.a need to identify such toxic compounds and also to monitor their presence particularly in water bodies of Southern Africa where freshwater is scarce. Some of the methods, currently available to detect such toxins, include the measurement of parameters such as esterase activity (or its inhibition) for OP's, the extent of DNA damage (using the COMET assay) and induction/inhibition of detoxication enzymes (cytochrome P-450, glutathione S-transferase, antioxidant enzymes etc.) and induction of vitellogin synthesis (in fish). However, all these methods are not reliable or sufficiently sensitive. A summary of the data presented in the literature as well as that generated in our own laboratory will be presented.Biochemistry and Molecular Biology Societ
The Role Of Natural Products In Environmental Toxicology And Health.
No full textPresented at the Afassa Regional Symposium on Natural Products in June 2004.Many of natural products have been studied as crude extracts. Many active ingredients have also been purified and their chemical structures have been elucidated. Yet in most cases there is a paucity of information regarding their biological activity. Natural products have been tested widely in the ceArol of a number of parasitic diseases around the globe. In the control of malaria various chemicals have been tested for controlling
the mosquito vector e.g. extracts of neem. Several other natural compounds have also been tested for possible control of the parasite itself e.g. quinine and artemisinin (a sesquiterpene lactone) which have shown tremendous potential in the control of malaria. Aquatic mollusks transmit a number of other parasitic diseases such as schistosomiasis and fascioliasis in the tropics. A number of different compounds belonging to a variety of different chemical classes have been tested for their efficacy as molluscicides e.g. Azadirachta indica, Cedrus deodara, Allium sativum. Natural products have also been shown to affect animals in their natural ecosystems. There are a number of compounds that have been shown to affect reptilian species e.g. cinnamaldehyde and geranyl acetate. Other compounds such as genestitin, naringenin and zearalenone cause physiological systems in animals. Although the compounds have adverse effects in certain organisms they have beneficial effects in others. The mechanisms by which these natural compounds affect organisms are many and diverse. Such mechanisms include alteration of enzyme activities, receptor binding and macromolecular integrity. Altered enzyme activity includes key detoxication enzymes (xenobiotic metabolism) as well as those involved in intermediary metabolism. Altered binding to receptors of the endocrine system is an emerging area of research (endocrine disruption). Damage to DNA is also a possible target of natural compounds. While there is a large body of information on the effects of anthropogenic compounds on the above targets there is much less data available on the effects of natural products. More recently there is an upsurge in the effects of natural compounds on these targets and this paper will provide examples of the currently available information.Sida, SARE
Effect Of Cadmium On The Activltes Of Glutamate Dehydrogemase, Alanine And Aspartate Aminotransferase In Fresh Water Snails, Helisoma Duryi And Lymnea Natalensis
No full textPresented at the Sida,SAREC Water Project Conference in December 2000.Snails are known to accumulate metal ion pollutants in their tissues this being attributed to induction of metal binding proteins (Petering and Fowler. 1986). A consequence of the presence of pollutants in water inhabited by aquatic organisms may be the induction of enzymes required to metabolise or degrade the pollutants in such organisms. Other enzymes may also be induced in response to toxic effects of these pollutants on metabolic pathways in which these enzymes are involved. We are investigating the potential use of key enzymes of amino acid metabolism as markers of pollution due to metal ions in fresh water
snails. Helisoma dllryi and Lnnl1ea natalensis. Experimental snails were drawn from concrete breeding tanks where they were regularly fed on lettuce. The snails were exposed for 96 hours to 0.0 1. 0.1 and I ppm concentrations of cadmium ion as a chloride salt. After exposure. snails were shelled excluding any dead snails. The tissue was homogenised and centrifuged at 500 x g for 10 minutes at 4PC to pellet nuclei and unbroken cells. The post nuclear supernatant was centrifuged at 10 000 x g for 10 minutes at 4uC. After suspension of the resulting pellet in buffer. both the pellet fraction ("mitochondria'" fraction) and the supernatant (cytosolic fraction) were aliquoted and stored at -82uC. The samples \vere assayed for the activities of glutamate dehydrogenase. and aspartate and alanine aminotransferases. The concentration of cadmium in breeding waters and in shells and tissues (not homogenised) was also determined. The concentration of cadmium in tissues rose with increasing concentTation the metal ion in breeding waters. In the absence of Cd added i.e. 0.03 and 0.02 1lg./ml Cd concentration in the breeding waters of Helisoma and Ll'lIlI1t!a respectively. the concentration of Cd was 0.08Ilg/g. in Helisvma and Ln7lnea tissues. This concentration rose to 0.47 and 0.37 Ilg/g. at I ppm added Cd for Helisoma and L.1'ml1ea respectively. showing 5.9 and 4.6 fold increases over initial concentration. Cadmium was also found to accumulate in shells of the two snail species. In general the activities of glutamate dehydrogenase (GDH). aspartate and alanine aminotransferases (AST and ALT) increased with concentration of cadmium but then decreased at Ippm added metal for GDH and AST. and at 0.1 ppm for ALT. In both snails consistent changes in GDH activity were seen in the homogenate and 10 000 x g pellet. At 0.1 ppm added cadmium the increased
activity of GDH in the 10 000 x g pellet was 2.5 and 3.6 fold over initial activities for Helisol11a and Ll'Il1l1ea respectively. AST however showed consistent changes in the homogenates and 10 000 x g supernatants for both snails. At 0.1 ppm added cadmium the increased activity of AST in the 10 000 x g sup ematant was 3.4 and 1.8 over initial activities for Helisol11o and (1'IIlI1ea respectively. ALT also showed a similar pattern of activity change in the homogenate and 10 000 x g supernatant although decrease in activity staned much earlier at 0.1 ppm added metal. In the 10 000 x g pellets ALT activity progressively declined froin the initial values to reach 3-t?'0 and 43% of these values at I ppm added Cd for Helisol11a and (Hl/l1ea respectively. Since alanine and aspanate aminotransferases are known to be dually localised in the mitochondria and cy10so1 in a number of species. a possibility that enzyme could have redistributed due to organelle damage is unlikely in view of the low initial activities in the pellets. Funher the increase in enzyme activit. with metal ion concentration also occurred in the homogenates. The increases in enzyme activities were therefore likely to be due to induction of enzymes. Homogenate enzyme activities as well as those of pellet GDH and ALT. and supernatant AST could be sensitive indicators of Cd pollutionSida,SAREC Water Projec
Avoiding Negative Probabilities in Relativistic Quantum Mechanics.
