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At least 523 records · Page 29Linked to original sources
PubMed1993

The logic of misperceived distance (or location) theories of the Poggendorff illusion.

For the Poggendorff display (transversal interrupted by parallel lines), the typical distance-misperception theory postulates that a particular linear distance extending across the empty space between parallels is underestimated; examples are the intertransversal slant distance defined by the closest ends of the transversal segments (a "wings-in Müller-Lyer like" underestimation) or the perpendicular distance between parallels (parallels "attract"). Distance misperception by itself, however, can neither establish that perceived transversal misalignment exists for a Poggendorff display nor specify the perceived-location condition(s) that will produce perceptual collinearity. The perceptual displacement vector is introduced as a means of specifying fully the perceptual mislocation (displacement) of one transversal segment with respect to the other. Given this vector information (direction as well as distance), the logical soundness of theories postulating distance or location misperception were evaluated, and they were compared on the basis of extant data. Such vector information can be used to evaluate other classes of theories as well.

Distance Perception↗
PubMed2006

Breast tumor malignancy modelling using evolutionary neural logic networks.

The present work proposes a computer assisted methodology for the effective modelling of the diagnostic decision for breast tumor malignancy. The suggested approach is based on innovative hybrid computational intelligence algorithms properly applied in related cytological data contained in past medical records. The experimental data used in this study were gathered in the early 1990s in the University of Wisconsin, based in post diagnostic cytological observations performed by expert medical staff. Data were properly encoded in a computer database and accordingly, various alternative modelling techniques were applied on them, in an attempt to form diagnostic models. Previous methods included standard optimisation techniques, as well as artificial intelligence approaches, in a way that a variety of related publications exists in modern literature on the subject. In this report, a hybrid computational intelligence approach is suggested, which effectively combines modern mathematical logic principles, neural computation and genetic programming in an effective manner. The approach proves promising either in terms of diagnostic accuracy and generalization capabilities, or in terms of comprehensibility and practical importance for the related medical staff.

Artificial Intelligence↗
PubMed1995

Fuzzy logic and medical device technology.

This article introduces the concept of fuzzy logic and discusses its application in analytical processes. Terms such as fuzzy sets and membership functions, which can be used to describe the process states and conditions of a system, are defined. An example is given of how this reasoning technique could be applied to an actual device.

Biomedical Engineering↗
PubMedDate not supplied

Fuzzy logic and medical device design controls.

The second article in this series concentrated on the application of fuzzy logic in drug delivery systems and presented a specific example of respiratory therapy. This article completes the picture with a discussion of the regulatory issues, with particular reference to hardware and software design controls and applicable standards.

Computer-Aided Design↗
PubMed2000

Modeling anatomical spatial relations with description logics.

Although spatial relations are essential for the anatomy domain, spatial reasoning is only weakly supported by medical knowledge representation systems. To remedy this shortcoming we express spatial relations that can intuitively be applied to anatomical objects (such as 'disconnected', 'externally connected', 'partial overlap' and 'proper part') within the formal framework of description logics. A special encoding of concept descriptions (in terms of SEP triplets) allows us to emulate spatial reasoning by classification-based reasoning.

Anatomy↗
PubMed1975

[Hypnosis: logic and cybernetics].

Fundamental notions concerning cybernetics, as derived from the systematic application of logic to questions of communication and control, are illustrated. Particular attention is given to the concepts of "system" "structure" and "dynamics" and it is shown that these concepts ensure that better and more exact understanding and forecasting of reactions in organised beings can be obtained. Turing to hypnosis, it is made clear that a trance is the execution of a momentarily proposed programme; it is not the result of a generalised mechanical action, but is preordained and geared to various situations. The difficulty that the hypnotised subject finds in aciting against his own interests, or against moral priniciples, can be seen, for example, as a consequence of pre-programming. Another result is given moment and a given type of person. Since cybernetis has proved useful in psychology, the hope is expressed that it can be included as a teaching subject for those who learn, practise and teach hypnotism.

Cybernetics↗
PubMed2001

Prognosis of body fluid level by fuzzy logic technique.

Surgical fluid replacement is a critical issue in medicine as the fluid volume excess or deficit can both complicate the patient's condition. Currently, the administration of fluid volume is carried out primarily based on the experience and expertise of the anaesthetist as there is no analytical method available to estimate the patient's fluid level. The development of a decision support system (DSS) to assist the anaesthetist in estimating the required fluid infusion rate for a particular patient has been the focus of this research paper. The DSS is developed based on Fuzzy Logic Control (FLC) technique which is ideal for developing input/output models in an unstructured and/or complex environment. The fuzzy rules used in the DSS are derived automatically from the clinical data produced in surgical operations. The DSS employs a Multi Rule Base (MRB) learning scheme to adapt its model according to the significant variation in the physiological parameters of a patient. The performance of the developed algorithms is validated through experimental work using clinical data. The results obtained so far are encouraging.

