D.A. Linkens

Promoter hypermethylation identifies progression risk in bladder cancer.

Purpose: New methods to accurately predict an individual tumor behavior are urgently required to improve the treatment of cancer. We previously found that promoter hypermethylation can be an accurate predictor of bladder cancer progression, but it is not cancer specific. Here, we investigate a panel of methylated loci in a prospectively collected cohort of bladder tumors to determine whether hypermethylation has a useful role in the management of patients with bladder cancer. Experimental Design: Quantitative methylation-specific PCR was done at 17 gene promoters, suspected to be associated with tumor progression, in 96 malignant and 30 normal urothelial samples. Statistical analysis and artificial intelligence techniques were used to interrogate the results. Results: Using log-rank analysis, five loci were associated with progression to more advanced disease (RASSF1a, E-cadherin, TNFSR25, EDNRB, and APC; P < 0.05). Multivariate analysis revealed that the overall degree of methylation was more significantly associated with subsequent progression and death (Cox, P = 0.002) than tumor stage (Cox, P = 0.008). Neuro-fuzzy modeling confirmed that these five loci were those most associated with tumor progression. Epigenetic predictive models developed using artificial intelligence techniques identified the presence and timing of tumor progression with 97% specificity and 75% sensitivity. Conclusion: Promoter hypermethylation seems a reliable predictor of tumor progression in bladder cancer. It is associated with aggressive tumors and could be used to identify patients with either superficial disease requiring radical treatment or a low progression risk suitable for less intensive surveillance. Multicenter studies are warranted to validate this marker.

Survey of utilisation of fuzzy technology in medicine and healthcare

The complexity of biological systems, unlike physical science applications, makes the development of computerised systems for medicine not a straightforward algorithmic solution because of the inherent uncertainty which arises as a natural occurrence in these types of applications. Human minds work from approximate data, extract meaningful information from massive data, and produce crisp solutions. Fuzzy logic provides a suitable basis for the ability to summarise and extract from masses of data impinging upon the human brain those facts that are related to the performance of the task at hand. In practice, a precise model may not exist for biological systems or it may be too difficult to model. In these cases fuzzy logic is considered as an appropriate tool for modelling and control, since our knowledge and experience are directly contained and presented in control strategies without explicit mathematical models. This paper surveys the utilisation of fuzzy logic in medical sciences, with an analysis of its possible future penetration.

Learning control using fuzzified self-organizing radial basis function network

This note describes an approach to integrating fuzzy reasoning systems with radial basis function (RBF) networks and shows how the integrated network can be employed as a multivariable self-organizing and self-learning fuzzy controller. In particular, by drawing some equivalence between a simplified fuzzy control algorithm (SFCA) and a RBF network, we conclude that the RBF network can be interpreted in the context of fuzzy systems and can be naturally fuzzified into a class of more general networks, referred to as FBFN, with a variety of basis functions (not necessarily globally radial) synthesized from each dimension by fuzzy logical operators. On the other hand, as a result of natural generalization from RBF to SFCA, we claim that the fuzzy system like RBF is capable of universal approximation. Next, the FBFN is used as a multivariable rule-based controller but with an assumption that no rule-base exists, leading to a challenging problem of how to construct such a rule-base directly from the control environment. We propose a simple and systematic approach to performing this task by using a fuzzified competitive self-organizing scheme and incorporating an iterative learning control algorithm into the system. We have applied the approach to a problem of multivariable blood pressure control with a FBFN-based controller having six inputs and two outputs, representing a complicated control structure. >

Input selection and partition validation for fuzzy modelling using neural network

A simple and effective method for selecting significant input variables and determining optimal number of fuzzy rules when building a fuzzy model from data is proposed. In contrast to the existing clustering-based methods, in this approach both input selecting and partition validating are determined on the basis of a class of sub-clusters created by a self-organising network instead of on the data. The important input variables which independently and significantly influence the system output can be extracted by a fuzzy neural network. On the other hand, the optimal number of fuzzy rules can be determined separately via the fuzzy c-means algorithm with a modified fuzzy entropy as the criterion of cluster validation. The simulation results show that the proposed method can provide good model structures for fuzzy modelling and has high computing efficiency.

A survey of fuzzy logic monitoring and control utilisation in medicine

Intelligent systems have appeared in many technical areas, such as consumer electronics, robotics and industrial control systems. Many of these intelligent systems are based on fuzzy control strategies which describe complex systems mathematical models in terms of linguistic rules. Since the 1980s new techniques have appeared from which fuzzy logic has been applied extensively in medical systems. The justification for such intelligent systems driven solutions is that biological systems are so complex that the development of computerised systems within such environments is not always a straightforward exercise. In practice, a precise model may not exist for biological systems or it may be too difficult to model. In most cases fuzzy logic is considered to be an ideal tool as human minds work from approximate data, extract meaningful information and produce crisp solutions. This paper surveys the utilisation of fuzzy logic control and monitoring in medical sciences with an analysis of its possible future penetration.

