2,422 research outputs found
Strategies For Coping With Food Deficits In Rural Zimbabwe
A GJZ research article.The resourcefulness of African smallholders in the face of recurrent food deficits is often overlooked by professionals and officials concerned with food security. Food scarcity has provoked a wide range of interventions by exogenous institutions but only rarely have the coping strategies maintained by small farmers been recognized as affording a basis for such action. Research has shown that rural production systems in different parts of sub-Saharan Africa incorporate a wide range of activities designed to reduce the incidence and impact of food shortage (e.g. Campbell, D.J., 1984; Walts, 1983a; Matiza et al. 1989). These activities are integral to rural production systems and are based on resources and relationships found in the social, economic and political institutions of society and on the generosity of the local physical environment
Using Idea-2-Product Labs® as a strategy for accelerating technology transfer
Technology transfer poses particular problems to developing countries whose governments cannot always afford to fund expensive high-tech solutions. This article reports on the Idea 2 Product Labs® concept that was developed in South Africa to offer a low-cost open-source alternative. The motivation behind the work was to put innovative new technologies into the hands of more people within a shorter timeframe than would otherwise be possible. The background, planning, objectives, outcomes and impact of the project are reported together with some conclusions on how this model could be adopted across a wider domain
Parameters affecting spin casting of decorative and mechanical parts
Published ArticleSpin casting is widely used as a batch manufacturing process for decorative products. In the process, moulds are filled by taking advantage of the centrifugal effect, which is used to increase the pressure within the moulds, resulting in more detailed products. In this study, we analyse the different parameters that could affect the casting of mechanical parts through spin casting. Through this study, the user will be guided in the selection of parameters that will result in a certain degree of accuracy. The parameters were determined by performing numerous experiments using zinc alloy and tin-based pewter as casting materials. Results were obtained by casting approximately 15 000 parts in various positions, and at various clamping pressures, rotational speeds and temperatures in both the mould and the material. The experiments were undertaken by varying one parameter at a time, and with each set parameter repeated once, resulting in 100 test pieces per parameter for evaluation. From the results obtained, a series of critical factors and parameters, which are driven by part characteristics or features, has been studied. Contrary to following a modelling approach, the research was conducted following an action-research approach, with planned activities, but where actual results have defined the follow-up procedures. These guidelines will help industrial users ensure the accuracy of parts produced by spin casting. Also, since this project attempted to create a database of results that can be applied in future, it furthermore implies that the data created for the first time can be used in a numerical modelling approach in further / follow-up research. No such data was available from any previous research
Report of the SNOMS Project 2006 to 2012, SNOMS SWIRE NOCS Ocean Monitoring System. Part 1: Narrative description
The ocean plays a major role in controlling the concentration of carbon dioxide (CO2) in the atmosphere. Increasing concentrations of CO2 in the atmosphere are a threat to the stability of the earth’s climate. A better understanding of the controlling role of the ocean will improve predictions of likely future changes in climate and the impact of the uptake of CO2 itself on marine eco-systems caused by the associated acidification of the ocean waters. The SNOMS Project (SWIRE NOCS Ocean Monitoring System) is a ground breaking joint research project supported by the Swire Group Trust, the Swire Educational Trust, the China Navigation Company (CNCo) and the Natural Environment Research Council. It collects high quality data on concentrations of CO2 in the surface layer of the ocean. It contributes to the international effort to better quantify (and understand the driving processes controlling) the exchanges of CO2 between the ocean and the atmosphere. In 2006 and 2007 a system that could be used on a commercial ship to provide data over periods of several months with only limited maintenance by the ships crew was designed and assembled by NOCS. The system was fitted to the CNCo ship the MV Pacific Celebes in May 2007. The onboard system was supported by web pages that monitored the progress of the ship and the functioning of the data collection system. To support the flow of data from the ship to the archiving of the data at the Carbon Dioxide Information Analysis Center (CDIAC in the USA) data processing procedures were developed for the quality control