Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LOGIC”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1997

Automation of matrix-assisted laser desorption/ionization mass spectrometry using fuzzy logic feedback control.

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is a sensitive and versatile method for biomolecular analysis which has potential for high-throughput screening in many applications. To obtain mass spectra of optimal quality, however, laser fluence is continuously adjusted during data acquisition to be close to the threshold level of ion production, requiring a skilled operator and several minutes of acquisition time per sample. Using real-time fuzzy logic control of the laser fluence, we here demonstrate that the acquisition of MALDI spectra can be automated without reduction of data quality. The control algorithm evaluates signal intensity and mass resolution of the base peak. It then regulates the laser fluence to keep the ion signal intensity within the dynamic range of the data acquisition hardware while maintaining high mass resolution. This fuzzy logic control system allows unattended data acquisition using either static ion extraction or delayed ion extraction MALDI. Even for difficult samples such as femtomole-level peptide mixtures, no significant reduction in data quality is observed, as compared to manually obtained spectra. Automated analysis of 78 chromatographic fractions with high mass accuracy demonstrates the utility of the method. The control algorithm has been combined with other software modules to completely automate database identification of proteins by their peptide mass maps. The success of fuzzy logic in MALDI automation suggests wider uses of this technique in mass spectrometry.

Automation↗
PubMed2004

Boolean logic functions of a synthetic peptide network.

Living cells can process rapidly and simultaneously multiple extracellular input signals through the complex networks of evolutionary selected biomolecular interactions and chemical transformations. Recent approaches to molecular computation have increasingly sought to mimic or exploit various aspects of biology. A number of studies have adapted nucleic acids and proteins to the design of molecular logic gates and computational systems, while other works have affected computation in living cells via biochemical pathway engineering. Here we report that de novo designed synthetic peptide networks can also mimic some of the basic logic functions of the more complex biological networks. We show that segments of a small network whose graph structure is composed of five nodes and 15 directed edges can express OR, NOR, and NOTIF logic.

Amino Acid Sequence↗
PubMed1990

Personality correlates of logical and sociomoral judgment.

This study examined the relation of the California Psychological Inventory (CPI) to stages of logical and sociomoral judgment. Logical judgment was measured using adaptations of the pendulum and correlations tasks of Inhelder and Piaget; moral judgment was scored using the standard Kohlberg interview. In a sample of 143 adults, logical and sociomoral judgment were correlated .30 to .50 with most of the Class I (Factor 2) CPI scales, those capturing social poise and interpersonal adequacy, and Class III (Factor 3) CPI scales, those capturing achievement potential and intellectual efficiency. The findings offer support for a cognitive interpretation of competence and ego development.

Humans↗
PubMed1995

A measurement-theoretic analysis of the fuzzy logic model of perception.

The fuzzy logic model of perception (FLMP) is analyzed from a measurement-theoretic perspective. FLMP has an impressive history of fitting factorial data, suggesting that its probabilistic form is valid. The authors raise questions about the underlying processing assumptions of FLMP. Although FLMP parameters are interpreted as fuzzy logic truth values, the authors demonstrate that for several factorial designs widely used in choice experiments, most desirable fuzzy truth value properties fail to hold under permissible rescalings, suggesting that the fuzzy logic interpretation may be unwarranted. The authors show that FLMP's choice rule is equivalent to a version of G. Rasch's (1960) item response theory model, and the nature of FLMP measurement scales is transparent when stated in this form. Statistical inference theory exists for the Rasch model and its equivalent forms. In fact, FLMP can be reparameterized as a simple 2-category logit model, thereby facilitating interpretation of its measurement scales and allowing access to commercially available software for performing statistical inference.

Attention↗
PubMed2001

Distinguishing logic from association in the solution of an invisible displacement task by children (Homo sapiens) and dogs (Canis familiaris): using negation of disjunction.

Prior research on the ability to solve the Piagetian invisible displacement task has focused on prerequisite representational capacity. This study examines the additional prerequisite of deduction. As in other tasks (e.g., conservation and transitivity), it is difficult to distinguish between behavior that reflects logical inference from behavior that reflects associative generalization. Using the role of negation in logic whereby negative feedback about one belief increases the certainty of another (e.g., a disjunctive syllogism), task-naive dogs (Canis familiaris; n=19) and 4- to 6-year-old children (Homo sapiens; n=24) were given a task wherein a desirable object was shown to have disappeared from a container after it had passed behind 3 separate screens. As predicted, children (as per logic of negated disjunction) tended to increase their speed of checking the 3rd screen after failing to find the object behind the first 2 screens, whereas dogs (as per associative extinction) tended to significantly decrease their speed of checking the 3rd screen after failing to find the object behind the first 2 screens.

Animals↗
PubMed2001

A molecular logic gate.

