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 577 records · Page 32Linked to original sources
PubMed1997

How Do Logical Inference Rules Help Construct Social Mental Models?

Starting from recent approaches in mental model research, it is argued that (1) logical inference rules are used in order to construct mental cliques from learned sentiment relations, and (2) social context cues (operationalized as primes) play a crucial role in activating such rules. Transitivity and antitransitivity are taken as examples, and are shown as core constituents of such models. In a first experiment, priming was achieved by announcing the sorting of fictitious persons in either two or three cliques. Thirty-one subjects studied eight sets of sentiment relations among these persons that either did or did not satisfy their primed clique expectations. They showed longer study times and more requests for additional information in the case of inconsistent fits between prime and set. Their sorting solutions also showed clear priming effects. A second experiment (n = 30) showed that when undergoing a recognition test after seeing the relation sets, subjects tended to confuse model-consistent distractors with information they had actually seen. In a third experiment (n = 30) the results from Experiment 1 were replicated using more realistic learning materials.

Journal Article↗
PubMed2001

Logical Self-Reference as a Model for Conscious Experience.

The structure of autoreferential statements that describe (or serve as a logical model for) the human conscious experience is analyzed. Autoreferential statements are introduced by autoreferential definitions, such as a=F(a, x), where F is a Boolean function and x is some atomic statement describing the content of the experience, or by analogous systems of inter-related definitions, such as a=F(b, x, y) and b=G(a, x, z). It is argued that only "noncreative" (systems of) definitions introduce statements that describe conscious experience, the noncreativeness meaning that no statement with non-tautological content can be derived from these definitions. The structure of such (systems of) definitions is comprehensively characterized in a series of theorems. A potential of the model in addressing empirical data is illustrated by applying it to the choice between two alternatives in the absence of a preference criterion. Copyright 2001 Academic Press.

Journal Article↗
PubMed2001

A logical analysis of the Drosophila gap-gene system.

This manuscript focuses on the formal analysis of the gap-gene network involved in Drosophila segmentation. The gap genes are expressed in defined domains along the anterior-posterior axis of the embryo, as a response to asymmetric maternal information in the oocyte. Though many of the individual interactions among maternal and gap genes are reasonably well understood, we still lack a thorough understanding of the dynamic behavior of the system as a whole. Based on a generalized logical formalization, the present analysis leads to the delineation of: (1) the minimal number of distinct, qualitative, functional levels associated with each of the key regulatory factors (the three maternal Bcd, Hb and Cad products, and the four gap Gt, Hb, Kr and Kni products); (2) the most crucial interactions and regulatory circuits of the earliest stages of the segmentation process; (3) the ordering of different regulatory interactions governed by each of these products according to corresponding concentration scales; and (4) the role of gap-gene cross-interactions in the transformation of graded maternal information into discrete gap-gene expression domains. The proposed model allows not only the qualitative reproduction of the patterns of gene expression characterized experimentally, but also the simulation and prediction of single and multiple mutant phenotypes.

Animals↗
PubMed1995

A ternary logic model for recurrent neuromime networks with delay.

In contrast to popular recurrent artificial neural network (RANN) models, biological neural networks have unsymmetric structures and incorporate significant delays as a result of axonal propagation. Consequently, biologically inspired neural network models are more accurately described by nonlinear differential-delay equations rather than nonlinear ordinary differential equations (ODEs), and the standard techniques for studying the dynamics of RANNs are wholly inadequate for these models. This paper develops a ternary-logic based method for analyzing these networks. Key to the technique is the realization that a nonzero delay produces a bounded stability region. This result significantly simplifies the construction of sufficient conditions for characterizing the network equilibria. If the network gain is large enough, each equilibrium can be classified as either asymptotically stable or unstable. To illustrate the analysis technique, the swim central pattern generator (CPG) of the sea slug Tritonia diomedea is examined. For wide range of reasonable parameter values, the ternary analysis shows that none of the network equilibria are stable, and thus the network must oscillate. The results show that complex synaptic dynamics are not necessary for pattern generation.

Animals↗
PubMedDate not supplied

Tumescent and syringe liposculpture: a logical partnership.

