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At least 235 records · Page 13Linked to original sources
PubMed1986

Cellular logic implementation on a generalized image processor applied to biomedical image processing.

The implementation on a generalized image processor of a cellular logic package that performs non-recursive cellular-logic operations (CLOs) in real time is described. This system takes advantage of up to 20 512 X 512 X 8-bit memory planes within the image processor and can manipulate cells with up to 256 symbolic states. The flexibility of the image processor allows the use of an expanded cellular transition set, beyond bit-on or bit-off, as well as application-specific neighborhood configurations. The use of concurrent data-dependent global calculations, including CLO iteration termination control, is described. The array processor implementation specifics are discussed. This general cellular logic package is applied to biomedical images in the Image Processing Laboratory, Department of Radiological Sciences, University of California at Los Angeles. Geometric information is acquired from the images using real-time operators on the image array processor. This information includes image segmentation, area calculation, object counting, centroid determination and shape analysis. Initial clinical results are presented, and possible future medical applications are discussed.

Computers↗
PubMed1999

Incorporating qualitative knowledge in enzyme kinetic models using fuzzy logic.

Modeling of metabolic pathway dynamics requires detailed kinetic equations at the enzyme level. In particular, the kinetic equations must account for metabolite effectors that contribute significantly to the pathway regulation in vivo. Unfortunately, most kinetic rate laws available in the literature do not consider all the effectors simultaneously, and much kinetic information exists in a qualitative or semiquantitative form. In this article, we present a strategy to incorporate such information into the kinetic equation. This strategy uses fuzzy logic-based factors to modify algebraic rate laws that account for partial kinetic characteristics. The parameters introduced by the fuzzy factors are then optimized by use of a hybrid of simplex and genetic algorithms. The resulting model provides a flexible form that can simulate various kinetic behaviors. Such kinetic models are suitable for pathway modeling without complete enzyme mechanisms. Three enzymes in Escherichia coli central metabolism are used as examples: phosphoenolpyruvate carboxylase; phosphoenolpyruvate carboxykinase; and pyruvate kinase I. Results show that, with fuzzy logic-augmented models, the kinetic data can be much better described. In particular, complex behavior, such as allosteric inhibition, can be captured using fuzzy rules. The resulting models, even though they do not provide additional physical meaning in enzyme mechanisms, allow the model to incorporate semiquantitative information in metabolic pathway models.

Bacterial Proteins↗
PubMed1998

A new correlation-based fuzzy logic clustering algorithm for fMRI.

Fuzzy logic clustering algorithms are a new class of processing strategies for functional MRI (fMRI). In this study, the ability of such methods to detect brain activation on application of a stimulus task is demonstrated. An optimization of the selected algorithm with regard to different parameters is proposed. These parameters include (a) those defining the pre-processing procedure of the data set; (b) the definition of the distance between two time courses, considered as p-dimensional vectors, where p is the number of sequential images in the fMRI data set; and (c) the number of clusters to be considered. Based on the assumption that such a clustering algorithm should cluster the pixel time courses according to their similarity and not their proximity (in terms of distance), cross-correlation-based distances are defined. A clear mathematical description of the algorithm is proposed, and its convergence is proven when similarity measures are used instead of conventional Euclidean distance. The differences between the membership function given by the algorithm and the probability are clearly exposed. The algorithm was tested on artificial data sets, as well as on data sets from six volunteers undergoing stimulation of the primary visual cortex. The fMRI maps provided by the fuzzy logic algorithm are compared to those achieved by the well established cross-correlation technique.

Algorithms↗
PubMed1997

Referential cohesion and logical coherence of narration after right hemisphere stroke.

A group with right hemisphere dysfunction was compared to neurologically intact controls regarding the referential cohesion and logical coherence of narrative production. A somewhat varied sample of six stories was obtained with tasks of cartoon-elicited story-telling and auditory-oral retelling. We found deficits in the patient group with respect to referential cohesion, logical coherence, and accuracy of narration, but the occurrence of deficits depended on the condition in which narration was produced and, to some extent, on the particular story used in each condition. The primary implications of this study pertain to the attention given by researchers to the feature of discourse production being studied.

