383 research outputs found
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On the Perihelion Precession of Solar Planetary Orbits
No full textThis is an articleThe present letter presents an improved version of the Azimuthally Symmetric
Theory of Gravitation (ASTG-model) which was presented for the first time in the
present journal four years ago. We propose a solution to the standing problem of
the -parameters in which effort we put the ASTG-model on a clear pedestal for
falsification. As in the maiden reading, the perihelion precessional data of Solar
planetary orbits is used to set the theory into motion
A ?one-stop shop? approach in antenatal care: does this improve antiretroviral treatment uptake in Zimbabwe?
No full textA ?one-stop shop? approach in antenatal care:
does this improve antiretroviral treatment
uptake in Zimbabwe, is a journal article.A one-stop shop approach to ART integration along with task-shifting considerably increased ART uptake and is
of benefit to mothers and newborns. This is in line with the goal of ensuring that no child is born with HIV by 2015
Esterase Activity of Two Aquatic Snail Species Helisoma Duryi And Lymnaea Natalensis
No full textA paper presented on Research Day on 27th October 2000, hosted by the Biochemistry and Molecular Biology Society of Zimbabwe.Previous work has shown that inhibition of esterase activity is likely to be a useful parafrieter to develop as a biomarker of organophosphate pollutants. We have extended our preliminary study and have now tested for esterase activity with two new substrates (five in total) while measuring the esterase activity in a newly established colony of the aquatic snails Lymnaea natalensis and Helisoma duryi. Post mitochondrial fractions prepared from whole body homogenates were used to measure esterase activity with the following 5 substrates: p-nitrophenyl acetate ( PNPA), (-naphthyl acetate (ANA), phenyl acetate (pHA), carboxylic esterase activity and acetylthiocholine iodide (Ach!) and S-butyrylthiocholine iodide (BthI) cholinesterase activity. Our data shows that the carboxylic esterase (CbE) activity measured in our new stock of snails was decreased (depending on the substrate used a range from 30% to 50%) compared to values obtained previously. Since the cholinesterase (ChE) activity was measured for the first time in these two species a comparison could not be made. In general, the esterase activity was found to be slightly higher in H. duryi than in
L.natalensis. The reasons for the altered activity in the new snail colony is not clear but nutrient and climatic factors are likely to be responsible.Biochemistry and Molecular Biology Society of Zimbabw
In Vitro Effects of Carbaryl and Dimethoate on Esterases of Lymnaea Natalensis.
No full textPresented in October 2002.Agrochemicals have adverse biochemical and physiological effects on organisms and can ultimately cause disturbances in ecosystems. It is therefore important that sensitive techniques are available to monitor their presence and persistence in the environment be monitored. We are pursuing the possibility of developing modified esterase activity in aquatic snails as a potential biomarker for the detection of organophosphate and carbamate pesticides in contaminated waters. We have previously reported that exposure in vivo of the aquatic snail Lymnaea natalensis to a number of organophosphorus and carbamate pesticides causes inhibition of esterase activity to varying degrees in a pesticide and esterase substrate specific manner. Here we report on the effects of two commonly used pesticides, dimethoate and carbaryl in vitro, on the esterase activity of an aquatic snail L. natalensis. Post mitochondrial fractions were prepared from adult L. natalensis bred in outdoor cement aquaria. Esterase activity was measured in the presence of various concentrations of dimethoate or carbaryl. Our results showed a non-linear, but dose dependent, inhibition of esterase activity with both pesticides using 5 different substrates which were used to differentiate (choline and non-choline) esterase activity. Esterase activity was reduced significantly, depending on the substrate used, in the presence of both dimethoate (11 "10 - 78'Yo) and carbaryl (l5'Yo-93"1o). Both dimethoate and carbaryl showed similar IC50 values but variations were noted depending on the substrate used to determine esterase activity. Dimethote was, however, the mor'e potent of the two pesticides as shown by the its lower IC50 values when compared to carbaryl. Our data suggests there is a potential for the use of esterase activity in L. natalensis as a biomarker of organophosphorus and carbamate pesticidesBiochemistry and Molecular Biology Society of Zimbabw
Recovery Of Choline And Non-Cholinesterase Activity Of The Freshwater Snail Lymnaea Natalensis Following Exposure To Six Pesticides
No full textPresented at the 5th Congress of the Federation of African Societies of Biochemistry and Molecular Biology in November 2006.Organophosphates and carbamates are the most widely used insecticides mainly because they are readily biodegradable in the environment. We investigated the recovery of esterase activity of an aquatic snail L. natalensis following a 24-hour exposure to 6 different pest.icides. A third of the snails were sacrificed after 24 hours while another third was allowed to recover in clean water for 14 days and the remainder for 28 days. All pesticides caused significant inhibition of esterase activity. Aldicarb caused the highest inhibition in esterase activity 98 % while thiamethoxam caused the least 61 %. Esterase activity improved significantly in the recovery period and 14 days in the recovery period, aldicarb and thiamethoxam exposed snails had recovered to 57 % and 67 % of control.
