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 289 records · Page 16Linked to original sources
PubMed1998

Segmentation of intrathoracic airway trees: a fuzzy logic approach.

Three-dimensional (3-D) analysis of airway trees extracted from computed tomography (CT) image data can provide objective information about lung structure and function. However, manual analysis of 3-D lung CT images is tedious, time consuming and, thus, impractical for routine clinical care. We have previously reported an automated rule-based method for extraction of airway trees from 3-D CT images using a priori knowledge about airway-tree anatomy. Although the method's sensitivity was quite good, its specificity suffered from a large number of falsely detected airways. We present a new approach to airway-tree detection based on fuzzy logic that increases the method's specificity without compromising its sensitivity. The method was validated in 32 CT image slices randomly selected from five volumetric canine electron-beam CT data sets. The fuzzy-logic method significantly outperformed the previously reported rule-based method (p < 0.002).

Animals↗
PubMed2004

Analysing interpretation and reinterpreting analysis: exploring the logic of critical reflection.

This paper examines the distinction that is sometimes drawn between analysis and interpretation in the context of qualitative research, and the processes of critical analysis that underpin reflective practice. The authors consider the complementary logical processes involved in analysis and interpretation, and propose a cycle of reductive, inductive and hypothetico-deductive testing that is both rational and creative. The authors argue that the goal of critical reflection and qualitative data analysis is not to produce knowledge that can be justified in terms of 'correspondence' to 'reality'. Instead we propose a pragmatic, coherence view of knowledge that emphasizes the centrality of dialogue with texts, evidence, beliefs and practice. We conclude that evidence and belief are inextricably linked and that combined processes of reductive, inductive and hypothetico-deductive logic need to be used in a transparent manner to establish the credibility of an interpretation. Although there is no clear demarcation between what is found and what is constructed, a commitment to coherence is the basis of a pragmatic theory of knowledge.

Data Interpretation, Statistical↗
PubMed1980

Analysis of a paradoxical logic: a case study.

A case study of a normally functioning married couple was conducted to investigate the relation between their logic and their communication patterns. Two communication theories, the Interactional View and the Coordinated Management of Meaning, were employed in an analysis of the couple's logic and communication. A triangulated methodology, consisting of interviews, written self-reports, and role-playing, was used to elicit the couple's constitutive and regulative rules. The discovery of paradoxical rules led to several propositions concerning the circular relation between communication and socially created realities. Specifically, the analysis revealed paradoxical rules associated with restricted episodes in which the couple could not obtain their goal of eliminating conflict.

Communication↗
PubMedDate not supplied

Kinetic logic: a tool for describing the dynamics of infectious disease behavior.

Most of the infectious diseases imply biological regulations controlled by several feedback loops or circuits. Kinetic logic, which is a method easily accessible to biologists or physicians, and which takes time and thresholds of activity into account, seems a convenient method for building simplified models related to this field. This implies usually qualitative predictions concerning the dynamics of such biological systems, leading to a movement back and forth between experimentation or observation and logical description. Here, we illustrate this simple modelling method in building elementary models concerning prion infection to demonstrate how to proceed. We also discuss and summarize how this method has been used for studying several viral diseases. As an example, we show how predictions related to the rhabdovirus cycle, were experimentally verified.

Animals↗
PubMed1981

Disease concepts and the logic of classes.

Four different disease concepts are examined. In pre-scientific times, diseases were regarded as independent entities outside and inside the body of patients. This view is still alive in such expressions as "disease carrier' and similar idioms. Sydenham's disease entity was akin to a Platonic "idea'; namely as "species', "substantial form' or "essence' which had a singular independent existence in some metaphysical realm. Therefore, the talk at the time was that a patient suffered from, say, "the' pox. Virchow's disease entities were semi-independent parasitic parts in the bodies of different patients. Therefore, patients were said to suffer from, say "a' pneumonia. In modern times diseases are no longer regarded as independent or semi-independent entities. They are merely attribute complexes in patients. As such, they require no grammatical article. Patients are said to suffer from, say, pneumonia. The different views of disease concepts are finally examined within a framework provided by the modern logic of classes. The pre-scientific and Virchowian disease entities are members in a class "extension'. Sydenham's disease entity corresponds to a class entity abstracted from class members. Modern diseases are attributes listed in the class "intension'. The different disease concepts thus have different logical implications.

Disease↗
PubMed2003

Fuzzy logic guided inverse treatment planning.

A fuzzy logic technique was applied to optimize the weighting factors in the objective function of an inverse treatment planning system for intensity-modulated radiation therapy (IMRT). Based on this technique, the optimization of weighting factors is guided by the fuzzy rules while the intensity spectrum is optimized by a fast-monotonic-descent method. The resultant fuzzy logic guided inverse planning system is capable of finding the optimal combination of weighting factors for different anatomical structures involved in treatment planning. This system was tested using one simulated (but clinically relevant) case and one clinical case. The results indicate that the optimal balance between the target dose and the critical organ dose is achieved by a refined combination of weighting factors. With the help of fuzzy inference, the efficiency and effectiveness of inverse planning for IMRT are substantially improved.

