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At least 199 records · Page 11Linked to original sources
PubMed2004

Automated human frontal lobe identification in MR images based on fuzzy-logic encoded expert anatomic knowledge.

Identification of human brain structures in MR images comprises an area of increasing interest, which also presents numerous methodological challenges. Here we describe a new knowledge-based automated method designed to identify several major brain sulci and then to define the frontal lobes by using the identified sulci as landmarks. To identify brain sulci, sulcal images were generated by morphologic operations and then separated into different components based on connectivity analysis. Subsequently, the individual anatomic features were evaluated by using fuzzy membership functions. The crisp decisions, i.e., the identification of sulci, were made by taking the maximum of the summation of all the membership functions. The identification was designed in a hierarchical order. The longitudinal fissure was extracted first. The left and right central sulci were then identified based on the left and right hemispheres. Next, the lateral sulci were identified based on the central sulci and hemispheres. Finally, the left and right frontal lobes were defined from the two hemispheres. The method was evaluated by visual inspection, comparison with manual segmentation, and comparison with manually volumetric results in references. The average Jaccard similarities of left and right frontal lobes between the automated and manual segmentation were 0.89 and 0.91, respectively. The average Kappa indices of left and right frontal lobes between the automated and manual segmentation were 0.94 and 0.95, respectively. These results show relatively high accuracy of using this novel method for human frontal lobe identification and segmentation.

Algorithms↗
PubMed2003

New approach based on fuzzy logic and principal component analysis for the classification of two-dimensional maps in health and disease. Application to lymphomas.

Two-dimensional (2D) electrophoresis is the most wide spread technique for the separation of proteins in biological systems. This technique produces 2D maps of high complexity, which creates difficulties in the comparison of different samples. The method proposed in this paper for the comparison of different 2D maps can be summarised in four steps: (a) digitalisation of the image; (b) fuzzyfication of the digitalised map in order to consider the variability of the two-dimensional electrophoretic separation; (c) decoding by principal component analysis of the previously obtained fuzzy maps, in order to reduce the system dimensionality; (d) classification analysis (linear discriminant analysis), in order to separate the samples contained in the dataset according to the classes present in said dataset. This method was applied to a dataset constituted by eight samples: four belonging to healthy human lymph-nodes and four deriving from non-Hodgkin lymphomas. The amount of fuzzyfication of the original map is governed by the sigma parameter. The larger the value, the more fuzzy theresulting transformed map. The effect of the fuzzyfication parameter was investigated, the optimal results being obtained for sigma = 1.75 and 2.25. Principal component analysis and linear discriminant analysis allowed the separation of the two classes of samples without any misclassification.

Electrophoresis, Gel, Two-Dimensional↗
PubMed2006

Fine-resolution mapping of wildfire fuel types for Canada: Fuzzy logic modeling for an Alberta pilot area.

The Canadian Forest Fire Danger Rating System (CFFDRS) is used daily across Canada for evaluating forest fire danger. Fuel-type information is one of the inputs required by the models used in the CFFDRS. In this project, three fuel-type maps with a 25 m resolution were produced for a pilot study area located in Alberta using land cover only; land cover and biomass; and, land cover, biomass and leaf area index data derived from satellite imagery. The relationships between inputs and fuel types were determined mainly by the opinions of forest fire scientists and incorporated into a computer program using fuzzy set methodology. Not all the CFFDRS fuel types could be distinguished using these inputs; three of the coniferous types had to be grouped into one common fuel type. Overall accuracy was between 74 and 83% based on ground-truth comparisons. The most accurate map resulted from land cover and biomass data. Detailed accuracy assessment indicated that the overall accuracy increased up to 86% if ambiguous fuel type identification was considered. No combination of inputs was able to define a fuel type with absolute certainty, which is a reflection of differing expert opinions and the small number of inputs used to produce the maps.

Alberta↗
PubMed2004

[Fuzzy logic in urology. How to reason in inaccurate terms].

