84 research outputs found
An immune network approach to learning qualitative models of biological pathways
ACKNOWLEDGMENT GMC is supported by the CRISP project (Combinatorial Responses In Stress Pathways) funded by the BBSRC (BB/F00513X/1) under the Systems Approaches to Biological Research (SABR) Initiative. WP and GMC are also supported by the partnership fund from dot.rural, RCUK Digital Economy research.Postprin
Learning qualitative models from physiological signals
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 165-169).by David Tak-Wai Hau.M.S
Qualitative System Identification from Imperfect Data
Experience in the physical sciences suggests that the only realistic means of
understanding complex systems is through the use of mathematical models.
Typically, this has come to mean the identification of quantitative models
expressed as differential equations. Quantitative modelling works best when the
structure of the model (i.e., the form of the equations) is known; and the
primary concern is one of estimating the values of the parameters in the model.
For complex biological systems, the model-structure is rarely known and the
modeler has to deal with both model-identification and parameter-estimation. In
this paper we are concerned with providing automated assistance to the first of
these problems. Specifically, we examine the identification by machine of the
structural relationships between experimentally observed variables. These
relationship will be expressed in the form of qualitative abstractions of a
quantitative model. Such qualitative models may not only provide clues to the
precise quantitative model, but also assist in understanding the essence of
that model. Our position in this paper is that background knowledge
incorporating system modelling principles can be used to constrain effectively
the set of good qualitative models. Utilising the model-identification
framework provided by Inductive Logic Programming (ILP) we present empirical
support for this position using a series of increasingly complex artificial
datasets. The results are obtained with qualitative and quantitative data
subject to varying amounts of noise and different degrees of sparsity. The
results also point to the presence of a set of qualitative states, which we
term kernel subsets, that may be necessary for a qualitative model-learner to
learn correct models. We demonstrate scalability of the method to biological
system modelling by identification of the glycolysis metabolic pathway from
data
An integrative top-down and bottom-up qualitative model construction framework for exploration of biochemical systems
The authors would like to thank the support on this research by the CRISP project (Combinatorial Responses In Stress Pathways) funded by the BBSRC (BB/F00513X/1) under the Systems Approaches to Biological Research (SABR) Initiative.Peer reviewedPublisher PD
Tracking features in image sequences using discrete Morse functions
The goal of this contribution is to present an application of discrete Morse theory
to tracking features in image sequences. The proposed algorithm can be used for tracking
moving figures in a filmed scene, for tracking moving particles, as well as for detecting canals
in a CT scan of the head, or similar features in other types of data. The underlying idea
which is used is the parametric discrete Morse theory presented in [13], where an algorithm
for constructing the bifurcation diagram of a discrete family of discrete Morse functions was
given. The original algorithm is improved here for the specific purpose of tracking features
in images and other types of data, in order to produce more realistic results and eliminate
irregularities which appear as a result of noise and excess details in the data
Ascending and descending regions of a discrete Morse function
We present an algorithm which produces a decomposition of a regular cellular
complex with a discrete Morse function analogous to the Morse-Smale
decomposition of a smooth manifold with respect to a smooth Morse function. The
advantage of our algorithm compared to similar existing results is that it
works, at least theoretically, in any dimension. Practically, there are
dimensional restrictions due to the size of cellular complexes of higher
dimensions, though. We prove that the algorithm is correct in the sense that it
always produces a decomposition into descending and ascending regions of the
critical cells in a finite number of steps, and that, after a finite number of
subdivisions, all the regions are topological discs. The efficiency of the
algorithm is discussed and its performance on several examples is demonstrated.Comment: 23 pages, 12 figure
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