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Bayesian testing of many hypotheses × many genes : A study of sleep apnea
(2009-03) Jensen, Shane T.; Erkan, Ibrahim; Arnardottir, Erna S.; Small, Dylan S.; Department of Engineering
Substantial statistical research has recently been devoted to the analysis of large-scale microarray experiments which provide a measure of the simultaneous expression of thousands of genes in a particular condition. A typical goal is the comparison of gene expression between two conditions (e.g., diseased vs. nondiseased) to detect genes which show differential expression. Classical hypothesis testing procedures have been applied to this problem and more recent work has employed sophisticated models that allow for the sharing of information across genes. However, many recent gene expression studies have an experimental design with several conditions that requires an even more involved hypothesis testing approach. In this paper, we use a hierarchical Bayesian model to address the situation where there are many hypotheses that must be simultaneously tested for each gene. In addition to having many hypotheses within each gene, our analysis also addresses the more typical multiple comparison issue of testing many genes simultaneously. We illustrate our approach with an application to a study of genes involved in obstructive sleep apnea in humans.
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Kæfisvefn veldur hjarta- og æðasjúkdómum - segir doktorsnemi í líffræöi
(2009) Arnardóttir, Erna Sif; Verkfræðideild
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Distributed and high-performance multimedia : Introduction
(2007) Kosh, Harald; Amsaleg, Laurent; Pauwels, Eric; Jónsson, Björn Þór; Department of Computer Science
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Performance and overhead of semantic cache management
(2006) Jónsson, Björn Þór; Arinbjarnar, María; Þórsson, Bjarnsteinn; Franklin, Michael J.; Srivastava, Divesh; Department of Computer Science
The emergence of query-based online data services and e-commerce applications has prompted much recent research on data caching. This article studies semantic caching, a caching architecture for such applications, that caches the results of selection queries. The primary contribution of this article is to revisit the performance and overhead of semantic caching using a modern database server and modern hardware. Initially, the performance study focuses on simple workloads and demonstrates several benefits of semantic caching, including low overhead, insensitivity to the physical layout of the database, reduced network traffic, and the ability to answer some queries without contacting the server. With moderately complex workloads, careful coding of remainder queries is required to maintain efficient query processing at the server. Using very complex workloads, we demonstrate that semantic caching works well in a range of applications, especially in network-constrained environments.
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The 26 December 2004 tsunami source estimated from satellite radar altimetry and seismic waves
(2005-10-28) Song, Y. Tony; Ji, Chen; Fu, L. L.; Zlotnicki, Victor; Shum, C. K.; Yi, Yuchan; Hjorleifsdottir, Vala; Department of Engineering
The 26 December 2004 Indian Ocean tsunami was the first earthquake tsunami of its magnitude to occur since the advent of both digital seismometry and satellite radar altimetry. Both have independently recorded the event from different physical aspects. The seismic data has then been used to estimate the earthquake fault parameters, and a three-dimensional ocean-general-circulation-model (OGCM) coupled with the fault information has been used to simulate the satellite-observed tsunami waves. Here we show that these two datasets consistently provide the tsunami source using independent methodologies of seismic waveform inversion and ocean modeling. Cross-examining the two independent results confirms that the slip function is the most important condition controlling the tsunami strength, while the geometry and the rupture velocity of the tectonic plane determine the spatial patterns of the tsunami.

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