Liposuction has been traditionally performed under general anesthesia. Standard instrumentation for the procedure has included blunt-tipped suction cannulae connected to an electric vacuum pump by noncollapsible tubing. A subcutaneous injection of Lidocaine with Epinephrine is routinely employed to minimize blood loss during the procedure. This infiltration has been described as the "wet technique," but it is not a method to supplant general anesthesia. The tumescent technique, a method of infusing very large volumes of dilute lidocaine with epinephrine solutions, has been advocated as a satisfactory means for providing conscious anesthesia for liposuction procedures, avoiding the need for general anesthesia. The syringe technique employs blunt-tipped suction cannulae connected to a syringe. Drawing back the syringe plunger generates the negative pressures needed to remove fat during liposuction and replaces the electric vacuum pump and connecting tubing traditionally used for this procedure. This study evaluates the combined tumescent and syringe techniques for liposuction. One hundred consecutive patients were treated with the tumescent technique as the sole means of anesthesia and the syringe technique as the sole means of performing liposuction. A modified tumescent formula is presented. A comparison of liposuction aspirates using this modified tumescent technique is compared and contrasted to liposuction aspirates obtained using the "dry technique" and the "wet technique." A historical review of the syringe technique and its perceived attributes is also presented. Technical descriptions of the tumescent infusion method, tumescent fluid formulation, and suggested patient sedation and monitoring is presented. Photographic documentation of patients who underwent the combined tumescent and syringe liposculpture treating various body areas is shown. A critical analysis of the limitations of this combined technique is also described noting added time requirements, difficulties with under-correction of deformities, and need for reoperation, methods for determining the "end-point" for the procedure, as well as addressing large-volume liposuction problems. The conclusion reached by this study is that combining the tumescent technique and the syringe technique is a logical partnership. Each method complements the other, allowing liposuction to be performed with considerable advantage over traditional methods. These advantages include eliminating the need for general anesthesia, lessening blood loss and postoperative bruising, greater accuracy, precision, and overall high patient satisfaction.

Adolescent↗
PubMed1993

The Arden syntax for medical logic modules.

The Arden Syntax for sharing medical knowledge bases is described. Its current focus is on knowledge that is represented as a set of independent modules that can provide therapeutic suggestions, alerts, diagnosis scores, etc. The syntax is based largely upon HELP and the Regenstrief Medical Record System. Each module, called a Medical Logic Module or MLM, is made of slots grouped into maintenance, library, and knowledge categories. The syntax has provisions for querying a clinical database and representing time. Several clinical information systems were analyzed and appear to be compatible with the syntax. The syntax has been tested for syntactic ambiguities using the tools lex and yacc. Seventeen institutions are currently in the process of adopting the Arden Syntax for their decision-support systems. A subcommittee of ASTM has been formed to develop standards for sharing medical knowledge bases. The Arden Syntax has been published by ASTM as a initial standard for sharing medical knowledge.

Artificial Intelligence↗
PubMed1983

A logic-tree approach to the St. Crispin Hospital fire.

Fatality or injury due to fire is an aspect of the working of an entire system. That is, casualty due to fire represents a failure of a system and ultimately, this includes the social system within which we live. As part of such a consideration, many different techniques and models may be used, and one such technique is that of logic-tree analysis.

England↗
PubMed1980

Limits of high frequency percutaneous transtracheal jet ventilation using a fluidic logic controlled ventilator.

A study was undertaken on dogs to find the limit of carbon dioxide exchange with high frequency jet ventilation using a fluidic logic controlled oxygen jet ventilator. Fifteen dogs were ventilated through a transtracheal catheter at respiratory rates up to 600 per minute. The following were recorded: aortic, pulmonary artery, pulmonary arterial wedge, and central venous blood pressures; intratracheal pressure, electrocardiogram; inspiratory and expiratory time of the jet; arterial and central venous blood gases; intermittent cardiac output. Normal gas exchange was found up to a respiratory rate of 400 per minute with low tidal volume and low intratracheal pressures. There were no adverse circulatory effects up to a rate of 400 per minute. At rates of 500 and 600 per minute, cardiac contractility was unaffected, but a decreased heart rate and increased peripheral resistance produced a fall in cardiac output. There was no interference with the resumption of spontaneous ventilation during weaning. In a control series of five dogs, apnoeic oxygenation was used. The PaCO2 was allowed to reach 15.96 kPa (120 torr). High frequency jet ventilation was then started at a rate of 600 per minute and decreased in increments to 100 per minute. Arterial blood gases were continuously recorded through an intra-arterial catheter connected to a mass spectrometer. The PaCO2 gradually declined to normal levels as the rate decreased.