A systematic neuro-fuzzy modeling framework with application to material property prediction

A systematic neural-fuzzy modeling framework that includes the initial fuzzy model self-generation, significant input selection, partition validation, parameter optimization, and rule-base simplification is proposed in this paper. In this framework, the structure identification and parameter optimization are carried out automatically and efficiently by the combined use of a sell-organization network, fuzzy clustering, adaptive back-propagation learning, and similarity analysis-based model simplification. The proposed neuro-fuzzy modeling approach has been used for nonlinear system identification and mechanical property prediction in hot-rolled steels from construct composition and microstructure data. Experimental studies demonstrate that the predicted mechanical properties have a good agreement with the measured data by using the elicited fuzzy model with a small number of rules.

Mathematical Modeling of the Colorectal Myoelectrical Activity in Humans

Measurement of the colorectal myoelectrical activity in humans has revealed three basic patterns of behavior, comprising a lower frequency oscillation of about 0.05 Hz, a higher frequency of about 0.12 Hz and periods of zero activity. To simulate these myoelectrical patterns, the concept of linked relaxation oscillators is extended in this paper using three different mathematical model structures. In the three models two of the activity patterns are obtained as two stable limit cycle solutions produced by symmetrically coupling together two relaxation oscillators. The first model comprises a ring of interconnected oscillators which produces a third stable solution representing the higher frequency of oscillation. Summation of adjacent oscillator outputs reproduces the zero activity when the oscillators are in antiphase. By addition of an extra coefficient into the basic relaxation oscillator equation for the second model, the zero state becomes a stable condition and the three patterns are obtained without the necessity of a ring structure. The third model requires an in-situ change in a parameter value for the lower and higher frequencies to decay away to the zero activity condition.

Fuzzy Logic-Based Anti-Sway Control Design for Overhead Cranes

A non-linear model for an overhead crane system is derived which takes into account a combination of a trolley and a pendulum. The overall mathematical model obtained is simulated using MATLAB-SIMULINK. Open-loop simulations run on cases depending on whether the air resistance is taken into account or not, and whether the angle of oscillation is small or large, indicate the validity of such model, hence reflecting similar trends in industries which are concerned with material handling equipment. A hand-crafted fuzzy controller, which includes two rule bases, one for position control, the other for sway-angle control, was designed and successfully implemented on the above simulated model. Preliminary results are very encouraging, and indicate the feasibility of such a two rule base control strategy. The results obtained are presented, analysed and discussed.

FCMAC: a fuzzified cerebellar model articulation controller with self-organizing capacity

Abstract The Albuss Cerebellar Model Articulation Controller (CMAC) network has been used in many practical areas with considerable success. This paper presents a fuzzified CMAC network (FCMAC) acting as a multivariable adaptive controller with the feature of self-organizing association cells and the further ability of self-learning the required teacher signals in real-time. In particular, the original CMAC has been reformulated within a framework of a simplified fuzzy control algorithm (SFCA) and the associated self-learning algorithms have been developed as a result of incorporating the schemes of competitive learning and iterative learning control into the system. By using a similarity-measure-based, instead of coding-algorithm-based, content-addressable scheme, FCMAC is capable of dealing with arbitrary-dimensional continuous input space in a simple manner without involving complicated discretizing, quantizing, coding, and hashing procedures used in the original CMAC. The learning control system described here can be thought of as either a completely unsupervised fuzzy-neural control strategy without relying on the process model or equivalently an automatic real-time knowledge acquisition scheme for the implementation of fuzzy controllers. The proposed approach has been applied to a multivariable blood pressure control problem which is characterized by strong interaction between variables and large time delays.

A hybrid neuro-fuzzy PID controller

A hybrid neuro-fuzzy control strategy and its corresponding rule generating approach is proposed. According to this approach, the fuzzy control rules can be generated automatically via fuzzy inputs, and then the appropriate control action can be deduced efficiently by a simplified fuzzy inference engine. By combining the use of an incremental PI algorithm and a positional PD algorithm, a PID fuzzy control strategy can be implemented simply from two input variables. It results in the number of control rules being significantly reduced without decreasing the control performance. The control parameters can be self-tuned by introducing a single neuron together with a modified back-propagation learning algorithm. Simulation results show that the proposed fuzzy controller is able to control unknown processes and provide good performance. Compared to traditional self-organising and neural-network-based fuzzy controllers, this method has simpler control algorithms and less computational burden.