Browsing by Author "Liao, Wei-Li"

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A Human DNA methylation site predictor base on SVM
(2009)
Sun, Yi-Ming
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Liu, Baw-Jhiune
;
Liao, Wei-Li
;
Chang, Cheng-Wei
;
Huang, Hsien-Da
During gene expression, transcription factors are unable to bind to a transcription binding site (TFBS) involved in regulation if DNA methylation has occurred at the TFBS. Methyl-CpG-binding proteins may also occupy the TFBS and prevent the functioning of a transcription factor. Thus, the methylation status of CpG sites is an important issue when trying to understand gene regulation and shows strong correlation with the TFBS involved. In addition, CpG islands would seem to undergo cell-specific and tissue-specific methylation. Such differential methylation is presented at numerous genetic loci that are essential for development. Current DNA methylation site prediction tools need to be improved so that they include TFBS features and have greater accuracy in terms of the DNA region that is involved in methylation. We developed models that compare the differences across these regions and tissues. The TFBSs, DNA properties and DNA distribution were used as features for this classification. From the results, we found some TFBSs that were able to discriminate whether a sequence was methylated or not. The sensitivity, specificity and accuracy estimated using 10-fold cross validation were 90.8%, 80.54%, and 86.07%, respectively. Thus, for these four regions and twelve tissues, the performance levels (ACC) were all greater than 80%. We propose that the differential features or methylations vary between the different regions because the features common to each DNA region made up only 50% of the top 70 features. An online predictor based on EpiMeP is available at http://140.115.51.41/EpiMeP/. Supplementary file is available at http://140.115.51.41/EpiMeP/supplementary.doc.
Corporate governance and equity liquidity: analysis of S&P transparency and disclosure rankings
(2007-07-01)
Chen, Wei-Peng
;
Chung, Huimin
;
Lee, Chengfew
;
Liao, Wei-Li
;
管理科學系
This paper sets out to investigate the effects of disclosure, and other corporate governance mechanisms, on equity liquidity, arguing that those companies adopting poor information transparency and disclosure practices will experience serious information asymmetry. Since poor corporate governance leads to greater information asymmetry, liquidity providers will incur relatively higher adverse information risks and will therefore offer higher information asymmetry components in their effective bid-ask spreads. The Transparency and Disclosure (T&D) rankings of the individual stocks on the S&P 500 index are employed to examine whether firms with greater T&D rankings have lower information asymmetry components and lower stock spreads. Our results reveal that the economic costs of equity liquidity, i.e. the effective spread and the quoted half-spread, are greater for those companies with poor information transparency and disclosure practices.