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PubMed1994

Use of artificial neural networks within deterministic logic for the computer ECG diagnosis of inferior myocardial infarction.

An investigation into the use of software-based artificial neural networks for the electrocardiographic (ECG) detection of inferior myocardial infarction was made. A total of 592 clinically validated subjects, including 208 with inferior myocardial infarction, 300 normal subjects, and 84 left ventricular hypertrophy cases, were used in this study. A total of 200 ECGs (100 from patients with inferior myocardial infarction and 100 from normal subjects) were fed to 66 supervised feedforward neural networks for training using a back-propagation algorithm. QRS and ST-T wave measurements were used as the input parameters for the neural networks. The best performing network using QRS measurements only and the best using QRS and ST-T data were selected by assessing a test set of 292 ECGs (108 from patients with inferior myocardial infarction, 84 from patients with left ventricular hypertrophy, and 100 from normal subjects). These two networks were then implanted separately into the deterministic Glasgow program for further study. After the implementation, it was found necessary to include a small inferior Q criterion to improve the specificity of reporting inferior myocardial infarction, thereby producing a small loss of sensitivity as compared with use of the network alone. The use of an artificial neural network within the deterministic logic performed better than either alone in the diagnosis of inferior myocardial infarction, producing a 20% gain in sensitivity with 2% loss in overall specificity compared with the original deterministic logic.

Diagnosis, Computer-Assisted↗
PubMed2003

Segmenting the fly embryo: a logical analysis of the pair-rule cross-regulatory module.

This manuscript reports a dynamical analysis of the pair-rule cross-regulatory module controlling segmentation in Drosophila melanogaster. We propose a logical model accounting for the ability of the pair-rule module to determine the formation of alternate juxtaposed Engrailed- and Wingless-expressing cells that form the (para)segmental boundaries. This module has the intrinsic capacity to generate four distinct expression states, each characterized by the expression of a particular combination of pair-rule genes or expression mode. The selection of one of these expression modes depends on the maternal and gap inputs, but also crucially on cross-regulations among pair-rule genes. The latter are instrumental in the interpretation of the maternal-gap pre-pattern. Our logical model allows the qualitative reproduction of the patterns of pair-rule gene expressions corresponding to the wild type situation, to loss-of-function and cis-regulatory mutations, and to ectopic pair-rule expressions. Furthermore, this model provides a formal explanation for the morphogenetic role of the initial bell-shaped expression of the gene even-skipped, i.e. for the distinct effects of different levels of the Even-skipped protein on its target pair-rule genes. It also accounts for the requirement of Even-skipped for the formation of all Engrailed-stripes. Finally, it provides new insights into the roles and evolutionary origins of the apparent redundancies in the regulatory architecture of the pair-rule module.

Animals↗
PubMed2003

Master Logic Diagram: method for hazard and initiating event identification in process plants.

Master Logic Diagram (MLD), a method for identifying events initiating accidents in chemical installations, is presented. MLD is a logic diagram that resembles a fault tree but without the formal mathematical properties of the latter. MLD starts with a Top Event "Loss of Containment" and decomposes it into simpler contributing events. A generic MLD has been developed which may be applied to all chemical installations storing toxic and/or flammable substances. The method is exemplified through its application to an ammonia storage facility.

Accidents, Occupational↗
PubMed1999

The logic of follicular unit transplantation.

Follicular unit transplantation is a method of hair restoration surgery where hair is transplanted exclusively in its naturally occurring, individual follicular units. The evolution and rational for follicular unit transplantation will be discussed, as well as the logic for the various techniques used in its implementation. Specifically, the logic for single strip harvesting, stereo-microscopic dissection, automated graft insertion, and large transplant sessions will be reviewed. The central role of the follicular unit constant in the surgical planning will also be discussed.

Hair Follicle↗
PubMed2003

Off-pump coronary artery bypass grafting: the myth, the logic and the science.

Coronary artery bypass grafting is a highly investigated surgical procedure and yet continues to attract rigorous research aimed at reducing observed and potential morbidity and mortality. Improvements in perioperative care, surgical technique and methods of attenuating the untoward effects of cardiopulmonary bypass have resulted in improved clinical outcome of on-pump myocardial revascularisation. The continuing drive to improve clinical outcome and compete with the ever-evolving non-surgical methods of myocardial revascularisation has provided the incentive for the rebirth of off-pump coronary artery bypass grafting (OPCAB). The appeal of avoiding cardiopulmonary pass with its direct and indirect physiological insult, the prospect of improved clinical outcomes, and the favourable economic impact gives OPCAB the potential of preference that may mark the dawn of a new era in our search for the optimal surgical strategy for the treatment of coronary artery disease. However, there are very genuine and serious concerns with this surgical technique. The logical appeal of OPCAB can only be validated by scientific scrutiny otherwise it would remain a myth. This comprehensive review examines the "physiological cost" of cardiopulmonary bypass, the theoretical and clinical benefits of OPCAB, the concerns with this technique and strategies for maximizing the benefits. And in so doing, explore the myth, the logic and the science of this surgical technique.