Animals↗
PubMed2001

The Microbial Logic behind the Prevalence of Incomplete Oxidation of Organic Compounds by Acetogenic Bacteria in Methanogenic Environments.

Microbial degradation of organic material in methanogenic ecosystems is a multistep process in which subsequent groups use the products of the first groups of organisms in the chain as substrates. The acetogenic bacteria in these systems produce both H2 and acetate. In the present minireview a thermodynamic approach is taken to evaluate the logic behind this duality. The evaluation shows that at the H2 partial pressures that usually occur in methanogenic ecosystems the acetogenic oxidation of known acetogenic substrates such as propionate, butyrate, and benzoate yields more energy than their complete oxidation to H2/CO2. Also, H2 partial pressures needed to achieve complete hydrogenogenic oxidation of these acetogenic substrates would have to be so low that H2 would be virtually unavailable to the hydrogenotrophic bacteria, in casu the methanogens.

Journal Article↗
PubMed2004

On the logic of hypothesis testing in functional imaging.

Statistics is nowadays the customary language of functional imaging. It is common to express an experimental setting as a set of null hypotheses over complex models and to present results as maps of p-values derived from sophisticated probability distributions. However, the growing interest in the development of advanced statistical algorithms is not always paralleled by similar attention to how these techniques may regiment the ways in which users draw inferences from their data. This article investigates the logical bases of current statistical approaches in functional imaging and probes their suitability to inductive inference in neuroscience. The frequentist approach to statistical inference is reviewed with attention to its two main constituents: Fisherian "significance testing" and Neyman-Pearson "hypothesis testing". It is shown that these conceptual systems, which are similar in the univariate testing case, dissociate into two quite different methods of inference when applied to the multiple testing problem, the typical framework of functional imaging. This difference is explained with reference to specific issues, like small volume correction, which are most likely to generate confusion in the practitioner. Further insight into this problem is achieved by recasting the multiple comparison problem into a multivariate Bayesian formulation. This formulation introduces a new perspective where the inferential process is more clearly defined in two distinct steps. The first one, inductive in form, uses exploratory techniques to acquire preliminary notions on the spatial patterns and the signal and noise characteristics. The (smaller) set of likely spatial patterns generated is then tested with newer data and a more rigorous multiple hypothesis testing technique (deductive step).

Algorithms↗
PubMed2003

A fuzzy logic approach toward solving the analytic enigma of health system financing.

Improved health, equity, macroeconomic efficiency, efficient provision of care, and client satisfaction are the common goals of any health system. The relative significance of these goals varies, however, across nations, communities and with time. As for health care finance, the attainment of these goals under varying circumstances involves alternative policy options for each of the following elements: sources of finance, allocation of finance, payment to providers, and public-private mix. The intricate set of multiple goals, elements and policy options defies human reasoning, and, hence, hinders effective policymaking. Indeed, "health system finance" is not amenable to a clear set of structural relationships. Neither is there a universe that can be subject to statistical scrutiny: each health system is unique. "Fuzzy logic" models human reasoning by managing "expert knowledge" close to the way it is handled by human language. It is used here for guiding policy making by a systematic analysis of health system finance. Assuming equal welfare weights for alternative goals and mutually exclusive policy options under each health-financing element, the exploratory model we present here suggests that a German-type health system is best. Other solutions depend on the welfare weights for system goals and mixes of policy options.

Journal Article↗
PubMed2004

Encoding microbial metabolic logic: predicting biodegradation.

Prediction of microbial metabolism is important for annotating genome sequences and for understanding the fate of chemicals in the environment. A metabolic pathway prediction system (PPS) has been developed that is freely available on the world wide web (http://umbbd.ahc.umn.edu/predict/), recognizes the organic functional groups found in a compound, and predicts transformations based on metabolic rules. These rules are designed largely by examining reactions catalogued in the University of Minnesota Biocatalysis/Biodegradation Database (UM-BBD) and are generalized based on metabolic logic. The predictive accuracy of the PPS was tested: (1) using a 113-member set of compounds found in the database, (2) against a set of compounds whose metabolism was predicted by human experts, and (3) for consistency with experimental microbial growth studies. First, the system correctly predicted known metabolism for 111 of the 113 compounds containing C and H, O, N, S, P and/or halides that initiate existing pathways in the database, and also correctly predicted 410 of the 569 known pathway branches for these compounds. Second, computer predictions were compared to predictions by human experts for biodegradation of six compounds whose metabolism was not described in the literature. Third, the system predicted reactions liberating ammonia from three organonitrogen compounds, consistent with laboratory experiments showing that each compound served as the sole nitrogen source supporting microbial growth. The rule-based nature of the PPS makes it transparent, expandable, and adaptable.