We propose a scheme for molecule-based information processing by combining well-studied spectroscopic techniques and recent results from chemical dynamics. Specifically it is discussed how optical transitions in single molecules can be used to rapidly perform classical (Boolean) logical operations. In the proposed way, a restricted number of states in a single molecule can act as a logical gate equivalent to at least two switches. It is argued that the four-level scheme can also be used to produce gain, because it allows an inversion, and not only a switching ability. The proposed scheme is quantum mechanical in that it takes advantage of the discrete nature of the energy levels but, we here discuss the temporal evolution, with the use of the populations only. On a longer time range we suggest that the same scheme could be extended to perform quantum logic, and a tentative suggestion, based on an available experiment, is discussed. We believe that the pumping can provide a partial proof of principle, although this and similar experiments were not interpreted thus far in our terms.

Absorption↗
PubMedDate not supplied

A PI-fuzzy logic controller for the regulation of blood glucose level in diabetic patients.

This manuscript investigates different fuzzy logic controllers for the regulation of blood glucose level in diabetic patients. While fuzzy logic control is still intuitive and at a very early stage, it has already been implemented in many industrial plants and reported results are very promising. A fuzzy logic control (FLC) scheme was recently proposed for maintaining blood glucose level in diabetics within acceptable limits, and was shown to be more effective with better transient characteristics than conventional techniques. In fact, FLC is based on human expertise and on desired output characteristics, and hence does not require precise mathematical models. This observation makes fuzzy rule-based technique very suitable for biomedical systems where models are, in general, either very complicated or over-simplistic. Another attractive feature of fuzzy techniques is their insensitivity to system parameter variations, as numerical values of physiological parameters are often not precise and usually vary from patient to another. PI and PID controllers are very popular and are efficiently used in many industrial plants. Fuzzy PI and PID controllers behave in a similar fashion to those classical controllers with the obvious advantage that the controller parameters are time dependant on the range of the control variables and consequently, result in a better performance. In this manuscript, a fuzzy PI controller is designed using a simplified design scheme and then subjected to simulations of the two common diabetes disturbances--sudden glucose meal and system parameter variations. The performance of the proposed fuzzy PI controller is compared to that of the conventional PID and optimal techniques and is shown to be superior. Moreover, the proposed fuzzy PI controller is shown to be more effective than the previously proposed FLC, especially with respect to the overshoot and settling time.

Algorithms↗
PubMed2005

Energy saving in a wastewater treatment process: an application of fuzzy logic control.

Many uncertain factors affect the operation of Wastewater Treatment Plants. Due to the complexity of biological wastewater treatment processes, classical methods show significant difficulties when trying to control them automatically. Consequently soft computing techniques and, specifically, fuzzy logic appears to be a good candidate for controlling these ill-defined, time-varying and non-linear systems. This paper describes the development and implementation of a Fuzzy Logic Controller to regulate the aeration in the Taradell Wastewater Treatment Plant. The main goal of this control process is to save energy without decreasing the quality of the effluent discharged. The fuzzy controller integrates the information coming from two different signals: the Dissolved Oxygen and Oxidation-Reduction Potential values. The simulation results proved that fuzzy logic is a good tool for controlling the aeration of the wastewater treatment plant. The results obtained show that energy savings of more than 10% can be achieved using aeration fuzzy control and at the same time still keeping the good removal levels.

Conservation of Energy Resources↗
PubMed1996

Fuzzy logic control of mechanical ventilation during anaesthesia.

We have examined a new approach, using fuzzy logic, to the closed-loop feedback control of mechanical ventilation during general anaesthesia. This control system automatically adjusts ventilatory frequency (f) and tidal volume (VT) in order to achieve and maintain the end-tidal carbon dioxide fraction (FE'CO2) at a desired level (set-point). The controller attempts to minimize the deviation of both f and VT per kg body weight from 10 bpm and 10 ml kg-1, respectively, and to maintain the plateau airway pressure within suitable limits. In 30 patients, undergoing various surgical procedures, the fuzzy control mode was compared with human ventilation control. For a set-point of FE'CO2 = 4.5 vol% and during measurement periods of 20 min, accuracy, stability and breathing pattern did not differ significantly between fuzzy logic and manual ventilation control. After step-changes in the set-point of FE'CO2 from 4.5 to 5.5 vol% and vice versa, overshoot and rise time did not differ significantly between the two control modes. We conclude that to achieve and maintain a desired FE'CO2 during routine anaesthesia, fuzzy logic feedback control of mechanical ventilation is a reliable and safe mode of control.

Adolescent↗
PubMed2002

Excessive recruitment of neural systems subserving logical reasoning in schizophrenia.

