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At least 127 records · Page 7Linked to original sources
PubMed2003

DNA microarray data and contextual analysis of correlation graphs.

BACKGROUND: DNA microarrays are used to produce large sets of expression measurements from which specific biological information is sought. Their analysis requires efficient and reliable algorithms for dimensional reduction, classification and annotation. RESULTS: We study networks of co-expressed genes obtained from DNA microarray experiments. The mathematical concept of curvature on graphs is used to group genes or samples into clusters to which relevant gene or sample annotations are automatically assigned. Application to publicly available yeast and human lymphoma data demonstrates the reliability of the method in spite of its simplicity, especially with respect to the small number of parameters involved. CONCLUSIONS: We provide a method for automatically determining relevant gene clusters among the many genes monitored with microarrays. The automatic annotations and the graphical interface improve the readability of the data. A C++ implementation, called Trixy, is available from http://tagc.univ-mrs.fr/bioinformatics/trixy.html.

Algorithms↗
PubMed2002

Optical generation of fuzzy-based rules.

In the last third of the 20th century, fuzzy logic has risen from a mathematical concept to an applicable approach in soft computing. Today, fuzzy logic is used in control systems for various applications, such as washing machines, train-brake systems, automobile automatic gear, and so forth. The approach of optical implementation of fuzzy inferencing was given by the authors in previous papers, giving an extra emphasis to applications with two dominant inputs. In this paper the authors introduce a real-time optical rule generator for the dual-input fuzzy-inference engine. The paper briefly goes over the dual-input optical implementation of fuzzy-logic inferencing. Then, the concept of constructing a set of rules from given data is discussed. Next, the authors show ways to implement this procedure optically. The discussion is accompanied by an example that illustrates the transformation from raw data into fuzzy set rules.

Journal Article↗
PubMed1997

Use of in vitro and in vivo data to estimate the likelihood of metabolic pharmacokinetic interactions.

This article reviews the information available to assist pharmacokineticists in the prediction of metabolic drug interactions. Significant advances in this area have been made in the last decade, permitting the identification in early drug development of dominant cytochrome P450 (CYP) isoform(s) metabolising a particular drug as well as the ability of a drug to inhibit a specific CYP isoform. The major isoforms involved in human drug metabolism are CYP3A, CYP2D6, CYP2C, CYP1A2 and CYP2E1. Often patients are taking multiple concurrent medications, and thus an assessment of potential drug-drug interactions is imperative. A database containing information about the clearance routes for over 300 drugs from multiple therapeutic classes, including analgesics, anti-infectives, psychotropics, anticonvulsants, cancer chemotherapeutics, gastrointestinal agents, cardiovascular agents and others, was constructed to assist in the semiquantitative prediction of the magnitude of potential interactions with drugs under development. With knowledge of the in vitro inhibition constant of a drug (Ki) for a particular CYP isoform, it is theoretically possible to assess the likelihood of interactions for a drug cleared through CYP-mediated metabolism. For many agents, the CYP isoform involved in metabolism has not been identified and there is substantial uncertainty given the current knowledge base. The mathematical concepts for prediction based on competitive enzyme inhibition are reviewed in this article. These relationships become more complex if the inhibition is of a mixed competitive/noncompetitive nature. Sources of uncertainty and inaccuracy in predicting the magnitude of in vivo inhibition includes the nature and design of in vitro experiments to determine Ki, inhibitor concentration in the hepatic cytosol compared with that in plasma, prehepatic metabolism, presence of active metabolites and enzyme induction. The accurate prospective prediction of drug interactions requires rigorous attention to the details of the in vitro results, and detailed information about the pharmacokinetics and metabolism of the inhibitor and inhibited drug. With the discussion of principles and accompanying tabulation of literature data concerning the clearance of various drugs, a framework for reasonable semiquantitative predictions is offered in this article.

Cytochrome P-450 Enzyme System↗
PubMed2004

New figures for a Web-accessible database of the 1,945 basic Japanese kanji, fourth edition.

On the basis of calculations using the latest lexical database produced by Amano and Kondo (2000), the fourth edition of a Web-accessible database of characteristics of the 1,945 basic Japanese kanji was produced by including the mathematical concepts of entropy, redundancy, and symmetry and by replacing selected indexes found in previous editions (Tamaoka, Kirsner, Yanase, Miyaoka, & Kawakami, 2002). The kanji database in the fourth edition introduces seven new figures for kanji characteristics: (1) printed frequency, (2) lexical productivity, (3) accumulative lexical productivity, (4) symmetry for lexical productivity, (5) entropy, (6) redundancy, and (7) numbers of meanings for On-readings and Kun-readings. The file of the fourth edition of the kanji database may be downloaded from the Psychonomic Society Web archive, http://www.psychonomics.org/archive/.

