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PubMed1995

Perceived necessity explains the dissociation between logic and meaning: the case of "only if".

The purpose of this article was to investigate why sentences of the form "p only if q" often appear to have a different meaning than sentences of the form "if p, then q," despite their logical equivalence. The results of 3 experiments indicate that when "if ... then" statements were equated with respect to necessity and temporal relations, different pragmatic relations (such as permission, causation, etc.) elicited similar "only if" judgments. However, different necessity relations elicited different "only if" judgments, regardless of the type of pragmatic relation expressed in the "if then" statement. These data suggest that "only if" judgements are primarily mediated by necessity and temporal relations and that pragmatic contexts may play a more indirect role, such as in the interpretation of necessity and temporal relations. Suggestions for how these findings might be incorporated into pragmatic schema theory (P. W. Cheng & K. J. Holyoak, 1985; P. W. Cheng, K. J. Holyoak, R. E. Nisbett, & L. M. Oliver, 1986) and mental models theory (P. N. Johnson-Laird & R. M. J. Byrne, 1991) are discussed.

Dissociative Disorders↗

PubMed2003

Intellectual performance and ego depletion: role of the self in logical reasoning and other information processing.

Some complex thinking requires active guidance by the self, but simpler mental activities do not. Depletion of the self's regulatory resources should therefore impair the former and not the latter. Resource depletion was manipulated by having some participants initially regulate attention (Studies 1 and 3) or emotion (Study 2). As compared with no-regulation participants who did not perform such exercises, depleted participants performed worse at logic and reasoning (Study 1), cognitive extrapolation (Study 2), and a test of thoughtful reading comprehension (Study 3). The same manipulations failed to cause decrements on a test of general knowledge (Study 2) or on memorization and recall of nonsense syllables (Study 3). Successful performance at complex thinking may therefore rely on limited regulatory resources.

Cognition↗

PubMed2005

Optimization of fertirrigation efficiency in strawberry crops by application of fuzzy logic techniques.

A high level of price support has favoured intensive agriculture and an increasing use of fertilisers and pesticides. This has resulted in the pollution of water and soils and damage to certain eco-systems. The target relationship that must be established between agriculture and environment can be called "sustainable agriculture". In this work we aim at relating strawberry total yield with nitrate concentration in water at different soil depths. To achieve this objective, we have used the Predictive Fuzzy Rules Generator (PreFuRGe) tool, based on fuzzy logic and data mining, by means of which the dose that allows a balance between yield and environmental damage minimization can be determined. This determination is quite simple and is done directly from the obtained charts. This technique can be used in other types of crops permitting one to determine in a precise way at which depth the appropriate dose of nitrate fertilizer must be correctly applied, on the one hand providing the maximum yield but, on the other hand, with the minimum loss of nitrates that leachate through the saturated zone polluting aquifers.

Agriculture↗

PubMed1997

Logical analysis of timing-dependent receptor signalling specificity: application to the insulin receptor metabolic and mitogenic signalling pathways.

We present a method for logical analysis of signal-transduction networks, focusing on metabolic and mitogenic signalling by the insulin receptor, with specific emphasis on dependence of the signalling properties on the timing of binding events. We discuss a basic model which demonstrates this dependence (hormone binding leads to activation of the receptor which can lead to a commitment to mitogenic signalling), and show how residence time of the hormone on the receptor can determine the specificity of signalling between the alternative metabolic or mitogenic pathways. The method gives conditions for the selection of specific branches in the signalling pathway expressed in terms of inequalities among the characteristic activation or deactivation times of components of that pathway. In this way, the conditions for mitogenic signalling can be given in terms of a required range of values of the hormone residence time on the receptor, which is directly related to the kinetic dissociation rate.

Animals↗

PubMed1998

A portable self-learning fuzzy logic control system for muscle relaxation.