Algorithms↗
PubMed2004

Use of logic relationships to decipher protein network organization.

A major focus of genome research is to decipher the networks of molecular interactions that underlie cellular function. We describe a computational approach for identifying detailed relationships between proteins on the basis of genomic data. Logic analysis of phylogenetic profiles identifies triplets of proteins whose presence or absence obey certain logic relationships. For example, protein C may be present in a genome only if proteins A and B are both present. The method reveals many previously unidentified higher order relationships. These relationships illustrate the complexities that arise in cellular networks because of branching and alternate pathways, and they also facilitate assignment of cellular functions to uncharacterized proteins.

Bacterial Physiological Phenomena↗
PubMed2006

Enzyme-free nucleic acid logic circuits.

Biological organisms perform complex information processing and control tasks using sophisticated biochemical circuits, yet the engineering of such circuits remains ineffective compared with that of electronic circuits. To systematically create complex yet reliable circuits, electrical engineers use digital logic, wherein gates and subcircuits are composed modularly and signal restoration prevents signal degradation. We report the design and experimental implementation of DNA-based digital logic circuits. We demonstrate AND, OR, and NOT gates, signal restoration, amplification, feedback, and cascading. Gate design and circuit construction is modular. The gates use single-stranded nucleic acids as inputs and outputs, and the mechanism relies exclusively on sequence recognition and strand displacement. Biological nucleic acids such as microRNAs can serve as inputs, suggesting applications in biotechnology and bioengineering.

Animals↗
PubMedDate not supplied

A logical foundation for representation of clinical data.

OBJECTIVE: A general framework for representation of clinical data that provides a declarative semantics of terms and that allows developers to define explicitly the relationships among both terms and combinations of terms. DESIGN: Use of conceptual graphs as a standard representation of logic and of an existing standardized vocabulary, the Systematized Nomenclature of Medicine (SNOMED International), for lexical elements. Concepts such as time, anatomy, and uncertainty must be modeled explicitly in a way that allows relation of these foundational concepts to surface-level clinical descriptions in a uniform manner. RESULTS: The proposed framework was used to model a simple radiology report, which included temporal references. CONCLUSION: Formal logic provides a framework for formalizing the representation of medical concepts. Actual implementations will be required to evaluate the practicality of this approach.

Computer Simulation↗
PubMed2004

Medical ethics, logic traps, and game theory: an illustrative tale of brain death.

Decision making and choices are frequent themes in medical ethics. Game theory is based upon modelled decision making. Game theory, and associated logic traps, may have relevance to the clinical practice of medicine and medical ethics. The "prisoner's dilemma" is one logic trap from game theory in which "rational" decision making on the part of participating individuals can lead to "suboptimal" situations. An example of such a situation involving brain death is presented and discussed from the perspective of the prisoner's dilemma.

Adult↗
PubMed2001

Neural networks and logical reasoning systems: a translation table.

A correspondence is established between the basic elements of logic reasoning systems (knowledge bases, rules, inference and queries) and the structure and dynamical evolution laws of neural networks. The correspondence is pictured as a translation dictionary which might allow to go back and forth between symbolic and network formulations, a desirable step in learning-oriented systems and multicomputer networks. In the framework of Horn clause logics, it is found that atomic propositions with n arguments correspond to nodes with nth order synapses, rules to synaptic intensity constraints, forward chaining to synaptic dynamics and queries either to simple node activation or to a query tensor dynamics.

Logic↗
PubMed2006

Programmable logic construction kits for hyper-real-time neuronal modeling.

Programmable logic designs are presented that achieve exact integration of leaky integrate-and-fire soma and dynamical synapse neuronal models and incorporate spike-time dependent plasticity and axonal delays. Highly accurate numerical performance has been achieved by modifying simpler forward-Euler-based circuitry requiring minimal circuit allocation, which, as we show, behaves equivalently to exact integration. These designs have been implemented and simulated at the behavioral and physical device levels, demonstrating close agreement with both numerical and analytical results. By exploiting finely grained parallelism and single clock cycle numerical iteration, these designs achieve simulation speeds at least five orders of magnitude faster than the nervous system, termed here hyper-real-time operation, when deployed on commercially available field-programmable gate array (FPGA) devices. Taken together, our designs form a programmable logic construction kit of commonly used neuronal model elements that supports the building of large and complex architectures of spiking neuron networks for real-time neuromorphic implementation, neurophysiological interfacing, or efficient parameter space investigations.

Action Potentials↗
PubMed2006

Polymetallated porphyrin ultrathin films as transducing elements for molecular devices and logic gates.

