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Embedding R in Windows applications, and executing R remotely

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PRSG Nirvana — A parallel tool to assess<br />

differential gene expression<br />

David Henderson<br />

PRSG Nirvana is a statistical package to assess statistical significance <strong>in</strong> differential<br />

gene expression data sets. The basis of the method is a two stage mixed<br />

l<strong>in</strong>ear model approach popularized <strong>in</strong> a fairly recent publication by R. Wolf<strong>in</strong>ger.<br />

The package takes advantage of the SNOW <strong>and</strong> Rmpi packages to create<br />

a parallel comput<strong>in</strong>g environment on common commodity comput<strong>in</strong>g clusters.<br />

Without the added comput<strong>in</strong>g power of cluster comput<strong>in</strong>g, bootstrapp<strong>in</strong>g of<br />

residuals to utilize the empirical distribution of a test statistic would not be<br />

practical. One would then have to rely on asymptotic thresholds for less than<br />

large data sets as <strong>in</strong>ference is based upon gene specific observations. Additional<br />

features of the package are a custom version of the now ubiquitous shr<strong>in</strong>kage estimators<br />

for <strong>in</strong>dividual gene variances <strong>and</strong> a dependent test false discovery rate<br />

adjustment of bootstrap p-values based upon work by Benjam<strong>in</strong>i <strong>and</strong> Yekutieli.<br />

The performance of the package for computational speed is compared to<br />

other s<strong>in</strong>gle processor compiled packages. The result<strong>in</strong>g lists of genes from each<br />

method are also compared us<strong>in</strong>g a small example data set where results are<br />

assumed known.

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