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At least 1,351 records · Page 75Linked to original sources
PubMed2006

Learning outdoor color classification.

We present an algorithm for color classification with explicit illuminant estimation and compensation. A Gaussian classifier is trained with color samples from just one training image. Then, using a simple diagonal illumination model, the illuminants in a new scene that contains some of the surface classes seen in the training image are estimated in a maximum likelihood framework using the Expectation Maximization algorithm. We also show how to impose priors on the illuminants, effectively computing a maximum a posteriori estimation. Experimental results are provided to demonstrate the performance of our classification algorithm in the case of outdoor images.

Algorithms↗
PubMed2004

Functional mapping of quantitative trait loci underlying growth trajectories using a transform-both-sides logistic model.

The incorporation of developmental control mechanisms of growth has proven to be a powerful tool in mapping quantitative trait loci (QTL) underlying growth trajectories. A theoretical framework for implementing a QTL mapping strategy with growth laws has been established. This framework can be generalized to an arbitrary number of time points, where growth is measured, and becomes computationally more tractable, when the assumption of variance stationarity is made. In practice, however, this assumption is likely to be violated for age-specific growth traits due to a scale effect. In this article, we present a new statistical model for mapping growth QTL, which also addresses the problem of variance stationarity, by using a transform-both-sides (TBS) model advocated by Carroll and Ruppert (1984, Journal of the American Statistical Association 79, 321-328). The TBS-based model for mapping growth QTL cannot only maintain the original biological properties of a growth model, but also can increase the accuracy and precision of parameter estimation and the power to detect a QTL responsible for growth differentiation. Using the TBS-based model, we successfully map a QTL governing growth trajectories to a linkage group in an example of forest trees. The statistical and biological properties of the estimates of this growth QTL position and effect are investigated using Monte Carlo simulation studies. The implications of our model for understanding the genetic architecture of growth are discussed.

Biometry↗
PubMed2002

Traumatic brain injury: assessment and management.

Suspected traumatic brain injury is a common presenting problem for emergency department staff. Sorting out who needs to have a computed tomography scan, who should be admitted and who should be followed up can be difficult. A framework for making these decisions is provided in this article.

Alcohol Drinking↗
PubMed2005

Linear operator theory of channeled spectropolarimetry.

Channeled spectropolarimetry is a snapshot method of measuring the spectral and polarization content of light. Wave-number domain amplitude modulation is employed to encode all four Stokes component spectra into a single optical power spectrum. We model the channeled spectropolarimeter as a linear operator, which facilitates treatment of nonideal effects and provides a convenient framework for simulations, calibration, and reconstruction. The operator's singular value decomposition is treated with analytic and computational approaches. This analysis highlights the importance of the choice of object space in constraining and imparting prior knowledge to linear reconstructions of data from underdetermined systems.

Journal Article↗
PubMed1975

Interrelation between glycosidic torsion, sugar pucker, and backbone conformation in 5'-beta-nucleotides. A 1H and 31P fast Fourier transform nuclear magnetic resonance investigation of the conformation of 8-aza-5'-beta-adenosine monophosphate and 8-aza-5'-beta-guanosine monophosphate.

Hydrogen-1 and phosphorus-31 nuclear magnetic resonance spectra of 5'-AMP, 5'-GMP, 8-aza-5'-GMP, adenosine, 8-aza-adenosine, and guanosine were obtained at biological pH values at a concentration sufficiently low to obtain information regarding their intramolecular solution conformation. The spectra were analyzed by computer simulation. It is shown that all of the above nucleosides and nucleotides have a flexible molecular framework in aqueous solution, 5'-AMP and 5'-GMP showing preference for anti(2-E in equilibrium 3-E)gg-g'g' conformations and the 8-aza analogs showing preference for (syn in equilibrium anti)-(2E in equilibrium 3-E) - g/t-g'g' conformations. In addition, aza substitution causes increase in 3-E sugar populations and in the populations of g'/t' conformers. It is argued that in the 8-aza analogs repulsive electrostatic interactions would prevail between --N (see article) at the 8 position and the negatively charged phosphate group, if the molecule existed in the anti-gg orientation. Such electrostatic repulsions can be relieved by rotating the C(4')--C(5') bond from gg to g/t orientations as well as by torsional variation about the glycosidic linkage from anti to syn conformation. Rotation from anti to syn orientation, for steric and electrostatic reasons, necessitates a simultaneous rotation about the C(4')--C(5') bond from gg to g/t conformation. The observation that the 8-aza substitution in 5'-beta-purine nucleotides cause a depopulation of gg and anti conformers with corresponding increase in the population of g/t and syn orientation seems to support the above thesis. The finding that rotational variation about a bond such as C(4')--C(5') is accompanied by torsional variation about C(5')--O(5') and the glycosidic bonds, as well as changes in the endocyclic torsion angles of the ribose moiety, gives important insight into the engineering of nucleic acid components: even though they in general prefer certain conformations, there is enough flexibility present in their molecular framework, that the entire system can undergo conformational adjustment in response to a perturbation. A conformational basis for the antileukemic effects of 8-aza purines is proposed.