The Occidental thinking is basically binary, based on opposites. The classic logic constitutes a systematization of these thinking. The methods of pure sciences such as physics are based on systematic measurement, analysis and synthesis. Nature is described by deterministic differential equations this way. Medical knowledge does not adjust well to deterministic equations of physics so that probability methods are employed. However, this method is not free of problems, both theoretical and practical, so that it is not often possible even to know with certainty the probabilities of most events. On the other hand, the application of binary logic to medicine in general, and to urology particularly, finds serious difficulties such as the imprecise character of the definition of most diseases and the uncertainty associated with most medical acts. These are responsible for the fact that many medical recommendations are made using a literary language which is inaccurate, inconsistent and incoherent. The blurred logic is a way of reasoning coherently using inaccurate concepts. This logic was proposed by Lofti Zadeh in 1965 and it is based in two principles: the theory of blurred conjuncts and the use of blurred rules. A blurred conjunct is one the elements of which have a degree of belonging between 0 and 1. Each blurred conjunct is associated with an inaccurate property or linguistic variable. Blurred rules use the principles of classic logic adapted to blurred conjuncts taking the degree of belonging of each element to the blurred conjunct of reference as the value of truth. Blurred logic allows to do coherent urologic recommendations (i.e. what patient is the performance of PSA indicated in?, what to do in the face of an elevated PSA?), or to perform diagnosis adapted to the uncertainty of diagnostic tests (e.g. data obtained from pressure flow studies in females).

Fuzzy Logic↗
PubMedDate not supplied

Influence of the dilution rate on the bioproductivity of lactose-utilizing yeasts: fuzzy logic modeling.

The studied problem is of commercial interest because whey, the cultivation substrate, is a waste by-product from the transformation of milk into cheese and casein. Investigations on the influence of the dilution rate (D) on the bioproductivity of lactose-utilizing yeasts were carried out with two model strains--the oxidative strain Candida blankii 35 and the fermentative strain Candida pseudotropicalis 11. The increase of D led to the different changes in productivity. The best synthesizing ability of both continuously cultivated strains is established at D = 0.4 [h-1] despite the different type of metabolism. The oxidative strain C. blankii 35 is more effective in comparison with the fermentative strain C. pseudotropicalis 11 because of its ability to synthesize 1.5 fold higher biomass and protein yields. These experimental facts were proved also by simulative research with a Fuzzy Knowledge-Based System (FKBS) developed for modeling the influence of D on several process variables.

Biomass↗
PubMed1997

Fundamentals of feedback control: PID, fuzzy logic, and neural networks.

Feedback controllers have been shown to bring blood pressure, muscle relaxation, inhalation drug concentration, and ventilation to the target level and keep it at the target as quickly and as accurately as can a well-trained clinician. Feedback control is an effective and convenient clinical tool for optimizing the day-to-day delivery of anesthetics, reducing induction time, delivering a minimum amount of drug, and avoiding costly delays from failing to keep the patient in a desired state.

Anesthetics↗
PubMed2001

Fuzzy logic and mechanical ventilation.

Closed-loop control can achieve appropriate ventilation of the lungs in a healthy person by involving the continuous interaction of three components: sensors, controllers, and effectors. The sensors are the chemo-mechanoreceptors, which continuously monitor key bodily functions affected by ventilation. This information is relayed to the controllers, the respiratory centers in the brain, allowing them to determine how actual ventilation compares with that needed by the body. Finally, the controllers direct the effectors, the muscles of respiration, to adjust the ventilation accordingly. When a patient is in respiratory failure, the effector's role is taken over by a mechanical ventilator. The issue that is considered in this article is how the physician might be taken out of the feedback loop.

Algorithms↗
PubMedDate not supplied

New fuzzy logic strategies for bio-molecular recognition.

The concepts of molecular similarity and molecular complementarity, playing important roles in the broad field of molecular recognition, are chemical problems, in which the eyeball technique used by a human observer is very successful but which are very hard to code into a computer algorithm. Based on the model of molecular surfaces, our new approach defines overlapping surface patches with similar molecular properties. These patches are used to represent local features of the molecule in a way, which is beyond the atomistic resolution but can nevertheless be applied in partial similarity as well as complementarity analyses in a very general sense. It is shown that this molecular description can be used as the first step in a docking algorithm for complexes, where the structures of both molecules are known, as well as for the identification of possible active sites without the knowledge of specific molecules binding to this site.