We have assessed the practicality and performance of the Vital Signs Paragraph neuromuscular blockade monitor as part of a 'self-learning' fuzzy logic control feedback system used to administer atracurium to a required depth of neuromuscular blockade. Fifteen patients undergoing surgery expected to last longer than 90 min entered the study. A Vital Signs Paragraph was used to measure the degree of neuromuscular blockade and control it such that the first twitch of the train-of-four was kept at 10% of its baseline value. The controller instructed a Graseby Medical 3400 infusion pump to administer an atracurium infusion to maintain this level of blockade. Five patients (33%) were withdrawn from the study due to inadequate piezo-electric sensor function. In the remaining 10 patients, the system achieved stable control of neuromuscular blockade with a mean (range) error for the first twitch of the train-of-four of -0.45 (-1.06 to 0.13)%. The mean atracurium infusion rate ranged from 0.13 to 0.67 mg.kg-1.h-1. These results compare reasonably well with previous results using the Datex Relaxograph, whilst the system itself was portable and easy to use. However, the reliability of the system was limited due to variability in the sensitivity of piezoelectric sensors.

Adult↗

PubMed2005

Prediction of morbidity after lung resection in patients with lung cancer using fuzzy logic.

BACKGROUND: Preoperative evaluation of patients with potentially resectable non-small cell lung cancer aims to estimate the risk of planned surgery. Evidence of several factors that identify patients at risk for complications from thoracotomy is controversial. The aim of this study was to introduce and implement in medical practice a fuzzy system used in risk assessment of pulmonary resection for lung cancer. METHODS: Ninety-one consecutive patients who underwent pulmonary resection for lung cancer were investigated. The overall complication rate was 39.6 % (a total of 63 complications were seen in 36 patients). A fuzzy logic model was created with 9 input (presence of chest pain, weight loss, clinical T stage of the tumor, FEV 1, serum protein, preoperative arterial partial oxygen pressure and cigarette smoking, erythrocyte sedimentation rate and peripheral blood leukocyte count) and two output classes (high-risk and low-risk groups). The fuzzy classifier's performance was tested. RESULTS: The model was able to predict correctly the occurrence of complications in 22 out of 29 patients in the high-risk group with a sensitivity of 76 %, while 9 out of the 52 patients from the low-risk group developed complications (17 %). CONCLUSION: The fuzzy classification system provides an accurate tool to predict complications of resections in patients with non-small cell lung cancer.

Carcinoma, Non-Small-Cell Lung↗

PubMed1976

Medication, logic, and schizophernic thinking: a reply to Marini.

This article attempts to answer Marini's critique of my paper and to clarify the issue of medication in the study of the role of logic in the production of schizophrenic thought. It is argued that clinical observations do not lead one to believe that either the form or the content of schizophrenic thought disorder changes in any fundamental way as a result of medication. Consequently, the fact that most of the schizophrenic Ss were medicated at the time of the original research does not negate the conclusion that the thinking pathology found in schizophrenics cannot be accounted for by positing a basic defect in their deductive reasoning process.

Antipsychotic Agents↗

PubMed1980

The relationship between spatial and logical functioning in the child.

A standard multiple classification problem (simple intersection) was modified so that measurement ability, as well as the ability to attend to two dimensions at once, was required for its solution. This was administered to 20 boys and girls at each of three age levels in conjunction with a Piagetian landscape test of spatial functioning to determine the degree of relationship between logical and sublogical operations by defining their common cognitive components. A significant intertask relationship was expected, since both apparently require the same cognitive abilities. Performance on both tasks improved significantly with age, and the relationship between them was significant. The sequence and pattern of development of the individual cognitive skills required to solve the tasks were discussed.

Child↗

PubMedDate not supplied

A fuzzy logic based apnoea monitor for SIDS risk infants.

A unit has been designed which monitors newborn infants at risk of Sudden Infant Death Syndrome (SIDS) in a home environment. The unit monitors respiration, electrocardiogram (ECG) and haemoglobin oxygen saturation (SpO2) in combination, in order to detect any potentially life threatening event at an early stage. Provision is made for the generation of both audible and silent alarms and for the storage of signals and other information before, during and after an alarm episode for diagnostic purposes. An intelligent fuzzy logic algorithm is used to process the signals monitored and to implement several propositions concerning their status in order to determine the probability of an apnoea event and initiate the appropriate action. This has substantially reduced the number of false alarms and of undetected dangerous situations compared with previous units, which greatly improves the reliability and usefulness of such a monitor.

Algorithms↗

PubMed2006

Process improvement and energy saving in a full scale wastewater treatment plant: air supply regulation by a fuzzy logic system.