Adult↗
PubMed1996

Informational properties of neural nets performing algorithmic and logical tasks.

It is argued that the genetic information necessary to encode an algorithmic neural processor tutoring an otherwise randomly connected biological neural net is represented by the entropy of the analogous minimal Turing machine. Such a near-minimal machine is constructed performing the whole range of bivalent propositional logic in n variables. Neural nets computing the same task are presented; their informational entropy can be gauged with reference to the analogous Turing machine. It is also shown that nets with one hidden layer can be trained to perform algorithms solving propositional logic by error back-propagation.

Algorithms↗
PubMed1994

Logic, truth and language in concepts of pain.

Logic and language influence our ideas about the truth of pain, and can alter our understanding of it. Physicians should not tell their patients that there is nothing wrong with them if all their test results are negative, as this denies their patients' experiences of pain. Popular methods of conceptualizing pain may be erroneous. Diagrams of pain or disability are misleading and unhelpful--it is not usually possible to distinguish their components in practice. Giving patients a high or low score for pain behaviour, depression or for health locus of control can influence our views on aetiology in a seriously misleading way. Anyway, aetiological attributions are not always possible from analyses of the experience of pain. The problems of logic and language inherent in assigning pain to emotional causes, in using behavioural approaches, and in defining idiopathic pain and somatization are discussed. The IASP definition of pain is important and useful, provided that it is used appropriately. The recommended version is now 'an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.'

Humans↗
PubMed1980

The concept of homology in quantitative organelle pathology. Application of symbolic logic to glycogenosis type I in the liver.

The process of quantification has led pathology into an objective and abstract direction to which it is unaccustomed. The introduction of the concept of homology in pathology by Doerr has proven to be very fruitful, since it has helped to clarify otherwise poorly understood relationships. As shown in the foregoing paper, the success of the homology concept applies also to quantitative organelle pathology. Homologies have demonstrated relationships within the ergastoplasmic - mitochondrial - peroxisomal system which are apparent only with the help of symbolic logic. These homologies permit inferences, shown here with the example of glycogenosis type I, regarding the adaptive potential of the cell and the degree of cellular damage. In addition, these homologies, which are described in terms of formal logic, may serve as a model for human pathologic anatomy.

Glycogen Storage Disease Type I↗
PubMed1984

The mathematical logic of life.

Protein synthesis can be likened to a particular coded information storage, transmission and execution system. Noise, error or mutations are the essential phenomena to which a living organism is subjected. Genetic coding aims at preserving the integrity of a structure under aggression from the surroundings. It can be shown that the different amino acids translated in the proteins, except the particular case of SER, obey a logical code for optimization of resistance to mutation effects. The study of the structure of this code allows a better comprehension of the logic of life.

Escherichia coli↗
PubMed1977

Logic as a tool for clinical training in social work.

The paper is an attempt to illustrate the usefulness of logic as a technique in the clinical training of mental health professionals. The specific concepts that are examined include the nature of deductive and inductive reasoning, hypothesis testing, necessary and sufficient conditions, "if-then" propositions, and the nature of clinical evidence. Knowledge and use of these concepts was tested in a tutorial program directed toward students who were beginning graduate studies in the field of social work. Some of the difficulties encountered by these students, especially in the clinical aspects of their training, were directly related to an inadequate understanding of these logical forms of reasoning. It is suggested that a portion of the clinical training in mental health fields be directed towards a deeper understanding and utilization of these basic concepts.

Curriculum↗
PubMed1993

Computational logic: a method for formal analysis of the ICU knowledge base.

The object of clinical computing is to support the making of clinical decisions. This takes place in an integrated context of care that involves processes of three different kinds: (1) the physiologic processes in the patient, (2) the processes of physiologic data as stored in, and moved within, a distributed computing system, and (3) the therapeutic and decision-making processes of the clinical staff. The clinical computing system is complex, and as we press it further to work as a partner in the complete care context, it tends to become unmanageably so. In this article, we try to suggest how one might begin using a formal mathematical theory, called 'computational logic,' to give theoretical analyses that might help one to understand the computing system and thereby to try to increase its ability to meet demands on it, and might help one to understand the care context as a whole. We examine the three levels, one at a time, looking for structural analogies between them, and trying to identify the ways that they are linked together. Computational logic provides us with a common set of notions for doing so.