Diagnosis, Computer-Assisted↗
PubMed2001

Application of a new logic domain method for the diagnosis of hepatocellular carcinoma.

In this paper we describe the application of a new learning tool for the diagnosis of hepatocellular carcinoma. The method adopted operates in the logic domain and presents several interesting features for the development of medical diagnostic systems. We consider a database of 128 patients, 64 of which affected by hepatocellular carcinoma, while the others affected by cirrhosis but not from hepatocellular carcinoma. Each patient is described by a number of attributes measured in non-invasive way. The system, after the training, is able to correctly separate the 64 patients affected by cirrhosis from the others 64 affected by hepatocellular carcinoma and is now ready to produce automatic diagnosis for new patients. The hepatocellular carcinoma is one of the most widely spread malignant tumors in the world. The ability to detect the tumor in its early stages in a minimally invasive way is crucial to the treatment of patients with this disease.

Algorithms↗
PubMed2001

Modeling uncertainty in computerized guidelines using fuzzy logic.

Computerized Clinical Practice Guidelines (CPGs) improve quality of care by assisting physicians in their decision making. A number of problems emerges since patients with close characteristics are given contradictory recommendations. In this article, we propose to use fuzzy logic to model uncertainty due to the use of thresholds in CPGs. A fuzzy classification procedure has been developed that provides for each message of the CPG, a strength of recommendation that rates the appropriateness of the recommendation for the patient under consideration. This work is done in the context of a CPG for the diagnosis and the management of hypertension, published in 1997 by the French agency ANAES. A population of 82 patients with mild to moderate hypertension was selected and the results of the classification system were compared to whose given by a classical decision tree. Observed agreement is 86.6% and the variability of recommendations for patients with close characteristics is reduced.

Decision Making, Computer-Assisted↗
PubMed2002

Usability of expressive description logics--a case study in UMLS.

Research in (medical) terminological knowledge representation is showing an increased interest in the family of Description Logics (DLs), as they allow for automatic reasoning. This interest is driven by an increase in demands on the quality of and reasoning ability with medical terminological knowledge. Recent advances in Computer Science have demonstrated the computational decidability and empirical tractability of quite expressive DLs. The question arises whether this expressivity is usable and useful. This paper motivates and describes an exploratory study to address this question by examining the surplus value of individual DL constructors based on an investigation of UMLS terms. Our study indicates that the disjunction and negation operators comprise very valuable extensions to current DLs. The impact of formalization depends on the involved semantic type; "Injury and Poisoning" is one of the semantic types in which a large portion of concepts will benefit from the extension.

Logic↗
PubMedDate not supplied

A new approach to the statistical treatment of 2D-maps in proteomics using fuzzy logic.

A new approach to the statistical treatment of 2D-maps has been developed. This method is based on the use of fuzzy logic and allows to take into consideration the typical low reproducibility of 2D-maps. In this approach the signal corresponding to the presence of proteins on the 2D-maps is substituted with probability functions, centred on the signal itself. The standard deviation of the bidimensional gaussian probability function employed to blur the signal allows to assign different uncertainties to the two electrophoretic dimensions. The effect of changing the standard deviation and the digitalisation resolution are investigated.

Electrophoresis↗
PubMed2003

Preliminary evaluation of a fuzzy logic-based automatic quantitative analysis in myocardial SPECT.

UNLABELLED: This study validates a new quantitative myocardial perfusion SPECT software. METHODS: The processing starts with the extraction of the morphologic skeleton of the left ventricular myocardium from reconstructed transverse sections. Fuzzy logic is used to decide whether a pixel belongs to the myocardium and any perfusion defect is filled according to a truncated bullet model. The resulting image is partitioned in 18 isovolumetric sectors. Sex-matched normal limits, criteria of abnormality for rest (201)Tl and (99m)Tc-labeled perfusion tracers, reproducibility studies, and detection of coronary artery disease were developed and validated in an overall population of 343 patients. The sex- and tracer-matched means and SDs of a normal response were calculated in 93 male and 93 female patients with a <5% likelihood of coronary artery disease. Reproducibility measurements and assignment of different sectors of the myocardium to a specific coronary were performed from data collected in 49 and 60 patients, respectively. The accuracy of the detection of a coronary artery occlusion was assessed in 48 patients who also underwent coronary angiography. RESULTS: The intra- and interoperator reproducibility of the sectorial activity was high with a linear regression coefficient of 0.97 and a SD of the difference measurement at 4.4% and 3.8%, respectively. Overall sensitivity and specificity for the detection of occluded coronary artery were 90% and 80%, respectively. For the detection of left anterior descending, left circumflex, and right artery coronary occlusion, sensitivity was 92%, 75%, and 92.5%, respectively, and specificity was 75%, 78%, and 90%, respectively. CONCLUSION: The new quantitative myocardial perfusion SPECT software appears to be a very helpful program for the objective analysis of perfusion tracer distribution in myocardial SPECT and a very accurate tool in the detection and localization of coronary artery occlusion.

