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PubMed1997

Automatic detection of cardiac contours on MR images using fuzzy logic and dynamic programming.

This paper deals with the use of fuzzy logic and dynamic programming in the detection of cardiac contours in MR Images. The definition of two parameters for each pixel allows the construction of the fuzzy set of the cardiac contour points. The first parameter takes into account the grey level, and the second the presence of an edge. A corresponding fuzzy matrix is derived from the initial image. Finally, a dynamic programming with graph searching is performed on this fuzzy matrix. The method has been tested on several MR images and the results of the contouring were validated by an expert in the domain. This preliminary work clearly demonstrates the interest of this method, although a formal evaluation has to be done.

Fuzzy Logic↗
PubMed1997

A new fuzzy logic based image enhancement.

In this paper a new fuzzifier (fh) and a new contrast intensification operator (NINT) have been proposed for the enhancement of computerized tomography (CT) images. The performance of the proposed technique has been compared with an existing fuzzy logic based enhancement technique in terms of a new fuzzy contrast measure. The superiority of the proposed technique has been established.

Fuzzy Logic↗
PubMed1998

Scalable methodologies for distributed development of logic-based convergent medical terminology.

As the size and complexity of medical terminologies increase, terminology modelers are increasingly hampered by lack of tools and methods to manage the development process. This paper presents our use and ongoing evaluation of a description-logic classifier to support cognitive scalability of the underlying terminology and our enhancements to that classifier to support concurrent development utilizing semantics-based concurrency control methods. Our enhancements, collectively referred to as the Gálapagos, consist of several applications that take locally-developed terminology enhancements from multiple sites, identify conflicting design decisions, support the modelers' reconciliation of the conflicting designs, and efficiently disseminate updates tailored for locally enhanced terminologies. We have tested our ideas through concurrent evolutionary enhancement of SNOMED International at three Kaiser Permanente regions and the Mayo Clinic. We have found that the underlying environment has met our design objectives, and supports semantic-based concurrency control, and identification and resolution of conflicting design decisions.

Artificial Intelligence↗
PubMed1998

Part-whole reasoning in medical ontologies revisited--introducing SEP triplets into classification-based description logics.

The development of powerful and comprehensive medical ontologies that support formal reasoning on a large scale is one of the key requirements for clinical computing in the next millennium. Taxonomic medical knowledge, a major portion of these ontologies, is mainly characterized by generalization and part-whole relations between concepts. While reasoning in generalization hierarchies is quite well understood, no fully conclusive mechanism as yet exists for part-whole reasoning. The approach we take emulates part-whole reasoning via classification-based reasoning using SEP triplets, a special data structure for encoding part-whole relations that is fully embedded in the formal framework of standard description logics.

Artificial Intelligence↗
PubMed2002

A logical and stepwise operative approach to radical neck dissection.

A thorough understanding of the anatomy of the neck is essential to avoid injury to vital structures when performing radical neck dissection. The complicated anatomical relations of the various nerves, vessels, and muscles within the confined area of the neck can often be daunting. We outline strategic anatomical landmarks and their relationships to important nerves, arteries, veins, and lymphatics to simplify the complicated and formidable anatomy of the neck. We also delineate key maneuvers that, when combined with the anatomical landmarks, offer a stepwise and logical approach to performing radical neck dissection that confers improved safety.

Humans↗
PubMed1999

Logical problems and misunderstandings in "Problems with dimensionless measurement models of synchrony in biological systems".

A model for the standardized measurement of synchrony in behavioral or biological states was proposed for use in comparative analyses of synchrony's adaptive significance. A recent critique attempts to discredit dimensionless (unitless) or standardized measures of synchrony in general and the proposed model in particular. Although the critique helps define and sharpen thinking about the measurement of synchrony and makes some well-taken points, it also arrives at questionable conclusions based upon dubious assumptions. The critique proceeds from a fictional example in which all biological states being considered always have exactly the same durations for all individuals and always start or end for all individuals at exactly the same instants in time. These unreal, biologically meaningless premises, together with other questionable assumptions, are the basis of inappropriate analyses of standardized measures. The critique's arguments reveal a failure to understand the basic underlying principle of the standardized method and are dependent upon faulty logic. A statistical discussion contains both worthy points and arguable comments based not on data or actual probabilities of real events but on irrelevant chance outcomes derived from the biologically meaningless assumptions. The critique's conclusions are not credible, and its basic question probably is not scientifically answerable.

Animals↗
PubMed1999

The dilemmas of incrementalism: logical and political constraints in the design of health insurance reforms.

