25 research outputs found
Smallholder farmer perceived effects of climate change on agricultural productivity and adaptation strategies
The agriculture sector is sensitive to climate change and the capacity of smallholder farmers in developing countries to adapt is limited. Similar to adoption of any development-oriented strategies, perception is pre-requisite to successful adaptation of agricultural strategies against climate change effects. This study was conducted in the semi-arid Lower Gweru Communal area of Central Zimbabwe to sensitize smallholder farmers on climate change and to establish their perceptions of the projected climate of Zimbabwe by 2050. Data were collected during 2011 from a total of 60 farmers drawn from six villages in Mdubiwa and Nyama Wards. Farmers were selected using systematic random sampling from a households list and grouped into three wealth groups: resource rich; resource poor and intermediate. Focus Group Discussions were conducted with each group to investigate their perceptions of the projected climate by 2050 and their proposed adaptive strategies. Farmers perceived the projected climate to have negative effects on their livelihoods and there were no outstanding differences in the nature of responses across the three categories of farmers. Farmers’ responses showed that they were concerned about crop and livestock productivity as well as availability of water resources, food and nutrition security and about their general well-being. The intermediate wealth group, which had more than half of its members above 70 years of age provided the least number of ideas for adaptations. Farmers also suggested how they could possibly counteract some of the predicted negative effects or maximize on positive effects. Strategies that were suggested by the farmers were largely concerned with cropping and tended to address water shortages. It was concluded that almost all strategies suggested by farmers were self-directed, rather than directed at authorities like government or donors to do something for them thus showing that farmers had the will power to deal with climate change themselves
Interfacial Profile and Propagation of Frontal Photopolymerization Waves
We investigate the frontal photopolymerization
of a thiol–ene
system with a combination of experiments and modeling, focusing on
the interfacial conversion profile and its planar wave propagation.
We spatially resolve the solid-to-liquid front by FT-IR and AFM mechanical
measurements, supplemented by differential scanning calorimetry. A
simple coarse-grained model is found to describe remarkably well the
frontal kinetics and the sigmoidal interface, capturing the effects
of UV light exposure time (or dose) and temperature, as well as the
front position and resulting patterned dimensions after development.
Analytical solutions for the conversion profile enable the description
of all conditions with a single master curve in the moving frame of
the front position. Building on this understanding, we demonstrate
the design and fabrication of gradient polymer materials, with tunable
properties <i>along</i> the direction of illumination, which
can be coupled with lateral patterning by modulated illumination or
grayscale lithography
Magnetic resonance imaging of spiral patterns in crosslinked polymer gels produced via frontal polymerization
Frontal polymerization is a process in which a localized reaction zone propagates through a monomer reactant mixture, leaving a polymer product in its wake, and is the result of the coupling of the thermal transport and Arrhenius dependence of the exothermic polymerization. Under most conditions, a planar front is stable. However, for multifunctional acrylates at room temperature, fronts may propagate in a helical fashion along the axis of the reactor. This front propagation is typical of what is called a spin mode, in which the subsequent polymer sample has alternating spiral patterns of low and high monomer conversion evident on the sample surface. For the first time, we demonstrate that magnetic resonance imaging on a submillimeter scale can be used to show that the spiral patterns are not restricted to the sample surface but are distributed throughout the volume. Samples were soaked in water, and the transverse proton relaxation times were imaged. The results suggest proton mobility is smaller in the high‐conversion region in which the hot spot propagated than in the low‐conversion region. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1075–1080, 200
Bubble Behavior in Frontal Polymerization: Results From KC-135 Parabolic Flights
Frontal polymerization is a mode of converting monomer into polymer via a localized exothermic reaction zone that propagates through the coupling of thermal diffusion and the Arrhenius reaction kinetics of an exothermic polymerization. Studies were carried out aboard the NASA KC-135 aircraft to determine the effects of gravity on the interactions of bubbles with descending polymerization fronts with monofunctional and difunctional acrylates. The absence of buoyancy allowed bubbles to grow larger ahead of fronts of diacrylate polymerization. Bubbles formed in thermoplastic fronts appeared to aggregate and form periodic patterns behind the fronts but the poor quality and short duration of the low gravity precludes definitive conclusions about the mechanism
Nonaxisymmetric and Axisymmetric Convection in Propagating Reaction-Diffusion Fronts
Observations of steady nonaxisymmetric chemical wave fronts are reported for upward propagation in iodate-arsenous acid solutions within vertical capillary tubes. These observations confirm a recent prediction of hydrodynamic stability theory that the onset of convection in such fronts should be nonaxisymmetric. The nonaxisymmetric waveform reflects the presence of a single convective roll in the vicinity of the moving front
Use of Indigenous Knowledge Systems and Scientific Methods for Climate Forecasting in Southern Zambia and North Western Zimbabwe.
The semi-arid areas of Southern Africa receive low and erratic rainfall which varies in both seasons and from year to year resulting in food insecurity. Few of the smallholder farmers have access to seasonal climate forecasts from the meteorological department hence they depend mostly on their indigenous knowledge systems for forecasting seasons which they make use of to develop crop management adaptive strategies. The study shows that farmers have several indicators for weather forecasting and some of these are similar in both Zambia and Zimbabwe. Some of these indicators include; floods or excessive rains in the preceding season, strong winds around October, an extended cold season that goes up to August and sometimes September and abundance or scarcity of certain fruits. The indicators conflict in some seasons and in such cases the farmers resort to using those that they know to have stronger signals from their reliability factors. Positive relationship between indigenous knowledge systems and modern science were observed between the 2008/9 season and 2009/10 which confirms that indigenous knowledge systems, when fully developed could be very helpful in seasonal forecasting. The study recommends the importance of the restoration of the confidence of the indigenous people in their traditional knowledge and skills of weather forecasting
Building adaptive capacity to cope with increasing vulnerability due to climate change
The project objective was to develop educational curricula and research and extension competencies of present and future scientists to better assist farmers identify technology options that enhance their adaptive capacity to cope with risks and opportunities associated with climate change and variability. Research conducted by five PhD itwo women) and four MPhils (one woman) students contributed to project outputs. Baselme data to describe cropping system and management tinder current climate variability and farmer perceptions about climate change across 4 districts of Zimbabwe and Zambia was collected and analysed. Indigenous knowledge of climate and indicators to seasonal conditions were also documented and compared with scientific forecasts. Seven workshops were held to educate farmers and extension agents on interpretation of the Seasonal Climate Forecast (SCF) and explore together its application in making cropping decisions. Management options in response to the SCF were then tested in participatory on-farm trials. Most smallholder farmers (at 3 of the 4 sites) were not aware of the existence of the SCF. However, in both seasons the farmers' prediction of seasonal
climate was consistent with that from the meteorological department. Engaging smallholder farmers with SCF assists them in making investment decisions on crop management options and in particular. on-fann trial results showed that fanners could derive reliable and substantial benefit from the SCF us decisions related to fertility input levels. The project demonstrated that fainter uptake and use of SC F benefits from an extended participatory approach that provides timely access and interpretation of the SC F. experimentation, monitoring and a post mortem of results which enhances farmer ownerslup and adoption after the project