No full textThis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any
medium, provided the original work is properly cited.As currently understood since its discovery, the bare Klein-Gordon theory consists
of negative quantum probabilities which are considered to be physically meaningless if not outright obsolete. Despite this annoying setback, these negative probabilities are what led the great Paul Dirac in 1928 to the esoteric discovery of the Dirac equation. The Dirac equation led to one of the greatest advances in our understanding of the physical World.
In this reading, we ask the seemingly senseless question, ?Do negative probabilities exist
in quantum mechanics?? In an effort to answer this question, we arrive at the conclusion that depending on the choice one makes of the quantum probability current, one will
obtain negative probabilities. We thus propose a new quantum probability current of the Klein-Gordon theory. This quantum probability current leads directly to positive definite quantum probabilities. Because these negative probabilities are in the bare Klein-Gordon theory, intrinsically a result of negative energies, the fact that we-here arrive at a theory with positive probabilities, means that negative energy particles are not to be considered problematic as is the case in the bare Klein-Gordon theory. From an abstract-objective
stand-point; in comparison with positive energy particles, the corollary is that negative energy particles should have equal chances to exist. As to why these negative energy particles do not exist, this is analogous to asking why is it that Dirac?s antimatter does not exist in equal proportions with matter. This problem of why negative energy particles do not exist in equal proportions with positive energy particles is a problem that needs to be solved by a future theory.Research Board, National University of Science and Technology
Investigation of the Effects of Lubricant Fat Content on Drawn Copper Wires.
No full textPresented as part of SAIIE25 Proceedings, 9th ? 11th of July 2013, Stellenbosch, South Africa ? 2013 SAIIE.The Lean Manufacturing goal of reducing waste and increasing productivity has made it a
necessity to produce good quality products in manufacturing industries at a low cost. In the
cable manufacturing companies this can be achieved by optimising the wire drawing process.
One way to meet the desired quality of the drawn wires is to improve lubricant efficiency through installation of an automatic, continuous lubricant fat content control system on the
drawing machine. The paper shows a method of finding the optimum lubricant concentration
for producing good quality copper wires using Taguchi experiments. Taguchi experiments are
employed to analyse the effects of different lubricant fat content levels on the tensile
strength and lubricant temperature. The results from the experiments indicated that the
tensile strength of the wire is affected by low lubricant fat content. The lower the lubricant
fat content: the lower the tensile strength drawing lubricant resulting in numerous wire
breakages that affect the quality of the final product, namely the cable
A cost-benefit analysis of document management strategies used at a financial institution in Zimbabwe: A case study
No full textThis work is licensed under the Creative Commons Attribution LicenseBackground: Choosing a cost-effective document management approach has become a priority to many organisations, especially in view of the rapidly changing technological environment in
which information is being created and managed. A literature survey indicated that document management strategies have the potential to provide some substantial cost-saving benefits if
they are used judiciously.
Objectives: This study investigated a commercial bank?s document management approaches in a bid to ascertain the costs and benefits of each strategy and related issues.
Method: A quantitative research approach was employed through a case study which was
used to gather data from a sampled population in the bank.
Results: The document management approaches used were not coordinated to improve
operational efficiency. There were regulations governing documents management. The skills
and competences of staff on both document management and cost analysis are limited. That is partly due to limited training opportunities availed to them. That means that economies
are not achieved in the management of records. That has a negative impact on the overall
efficiency, effectiveness and legal compliance of the banking institution.
Conclusion: The financial institutions should create regulations enabling periodical cost-benefit
analysis of document management regimes used by the bank at least at quarterly intervals as recommended by the National Archives of Australia. A hybrid approach in managing records is recommended for adoption by the financial institution. There should be on-the-job staff
training complimented by attendance at relevant workshops and seminars to improve the staff?s understanding of both the cost-benefit analysis concept and document management
SME Lending: Do Lending Technologies Matter? Sample Evidence from Zimbabwe
No full textThis is an article published in the journal of World Review of Business Research. The article examines the lending technologies used by Zimbabwean banks to lend money to SMEs. This is examined within the context of Black empowerment and indigenisation policy of Zimbabwe.This paper examines and tests the claim that bank lending technologies are responsible for the low volume of lending to SMEs in Zimbabwe. Based on a survey of directors of SMEs and bank lending officers, tests are conducted to determine if there is any evidence of discrimination against SMEs based on age, management, size, and information attributes. The study reveals that application of uniform lending criteria to SMEs and large corporates does not result in discrimination against SMEs based on age, size, management, or information attributes. Based on this evidence, the study submits that differences in SME lending between foreign and indigenous banks are due to factors other than their lending technologies. The study further provides rationale for collateral-based lending in the SMEs sector in Zimbabwe. The study however questions the static nature of lending technologies used by banks in Zimbabwe, in the wake of high nonperforming loans