Algorithms↗
PubMed2003

Automatic control of volatile fatty acids in anaerobic digestion using a fuzzy logic based approach.

A control law based on fuzzy logic was developed and validated for an anaerobic wastewater treatment process. The controlled variable was the concentration of volatile fatty acids (VFA) in the reactor and the manipulated variable was the input flow rate. In order to use it as the input of the fuzzy sets, the controlled variable was treated using an algorithm of interpolation, extrapolation and filtering. The treatment of VFA values attempted to anticipate the behaviour of the variable and to avoid the inherent delay of the response, associated to the time constant of the system. Furthermore, the controlled variable derivative was used as a second input of the fuzzy sets to increase or decrease the speed of the control action. The control law was applied to a 0.948 m3 fixed-bed anaerobic reactor treating raw and diluted (1:2) industrial distillery vinasses. The validation was performed establishing different transient states between different set points in the range of 0.8 and 1.8 g VFA/l and different concentrations of the influent. The control law proved to be reliable supplying an adequate control action in terms of amplitude and velocity to achieve the desired set point for different types of perturbation and control purposes.

Automation↗
PubMedDate not supplied

Multi-valued logic in breast cancer detection.

The aim of this paper is to determine the type of the breast cancer disease. The two classes of separation are malignant respectively benign. A multi-valued logic system (fuzzy system) was develop and applied in this classification. The system uses nine attributes as inputs that were scaled with an integer value in the range between 1 and 10. The attributes represent: 1. Clump Thickness, 2. Uniformity of Cell Size, 3. Uniformity of Cell Shape, 4. Marginal Adhesion, 5. Single Epithelial Cell Size, 6. Bare Nuclei, 7. Bland Chromatin, 8. Normal Nucleoli, 9. Mitoses. After training the system managed to get a good detection with an error less than 5%.

Algorithms↗
PubMed1992

Hospitalization style of physicians in Manitoba: the disturbing lack of logic in medical practice.

Variations in hospital admission rates across small areas are ubiquitous, and it is increasingly assumed that high rates result from physicians' discretionary decisions. Data for elderly patients from the health insurance system of Manitoba were used to construct an index that divided physicians into four groups based on their propensity to admit patients to the hospital. I then determined whether physicians who are more prone to admit patients use hospitals for more discretionary purposes and admit patients who are less ill. Although the differences between physicians with different practice styles were in the expected direction, the most compelling finding was the similarity in characteristics of patients admitted by physicians with markedly different practice styles. Such findings suggest a very wide latitude in physicians' decisions to admit patients; this latitude is not well captured by a model that posits a logical relationship between physician treatment patterns and patient need.

Aged↗
PubMed2003

A fuzzy logic approach to control anaerobic digestion.

One of the goals of the EU-Project AMONCO (Advanced Prediction, Monitoring and Controlling of Anaerobic Digestion Process Behaviour towards Biogas Usage in Fuel Cells) is to create a control tool for the anaerobic digestion process, which predicts the volumetric organic loading rate (Bv) for the next day, to obtain a high biogas quality and production. The biogas should contain a high methane concentration (over 50%) and a low concentration of components toxic for fuel cells, e.g. hydrogen sulphide, siloxanes, ammonia and mercaptanes. For producing data to test the control tool, four 20 l anaerobic Continuously Stirred Tank Reactors (CSTR) are operated. For controlling two systems were investigated: a pure fuzzy logic system and a hybrid-system which contains a fuzzy based reactor condition calculation and a hierachial neural net in a cascade of optimisation algorithms.

Anaerobiosis↗
PubMed2004

Segmentation of human brain MR images using rule-based fuzzy logic inference.

The analysis of medical images for the purpose of computer-aided diagnosis and therapy planning includes the segmentation as a preliminary stage for the visualization or the quantification of such data. In this paper, we present a fuzzy segmentation system that is capable of segmenting magnetic resonance (MR) images of a human brain. The presented method consists of two main stages. The histogram analysis based on the S-function membership and Shannon's entropy function is the first step. In the final stage, pixel classification is performed using the rule-based fuzzy logic inference. After the segmentation is complete, attributes of different tissue classes may be determined (e.g., volumes), or the classes may be visualized as spatial objects. The implemented system provides many advanced 3D imaging tools, which enable visual exploration of segmented anatomical structures.

Algorithms↗