Achieving good performance in air supply control is an important goal in the management of wastewater treatment plants, whose highly nonlinear behaviour makes the application of conventional control techniques problematic. This paper presents the development and experimentation of a fuzzy logic system for air supply regulation in a full scale municipal wastewater treatment plant. The system is composed of two main modules, one devoted to continuously adjusting the DO set point on the basis of the current effluent NH4(+)-N concentration (on-line measurement), and the other devoted to achieve the DO set point by controlling air supply devices. The experiment was carried out on the plant for about one year, leading to significant advantages in terms of both process stability and energy saving.

Air Movements↗

PubMed1995

Bias in conditional inference: implications for mental models and mental logic.

Three experiments are reported in which subjects are given the opportunity to make any of the four inferences associated with conditional statements: modus ponens (MP), denial of the antecedent (DA), affirmation of the consequent (AC), and modus tollens (MT). The primary purpose of the research was to establish the generality and robustness of polarity biases that may be occasioned by systematic rotation of negative components in the conditional rules. In Experiments 1 & 2, three forms of conditionals were used: "if (not) p then (not) q", "(not) p only if (not) q" and "(not) q if (not) p". Experiment 1 used a conclusion evaluation task, whereas Experiment 2 used a conclusion production task. In Experiment 3, thematic conditionals were presented with and without a preceding scenario. The biases investigated were (a) affirmative premise bias--the tendency to draw more inferences with negative conclusions. The suggestive evidence for affirmative premise bias in the literature was not supported: very little evidence was found for it in the current experiments. Robust findings of negative conclusion bias were, however, found across the three experiments, although the bias was mostly restricted to DA and MT inferences. This suggests that the bias is best regarded as a difficulty with double negation. The results are discussed with respect to both the mental logic and mental model accounts of propositional reasoning. Neither theory as currently formulated can explain all of our findings, although a plausible revision of each is considered.

Adult↗

PubMed2001

Logic and ethics in radiation protection.

The International Commission on Radiological Protection (ICRP) continues to accept the assumption of a linear non-threshold dose-response relationship (LNT) as the most likely one. In that case, basic logic as well as widely accepted ethics require that the full collective dose be used for detriment assessments and in procedures for optimisation of radiation protection. This means that even the smallest doses must be taken into account in the assessment of the global collective dose if they contribute significantly together. However, in calculating collective doses over time, some reasonable restriction of the integration period has to be employed, mainly because of the uncertainties involved in the assessment of future detriment. There are also uncertainties in the LNT assumption, but the precautionary principle would not permit that this is taken as an excuse for neglecting small doses.

Cadaver↗

PubMed1987

Expert systems: frames, rules or logic for species identification?

The role of expert systems in species identification, with particular reference to the problems posed by damaged specimens and inexperienced taxonomists, is discussed. Of the three main types of expert systems available, the frame-based system is shown to provide the most appropriate model for a taxonomic expert system rather than a logic- or rule-based system. The advantages of an expert system over other computer-aided methods of identification are considered. A rule-based system requires the original knowledge (species descriptions) to be structured into rules, whereas a frame-based system can store the generic and specific descriptions in a series of frames. The frames fall into a hierarchy which closely resembles the taxonomic hierarchy, and down which information can be inherited. Two aspects of frame-based systems considered are the use of probabilities in identification, and the optimum structure of the knowledge base. The conventional use of probabilities is to provide an indication of the correctness of the result. However, in some studies involving the identification of many specimens, the speed of identification may be increased (with a reduction in accuracy) if identifications are made to a predetermined probability level. Although frames allow accurate representation of the taxonomic hierarchy, a semantic net, incorporating structures of the organism and/or details of the habitat may result in a more efficient expert system.

Animals↗

PubMed1997

Self-learning fuzzy logic control of neuromuscular block.