Adenosine↗
PubMed2002

[Traumatic rupture of the diaphragm in blunt injuries].

The authors present a group of 12 casualties operated on account of a traumatic rupture of the diaphragm. The rupture of the diaphragm was part of an associated thoracoabdominal injury or multiple injury. The casualties were examined within the framework of the diagnostic algorithm, in 11 of them rupture of the diaphragm was proved by spiral computed tomography. The diaphragm was injured in 7 subjects on the left and in 5 on the right. In 8 casualties during injury of the diaphragm also a serious intrathoracic injury was treated (in 5 laceration of the lungs) and of intraabdominal organs (in 4 laceration of the liver and in 2 laceration of the spleen). On the left side injuries of the diaphragm were always treated from laparotomy, on the right in 4 patients from thoracotomy. In 4 patients with concurrent injury of the intrathoracic and intraabdominal organs a thoracoabdominal approach was selected. During the postoperative period one female patient with multiple injuries died. The cause of death was contusion of the brain. According to the authors' experience it is useful to apply for early diagnosis of diaphragmatic injuries modern non-invasive imaging methods (spiral post-contrast computed tomography). The surgical approach depends on the presence of associated intrathoracic and intraabdominal injuries. The therapeutic results are limited by the presence of serious associated injuries.

Adult↗
PubMed1955

Sickness absenteeism.

In this paper, sickness statistics are discussed, with special reference to the differences between medical statistics and those of the sickness benefit organizations. Special attention is paid to the comparability of data from different sources.The distribution of sickness absence among workers appears to be approximately similar to that of a chance event (Poisson distribution). This conclusion applies to pre-war years as well as to the post-war period. Although in the latter period the annual average of sickness absences per worker is much greater, there are no indications that the increase in the frequency rate has to be attributed to specified groups of workers; all workers are equally responsible.The high disability rate cannot be accounted for today by causes such as malnutrition, so the phenomenon must be due to a lowering of the standards by which incapacity for work is judged. Since it is the family physician who sets these standards for the worker, it follows that it is he who is largely responsible for the increased rate of sickness absenteeism. The fact that social insurance has concealed the economic consequences of disabling illnesses from the doctor as well as from the patient is one of the reasons why physicians have tended to relax their disability standards.Family physicians practising under favourable and almost identical conditions within the framework of an industrial health centre may, nevertheless, show considerable differences in attitude. When disability rates were computed separately for the practices of nine general practitioners in the full-time employment of the Medical Department of Philips' Gloeilampenfabrieken, Eindhoven, Netherlands, the results showed that there was no common opinion among the doctors with regard to standards of disability. A closer examination of the available data allows the conclusion to be drawn that it is in the power of medicine to reduce sickness absenteeism substantially without damaging the worker's health.Finally, some proposals are made for promoting research on sickness absenteeism and on the diagnosis of disability.

Absenteeism↗
PubMed1996

[Studies of the system analysis of social motivation, IV: The varieties of smiling and the problem of motivational adjustment].

A formal theory is proposed that accounts for the motivational architecture underlying the spontaneous smiling response in its most salient varieties (i.e., smiling due to security, relief, embarrassment, fear, amazement, submission, and triumph). The theory is based on a single assumption according to which the smiling response, in all instances named, is due to a reduction of "autonomy claim" as defined within the framework of the Zurich Model of Social Motivation. The theory's consistency is evinced by way of computer simulation, its phenomenological plausibility can be demonstrated by animation based on Ekman's Facial Action Coding System.

Adult↗
PubMed1990

A two-dimensional analog VLSI circuit for detecting discontinuities in early vision.

A large number of computer vision algorithms for finding intensity edges, computing motion, depth, and color, and recovering the three-dimensional shape of objects have been developed within the framework of minimizing an associated "energy" or "cost" functional. Particularly successful has been the introduction of binary variables coding for discontinuities in intensity, optical flow field, depth, and other variables, allowing image segmentation to occur in these modalities. The associated nonconvex variational functionals can be mapped onto analog, resistive networks, such that the stationary voltage distribution in the network corresponds to a minimum of the functional. The performance of an experimental analog very-large-scale integration (VLSI) circuit implementing the nonlinear resistive network for the problem of two-dimensional surface interpolation in the presence of discontinuities is demonstrated; this circuit is implemented in complementary metal oxide semiconductor technology.

Algorithms↗
PubMed2003

Conformational flexibility of two RNA trimers explored by computational tools and database search.