Algorithms↗
PubMed2003

The "fuzzy logic" of the death-inducing signaling complex in lymphocytes.

Receptors belonging to the tumor necrosis factor receptor family have long been thought to play an important role in the regulation of immunity. Although this family is composed of a large number of surface receptors that potentiate myriad functions in vivo, a subset is known to directly convey apoptotic signals. One such molecule belonging to this subset is CD95. Ligation of CD95 instigates the formation of a complex known as the "death-inducing signaling complex" or DISC, which is composed of molecules including FADD (Fas associated with death domain) and RIP (receptor-interacting kinase), as well as procaspases-8 and -10, and a caspase-8-like molecule that lacks proteolytic activity called c-FLIP. Although the DISC was initially thought to serve an exclusively proapoptotic role, humans and mice with defects in various components of this complex demonstrate a variety of developmental and hematopoietic defects that are not apparently due to aberrant apoptosis. These findings paint a far more complex picture of the numerous components of the DISC, and provide evidence that these complexes serve nonapoptotic functions. Herein, we summarize the experimental evidence challenging the notion that the DISC imparts an exclusively apoptotic function and provide hypotheses to account for these alternative roles. Rather than operating as a binary system, we propose that the DISCs formed around various DRs transduce signals leading to a variety of cellular fates.

Animals↗
PubMed1997

Design and validation of an intelligent patient monitoring and alarm system based on a fuzzy logic process model.

The process of patient care performed by an anaesthesiologist during high invasive surgery requires fundamental knowledge of the physiologic processes and a long standing experience in patient management to cope with the inter-individual variability of the patients. Biomedical engineering research improves the patient monitoring task by providing technical devices to measure a large number of a patient's vital parameters. These measurements improve the safety of the patient during the surgical procedure, because pathological states can be recognised earlier, but may also lead to an increased cognitive load of the physician. In order to reduce cognitive strain and to support intra-operative monitoring for the anaesthesiologist an intelligent patient monitoring and alarm system has been proposed and implemented which evaluates a patient's haemodynamic state on the basis of a current vital parameter constellation with a knowledge-based approach. In this paper general design aspects and evaluation of the intelligent patient monitoring and alarm system in the operating theatre are described. The validation of the inference engine of the intelligent patient monitoring and alarm system was performed in two steps. Firstly, the knowledge base was validated with real patient data which was acquired online in the operating theatre. Secondly, a research prototype of the whole system was implemented in the operating theatre. In the first step, the anaesthetists were asked to enter a state variable evaluation before a drug application or any other intervention on the patient into a recording system. These state variable evaluations were compared to those generated by the intelligent alarm system on the same vital parameter constellations. Altogether 641 state variable evaluations were entered by six different physicians. In total, the sensitivity of alarm recognition is 99.3%, the specificity is 66% and the predictability is 45%. The second step was performed using a research prototype of the system in anaesthesiological routine. The evaluation of 684 events yielded a sensitivity, specificity and predictability of the alarm recognition of more than 99%.

Anesthesiology↗
PubMed2005

From fuzzy logic toward plurimonism: the science of active and empathic observation.

Plurimonism is a new philosophy and method of science. It holds that the revolution in computer science and artificial intelligence has reached the point that all the sciences in general can now account for the complex relations of an irreducible plurality of unique observers engaged in describing the same event. Plurimonism seeks to describe the conscious and unconscious relations of the scientific observer during the act of observation of a given event while preserving the historical uniqueness and indivisible identity of each such observer. Using the framework of plurimonism, we mathematically formulate the problem of empathy. This self-reflective mathematical model entails four components of the empathic process involving two observers. They are: 1) the self; 2) the self's-other; 3) the other; and 4) the other's-self. It measures the degree of accuracy of the therapist-observer's empathy, as well as conscious and unconscious processes involved in the patient-observer's idealization and the therapist-observer's confidence in clinical psychotherapy. Ratings are obtained from both patient and therapist from four different points of view. The plural views of the patient's global assessment of functioning (GAF) are from: 1) the therapist's view (TGAF); 2) the patient's view (PGAF); 3) the therapist empathic view (TEGAF), which represents the therapist's estimate of PGAF; and 4) the patient's empathic estimate of the TGAF. The GAF scale is the standard dimensional 100-point-scale measure used in psychiatry for recording a patient's functioning. The patient's estimate of the therapist's degree of accuracy as well as the therapist's confidence in his or her empathic accuracy is also represented. Three formulae are presented that describe the degree of the therapist's empathic accuracy, the patient's over-idealization/under-idealization, and the therapist's over-confidence/under-confidence. The concept of empathy is here restricted to mean the degree to which one observer can take the point of view of another observer when both are observing the same thing.

