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东太平洋多金属结核中铁、锰元素的分形演化及其意义 被引量:2
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作者 韩喜球 李家彪 +3 位作者 王英 章伟艳 马维林 何高文 《海洋学报》 CAS CSCD 北大核心 2004年第4期65-70,共6页
运用分形理论,通过建立不同的相空间,计算了东太平洋多金属结核中的铁、锰元素的时间序列在各相空间中的关联分维,并与其在沉积物岩心中的关联分维进行了对比.通过研究发现,多金属结核中铁、锰元素和沉积物中Fe2O3及MnO在分形演化过程... 运用分形理论,通过建立不同的相空间,计算了东太平洋多金属结核中的铁、锰元素的时间序列在各相空间中的关联分维,并与其在沉积物岩心中的关联分维进行了对比.通过研究发现,多金属结核中铁、锰元素和沉积物中Fe2O3及MnO在分形演化过程中均存在分维吸引子,认为沉积物中的Fe2O3和MnO可以用3个变量来描述,它们可能代表了火山、生物和陆地的三种来源,而描述结核中的铁、锰元素却需要14个变量,反映多金属结核中铁、锰元素的来源和/或赋存非常复杂,至少有14个因素在起作用,可能暗示了结核在形成过程中存在复杂的生物化学作用,为多金属结核的生物成因提供了间接的数学证据,同时也合理解释了结核生长结构所具有的自相似韵律现象. 展开更多
关键词 太平洋 多金属结核 元素时间序列 关联分维 分形
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Cross-Listing and Valuation Effects" Evidence From Nairobi Securities Exchange
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作者 Kennedy Munyua Waweru Ganesh P. Pokhariyal Muroki F. Mwaura 《Journal of Modern Accounting and Auditing》 2012年第9期1371-1380,共10页
The purpose of this study is to analyze the valuation effects of cross-listing. The study has conducted a univariate analysis of the Tobin's Q and the market-to-book ratio for the period before and after the cross-li... The purpose of this study is to analyze the valuation effects of cross-listing. The study has conducted a univariate analysis of the Tobin's Q and the market-to-book ratio for the period before and after the cross-listing by using paired tests. Non-cross-listed firms are then included in multivariate regressions by using pooled Time Series Cross Section (TSCS) and Panel Corrected Standard Error (PCSE) regressions for a period of 13 years to find out if there is a difference in the valuations between cross-listed firms and non-cross-listed firms. The study's results indicate that the Tobin's Q of cross-listed-firms increases two years prior to cross-listing and that it continues to increase two years after cross-listing. The market-to-book ratios also show an increase two years prior to cross-listing and up to one year after cross-listing, then decrease in the second year after cross-listing. When non-cross-listed firms are included in the analysis, results indicate that cross-listed firms are valued higher than non-cross-listed firms. When data are portioned for positive earnings per share (EPS) and dividends, results indicate that valuation is the highest when EPS is positive. Since segmentation theories cannot be ruled out, the study's findings are more in support of the growth opportunity hypothesis. 展开更多
关键词 CROSS-LISTING valuation effects Tobin's Q market-to-book ratio
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