Artificial Intelligence↗
PubMed1997

Computer-assisted interpretation of electromyograms of corpora cavernosa using fuzzy logic.

An electromyogram of the corpora cavernosa (CC-EMG) imparts information on the autonomic cavernous innervation and/or the cavernous smooth muscles. The CC-EMG is interpreted mainly by evaluation of signal patterns of higher activity. The time required for interpretation is reduced by the implementation of a computer-assisted diagnosis program with a Microsoft Windows user interface. The program offers four levels of diagnosis: on the first level, recordings can be edited; on the second and third levels, signal patterns can be searched or evaluated; and on the last level the final diagnosis is provided. The computer-assisted interpretation is based on digital measurement data. These data have been obtained through a 170.6-Hz sampling frequency and a quantization of 10 V/12 Bit of the amplified signal. The first task of this diagnosis program is to discover and extract signal patterns of higher activity from data stored on the hard disk of a personal computer (PC). For a mathematic description of these patterns the following features were defined: relative time position, relative reproducibility, part of normal phases, and part of whip phases. Syntactic pattern recognition was introduced to identify the characteristic signal forms. An evaluation of the patterns could be derived from these features using fuzzy logic. For a summary of the evaluated patterns the variable global normality was established. The global normality forms an important evaluation basis along with the global synchronism, which represents an investigator's first impression of a recording. The final diagnosis is completed using fuzzy logic. The program was tested by comparison of expert and computer diagnoses. A total of 30 records were independently evaluated by an expert team and the computer program. With reference to the four classified levels of diagnosis a correspondence of 70% could be found. Furthermore, the rate in each of the classified levels was higher than 50%. The discrimination between normal and abnormal evaluation was 80% for clinical routine. Our results show that a computer-assisted interpretation of the CC-EMG can be achieved using mathematically based software. Within the last 7 months this computer-assisted CC-EMG program proved to be of great help in routine diagnosis. Furthermore, it demonstrated results comparable with a blinded-expert interpretation. This approach should bring about dramatic improvements in the diagnosis of erectile dysfunction.

Electromyography↗
PubMed2006

Fuzzy logic control of bioreactor for enhanced biosynthesis of alkaline protease by an alkalophilic strain of Bacillus subtilis.

Present studies describe the optimization of some cultural parameters such as medium pH, incubation temperature, and agitation rate for the biosynthesis of alkaline protease by Bacillus subtilis IH-72 in a bioreactor using fuzzy logic control. The process of fermentation was carried out in a 7.5-L bioreactor (New Brunswick Scientific, USA) with a working volume of 5 L. All of the parameters were automatically controlled with the help of attached software. The optimum pH, temperature, and agitation for the production of alkaline protease by B. subtilis IH-72 were found to be 9.0, 35 degrees C, and 175 rpm, respectively. The performance of the fuzzy logic of the bioreactor was found to be encouraging for enhanced production of the enzymes. The maximum production of alkaline protease during the present study was found to be 9.6 U mL-1.

Bacillus subtilis↗
PubMed1997

Control model of human stance using fuzzy logic.

A control model of human stance is proposed based on knowledge from behavioral experiments and physiological systems. The proposed model is based on the control of global variables specific to body orientation and alignment, rather than on the control of the body's center of mass within the base of support. Furthermore, the proposed control model is not based on purely inverted pendulum body mechanics where only motion at one joint is controlled, as for instance the ankle. In the proposed model, the degrees of freedom are controlled by using reciprocal and synergistic muscle actions at multiple joints. The control model is based on three sets of different global variables which act in parallel: (1) limb length and its derivative, (2) limb orientation and its derivative, and (3) trunk attitude and its derivative. An important feature of the control model is the use of fuzzy logic, which enables us to model experimental findings and physiological knowledge in a meaningful and explicit way using fuzzy if-then rules. In the control model, 36 fuzzy if-then rules are implemented and applied using a four-linked segment model consisting of a trunk, thigh, shank and foot. Uni- and biarticular limb muscles and trunk muscles are represented as torque actuators at each individual joint. In the model, three sets of global variables act in parallel and make corrective and coordinated responses to internal, self-induced perturbations. The data show that the use of global variables and fuzzy logic successfully enables us to model human standing with sway about a point of equilibrium. Small changes in, for example, total body sway are comparable to those seen during natural sway in human stance. The selected controllers--limb length, limb orientation and trunk attitude--seem to be appropriate for human stance control.