We have assessed the performance of a "self-learning" fuzzy logic controller to administer atracurium to a required depth of neuromuscular block. We studied 20 ASA I and II patients undergoing surgery anticipated to last longer than 90 min. A Datex Relaxograph was used to measure the degree of neuromuscular block, and control to a T1 twitch height set point of 10% of baseline neuromuscular function was selected. The controller commenced with a blank rule-base and instructed a Graseby 3400 infusion pump to administer an atracurium infusion to maintain this level of block. The system achieved stable control of neuromuscular block with a mean T1 error of -0.52% (SD 0.55%) accommodating a range in mean atracurium infusion rate of 0.25-0.44 mg kg-1 h-1. These results compare favourably with the more computationally intensive and unwieldy adaptive control strategies for atracurium infusion used previously. There was less variation in infusion rates than in our previously studied fixed rules fuzzy controller.

Adult↗

PubMed1999

Fuzzy logic and measles vaccination: designing a control strategy.

BACKGROUND: The State of São Paulo, the most populous in Brazil, was virtually free of measles from 1987 until the end of 1996 when the number of cases started to rise. It reached alarming numbers in the middle of 1997 and local health authorities decided to implement a mass vaccination campaign. METHODS: Fuzzy Decision Making techniques are applied to the design of the vaccination campaign. RESULTS: The mass vaccination strategy chosen changed the natural course of the epidemic. It had a significant impact on the epidemic in the metropolitan area of São Paulo city, but a second epidemic in the State's interior forced the public health authorities to implement a second mass vaccination campaign 2 months after the first. CONCLUSIONS: Fuzzy Logic techniques are a powerful tool for the design of control strategies against epidemics of infectious diseases.

Brazil↗

PubMed1996

The use of fuzzy logic in nutrition.

Fuzzy logic is a mathematical approach to deal with systems that can not be defined precisely. Nutrient requirements fall into this category. Dietary intakes of nutrients are such that if a nutrient is given in graded amounts, with all other nutrients constant, there is no definitive border where, for example, one intake is deficient and another, slightly higher intake, adequate. Thus, fuzzy sets were developed that describe the range of intakes of a nutrient, ranging from deficiency to excess. On the basis of these fuzzy sets and the known nutrient composition of the food, an index is derived that reflects how closely the diet of an individual meets all the nutrient requirements set by the German Society of Nutrition. Because this is a computer-based system, alterations in the diet are suggested if the diet does not meet requirements. The suggested dietary alterations are usually small but nevertheless allow the diet to meet recommendations. It is important that the suggested alterations be small because the fewer the suggested changes in a diet, the greater the change a person will accept the changes. Thus nutrient intake can be described and evaluated by using fuzzy decision making. This has present applicability in nutrition education and could possibly be used as a tool in determining recommended dietary allowances.

Fuzzy Logic↗

PubMed1999

Automatic detection of left ventricular contours from cardiac cine magnetic resonance imaging using fuzzy logic.

RATIONALE AND OBJECTIVES: Gated cardiac cine magnetic resonance imaging provides accurate dynamic data of the left ventricular function. However, the manual extraction of important physiologic parameters such as myocardium wall thickness and left ventricular volumes is invariably time consuming and subjective. To reduce the variability and time constraints inherent in observer contour tracing, the authors developed an automatic left ventricle contour-detection method. METHODS: The purpose was to apply fuzzy logic-based automatic contour detection to identification of endocardial and epicardial borders in short-axis magnetic resonance images. The automatic contouring was compared with manual tracing using the calculated ejection fraction as the comparison criterion. RESULTS: A good correlation was found between the two approaches (r2 = 0.98). CONCLUSIONS: The ejection fraction can be obtained using this automatic contouring method.

Adult↗

PubMed1980

Optimal and logical quality: two neglected aspects of the quality of health services.

Many current quality assurance programs aim at maximizing the quality of health services instead of optimizing it, because they rest on the erroneous "best to all" approach, which overemphasizes the scientific and technical aspects of quality. The result is prohibitively expensive "Cadillac care." It is suggested that the optimal qualitative level can be identified by answering a chain of hierarchical questions beginning with the relevance of medical care to the solution of the problem at hand and ending with such detailed questions as what diagnostic procedures should be performed by whom, and with what technique. Using the functional definition of quality applied in industrial quality control, a mathematical model is developed to illustrate the relative nature of the concept of quality and its implications for quality assurance programs. Special attention is paid to logical quality, i.e., the efficacy with which information is used in arriving at decisions.

Decision Making↗