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A ROBUST B AYESIAN TWO - SAMPLE TEST FOR DETECTING INTERVALS OF DIFFERENTIAL GENE EXPRESSION IN MICROARRAY TIME SERIES Oliver Stegle, Katherine Denby, David L. Wild, Zoubin Ghahramani, Karsten M. Borgwardt Journal of Computational Biology 1 VC Lab, Dept. of Computer Science, NTHU, Taiwan
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O VERVIEW Introduction Differential Expression Method and Model Bayesian network Score Gaussian process Experiment Conclusion Reference 2 VC Lab, Dept. of Computer Science, NTHU, Taiwan
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I NTRODUCTION Differential Expression Distribution is defined by mean and stdv. Significant change in mean of measurements Methods SAM(Significance analysis of microarrays) T-test Whether / When 3 VC Lab, Dept. of Computer Science, NTHU, Taiwan http://www.mikromatrise.no/files/resourcesmodule/@random45250567733de/1222169578_Microsoft_PowerP oint___Differential_Expression.ppt.pdf http://www.mikromatrise.no/files/resourcesmodule/@random45250567733de/1222169578_Microsoft_PowerP oint___Differential_Expression.ppt.pdf
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M ETHOD AND M ODELS Bayesian network 4 VC Lab, Dept. of Computer Science, NTHU, Taiwan
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M ETHOD AND M ODELS Score Logarithm of the Bayes factor 5 VC Lab, Dept. of Computer Science, NTHU, Taiwan Observed expression levels Gaussian process models Hyperparameters I: independent S: shared
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M ETHOD AND M ODELS Gaussian process Robustness Detect true differential expression 6 VC Lab, Dept. of Computer Science, NTHU, Taiwan Global noise Covariance matrix Latent replicate observations Pre-replicate noise set of all hyperparameters for kernel, likelihood and the replicate noise levels.
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M ETHOD AND M ODELS Gaussian process (Cont.) Simplify 7 VC Lab, Dept. of Computer Science, NTHU, Taiwan variance of observation noise
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M ETHOD AND M ODELS Gaussian process (Cont.) Gaussian predictive distribution Bayes factor Most probable parameter (from posterior probbility) 8 VC Lab, Dept. of Computer Science, NTHU, Taiwan characteristic function
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M ETHOD AND M ODELS Gaussian process (Cont.) Robustness with respect to outliers Mixture model Expectation Propagation(EP) Update one factor, leave others fixed. 9 VC Lab, Dept. of Computer Science, NTHU, Taiwan Probability of being a regular observation Probability of being a outlier
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E XPERIMENT Differential gene expression in Arabidopsis thaliana after fungal infection Botrytis cinerea 10 VC Lab, Dept. of Computer Science, NTHU, Taiwan A rea u nder the c urve T ime c ourse method
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E XPERIMENT Detecting intervals of differential gene expression Bernoulli distribution 11 VC Lab, Dept. of Computer Science, NTHU, Taiwan
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R ESULTS 12 VC Lab, Dept. of Computer Science, NTHU, Taiwan
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R ESULTS 13 VC Lab, Dept. of Computer Science, NTHU, Taiwan
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C ONCLUSION Detecting differential gene expression Gaussian process framework When Regulatory network 14 VC Lab, Dept. of Computer Science, NTHU, Taiwan
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R EFERENCE Ziv Bar-Joseph et al., Cross Species Expression Analysis of Innate Immune Response, Journal of Computational Biology 355~367, March, 2010 http://www.mikromatrise.no/files/resourcesmodul e/@random45250567733de/1222169578_Microsoft _PowerPoint___Differential_Expression.ppt.pdf http://www.mikromatrise.no/files/resourcesmodul e/@random45250567733de/1222169578_Microsoft _PowerPoint___Differential_Expression.ppt.pdf 15 VC Lab, Dept. of Computer Science, NTHU, Taiwan
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