Bacteria↗
PubMed1981

Hepatic resection: the logical approach to surgical management of major trauma to the liver.

Recent reports on the management of hepatic trauma have discouraged hepatic resection and supported hepatic artery ligation, "resectional debridement" and even packing. These nonresectional procedures are based on misguided principles and should never replace resection. Traditional methods of conducting hepatic resection in an emergency as used in the West probably cause delay in achieving immediate hemostasis, thus contributing to mortality. Compared with Western reports, our mortality for major hepatic resections is considerably low. This is probably due to faster resection and achievement of hemostasis by our clamping techniques. We conclude that it is quite logical to perform resection as the first line of treatment in major hepatic trauma.

Humans↗
PubMed1989

Testing between the TRACE model and the fuzzy logical model of speech perception.

The TRACE model of speech perception (McClelland & Elman, 1986) is contrasted with a fuzzy logical model of perception (FLMP) (Oden & Massaro, 1978). The central question is how the models account for the influence of multiple sources of information on perceptual judgment. Although the two models can make somewhat similar predictions, the assumptions underlying the models are fundamentally different. The TRACE model is built around the concept of interactive activation, whereas the FLMP is structured in terms of the integration of independent sources of information. The models are tested against test results of an experiment involving the independent manipulation of bottom-up and top-down sources of information. Using a signal detection framework, sensitivity and bias measures of performance can be computed. The TRACE model predicts that top-down influences from the word level influence sensitivity at the phoneme level, whereas the FLMP does not. The empirical results of a study involving the influence of phonological context and segmental information on the perceptual recognition of a speech segment are best described without any assumed changes in sensitivity. To date, not only is a mechanism of interactive activation not necessary to describe speech perception, it is shown to be wrong when instantiated in the TRACE model.

Adult↗
PubMed1985

Further comments on the logic of the application of uncoupler- inhibitor titrations for the elucidation of the mechanisms of energy coupling.

Following the appearance of two papers in this journal commenting on the logic of the application of uncoupler-inhibitor titrations as a means of discriminating between 'delocalized' and 'localized' chemiosmotic mechanisms [(1984) FEBS Lett. 176,79-82; (1985) FEBS Lett. 186, 8-10], and in contrast with the arguments presented there and elsewhere, we show that in a linear model the increase in delta mu H which accompanies partial inhibition of the ATPases always leads to a relatively higher decrease of the rate of ATP synthesis by a given concentration of uncoupler in the presence of an ATPase inhibitor than in its absence. This is due to the fact that the same titre of uncoupler leads to a higher dissipative H+ flow in the presence of inhibitor, since the driving force delta mu H is higher.

Adenosine Triphosphatases↗
PubMed1978

Logic-based program system for predicting drug interactions.

This paper deals with the application of an AI language, based on mechanical theorem prover (PROLOG), to deduce drug interactions. One hundred and thirty-one drug interactions were predicted by logical deduction with a program system comprising about 52 drugs in practice and 32 independent possibilities of deduction. The database of the system contains the chemical and pharmaceutical characteristics of the active components of the drug preparations, and the deductions are based on general pharmacokinetic, pharmacodynamic or other biochemical relationships concerning interactions.

Computers↗
PubMed1992

Application of fuzzy logic to the Apgar scoring system.

Apgar fuzzy expert system (AFES) applied fuzzy logic to the Apgar Scoring System (APG). We prepared the AFESs for both an inexperienced obstetrician (resident A) and an experienced obstetrician (specialist B) separately. We then compared their evaluations of the same 80 neonates at 1 min after birth using both the AFES and the APG. Analysis of the relationship of the general evaluation by the APG (scores below 6 or over 7) and the AFES (bad or good) to the umbilical arterial blood gases (pH below or above 7.20) showed that the sensitivities were 0.36 for the APG evaluation by resident A, 0.50 for the APG evaluation by specialist B, 0.60 for the AFES rating by resident A, and 0.71 for the AFES rating by specialist B. The specificities were 0.94, 0.95, 0.97 and 0.97, respectively. These results demonstrated that the AFES was capable of reflecting the recognition of the examiner.

Apgar Score↗