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The key to agricultural development in the eastern region of India, where problems of excess water and water scarcity coexist, is the scientific management of water resources with the adoption of recommended water-management technologies. A vast networking of infrastructure for the development and dissemination of water- management technologies have been designed since the very inception of planned economic change. Despite these concerted efforts, a large number of recommended technologies are either being adopted in piece-meal or not at all. The research and extension systems have been generating and disseminating technologies, therefore, it was felt worthwhile to assess the feasibility and appropriateness of recommended tecnologies as perceived in the first instance by the personnel of the research system and followed by the extension personnel. These steps were felt to be a precursor to screen the recommended technologies for their dissemination and evaluation in different farming systems. The assessment of recommended water-management technologies was performed after their documentation from different organisations working in the field of water management in two eastern India states viz. Orissa and West Bengal. The perception of 30 personnel members of the research system regarding the feasibility of these technologies elucidated that out of 86 documented recommended water-management technologies, 40 were having feasibility scores of ≥ 4.0; 8 technologies with score £ 3.0 and the rest of the 38 technologies with a score between 3.0 and 4.0 on a feasibility continuum range from 1.0 (not feasible) to 5.0 (highly feasible). Out of 40 recommended technologies (already assessed as highly feasible by the research personnel), extension personnel have perceived 16 and 10 technologies as highly appropriate and feasible, respectively. While six and four technologies were found to be less appropriate and feasible, respectively. Correlation of all nine indicators of appropriateness with feasibility of technologies was significant. Five indicators of appropriateness viz. simplicity, physical compatibility, production sustainability, cultural compatibility and cost together constituted 36.8 per cent of the total variation in feasibility with the ‘t’ values and ‘F’ values being significant. It indicates that not appropriateness of technologies alone but other factors influence the feasibility of technologies.  相似文献   
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This study examined the effectiveness of 3 curriculum interventions focused on strengthening children’s ability to solve area measurement problems and explored the instructional perspectives of the instructor who implemented the interventions. The interventions involved various degrees of emphasis on area measurement and knowledge of 2-dimensional geometry. Participants were 131 fourth graders, recruited from a city in northern Taiwan, and 1 instructor. The results confirmed the effectiveness of an enriched curriculum integrating knowledge of 2-dimensional geometry in enhancing children’s conceptual understanding of area measurement. The group that received the enriched curriculum outperformed the other groups that received the curricula stressing only 2-dimensional geometry or numerical calculations for area measurement in solving the area problems requiring mathematical judgments and explanations. The curriculum also facilitated children’s reasoning in distinguishing between the perimeter and area of a rectangle, which required higher-order mathematical thinking. Interview data revealed that approximately all children from the 3 intervention groups could identify the mathematical subject-matter components highlighted in the curricula. Interviewees tended to consider the use of formulae to solve area measurement problems to be important, despite some differences in learning gains among the 3 groups. In interviews, the participating instructor revealed a change of perspective regarding the importance of offering students opportunities for manipulation and geometric operations when teaching area measurement, prompted by curriculum enactment.  相似文献   
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Gödel’s proof     
In 1931, the great Austrian mathematician Kurt Gödel proved “all consistent axiomatic formulations of number theory include undecidable propositions”. This discovery of Gödel and its proof had enormous repercussions in mathematics and computer science. The proof hinged upon the writing of a self-referential mathematical statement, in the same way as the liar’s paradox — I am lying — is a self-referential statement. In this three-part article, we describe Gödel’s discovery and his famous proof.  相似文献   
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INTRODUCTION Left-handed materials (LHMs), first investigated theoretically by Veselago (1968), have received sub- stantial attention in the scientific and engineering communities. The unique properties of these meta- materials are promising for a diversity of microwave applications, such as new types of beam steerers, modulators, filters, superlens (Pendry, 2000), cou- plers and antenna radoms (Smith et al., 2004). Re- cently, a transmission line (TL) approach has been successfully in…  相似文献   
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Moral minds     
Steve Clarke 《Minerva》2008,46(1):147-150
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