and systematic handling of the data. Data from samples of seawater collected by the ships crew and analysed in NOC (730 samples) have been used to confirm the consistency of the data from the automated measurement system on the ship. To examine the data collected between 2007 and 2012 the movements of the ship are divided into 16 voyages. Initially The Celebes traded on a route circum-navigating the globe via the Panama and Suez Canals. In 2009 the route shifted to one between Australia and New Zealand to USA and Canada. Analysis of the data is an on going process. It has demonstrated that the system produces reliable data. Data are capable of improving existing estimates of seasonal variability. The work has improved knowledge of gas exchange processes. Data from the crew-collected-samples are helping improve our ability to estimate alkalinity in different areas. This helps with the study of ocean acidification. Data from the 9 round trips in the Pacific are currently being examined along with data made available by the NOAA-PMEL laboratory forming time series from 2004 to 2012. The data from the Pacific route are of considerable interest. One reason is that the data monitors variations in the fluxes of CO2 associated with the current that flows westwards along the equator. This is one of the major natural sources of CO2 from the ocean into the atmosphere
Associations of inflammatory and hemostatic variables with the risk of recurrent stroke
<p><b>Background and Purpose:</b> Several prospective studies have shown significant associations between plasma fibrinogen, viscosity, C-reactive protein (CRP), fibrin D-dimer, or tissue plasminogen activator (tPA) antigen and the risk of primary cardiovascular events. Little has been published on the associations of these variables with recurrent stroke. We studied such associations in a nested case-control study derived from the Perindopril Protection Against Recurrent Stroke Study (PROGRESS).</p>
<p><b>Methods:</b> Nested case-control study of ischemic (n=472) and hemorrhagic (n=83) strokes occurring during a randomized, placebo-controlled multicenter trial of perindopril-based therapy in 6105 patients with a history of stroke or transient ischemic attack. Controls were matched for age, treatment group, sex, region, and most recent qualifying event at entry to the parent trial.</p>
<p><b>Results:</b> Fibrinogen and CRP were associated with an increased risk of recurrent ischemic stroke after accounting for the matching variables and adjusting for systolic blood pressure, smoking, peripheral vascular disease, and statin and antiplatelet therapy. The odds ratio for the last compared with the first third of fibrinogen was 1.34 (95% CI, 1.01 to 1.78) and for CRP was 1.39 (95% CI, 1.05 to 1.85). After additional adjustment for each other, these 2 odds ratios stayed virtually unchanged. Plasma viscosity, tPA, and D-dimer showed no relationship with recurrent ischemic stroke, although tPA was significant for lacunar and large artery subtypes. Although each of these variables showed a negative relationship with recurrent hemorrhagic stroke, none of these relationships achieved statistical significance.</p>
<p><b>Conclusions:</b> Fibrinogen and CRP are risk predictors for ischemic but not hemorrhagic stroke, independent of potential confounders.</p>
Direct DNA injection of vascular endothelial growth factor induces angiogenesis in non-ischemic myocardium
Using additive manufacturing with blow moulding to facilitate accurate consumer testing
A South African entrepreneur needed a fast and accurate route to consumer testing for a
design of phlegm collection bottle for long-distance runners. Vaal University of Technology
was presented with an initial product concept which had to be developed into a fully
functional prototype required for field trials. The idea was converted into a practical product
proposal and modelled using a 3D computer aided design (CAD) system. The CAD data
were used for laser sintering of polyamide to produce an initial prototype for appearance and
ergonomic evaluation. For product testing in the field, a short run of fully functional
prototypes in thin-walled low density poly-ethylene (LDPE) was required. This required a
further design iteration and the production of tooling for the blow moulding process. A novel
hybrid modular approach to tool manufacture was followed, where the outer frame of the
tools were machined in aluminium and the tool inserts were laser sintered in AlumideTM.
Blow moulding trials were undertaken in LDPE which revealed a number of positive and
negative issues. The rough surface of the tool inserts produced a desirable textured surface
in the resultant blow-moulded bottles but also prevented a clean “shut-off” between the two
halves of the tool. This allowed air to escape from the cavity along the split plane, creating
unwanted holes in the bottles. In addition, the low thermal conductivity of AlumideTM resulted
in an unwanted overheating of the tools. Strategies were identified to overcome these issues
and these are explained in the paper
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