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Serum (200.6±64.8 mg/dl) and urinary zinc (1186.0±265.5 mg/l.) of zinc miners at Zawar were significantly higher as compared to zinc smelter workers (Serum 89.7±9.9. mg/dl; Urine 590.0±32.1 mg/l.). Debari and Udaipur residents (Serum 104.0±18.6 mg/dl; Urine 735.0±180.2 mg/l.). This was most likely attributable to higher dietary zinc intake by zinc miners due to higher zinc content of foodstuffs grown in Zawar areas as compared to Debari and Udaipur.  相似文献   
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Embryoid body (EB) formation forms an important step in embryonic stem cell differentiation invivo. In murine embryonic stem cell (mESC) cultures EB formation is inhibited by the inclusion of leukaemic inhibitory factor (LIF) in the medium. Assembly of mESCs into aggregates by positive dielectrophoresis (DEP) in high field regions between interdigitated oppositely castellated electrodes was found to initiate EB formation. Embryoid body formation in aggregates formed with DEP occurred at a more rapid rate-in fact faster compared to conventional methods-in medium without LIF. However, EB formation also occurred in medium in which LIF was present when the cells were aggregated with DEP. The optimum characteristic size for the electrodes for EB formation with DEP was found to be 75-100 microns; aggregates smaller than this tended to merge, whilst aggregates larger than this tended to split to form multiple EBs. Experiments with ESCs in which green fluorescent protein (GFP) production was targeted to the mesodermal gene brachyury indicated that differentiation within embryoid bodies of this size may preferentially occur along the mesoderm lineage. As hematopoietic lineages during normal development derive from mesoderm, the finding points to a possible application of DEP formed EBs in the production of blood-based products from ESCs.  相似文献   
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A number of policy proposals have recently been presented that seek to address the problem of declining productivity growth. Many of these are aimed at encouraging private R&D spending through tax incentives. This paper first reviews some of these proposals, then evaluates tax incentives per se as a policy tool for encouraging R&D growth, and finally offers suggestions for redesigning R&D related tax incentive policies.  相似文献   
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Retrieval practice has been shown to benefit learning. However, the benefit has sometimes been attenuated with more complex materials that require integrating multiple units of information. Critically, Tran et al. Psychonomic Bulletin & Review, 22, 135–140 (2015) found that retrieval practice improves sentence memory but not the drawing of inferences from the same sentences. In three experiments, we investigated whether this lack of benefit of retrieval practice for inferential ability was due to the presentation format of the material. Participants studied four sets of seven to nine related sentences by practicing retrieval for two sets and rereading the other two sets. A final test was given 2 days later. When sentences were presented one at a time during study/practice as in Tran et al., we found no effect of retrieval practice on a test requiring inferential reasoning. When sentences in a set were presented simultaneously during study/practice, retrieval practice in the form of fill-in-the-blank testing (experiments 1 and 2) and free recall (experiment 3) aided later deductive inference more than rereading. Our findings suggest that retrieval practice can improve deductive inference, but in order to optimize its utility, the format in which the material is presented during practice must not hinder relational processing of the individual sentences.  相似文献   
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Previous research has found a wide range of predictors of student performance in introductory college chemistry. These predictors are associated with both the students' backgrounds and their high school learning experiences. The purpose of this research study was to examine the link between high school chemistry pedagogical experiences and performance in introductory college chemistry while accounting for individual educational and demographic differences. The researchers surveyed 1531 students enrolled in first‐semester introductory college chemistry courses for science and engineering majors at 12 different U.S. colleges and universities. Using multiple regression analysis, the researchers uncovered several interesting high school pedagogical experiences that appeared to be linked with varying levels of performance in college chemistry. Most notably, the researchers found that repeating chemistry labs for understanding was associated with higher student grades, whereas overemphasis on lab procedure in high school chemistry was associated with lower grades in college. These results suggest that high school teachers' pedagogical choices may have a link to future student performance. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 987–1012, 2005  相似文献   
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