Two RNA sequences, AAA and AUG, were studied by the conformational search program CICADA and by molecular dynamics (MD) in the framework of the AMBER force field, and also via thorough PDB database search. CICADA was used to provide detailed information about conformers and conformational interconversions on the energy surfaces of the above molecules. Several conformational families were found for both sequences. Analysis of the results shows differences, especially between the energy of the single families, and also in flexibility and concerted conformational movement. Therefore, several MD trajectories (altogether 16 ns) were run to obtain more details about both the stability of conformers belonging to different conformational families and about the dynamics of the two systems. Results show that the trajectories strongly depend on the starting structure. When the MD start from the global minimum found by CICADA, they provide a stable run, while MD starting from another conformational family generates a trajectory where several different conformational families are visited. The results obtained by theoretical methods are compared with the thorough database search data. It is concluded that all except for the highest energy conformational families found in theoretical result also appear in experimental data. Registry numbers: adenylyl-(3' --> 5')-adenylyl-(3' --> 5')-adenosine [917-44-2] adenylyl-(3' --> 5')-uridylyl-(3' --> 5')-guanosine [3494-35-7].

Base Sequence↗
PubMedDate not supplied

The role of phasins in the morphogenesis of poly(3-hydroxybutyrate) granules.

Recent developments in the understanding of the structure of polyhydroxyalkanoate, PHA, granules in bacteria are documented in the literature and point to the role of structural proteins, phasins, in granule formation and stabilization. We have previously conceived a computer program which successfully simulates granule formation in vitro, in the absence of phasins. Now we are extending the computer model to a more complex system, including phasins, to quantify their anticipated effect on the granule properties. The simulation enabled us to propose real experiments to test the validity of the model and provide a framework for a better understanding of PHA granule formation in vivo.

Acyltransferases↗
PubMed1990

Modeling of cardiac rhythms. A signal-processing perspective.

The authors describe their perspective on the modeling of cardiac rhythms as a component of cardiac arrhythmia signal-processing algorithms. They emphasize that these models are for a specific end purpose and that the aspects of cardiac behavior that are captured by the models are only those relevant for the development of the signal-processing algorithms. The approach is to use statistics to describe ranges of cardiac behavior that share some common feature with respect to the purpose of the signal processing. The statistical approach has the advantage that, coupled with a statistical performance criterion, it specifies an optimal signal-processing algorithm. These optimal algorithms are often computationally intractable, however, especially for real-time use in instruments. Approximations are therefore crucial. The mathematical form of the model is then important since, even if two forms generate identical statistics, the approximations that are natural in different forms can be quite different. Two different mathematical formulations are described--stochastic Petri nets and interacting Markov chains--and the different types of approximately optimal signal-processing algorithms that are natural in these two frameworks are discussed.

Algorithms↗
PubMed1994

The PEN & PAD medical record model: development of a nursing record for hospital-based care of the elderly.

The PEN & PAD Medical Record model describes a framework for an information model, designed to meet the requirements of an electronic medical record. This model has been successfully tested in a computer-based record system for General Practitioners as part of the PEN & PAD (GP) Project. Experiences of using the model for developing computer-based nursing records are reported. Results show that there are some problems with directly applying the model to the nursing domain. Whilst the main purpose of the nursing record is to document and communicate a patient's care, it has several other, possibly incompatible, roles. Furthermore, the structure and content of the information contained within the nursing record is heavily influenced by the need for the nursing profession to visibly demonstrate the philosophical frameworks underlying their work. By providing new insights into the professional background of nursing records, this work had highlighted the need for nurses to clarify and make explicit their uses of information, and also provided them with some tools to assist in this task.

Aged↗
PubMed2004

Evolutionary fuzzy modeling human diagnostic decisions.

Fuzzy CoCo is a methodology, combining fuzzy logic and evolutionary computation, for constructing systems able to accurately predict the outcome of a human decision-making process, while providing an understandable explanation of the underlying reasoning. Fuzzy logic provides a formal framework for constructing systems exhibiting both good numeric performance (accuracy) and linguistic representation (interpretability). However, fuzzy modeling--meaning the construction of fuzzy systems--is an arduous task, demanding the identification of many parameters. To solve it, we use evolutionary computation techniques (specifically cooperative coevolution), which are widely used to search for adequate solutions in complex spaces. We have successfully applied the algorithm to model the decision processes involved in two breast cancer diagnostic problems, the WBCD problem and the Catalonia mammography interpretation problem, obtaining systems both of high performance and high interpretability. For the Catalonia problem, an evolved system was embedded within a Web-based tool-called COBRA-for aiding radiologists in mammography interpretation.

Breast Neoplasms↗
PubMed2026

X-intNMF: a cross- and intra-omics regularized NMF framework for multi-omics integration.