Fuzzy Logic↗
PubMed2004

Fuzzy logic automatic control of the Phoenix-7 total artificial heart.

Automatic physiological control of the pneumatic Phoenix-7 total artificial heart (TAH) occupies a pivotal position for clinical application of the device. We developed a fuzzy logic automatic control algorithm for the Phoenix-7. The object of the automatic control system is to regulate the cardiac output at a level desirable for the given preload. The system uses cardiac output-type fuzzy pressure control combined with expert knowledge, most of which is of the form "If condition, then action." As a demonstration of the utility of the control algorithm, the effects of inlet air pressures, aortic pressure, pulmonary artery pressure, and heart rate on the cardiac output were analyzed. In addition, an in vitro experiment was carried out that verified good performance of the control algorithm. This fuzzy logic control algorithm possesses the potential for totally automatic operation, eliminating any need for manual intervention under variable hemodynamic conditions.

Automation↗
PubMedDate not supplied

Why should we abandon the mental logic hypothesis?

Two hypotheses on deductive reasoning are under development: mental logic and mental models. It is often accepted that there are overwhelming arguments to reject the mental logic hypothesis. I revise these arguments and claim that they are either not conclusive, or point at problems which are troublesome for the mental model hypothesis as well.

Concept Formation↗
PubMed1994

A geometric model for codon recognition logic.

Known types of pairings between mRNA bases and tRNA nucleosides are shown to be consistent with the notion of a translation space TS constructed such that certain wobble-pairings cannot be used in the same translation system without engendering confusion between keto-final codon twins like AAU(ASN)/AAG(LYS) and between amino-final codon twins like AAC(ASN)/AAA(LYS). When TS is abstractly formalized using Coxeter's face-first three-dimensional projection of a four-dimensional hypercube, the resulting model suggests a specific configurational logic for codon recognition by cognate tRNAs. Although this logic will in general permit codons and anticodons to form matching configurations whose loci are six lines parallel to the axis of a cylinder, confusion of keto-final and amino-final codon twins may result from wobble-pairings whose loci are the two of these lines off the surface of the cylinder.

Anticodon↗
PubMed1995

Global logic resulting from disequilibration process.

Describing a system in which internal detection or observation proceeds at a finite velocity is always destined to end up with a form of self-contradiction. For any formal language, for such a description, we must assume that the velocity of observation propagation or VOP be infinity. In the present paper, we propose a self-referential scheme intended for formally describing a system exhibiting the process of disequilibration propagating at a finite VOP, and find that a global logic can emerge from local disequilibration. Conservative cellular automata of Margolus type, for instance, enable disequilibration to be replaced by such a process that the number of particles is not conserved globally while appearing to be conserved by local observers. One cannot determine local rules universally. Nevertheless, global logic emerges as a result of the dynamics of a one-to-many type mapping. This is a fundamental aspect of natural languages or communication relevant to natural life and intelligence.

Biological Evolution↗
PubMed1993

A constraint logic programming framework for constructing DNA restriction maps.

Restriction mapping is an important computational problem in molecular biology, particularly in genetic engineering and DNA sequencing. It is different in that it is not only a purely computational problem but involves an interaction between experimental data collection procedures and the mapping algorithms. Consequently, the problem is loosely defined and in practice requires a flexible and versatile algorithm. We describe a framework for solving many restriction mapping problems in the constraint logic programming language CLP (R) which takes advantage of the declarative and powerful features of constraint logic programming. A CLP (R) algorithm is developed for solving a simple restriction mapping problem. The algorithm is the extended to handle more complex variations of restriction mapping such as fragments with errors, circular maps, multiple enzymes and partial digests. The mapping variants are integrated within the same framework and differ in the constraints required to define the kind of map consistency. Various search heuristics and control strategies to improve the search process are also incorporated as constraints.

Algorithms↗