Schizophrenic patients generally perform poorly on tasks that address executive functions. According to several imaging studies, the dorsolateral prefrontal cortex is hypoactive in schizophrenic patients during these tasks. It is not, however, clear whether this finding is associated more with impaired performance than with the illness itself, as performance has not been taken into account. We examined brain activity associated with executive function in schizophrenia using an experimental fMRI design that reveals performance effects, enabling correction for performance differences between groups. As this approach has not been reported before, and because brain function can be affected by medication, the effect of antipsychotic medication was also investigated. A task was used that requires logical reasoning, alongside a closely matched control task. Performance was accounted for by including individual responses in fMRI image analyses, as well as in group-wise analysis. Effects of medication were addressed by comparing medication-naïve patients and patients on atypical antipsychotic medication with healthy controls in two separate experiments. Imaging data were analysed with a novel, performance-driven method, but also with a method that is similar to that used in earlier studies, which reported hypofrontality. A modest reduction in performance was found in both patient groups. Brain activity associated with logical reasoning was correlated positively with performance in all groups. In patients on medication, activity did not differ from that in controls after correcting for difference in performance. In contrast, performance-corrected activity was significantly elevated in medication-naïve patients. This study indicates that schizophrenia may be associated with excessive recruitment of brain systems during logical reasoning. Considering the fact that performance was reduced in the patients, we argue that the efficiency of neural communication may be affected by the illness. It appears that in patients on atypical antipsychotic medication, this neural inefficiency is normalized. The study shows that performance is an important factor in the interpretation of differences between schizophrenic patients and controls. The reported association between performance and brain activity is relevant to clinical imaging studies in general.

Adult↗
PubMed1998

Neuromagnetic activity in the human left cerebral hemisphere concerning logical processing during auditory oddball stimulation.

The aim of this study was to examine the cortex during the logical processing of auditory information using a whole-cortex type dc-SQUID gradiometer. The task modified the normal auditory oddball paradigm to require the processing of simple logic before counting a rare stimulus mentally. Although the latency of P300 m did not change, a dipolar magnetic field pattern was observed over the left cerebral hemisphere at approximately 280 ms poststimulus before forming the field pattern of P300 m. The equivalent current dipole source was estimated to be medial to the N100 m source. It was suggested that the additional load of logic processing may activate Heschl's gyri in the left hemisphere.

Acoustic Stimulation↗
PubMed2002

Automatic determination of aortic compliance with cine-magnetic resonance imaging: an application of fuzzy logic theory.

RATIONALE AND OBJECTIVES: Aortic compliance is defined as the relative change in aortic cross-sectional area divided by the change in arterial pressure. Magnetic resonance imaging (MRI) is a useful imaging modality for the noninvasive evaluation of aortic compliance. However, manual tracing of the aortic contour is subject to important interobserver variations. To estimate the aortic compliance from cine-MRI, a method based on fuzzy logic theory was elaborated. MATERIALS AND METHODS: Seven healthy volunteers and eight patients with Marfan syndrome were examined using an ECG gated cine-MRI sequence. The aorta was imaged in the transverse plane at the level of the pulmonary trunk. A method based on fuzzy logic was developed to automatically detect the aortic contour. RESULTS: Through our robust automatic contouring method, the calculation of aortic cross-sectional areas allows an estimation of the aortic compliance. CONCLUSION: The aortic compliance can be obtained from a fuzzy logic based automatic contouring method, thereby avoiding the important interobserver variation often associated with manual tracing.

Adolescent↗
PubMed2006

Comparison of the applicability of rule-based and self-organizing fuzzy logic controllers for sedation control of intracranial pressure pattern in a neurosurgical intensive care unit.

This paper assesses the controller performance of a self-organizing fuzzy logic controller (SOFLC) in comparison with a routine clinical rule-base controller (RBC) for sedation control of intracranial pressure (ICP) pattern. Eleven patients with severe head injury undergoing different neurosurgeries in a neurosurgical intensive care unit (NICU) were divided into two groups. In all cases the sedation control periods lasted 1 h and assessments of propofol infusion rates were made at a frequency of once per 30 s. In the control group of 10 cases selected from 5 patients, a RBC was used, and in the experimental group of 10 cases selected from 6 patients, a self-organizing fuzzy logic controller was used. A SOFLC was derived from a fuzzy logic controller and allowed to generate new rules via self-learning beyond the initial fuzzy rule-base obtained from experts (i.e., neurosurgeons). The performance of the controllers was analyzed using the ICP pattern of sedation for 1 h of control. The results show that a SOFLC can provide a more stable ICP pattern by administering more propofol and changing the rate of delivery more often when rule-base modifications have been considered.

Algorithms↗
PubMed2006

A sound and complete fuzzy temporal constraint logic.

