458 research outputs found

    The political economy of wheat consumption and production with special reference to Sub-Saharan Africa.

    Get PDF
    A position paper on the increased importance of wheat as a staple nutrition cereal in Sub-Saharan Africa.Over the past 25 years, one of the most dramatic changes in dietary patterns in developing countries has been the increasing role of wheat as a staple food. Wheat consumption has risen rapidly both in countries where wheat is a traditional staple (e.g., in the Middle East and North Africa) and in countries where wheat is an "introduced" food, especially in the tropical countries lying between 23°S and 23°N latitude . In most cases, increased wheat consumption has been made possible by rapid increases in imports; over 80% of increased wheat consumption over the past two decades in these two groups of countries has been supplied from wheat imports . Only in the large mixed-cereal economies of India, China, and Mexico that experienced the Green Revolution in wheat production has increased wheat consumption been largely supplied from domestic sources.The research supporting the preparation the proceedings papers was financed by the U.S. Agency for International Development, Bureau of Science and Technology; Bureau for Africa; and the Southern Africa Regional Programme; under a Food Security in Africa cooperative agreemen

    Fault growth and acoustic emissions in confined granite

    Get PDF
    The failure process in a brittle granite was studied by using acoustic emission techniques to obtain three dimensional locations of the microfracturing events. During a creep experiment the nucleation of faulting coincided with the onset of tertiary creep, but the development of the fault could not be followed because the failure occurred catastrophically. A technique has been developed that enables the failure process to be stabilized by controlling the axial stress to maintain a constant acoustic emission rate. As a result the post-failure stress-strain curve has been followed quasi-statically, extending to hours the fault growth process that normally would occur violently in a fraction of a second. The results from the rate-controlled experiments show that the fault plane nucleated at a point on the sample surface after the stress-strain curve reached its peak. Before nucleation, the microcrack growth was distributed throughout the sample. The fault plane then grew outward from the nucleation site and was accompanied by a gradual drop in stress. Acoustic emission locations showed that the fault propagated as a fracture front (process zone) with dimensions of 1 to 3 cm. As the fracture front passed by a given fixed point on the fault plane, the subsequent acoustic emission would drop. When growth was allowed to progress until the fault bisected the sample, the stress dropped to the frictional strength. These observations are in accord with the behavior predicted by Rudnicki and Rice's bifurcation analysis but conflict with experiments used to infer that shear localization would occur in brittle rock while the material is still hardening

    In Situ Study of the Physical Mechanisms Controlling Induced Seismicity at Monticello Reservoir, South Carolina

    Get PDF
    In two ~1.1-km-deep wells, the magnitudes of the principal in situ stresses, pore pressure, permeability, and the distribution of faults, fractures, and joints were measured directly in the hypocentral zones of earthquakes induced by impoundment of Monticello Reservoir, South Carolina. Analysis of these data suggests that the earthquakes were caused by an increase in subsurface pore pressure sufficiently large to trigger reverse-type fault motion on preexisting fault planes in a zone of relatively large shear stresses near the surface. The measurements indicated (1) near-critical stress differences for reverse-type fault motion at depths less than 200-300 m, (2) possibly increased pore pressure at depth relative to preimpoundment conditions, (3) the existence of fault planes in situ with orientations similar to those determined from composite focal plane mechanisms, and (4) in situ hydraulic diffusivities that agree well with the size of the seismically active area and time over which fluid flow would be expected to migrate into the zone of seismicity. Our physical model of the seismicity suggests that infrequent future earthquakes will occur at Monticello Reservoir as a result of eventual pore fluid diffusion into isolated zones of low permeability. Future seismic activity at Monticello Reservoir is expected to be limited in magnitude by the small dimensions of the seismogenic zones

    Factors that transformed maize productivity in Ethiopia

    Get PDF
    Published online: 26 July 2015Maize became increasingly important in the food security of Ethiopia following the major drought and famine that occurred in 1984. More than 9 million smallholder house- holds, more than for any other crop in the country, grow maize in Ethiopia at present. Ethiopia has doubled its maize produc- tivity and production in less than two decades. The yield, currently estimated at >3 metric tons/ha, is the second highest in Sub-Saharan Africa, after South Africa; yield gains for Ethiopia grew at an annual rate of 68 kg/ha between 1990 and 2013, only second to South Africa and greater than Mexico, China, or India. The maize area covered by improved varieties in Ethiopia grew from 14 % in 2004 to 40 % in 2013, and the application rate of mineral fertilizers from 16 to 34 kg/ ha during the same period. Ethiopia ’ s extension worker to farmer ratio is 1:476, compared to 1:1000 for Kenya, 1:1603 for Malawi and 1:2500 for Tanzania. Increased use of im- proved maize varieties and mineral fertilizers, coupled with increased extension services and the absence of devastating droughts are the key factors promoting the accelerated growth in maize productivity in Ethiopia. Ethiopia took a homegrown solutions approach to the research and development of its maize and other commodities. The lesson from Ethiopia ’ s experience with maize is that sustained investment in agricul- tural research and development and policy support by the national government are crucial for continued growth of agricultur

    How can developing countries harness biotechnology to improve health?

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>The benefits of genomics and biotechnology are concentrated primarily in the industrialized world, while their potential to combat neglected diseases in the developing world has been largely untapped. Without building developing world biotechnology capacity to address local health needs, this disparity will only intensify. To assess the potential of genomics to address health needs in the developing world, the McLaughlin-Rotman Centre for Global Health, along with local partners, organized five courses on Genomics and Public Health Policy in the developing world. The overall objective of the courses was to collectively explore how to best harness genomics to improve health in each region. This article presents and analyzes the recommendations from all five courses.</p> <p>Discussion</p> <p>In this paper we analyze recommendations from 232 developing world experts from 58 countries who sought to answer how best to harness biotechnology to improve health in their regions. We divide their recommendations into four categories: science; finance; ethics, society and culture; and politics.</p> <p>Summary</p> <p>The Courses' recommendations can be summarized across the four categories listed above:</p> <p>Science</p> <p>- Collaborate through national, regional, and international networks</p> <p>- Survey and build capacity based on proven models through education, training, and needs assessments</p> <p>Finance</p> <p>- Develop regulatory and intellectual property frameworks for commercialization of biotechnology</p> <p>- Enhance funding and affordability of biotechnology</p> <p>- Improve the academic-industry interface and the role of small and medium enterprise</p> <p>Ethics, Society, Culture</p> <p>- Develop public engagement strategies to inform and educate the public about developments in genomics and biotechnology</p> <p>- Develop capacity to address ethical, social and cultural issues</p> <p>- Improve accessibility and equity</p> <p>Politics</p> <p>- Strengthen understanding, leadership and support at the political level for biotechnology</p> <p>- Develop policies outlining national biotechnology strategy</p> <p>These recommendations provide guidance for all those interested in supporting science, technology, and innovation to improve health in the developing world. Applying these recommendations broadly across sectors and regions will empower developing countries themselves to harness the benefits of biotechnology and genomics for billions who have long been excluded.</p
    • …
    corecore