A robust Bayesian two-sample test for detecting intervals of differential gene expression in microarray time series.

Understanding the regulatory mechanisms that are responsible for an organism's response to environmental change is an important issue in molecular biology. A first and important step towards this goal is to detect genes whose expression levels are affected by altered external conditions. A range of methods to test for differential gene expression, both in static as well as in time-course experiments, have been proposed. While these tests answer the question whether a gene is differentially expressed, they do not explicitly address the question when a gene is differentially expressed, although this information may provide insights into the course and causal structure of regulatory programs. In this article, we propose a two-sample test for identifying intervals of differential gene expression in microarray time series. Our approach is based on Gaussian process regression, can deal with arbitrary numbers of replicates, and is robust with respect to outliers. We apply our algorithm to study the response of Arabidopsis thaliana genes to an infection by a fungal pathogen using a microarray time series dataset covering 30,336 gene probes at 24 observed time points. In classification experiments, our test compares favorably with existing methods and provides additional insights into time-dependent differential expression.

Centrifuge modelling of the response of buildings to tunnelling

The response of surface structures to tunnelling induced ground movements is an area of great importance for any urban tunnelling project. Testing described in this paper aims to investigate soil structure interaction effects by observing the response of aluminium beams of varying stiffness to tunnelling, using the 8 m diameter beam centrifuge at Cambridge University. Soil and structure displacements are extensively monitored through a photo imaging technique which enables a detailed analysis of the interaction behaviour. Results to date indicate that the relative structure-soil stiffness is the governing factor in determining how a structure will respond to tunnelling. This parameter is highly dependent on both the structure and soil stiffness. It is also shown that contrary to common assumptions in the literature, negligible axial strains are transferred into the structure. This paper outlines the results of the research to date. © 2010 Taylor & Francis Group, London.

Centrifuge modelling of the response of buildings to tunnelling

Understanding how buildings respond to tunnelling induced ground movements is an area of great importance for many urban tunnelling projects. Testing described in this paper aims to investigate soil structure interaction effects by observing the response of elastic and non elastic beams of varying stiffness and geometry to tunnelling, using the 8 m diameter beam centrifuge at Cambridge University. Soil and structure displacements are extensively monitored through a photo imaging technique which enables a detailed analysis of the interaction mechanisms. Results demonstrate that buildings can significantly modify greenfield ground movements in both the vertical and horizontal planes. The magnitude of the modification is shown to be strongly dependent on the relative building stiffness. It is also shown that negligible horizontal strains are transferred into the model buildings. This can have significant implications for commonly adopted damage assessment methods. © 2012 Taylor & Francis Group.