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Abstract Among the many institutions addressing development issues at the international level, the 16 research centers of the Consultative Group of International Agricultural Research (CGIAR) focus on the goal of reducing poverty, hunger, and malnutrition by sustainably increasing productivity of resources in agriculture, forestry, and fisheries. The CGIAR has certain comparative advantages in carrying work in water at the various scales, from the farm up to global, that should be offered to the international community. This discussion paper addresses the question: what are the major water issues relevant to the CGIAR goal? The paper also presents a justification of the research needs and opportunities as well as some initial ideas for the development of a specific research agenda on each area. While other international organizations are very active in many international initiatives, the CGIAR is one of the few that could contribute much needed research information in many world areas. The CGIAR must focus more on water in relation to the plight of the poor in particular. There is a need to increase the adaptive capacity of the poor, and to manage the water supply and quality constraints. This could be achieved by focusing at the community level and by developing inexpensive, easy to use monitoring tools that would alert the communities of forthcoming problems and provide them with means to take remedial action. This action is often needed long before there is any hope of changes in policy and other macro-level interventions. The fundamental issue of water as a food requires that attention be given to the quantity and quality of water available for domestic use in poor households and communities. Health issues associated with domestic supply and with irrigation management have been important research themes in the CGIAR and demand increasing attention. Given the current composition, activitiesm and comparative advantages of the CGIAR, it is proposed that research on water management should focus on the following four broad general areas: (1) improving the efficiency of water use in agriculture through increased water productivity; (2) management of watersheds for multiple functions; (3) management of aquatic ecosystems, in particular those sharing boundaries with terrestrial ecosystems; and (4) policy and institutional aspects of water management. As the aim of water management research is to address water constraints and issues in an integrated manner, the four areas cannot be treated in isolation from each other. There is thus a need for the fifth area for achieving integration at and across different scales. 相似文献
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GH Posner MH Parker J Northrop JS Elias P Ploypradith S Xie TA Shapiro 《Canadian Metallurgical Quarterly》1999,42(2):300-304
In only three chemical operations, natural trioxane lactone artemisinin (1) was converted into a series of C-10 carbon-substituted 10-deoxoartemisinin compounds 4-9. The three steps involved lactone reduction, replacement of the anomeric lactol OH by F using diethylaminosulfur trifluoride, and finally boron trifluoride-promoted substitution of F by aryl, heteroaryl, and acetylide nucleophiles. All of these C-10 nonacetal, chemically robust, enantiomerically pure compounds 4-9 have high antimalarial potencies in vitro against Plasmodium falciparum malaria parasites, and furans 5a and 5b and pyrrole 7a are antimalarially potent also in vivo even when administered to rodents orally. 相似文献
34.
The radioisotope X-ray fluorescence method was applied to studies of the provenance of the ceramics fragments originated from the Mar-Takla site in Syria.The samples were irradiated 1000s by a ^109Cd radioisotope source and 13 elements (Ca,Ti,Mn,Fe,Zn,Ga,As,Rb,Sr,Y,Zr,Nb,and Pb)were determined in 35 samples.The data were subjected to two multivariate statistical methods,cluster and principal components analysis(PCA).It was shown from the combination of the statistical techniques and the determination of elemental composition of the samples that 94% of the ceramic samples analyzed can be considered to be manufactured using two sources of raw materials. 相似文献
35.
Elias ASSAYEHEGN Ananthakumar SOLAIAPPAN Yonas CHEBUDIE Esayas ALEMAYEHU 《材料科学前沿(英文版)》2019,13(4):352
Nitrogen-doped titanium dioxide (N/TiO2) nanophotocatalysts were successfully synthesized in the presence of environmentally benign nitrogen dopant source, guanidinium chloride, by the sol–gel method. The effect of calcination temperature (300–600 °C) on their physicochemical properties was investigated by means XRD, XPS, FESEM, HRTEM, Raman spectroscopy, UV-vis DRS, PL and BET. Moreover, their photocatalytic activities were evaluated against rhodamine B (RhB) degradation under direct sun light. Results showed that the crystal phase of spheroidal N/TiO2 nanoparticles was changed from anatase (300 °C) to rutile (600 °C) via an intermediate anatase/rutile (A/R) mixed phase (400–500 °C), and the RhB photodegradation performance was increased with the decrease of the calcination temperature. Notably, N/TiO2 prepared at 400 °C demonstrated the best degradation performance (99%) after 5 h irradiation. The enhanced performance with high photostability was mainly attributed to its higher surface area and pore volume, stronger light absorption, and lower recombination rate. Such nanomaterials have practical applications for environmental remediation. 相似文献
36.