Health care reform became a premier issue on the U.S. policy agenda in the 1990s. While the comprehensive proposal put forth by President Clinton failed, states and the federal government successfully pursued a variety of lesser initiatives. This article focuses on a set of reforms intended to make private health insurance more accessible and affordable to individuals and workers in small firms. It outlines the key arguments made by experts to justify stronger regulation of health insurance and the options and difficult tradeoffs that must be considered in policy design. It then examines the scope and strength of legislation adopted by 45 states and the federal government from 1990 to 1996. The substantial variation in state policies demonstrates that even though insurance market reform was the one issue that commanded nearly universal support in the health care debate, few design features were universally accepted by those who crafted the reforms. The article concludes by assessing the pattern of state and federal action. The reforms represent some progress on nominal access to insurance but little progress on the affordability of insurance for individuals and small groups. Few of the reforms present a serious challenge to existing practices and interests of the insurance industry. This pattern of policy design reflects the logical and political constraints of incrementalism. In a system where insurance coverage is voluntary, changes to increase access for one group tend to increase costs and thereby decrease access for another segment of the population. In addition, because incremental reforms will not attract sustained attention and support from the general public, it is politically difficult to impose substantial new regulation on a powerful industry.

Group Purchasing↗
PubMed1981

Logical reasoning deficits in schizophrenia and brain damage.

Von Domarus and Arieti have theorized that failure to reason by conventional logical rules is at the root of schizophrenic thought disorder, but the available research on this view is inconclusive. We compared the performance of schizophrenics (N = 100), brain-damaged patients (N = 50) and psychiatric controls (N = 50) on closely matched measures of Overexpansive and "Von Domarus" (similarity implies identity) syllogistic reasoning errors. Before the samples were matched for education and intelligence, the brain-damaged and schizophrenic patients made more Overexpansive errors than the controls, but the Von Domarus error difference was not significant. After matching, both differences were nonsignificant. The results indicate that inability to use syllogistic reasoning properly is probably not the root cause of schizophrenic thought disorder.

Adult↗
PubMed2001

A logical concept of structure prediction derived from supramolecular polymers of alkaline Earth metal halides formed by hydrogen bonding and complexation of the metal ion.

Several different dimensional polymers derived from alkaline earth metal iodides are obtained as a result of supramolecular noncovalent bonding modes of the metal ion, namely complexation and hydrogen bonding. These polymers consist of complex cations linked to the halide ions by hydrogen bonds of the water ligands coordinated to the metal. They are built up in a logical way, depending on the ratio of complexing ligands to complexing and hydrogen-bonding ligands so that their dimensionality and, to a certain extent, their structure can be predicted.

Journal Article↗
PubMed2002

Nanowires as building blocks for self-assembling logic and memory circuits.

The concept of assembling electronic circuits from metal nanowires is discussed. These nanowires are synthesised electrochemically by using porous membranes as templates. High aspect ratio wires, which range from 15 to 350 nm in diameter and contain "stripes" of different metals, semiconductors, colloid/polymer multilayers, and self-assembling monolayers have been made by this technique. By using the distinct surface chemistry of different stripes, the nanowires can be selectively derivatized and positioned on patterned surfaces. This allows the current-voltage properties of single and crossed nanowire devices to be measured. Nanowire conductors, rectifiers, switches, and photoconductors have been characterized. Techniques are still being developed for assembling sublithographic scale nanowires into cross-point arrays for memory and logic applications.

Journal Article↗
PubMedDate not supplied

The logical structure and validity of experimental designs in pharmacokinetics and clinical pharmacology.

Much of the literature on research design in clinical pharmacology and pharmacokinetics emphasizes statistical concerns, thus suggesting that a primary ingredient of a valid research design is an appropriate plan for statistical analysis of data. However, statistical validity is only one of several ways to evaluate an experimental study. The present paper reviews the underlying logic and sources of invalidity of experimental drug research suggesting influences and factors which may deceive or lure an experimenter into erroneous conclusions.

Models, Biological↗
PubMed1983

Recurrent gastrointestinal bleeding of obscure origin: report of 17 cases and a guide to logical management.

Seventeen patients with chronic obscure gastrointestinal bleeding presenting over a 5-year period are described. While representing only 6 per cent of the total number of admissions due to gastrointestinal haemorrhage they required a disproportionate amount of medical attention, including 67 admissions, 73 radiological and 56 endoscopic procedures and transfusion of a total of 198 units of blood. The diagnoses included 5 cases of recurrent acute upper gastrointestinal erosions, 7 small bowel abnormalities and 4 colonic lesions, with 1 patient undiagnosed. Eight arteriovenous malformations (AVM) were demonstrated angiographically and one Meckel's diverticulum identified by a 99Tcm pertechnetate scan. There were 5 cases in which laparotomy yielded the final diagnosis and in one of these peroperative endoscopy of the small bowel was required. On the basis of our experience and a review of other series, a logical plan of investigation is described for such difficult cases.

Adult↗
PubMed2003

Molecular logic circuits.

Miniaturization has been an essential ingredient in the outstanding progress of information technology over the past fifty years. The next, perhaps ultimate, limit of miniaturization is that of molecules, which are the smallest entities with definite size, shape, and properties. Recently, great effort has been devoted to design and investigate molecular-level systems that are capable of transferring, processing, and storing information in binary form. Some of these nanoscale devices can, in fact, perform logic operations of remarkable complexity. This research--although far from being transferred into technology--is attracting interest, as the nanometer realm seems to be out of reach for the "top-down" techniques currently available to microelectronics industry. Moreover, such studies introduce new concepts in the "old" field of chemistry and stimulate the ingenuity of researchers engaged in the "bottom-up" approach to nanotechnology.

