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Investigation of the intrinsic brain networks using the resting-state functional magnetic resonance imaging (rs-fMRI) is generally based on the assumption that the functional organization is stationary across the duration of the scan. Hence, the presence and potential of temporal and spatial dynamics of the functional connectivity (FC), which is usually measured by the correlation coefficients between...
This paper develops a new recursive nonstationarity detection method based on time-varying autoregressive (TVAR) modeling. A local likelihood estimation approach is introduced which gives more weights to observations near the current time instant but less to those distance apart. It thus allows the Wald test to be computed based on RLS-type algorithms with low computational cost. A reliable and efficient...
This paper proposes a new state-regularized (SR) and QR decomposition based recursive least squares (QRRLS) algorithm with variable forgetting factor (VFF) for recursive coefficient estimation of time-varying autoregressive (AR) models. It employs the estimated coefficients as prior information to minimize the exponentially weighted observation error, which leads to reduced variance and bias over...
Image-based rendering (IBR) is an emerging technology for rendering photo-realistic views of scenes from a collection of densely sampled images or videos. It provides a framework for developing revolutionary virtual reality and immersive viewing systems. This paper studies the design of a movable image-based rendering system based on a class of dynamic representations called plenoptic videos. It is...
A three-dimensional acoustic propagation code is united with fields from a regional ocean model to study time-varying acoustic propagation behavior in realistic environments. The resultant four-dimensional acoustic fields are examined here. The regional models used to date for this purpose have the limitations of invoking the hydrostatic approximation and having spatial resolution that is of order...
It is of increasing interest in systems biology to discover gene regulatory networks (GRNs) from time-series genomic data, i.e., to explore the interactions among a large number of genes and gene products over time. Currently, one common approach is based on Granger causality, which models the time-series genomic data as a vector autoregressive (VAR) process and estimates the GRNs from the VAR coefficient...
In this paper, we present an integrated model of 3D human ventricle to simulate the effects of ischemia on wave propagation. To deal with the no-flux boundary conditions, a phase-field method is employed. The major advantage of the method is that it can automatically handle the boundary conditions. Through the increasing of concentration of extracellular K+ and ischemic size, the propagation of spiral...
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