Elias Tragos George T. Karetsos Sofoklis A. Kyriazakos Kostas Vlahodimitropoulos 《Wireless Communications and Mobile Computing》2008,8(7):907-919
One of the most important initial steps, inherent in the planning procedure of cellular networks, is their segmentation in operational parts that is performed at different levels corresponding to the hierarchy and topology of the network. The major goal of this procedure is the efficient deployment of the system and management of the distributed segmented parts while minimizing the signaling overhead in the network. As we show here, it can take place even during the operational phase of the network when certain shortcomings appear. In this work, we present an approach based on graph theory for the segmentation of cellular networks at the Base Station Controller (BSC) level that achieves a significant increase in the performance of the network. In particular, with the proposed method, both the handover attempts when a mobile station is moving to a cell belonging to a different BSC as well as the corresponding handover failure rate are decreased significantly, allowing for a continuous network upgrade. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
37.
Extrusion of Rice,Bean and Corn Starches: Extrudate Structure and Molecular Changes in Amylose and Amylopectin 总被引:1,自引:0,他引:1 下载免费PDF全文
Nathan Levien Vanier Varatharajan Vamadevan Graziella Pinheiro Bruni Cristiano Dietrich Ferreira Vânia Zanella Pinto Koushik Seetharaman Elessandra da Rosa Zavareze Moacir Cardoso Elias Jose De J. Berrios 《Journal of food science》2016,81(12):E2932-E2938
The objective of this study was to evaluate the effects of starch source and amylose content on the expansion ratio, density, and texture of expanded extrudates, as well as to investigate the structural and molecular changes that occur in starch granules as a function of extrusion. The starches employed were rice starches (8%, 20%, and 32% amylose), carioca bean starch (35% amylose), and Hylon V® corn starch (55% amylose). The extrudates from rice starches containing 20% and 32% amylose exhibited the highest expansion ratio, while, extrudates from Hylon V® corn starch containing 55% amylose exhibited the lowest expansion ratio. The hardness values of the extrudates with 55% amylose were twice those of the extrudates with 20%, 32%, and 35% amylose. An additional finding was that although the amylopectin promoted the expansion of the gelatinized starch matrix, it failed to strengthen and sustain the walls of the extrudate bubbles during expansion. 相似文献
38.
Physical properties and effective thermal diffusivity of soybean grains as a function of moisture content and broken kernels 下载免费PDF全文
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Danae N. Antivachis Elias Chatzitheodoridis Nikolaos Skarpelis Konstantinos Komnitsas 《Mine Water and the Environment》2017,36(2):226-238
The Apliki mine, a Cyprus-type massive sulphide deposit in Cyprus, was exploited for copper until the mid-1970s. Abandonment of the mine left a deep pit that now hosts a lake fed by surface runoff from the surrounding mineralized zone and hydrothermally altered basalt. Oxidation of the sulphide minerals and factors such as climate and terrain relief control the water–rock interactions that generate acid mine drainage (AMD), which ultimately affects and defines the quality of the lake waters. Pyrite and chalcopyrite constitute an almost inexhaustible sulphide source that leads to the formation of a variety of secondary iron and copper mineral phases. The secondary mineral assemblages in the ore zone are mainly iron, copper, and magnesium sulphates, whereas the lakeshore assemblage is dominated by magnesium-, calcium-, sodium-, and aluminum-bearing sulphate minerals. Near the lakeshore, the highly soluble iron sulphate salts dissolve in the lake water, increasing its iron content. Other less soluble salts are more stable and persist in the lakeshore environment. The precipitation and dissolution of efflorescent salts, and, to a lesser extent, the oxidative weathering of the remaining ore minerals, produce additional AMD. Due to the perpetual cycle of mineral dissolution and precipitation, the lake has a low pH (≈3) and contains high concentrations of some contaminants. The processes that contribute to the formation of the efflorescent mineral assemblages and their environmental impact on pit lake waters, and indeed the complete geochemical system, is a typical example of secondary mineral formation in Cyprus-type Cu-pyrite massive sulphide ore deposits. 相似文献