Cardiopulmonary Bypass↗
PubMed2001

From logical neurons to poetic embodiments of mind: Warren S. McCulloch's project in neuroscience.

After more than half a century of eclipse, the mind (in contradistinction to brain and behavior) emerged in the 1950s as a legitimate object of experimental and quantitative research in natural science. This paper argues that the neural nets project of Warren S. McCulloch, in frequent collaboration with Walter Pitts, spearheaded this cognitivist turn in the 1940s. Viewing the project as a spiritual and poetic quest for the transcendental logos, as well as culturally situated epistemology, the paper focuses on McCulloch's and Pitts' efforts of logical modeling of the mind and on the social conditions that shaped that mission. From McCulloch's "experimental epistemology," the mind - purposes that ideas - emerged out of the regularities of neuronal interactions, or nets. That science of mind thus became a science of signals based on binary logic with clearly defined units of perception and precise rules of formation and transformation for representing mental states. Aimed at bridging the gulf between body and mind (matter and form) and the technical gulf between things man-made and things begotten, neural nets also laid the foundation for the field of artificial intelligence. Thus this paper also situates McCulloch;'s work within a larger historical trend, when cybernetics, information theory, systems theories, and electronic computers were coalescing into a new science of communication and control with enormous potential for industrial automation and military power in the Cold War era. McCulloch's modeling the mind as a system of command and control contributed to the actualization of this potential.

Brain↗
PubMed2005

A parallel electromagnetic molecular logic gate.

A theoretical study of transport through a three-terminal molecular ring in the presence of a magnetic field is presented. The physical principles necessary to achieve logic operations based on the Aharonov-Bohm effect are discussed. We show that a proper combination of a gate potential and a realistic magnetic field can be used to obtain parallel logic operations such as AND and AND+NOT.

Journal Article↗
PubMed1997

Logics and logistics of community intervention against osteoporosis: an evidence basis.

Under designations like small areas action research and intervention, directed 'ground-up' health promotion and prevention in the population form an important part of the ongoing medical systems development. There is recent evidence of the success of community intervention against cardiovascular disease. In osteoporosis, however, there is still a lack of conclusive data on both the logics and logistics of such an approach. Since 1988, a county health policy program has been formulated and implemented in Ostergötland, Sweden, following the principles and guidelines of the WHO HFA 2000 declaration. Vadstena (n approximately 7,600) was chosen for a local and generalizable osteoporosis prevention project mediated by the primary care organization by means of health promotion and education in the community. In the present report we emphasize that community intervention is an important new advancement of the medical systems, where the basic research questions include operational and management aspects as equally vital and measurable requisites and results as other performance and outcome variables. We found that a community intervention trial against osteoporosis is both motivated and feasible and in this report wish to provide evidence on these crucial issues of logics and logistics.

Adult↗
PubMed2000

The logic of interpreting evidence of developmental ordering: strong inference and categorical measures.

Developmental ordering is a fundamental prediction of developmental theories and a central issue in developmental research. However, logically sound evidence of developmental ordering is difficult to obtain. This article analyzes the logical basis of testing developmental order hypotheses with categorical measures. Depending on whether saltatory (i.e., discrete) or continuous developmental changes are being assessed, the observed relationship between categorical measures yields very different types of information about developmental ordering. When change is continuous, the relationship between the measures does not confirm any one ordering hypothesis, but rather, disconfirms one or more hypotheses. Whether an underlying variable undergoes saltatory or continuous development has long been recognized as an important theoretical issue, but its impact on the interpretation of developmental ordering has not previously been explicated.

Child↗
PubMed2000

Logical computation using algorithmic self-assembly of DNA triple-crossover molecules.

Recent work has demonstrated the self-assembly of designed periodic two-dimensional arrays composed of DNA tiles, in which the intermolecular contacts are directed by 'sticky' ends. In a mathematical context, aperiodic mosaics may be formed by the self-assembly of 'Wang' tiles, a process that emulates the operation of a Turing machine. Macroscopic self-assembly has been used to perform computations; there is also a logical equivalence between DNA sticky ends and Wang tile edges. This suggests that the self-assembly of DNA-based tiles could be used to perform DNA-based computation. Algorithmic aperiodic self-assembly requires greater fidelity than periodic self-assembly, because correct tiles must compete with partially correct tiles. Here we report a one-dimensional algorithmic self-assembly of DNA triple-crossover molecules that can be used to execute four steps of a logical (cumulative XOR) operation on a string of binary bits.