Cybernetics↗
PubMed2004

Design of a switching controller for nonlinear systems with unknown parameters based on a fuzzy logic approach.

This paper deals with nonlinear plants subject to unknown parameters. A fuzzy model is first used to represent the plant. An equivalent switching plant model is then derived, which supports the design of a switching controller. It will be shown that the closed-loop system formed by the plant and the switching controller is a linear system. Hence, the system performance of the closed-loop system can be designed. An application example on controlling a two-inverted pendulum system on a cart will be given to illustrate the design procedure of the proposed switching controller.

Journal Article↗
PubMed2005

Risk management and the precautionary principle: a fuzzy logic model.

The aim of this article is to illustrate a procedure for applying the precautionary principle within a strategy for reducing the possibility of underestimating the effective risk caused by a phenomenon, product, or process, and of adopting insufficient risk reduction measures or overlooking their need. We start by simply defining risk as the product between the numerical expression of the adverse consequences of an event and the likelihood of its occurrence or the likelihood that such consequences will occur. Uncertainty in likelihood estimates and several key concepts inherent to the precautionary principle, such as sufficient certainty, prevention, and desired level of protection, are represented as fuzzy sets. The strategy described may be viewed as a simplified example of a precautionary decision process that has been chiefly conceived as a theoretical contribution to the debate concerning the precautionary principle, the quantification of its application, and the formal approach to such problems.

Journal Article↗
PubMed2005

Fuzzy logic and continuous cellular automata in warfarin dosing of stroke patients.

"Evidence-based" recommendations for warfarin prescription in patients with history of ischemic stroke limit its use to prevention of stroke due to atrial fibrillation. Warfarin is also prescribed by the authors to prevent thrombosis in stroke patients with thrombophilia and potential cardiac or arterial source for thromboembolism. These potential conditions, in the face of thrombophilia, include, but may not be limited to, dilated cardiomyopathy, decreased left ventricular function, atrial septal aneurysm with or without patent foramen ovale (PFO), PFO with evidence of pelvic or lower extremity deep venous thrombosis or with clear thrombophilia, spontaneous echocardiographic contrast, intracardiac or intra-arterial thrombus, intra-aortic arch thrombus, high degree of stenosis of large- and medium-sized cerebrovascular arteries, and arterial dissection. Commonly diagnosed thrombophilic states in our population currently include protein S or C deficiency, antiphospholipid antibodies, and less commonly ATIII deficiency, factor V Leiden mutation, G20210A PT mutation, and plasminogen activator inhibitor-1 mutation. Thrombophilic states often occur in combination. The occurrence of combined arterial, cardiac, and thrombophilic sources of thromboembolism poignantly describes the complexity of causation of ischemic stroke in any one patient. Our practice of treating the complex interaction of thromboembolic sources is based on scientific evidence, which is not arbitrarily limited to probability-based statistics. Warfarin is well known in the clinical setting to interact with many different contextual factors of the individual patient, making its dosing and response unique to that patient. We have shown why the indications for warfarin use and its dosing cannot be directly extrapolated to the individual patient from the results of large, double-blind, randomized trials. In practice, the unique patient and his or her context must be considered by the expert physician who makes the therapeutic decision. The context includes, but is not limited to, known pathologies that contribute to thrombus formation according to the accepted pathophysiologic model of thrombosis based on Virchow's triad of altered flow, endothelium, and blood components.

Journal Article↗