Journal Article↗
PubMed2001

Sequence analysis using logic regression.

Logic Regression is a new adaptive regression methodology that attempts to construct predictors as Boolean combinations of (binary) covariates. In this paper we use this algorithm to deal with single-nucleotide polymorphism (SNP) sequence data. The predictors that are found are interpretable as risk factors of the disease. Significance of these risk factors is assessed using techniques like cross-validation, permutation tests, and independent test sets. These model selection techniques remain valid when data is dependent, as is the case for the family data used here. In our analysis of the Genetic Analysis Workshop 12 data we identify the exact locations of mutations on gene 1 and gene 6 and a number of mutations on gene 2 that are associated with the affected status, without selecting any false positives.

Algorithms↗
PubMed2001

Baseline conditions and subtractive logic in neuroimaging.

Discrepancies in the patterns of cortical activation across studies may be attributable, in part, to differences in baseline tasks, and hence, reflect the limits of the subtractive logic underlying much of neuroimaging. To assess the extent of these effects, three of the most commonly used baseline conditions (rest, tone monitoring, and passive listening) were compared using phoneme discrimination as the experimental task. Eight participants were studied in a fMRI study with a 4.1 T system. The three baseline conditions systematically affected the amount of activation observed in the identical phoneme task with major affects in Broca's area, the left posterior superior temporal gyrus, and the left and right inferior parietal regions. Two central findings were: 1) a differential effect of baseline within each region, with the rest baseline condition producing the greatest amount of activation and the passive listening condition producing the least, and 2) systematic baseline task activation in the inferior parietal regions. These results emphasize the relativity of activation patterns observed in functional neuroimaging, and the necessity to specify the baseline processes in context to the experimental task processes.

Adult↗
PubMed2004

Introducing triage logic as a new strategy for the detection of signals in the WHO Drug Monitoring Database.

PURPOSE: An important role for the WHO Programme for International Drug Monitoring is to identify signals of international drug safety problems as early as possible. The signal detection strategy, operated at the Uppsala Monitoring Centre (UMC), gave too many drug-adverse drug reaction (ADR) combinations for individual review. Therefore additional selection strategies were needed to improve the likely signal-to-noise ratio and for the UMC to complement the efforts of national centres in an efficient way. METHODS: The combinations database of the first quarter of 2001 was analysed using algorithms representing different strategies for finding relevant signals using triage logic. RESULTS: The strategies that together gave a manageable number of combinations, i.e. around 600, for further consideration in a single quarter were the algorithms for 'Rapid reporting increase', 'Serious reaction and new drug' and 'Special interests'. These filters began to be used routinely on the combinations database in late 2001. CONCLUSIONS: While stressing that human review is essential, triage strategies are useful when attempting analysis of large amounts of data. By definition, the use of triage strategies may exclude some potential signals from consideration, although the intention is to improve the chances of detection by focussing on areas of greatest importance.

Adverse Drug Reaction Reporting Systems↗
PubMed2004

Ovarian cancer detection by logical analysis of proteomic data.

A new type of efficient and accurate proteomic ovarian cancer diagnosis systems is proposed. The system is developed using the combinatorics and optimization-based methodology of logical analysis of data (LAD) to the Ovarian Dataset 8-7-02 (http://clinicalproteomics.steem.com), which updates the one used by Petricoin et al. in The Lancet 2002, 359, 572-577. This mass spectroscopy-generated dataset contains expression profiles of 15 154 peptides defined by their mass/charge ratios (m/z) in serum of 162 ovarian cancer and 91 control cases. Several fully reproducible models using only 7-9 of the 15 154 peptides were constructed, and shown in multiple cross-validation tests (k-folding and leave-one-out) to provide sensitivities and specificities of up to 100%. A special diagnostic system for stage I ovarian cancer patients is shown to have similarly high accuracy. Other results: (i) expressions of peptides with relatively low m/z values in the dataset are shown to be better at distinguishing ovarian cancer cases from controls than those with higher m/z values; (ii) two large groups of patients with a high degree of similarities among their formal (mathematical) profiles are detected; (iii) several peptides with a blocking or promoting effect on ovarian cancer are identified.

Algorithms↗
PubMed1995

An innovative dicrotic notch detection algorithm which combines rule-based logic with digital signal processing techniques.

Automated, real-time localization of the dicrotic notch, a component of the arterial pressure waveform, represents a deceptively complex problem in computerized biomedical signal processing. The high-frequency nature of the notch can make it difficult to distinguish from artifactual noise or from other high-frequency physiological components of the waveform. In addition, the contour of the notch varies with vascular status and with propagation through arterial beds, requiring any detection algorithm to recognize various possible notch conformations. Finally, location of the notch along the waveform may vary widely depending on other hemodynamic variables, further complicating detection algorithms. We have reviewed various published algorithms and have implemented a number of them to determine the strengths and shortcomings of each. We then developed a reliable and accurate hybrid algorithm which utilizes the strengths of the various algorithmic approaches reviewed; after analyzing the waveform, the algorithm selects the most appropriate method for accurate notch localization based on a series of waveform features. The application of rule-based logic represents a relatively unique approach to digital signal processing.

Algorithms↗