MOTIVATION: The rapid accumulation of multi-omics data presents a valuable opportunity to advance our understanding of complex diseases and biological systems, driving the development of integrative computational methods. However, the complexity of biological processes, spanning multiple molecular layers and involving intricate regulatory interactions, requires models that can capture both intra- and cross-omics relationships. Most existing integration methods primarily focus on sample-level similarities or intra-omics feature interactions, often neglecting the interactions across different omics layers. This limitation can result in the loss of critical biological information and suboptimal performance. To address this gap, we propose X-intNMF, a network-regularized non-negative matrix factorization (NMF) framework that simultaneously integrates intra- and cross-omics feature interactions into a shared low-dimensional representation (see Fig. 1). By modeling these multi-layered relationships, X-intNMF enhances the representation of biological interactions and improves integration quality and prediction accuracy. RESULTS: For evaluation, we applied X-intNMF to predict breast cancer phenotypes and classify clinical outcomes in lung and ovarian cancers using mRNA expression, microRNA expression, and DNA methylation data from TCGA. The results show that X-intNMF consistently outperforms state-of-the-art methods. Ablation studies confirm that incorporating both cross-omics and intra-omics interactions contributes significantly to the model's improved performance. Additionally, survival analysis on 25 TCGA cancer datasets demonstrates that the integrated multi-omics representation offers strong prognostic value for both overall survival and disease-free status. These findings highlight X-intNMF's ability to effectively model multi-layered molecular interactions while maintaining interpretability, robustness, and scalability within the NMF framework. AVAILABILITY AND IMPLEMENTATION: The source code and datasets supporting this study are publicly available at GitHub (https://github.com/compbiolabucf/X-intNMF) and archived on Zenodo (https://doi.org/10.5281/zenodo.18238385).

Multiomics↗
PubMed2001

The role of CT in the management of adult urinary tract trauma.

Computed tomography (CT) is now the investigation of choice for evaluating haematuria following major abdominal trauma. This pictorial review provides a logical framework for understanding the classification and features of urinary tract injuries, defines the indications and outlines the techniques for CT imaging in upper and lower urinary tract trauma. The use of other competing imaging modalities is also discussed.

Adult↗
PubMed1988

A unified framework for connectionist systems.

Pattern classification using connectionist (i.e., neural network) models is viewed within a statistical framework. A connectionist network's subjective beliefs about its statistical environment are derived. This belief structure is the network's "subjective" probability distribution. Stimulus classification is interpreted as computing the "most probable" response for a given stimulus with respect to the subjective probability distribution. Given the subjective probability distribution, learning algorithms can be analyzed and designed using maximum likelihood estimation techniques, and statistical tests can be developed to evaluate and compare network architectures. The framework is applicable to many connectionist networks including those of Hopfield (1982, 1984), Cohen and Grossberg (1983), Anderson et al. (1977), and Rumelhart et al. (1986b).

Animals↗
PubMed1996

A computational model of cholinergic disruption of septohippocampal activity in classical eyeblink conditioning.

A previous neurocomputational model of corticohippocampal interaction (Gluck & Myers, 1993) can provide a framework for examining the behavioral effects of septohippocampal modulation during classical conditioning. The model assumes that the hippocampal region is necessary for forming new stimulus representations during learning, but not for the formation of simple associations. This paper considers how septohippocampal interaction could affect this function. The septal nuclei provide several modulatory inputs to the hippocampus, including a cholinergic input which Hasselmo (1995) has suggested may function to regulate hippocampal dynamics on a continuum between two states: a storage state in which incoming information is encoded as an intermediate-term memory and a recall state when this information is reactivated. In this theory, anticholinergic drugs such as scopolamine should disrupt learning by selectively reducing the hippocampus's ability to store new information. An approximation of Hasselmo's idea can be implemented in the corticohippocampal model by a simple manipulation of hippocampal learning rate; this manipulation is formally equivalent to adjusting the amount of time the hippocampus spends in learning and recall states. With this manipulation, the model successfully accounts for the effects of scopolamine in retarding classical conditioning in humans (Solomon, Groccia-Ellison, Flynn, Mirak, Edwards, Dunehew, & Stanton, 1993) and animals (Solomon, Soloman, van der Schaaf, & Perry, 1983). The model further predicts that although cholinergic agonists (such as Tacrine) may improve learning in subjects with artificially depressed brain acetylcholine levels, there may be limited memory improvement in normal subjects from such cholinergic therapy. This is consistent with the general finding of a U-shaped dose response curve for cholinergic drugs in normal subjects: low to moderate doses may improve learning, but higher doses are ineffective or even degrade learning (e.g., Ennaceur & Meliani, 1992; Dumery, Derer, & Blozovski, 1988; etc.).

Animals↗