Algorithms↗
PubMed2004

An autonomous molecular computer for logical control of gene expression.

Early biomolecular computer research focused on laboratory-scale, human-operated computers for complex computational problems. Recently, simple molecular-scale autonomous programmable computers were demonstrated allowing both input and output information to be in molecular form. Such computers, using biological molecules as input data and biologically active molecules as outputs, could produce a system for 'logical' control of biological processes. Here we describe an autonomous biomolecular computer that, at least in vitro, logically analyses the levels of messenger RNA species, and in response produces a molecule capable of affecting levels of gene expression. The computer operates at a concentration of close to a trillion computers per microlitre and consists of three programmable modules: a computation module, that is, a stochastic molecular automaton; an input module, by which specific mRNA levels or point mutations regulate software molecule concentrations, and hence automaton transition probabilities; and an output module, capable of controlled release of a short single-stranded DNA molecule. This approach might be applied in vivo to biochemical sensing, genetic engineering and even medical diagnosis and treatment. As a proof of principle we programmed the computer to identify and analyse mRNA of disease-related genes associated with models of small-cell lung cancer and prostate cancer, and to produce a single-stranded DNA molecule modelled after an anticancer drug.

Antineoplastic Agents↗
PubMed2005

Novel electrical switching behaviour and logic in carbon nanotube Y-junctions.

Carbon-nanotube-based electronics offers significant potential as a nanoscale alternative to silicon-based devices for molecular electronics technologies. Here, we show evidence for a dramatic electrical switching behaviour in a Y-junction carbon-nanotube morphology. We observe an abrupt modulation of the current from an on- to an off-state, presumably mediated by defects and the topology of the junction. The mutual interaction of the electron currents in the three branches of the Y-junction is shown to be the basis for a potentially new logic device. This is the first time that such switching and logic functionalities have been experimentally demonstrated in Y-junction nanotubes without the need for an external gate. A class of nanoelectronic architecture and functionality, which extends well beyond conventional field-effect transistor technologies, is now possible.

Crystallization↗
PubMed2005

A fluorescent molecular logic gate with multiply-configurable dual outputs.

A simple molecule, L, diethylenetriamine bearing anthracene fragments at both ends, behaves as a fluorescent molecular logic gate with "multiply-configurable dual outputs", capable of demonstrating five different logic functions operated by proton (H+) and transition metal cations (Mn+) as inputs.

Journal Article↗
PubMed1980

An invariant for wheel-generated motions and the logic of its determination.

Observers appear to perceive the paths of abstract centers of point-light configurations in making judgments about movement. For configurations on rolling wheels a metric was derived that described the relative vertical motion of this point. It was hypothesized that the smaller the metric the more the stimulus should appear to move in a wheel-like manner with linear translation. In two experiments observers viewed pairs of stimuli and were asked to select either the event that appeared most wheel-like or the one that hopped the most. Viewers consistently selected the stimulus with the smaller metric as being more wheel-like, with a frequency that increased with the difference between metrics. The inverse of this pattern was found for those observers requested to select the stimulus that hopped most. In a second set of two experiments observers drew the translational paths of these stimuli. Their drawings corresponded to the motion paths of configural centroids. Together, these results strongly suggest that observers perceive the translational component of the motion of the configurations as the path described by their centroids, or geometric centers. We propose that this description of the stimulus event is determined by the logical ordering of information extraction provided by the perceptural system, and discuss this logic and cases where it seems evident.

Form Perception↗
PubMed2005

Logic functions of the genomic cis-regulatory code.

cis-Regulatory modules that control developmental gene expression process the regulatory inputs provided by the transcription factors for which they contain specific target sites. A prominent class of cis-regulatory processing functions can be modeled as logic operations. Many of these are combinatorial because they are mediated by multiple sites, although others are unitary. In this work, we illustrate the repertoire of cis-regulatory logic operations, as an approach toward a functional interpretation of the genomic regulatory code.

Animals↗
PubMed2003

Discrete two-terminal single nanocluster quantum optoelectronic logic operations at room temperature.

Readily formed at nanoscale break junctions, arrays of individual spatially isolated, strongly electroluminescent Ag(2)-Ag(8) nanoclusters perform complex logic operations within individual two-terminal nanoscale optoelectronics devices. Simultaneous electrical excitation of discrete room-temperature nanocluster energy levels directly yields AND, OR, NOT, XOR, and even full addition logic operations with either individual nanoclusters or nanocluster pairs as the active medium between only two electrodes. Imaged in parallel, noncontact electroluminescent readout obviates the need for electrically isolating individual features. This gated, pulsed, two-terminal device operation will likely drive future nano and molecular electronics advances without complicated nanofabrication.

Journal Article↗