Meso-tetrapyridylporphyrins peripherally coordinated to four ruthenium complexes, such as [Ru(bpy)2Cl] and [Ru(5-ClPhen)2Cl] (bpy = 2,2'-bipyridine; Phen = 1,10-phenanthroline), provide a versatile class of molecular materials in which the complexes act as co-factors, inducing electronic effects and acting as electron-transfer relays and electron pools or sinks, depending upon their oxidation state. These cationic porphyrins can be assembled into thin films by conventional methods, or into organized layer-by-layer structures by combining with negatively charged tetrasulfonated porphyrins or phthalocyanines. Their electrocatalytic and photoelectrochemical properties have been successfully exploited in chemical sensors. Their usefulness in molecular logic gates are being demonstrated by using modified transparent conducting electrodes in miniaturized flow injection cells. In such designs, the chemical, electrochemical, and light inputs can be readily combined to perform the basic logic functions, such as AND, OR, and NOT, for molecular computing.

Computers, Molecular↗
PubMed1989

Fuzzy logical approach to perception of dot numerosity.

The present study utilized a fuzzy logical approach for understanding human perception or judgments of dot numerosity. In Exp. 1 subjects were required to view dot patterns and to judge the truthfulness of the single and combined statements which asserted that the number of dots was large. The results indicated that (a) the rules based on the minimum and maximum truthfulness of the component statements best approximate subjective conjunction and disjunction about dot numerosity, when subjects kept the operations of the standard logic system in mind. (b) When the subjects based their judgments on perceptive impression, their judgments were best fitted by the multiplicative form.

Adult↗
PubMedDate not supplied

In search of tools to aid logical thinking and communicating about medical decision making.

To have real-time impact on medical decision making, decision analysts need a wide variety of tools to aid logical thinking and communication. Decision models provide a formal framework to integrate evidence and values, but they are commonly perceived as complex and difficult to understand by those unfamiliar with the methods, especially in the context of clinical decision making. The theory of constraints, introduced by Eliyahu Goldratt in the business world, provides a set of tools for logical thinking and communication that could potentially be useful in medical decision making. The author used the concept of a conflict resolution diagram to analyze the decision to perform carotid endarterectomy prior to coronary artery bypass grafting in a patient with both symptomatic coronary and asymptomatic carotid artery disease. The method enabled clinicians to visualize and analyze the issues, identify and discuss the underlying assumptions, search for the best available evidence, and use the evidence to make a well-founded decision. The method also facilitated communication among those involved in the care of the patient. Techniques from fields other than decision analysis can potentially expand the repertoire of tools available to support medical decision making and to facilitate communication in decision consults.

Carotid Stenosis↗
PubMed2006

Toward the creation of an institutional logic for the management of hospitals: efficiency in the early nineteen hundreds.

This research focuses on the creation of an institutional logic--efficiency--and on its organizing principles of standardization and business practices through a study of the American Hospital Association and its publication, the Modern Hospital. In the early years of the 20th century, efficiency began to emerge as a first institutional logic for the management of hospitals. The term was defined broadly, encompassing not only economy but also quality and breadth of services, as well as access to care. This early emphasis on efficiency foreshadowed three issues that affect health policy and hospital management to this day: the pressure on hospitals to introduce new technology while containing cost, the assumption that hospitals should act like businesses, and the practice of offering large hospitals as the model for other providers.

American Hospital Association↗
PubMed2006

Is abstinence education theory based? The underlying logic of abstinence education programs in Texas.

Authors examined the logic (or the implicit theory) underlying 16 abstinence-only-until-marriage programs in Texas (50% of all programs funded under the federal welfare reform legislation during 2001 and 2002). Defined as a set of propositions regarding the relationship between program activities and their intended outcomes, program staff's implicit theories were summarized and compared to (a) data from studies on adolescent sexual behavior, (b) a theory-based model of youth abstinent behavior, and (c) preliminary findings from the national evaluation of Title V programs. Authors interviewed 62 program directors and instructors and employed selected principles of grounded theory to analyze interview data. Findings indicated that abstinence education staff could clearly articulate the logic guiding program activity choices. Comparisons between interview data and a theory-based model of adolescent sexual behavior revealed striking similarities. Implications of these findings for conceptualizing and evaluating abstinence-only-until-marriage (or similar) programs are examined.

Adolescent↗
PubMed1996

The logic of causation in epidemiology.

The paper attempts to model causality with logical conditionals by way of conditional probability. This provides a broad conceptualisation of causality according to which we merely observe tendencies toward sufficiency or tendencies toward necessity. Cohort studies evaluate the first tendencies, and case-control studies the latter. This conceptual approach also clarifies the logic of what unifies the two methods. Ways to measure causal tendencies are proposed. Some of the consequences of this conceptual analysis are discussed and among them, the growing role of chance instead of determinism in science and, although rarely acknowledged yet, in epidemiology.

Case-Control Studies↗