After 28 days of recovery, aldicarb exposed snails had only 62 % esterase activity in comparison to controls. The results show that even after 28 days of recovery, esterase activity was still reduced by up to 38 % depending on the pesticide, an indication that recovery of the snails depends on the pesticide. From the results we suggest that where pesticides need to be applied more than once, a time gap between applications should be allowed to enable non-target organisms in soil and aquatic systems to recover from effects of previous applications thereby ensuring the good health of non-target organisms.Federation of African Societies of Biochemistry and Molecular Biolog
Agility for Sustainability in Zimbabwe: A Case Study for Manufacturing Companies in Bulawayo
No full textAgility in manufacturing is critical for competitiveness. It is an ability to quickly change in a flexible way to meet market demand. This requirement has come as a result of the globalization phenomenon that has affected all companies in one way or the other. This study was aimed at establishing the level of agility that exists in
Zimbabwean manufacturing companies. A case study of companies in Bulawayo with a focus on manufacturing diversity was conducted. Audits were carried out on a spectrum that covers textiles, beverages, pharmaceuticals,foundry, rubber manufacturing, including household and industrial chemicals. This enabled establishing the challenges that manufacturing companies face with a view of developing an appropriate model for agility and success. The current manufacturing practices were analyzed for selected companies while their ability to respond to
market demand fluctuation was assessed and an appropriate model developed. The model incorporates characteristics of the local operating environment. The main challenges the manufacturing companies face in the
global marketplace played a critical role in the development of the model. The manufacturing industry in Zimbabwe is stuck on mass production and traditional manufacturing practices. The world has changed and this change needs to be recognized as a vehicle for competitive success. Global competition has moved a step higher while companies in Zimbabwe have remained stagnant in their practices, technology, and agility. Many manufacturing companies elsewhere are employing agile manufacturing principles that drive them towards world class manufacturing status and sustainability in an ever-changing environment. Thus, the proposal for an agile
manufacturing model for Zimbabwe is outlined
An overview of the potential for biological monitoring of water pollution
No full textOne of the major concerns in Southern Africa is the
provision of adequate clean drinking water. As a result of
human agricultural and industrial activity many toxins are
released into the environment. Many of these toxins, which
include heavy metals (e.g.cadmium,lead,mercury) and organic
compounds (e.g. endosulfan, DDT) , are also likely to find
their way into freshwater bodies. Water that is contaminated
with such toxins would be unsuitable for human consumption.
With the prospect of increased industrialization and
agricultural output, it is likely that even larger quantities
, of industrial waste and agricultural pesticides will be
released into the environment including natural waterbodies.
Many of these chemicals are known toxins and they may
accumulate in the food chain and threaten not only humans,
but also wildlife, and indeed the ecosystem as a whole. It
is therefore important to monitor the presence of inorganic
and organic pollutants in water-bodies to predict its safety
for human/animal consumption. Several different methods have
been developed to attempt a prediction of the levels of these
pollutants or their fate in the environmentInternational Foundation for Science (Sweden); Research Board, University of Zimbabwe; and the International Programs in
Chemical Scienc
Project Management principles: Their importance in delivering value and high productivity within resource constraints.
No full textPublished in The Chronicle Newspaper of 2013 on the productivity column.The year 2013 has started and it is the time when many organizations look at their
planned projects for implementation, continuation or completion. There is also the other
side where after a break for the year-end holidays, workers go back to their continuing
projects. This is not withstanding that there are some projects that never get completed.
As such the author would like to highlight some basics of Project Management. These are
encompassed in principles that increase the chances of project completion with available
resource constraints. Projects should be managed properly so as to reduce wastage of
resources. This article is aimed at highlighting the general principles of project
management that can enhance increased value and productivity in project type of work