In this work, we define an extended fuzzy temporal constraint logic (EFTCL) based on possibilistic logic. EFTCL allows us to handle fuzzy temporal constraints between temporal variables and, therefore, enables us to express interrelated events through fuzzy temporal constraints. EFTCL is compatible with a theoretical temporal reasoning model: the fuzzy temporal constraint networks (FTCN). The syntax, the semantics and the deduction and refutation theorems for EFTCL are similar to those defined for the sound and noncomplete fuzzy temporal constraint logic (FTCL). In this paper, a resolution principle for performing inferences which take these constraints into account is proposed for EFTCL. Moreover, we prove the soundness and the completeness of the refutation by resolution in EFTCL.

Algorithms↗
PubMed1986

Children's reasoning about social, physical, and logical regularities: a look at two worlds.

In 2 studies, 6-, 8-, and 10-year-old children were interviewed about 3 different types of regularities or rules: social conventions, physical laws, and logical necessities. In the first study, children were asked if regularities could be changed (by consensus) and/or be different in another world. In the second study, children were asked if regularities could be different in another country (on Earth) or on a different planet. Results showed that social regularities were distinguished from the other types, but physical and logical regularities were treated similarly. While the evidence for age differences was equivocal, it was clear that even first graders did not judge physical items as alterable on Earth. This fails to replicate a previously reported finding that children pass through a stage where all items are seen as alterable. Finally, a sex difference emerged, with boys more willing to judge physical and logical regularities to be alterable in another world.

Child↗
PubMed1992

Mixed microprocessor-random logic approach for innovative pacing systems.

Modern pacing systems are becoming more and more sophisticated. Conversion of the information supplied by a sensor into suitable parameters for a rate controlling algorithm and the management of complex timing are common tasks for an integrated circuit (IC) in cardiac pacing. An effective solution consists of using a microprocessor to implement algorithms and pacing modes in a flexible way. The key point of using the same hardware resources for different tasks on a time sharing basis allows the design of a less complex IC when compared to a random logic structure with the same performances. The major design problems in a full microprocessor solution are its relatively low operating speed due to the low frequency clock necessary for low current drain, and the sequential structure of the machine itself. This can lead to unacceptable timing inaccuracy in all situations requiring the management of complex decision trees. In order to take full benefit from the advantages of a microprocessor structure without these drawbacks, a mixed microprocessor-random logic approach has been investigated. This architecture uses a microprocessor core to perform all high level nonreal-time operations (setup of the pacing cycle, data reduction and processing, data integrity checks) while a set of random logic peripherals is used for all critical timing aspects.

Algorithms↗
PubMed1999

Self-tuning fuzzy logic control for ultrasound hyperthermia with reference temperature based on objective functions.

The purpose of this paper is to develop and evaluate a self-tuning fuzzy logic controller for a scanned focused ultrasound hyperthermia system with the reference temperature (Tr) determined from objective functions. This work employs simulation programs to develop the power deposition for the scanned focused ultrasound system and to solve the responses of temperature profiles based on the transient bioheat transfer equation. A fuzzy logic control algorithm is employed to determine the output power level for the heating system and an observer for blood perfusion variation is used to enhance the capability of the controller to adjust the required output power level for the treatment due to the drastic change of the blood perfusion. The reference temperature (Tr) for the controller is based on objective functions to tune its value during the heating process, while a control temperature (Tc) from the thermosensors located in the tumor region is used as the input for the controller. The objective function based on the entire temperature profile is used to evaluate the appropriateness of the heating temperature distribution for a time-variational blood perfusion. Simulation results demonstrate that the tumor region can be rapidly heated to the desired temperature level and maintained at that level despite blood perfusion variation. The resulting temperature profile, the objective function, and the output power level are related to the magnitude of blood perfusion, but are almost independent of the Tc location and the initial setting value of Tr. The fuzzy logic control algorithm with Tr determined from objective functions can be used for controlling the entire temperature distribution through a single control temperature, and the combination of control and optimization allows appropriate temperature fields to be created during the entire heating process. The control algorithm does not require the accurate prior knowledge of the locations of the thermosensors and the appropriate setting value for Tr.

Fuzzy Logic↗
PubMed2004

The Body Logic Program for Adolescents: a treatment manual for the prevention of eating disorders.

The Body Logic Program for Adolescents was developed as a two-stage intervention to prevent the development of eating disorder symptoms. Preliminary results indicate that this program shows promise as an effective prevention effort. The current article provides a detailed description of the protocol for implementing Body Logic Part I, a school-based intervention. A brief review of Body Logic Part II, an intensive family-based intervention for high-risk students, is also provided. Examples of exercises are introduced and goals for practitioners are discussed. The authors hope that by providing this in-depth description of the protocol, researchers and clinicians can use this program in future prevention efforts.

Adolescent↗