Databases as Topic↗
PubMed1990

The effects of temporal modulation and spatial location on the perceived spatial frequency of visual patterns.

The perceived spatial frequency of a visual pattern can increase when a pattern drifts or is presented at a peripheral visual field location, as compared with a foveally viewed, stationary pattern. We confirmed previously reported effects of motion on foveally viewed patterns and of location on stationary patterns and extended this analysis to the effect of motion on peripherally viewed patterns and the effect of location on drifting patterns. Most central to our investigation was the combined effect of temporal modulation and spatial location on perceived spatial frequency. The group data, as well as the individual sets of data for most observers, are consistent with the mathematical concept of separability for the effects of temporal modulation and spatial location on perceived spatial frequency. Two qualitative psychophysical models suggest explanations for the effects. Both models assume that the receptive-field sizes of a set of underlying psychophysical mechanisms monotonically change as a function of temporal modulation or visual field location, whereas the perceptual labels attached to a set of channels remain invariant. These models predict that drifting or peripheral viewing of a pattern will cause a shift in the perceived spatial frequency of the pattern to a higher apparent spatial frequency.

Adult↗
PubMed1992

[Adjuvant therapy of surgically treated non-small cell lung cancer].

Adjuvant treatments of non-small cell lung cancers consist of radiotherapy and chemotherapy administered jointly or separately before or after surgery. These treatments have been tested in numerous trials, notably as regards postoperative chemotherapy. For a long time the results were disappointing, and in a randomized study none of the therapeutic regimens prescribed could improve the patients' survival. New hopes of advances in this matter were raised by Goldie and Coldman whose mathematical concept recommended a systemic treatment applied as early as possible in cases with localized tumour. The advent of platinum, the results obtained in metastatic tumours by including this agent in a variety of combinations, and those obtained in localized tumours by chemotherapy and radiotherapy combined have been the second promising element. Multicentre randomized trials have been set up after the encouraging results of a feasibility study on preoperative chemotherapy.

Carcinoma, Non-Small-Cell Lung↗
PubMed1992

[Current aspects of extrapyramidal disorders].

Within the past decade, the harmonious anatomic aspect of the basal ganglia has changed for inhomogeneous structures filled up with a wealth of neurotransmitters and receptor subtypes with massive vertical and horizontal interconnections, asking for new mathematical concepts like parallel distributed processing of computation to approach their respective functions. Moreover, not only the motor control, but also some important aspects of cognition, eye motions, and limbic functions seem to be processed in the basal ganglia. Their overall threshold of activity seems to be under the bipolar control of the substantia nigra and the subthalamic nucleus; this results in hyper or hypokinetic syndromes. Few practical or therapeutical results have come out from the last radiological technologies and biochemical studies of extrapyramidal disorders, but the wealth of information brings hope for new issues from the knowledge in molecular biology, neuropharmacology, and from earlier diagnosis of these diseases in the future.

Basal Ganglia↗
PubMed2005

A benchmark methodology for managing uncertainties in urban runoff quality models.

In this paper we present a benchmarking methodology, which aims at comparing urban runoff quality models, based on the Bayesian theory. After choosing the different configurations of models to be tested, this methodology uses the Metropolis algorithm, a general MCMC sampling method, to estimate the posterior distributions of the models' parameters. The analysis of these posterior distributions allows a quantitative assessment of the parameters' uncertainties and their interaction structure, and provides information about the sensitivity of the probability distribution of the model output to parameters. The effectiveness and efficiency of this methodology are illustrated in the context of 4 configurations of pollutants' accumulation/erosion models, tested on 4 street subcatchments. Calibration results demonstrate that the Metropolis algorithm produces reliable inferences of parameters thus, helping on the improvement of the mathematical concept of model equations.

Algorithms↗
PubMed1985

[A new alternative for estimating recommendations of protein intake in humans. Protein requirements of an adult population fed with a diet based on rice and beans].

This paper proposes a new approach to estimate the protein needs of a population; recommendations are also made on the protein intake of adults fed diets based on rice and beans. For this purpose, the nitrogen balance data previously reported for 40 adult human subjects who had participated in 160 nitrogen balance periods fed diets based on rice and beans, with and without animal protein and/or energy supplementation were used. The proposed method is based on the curvilinear response between nitrogen intake and its nitrogen balance. The second degree equation describing the relationship between nitrogen balance and intake is calculated. Using the mathematical concept of the first and second derivatives, the point of inflexion is obtained, and interpreted as that condition wherein the individual utilizes with maximum efficacy the ingested nitrogen; nitrogen ingestion, which corresponds to that point, is therefore taken as the dietary nitrogen recommendation for the individual. When the values obtained by means of the quadratic equation are compared to those obtained by the traditional linear equation, values were found to be statistically equal (p less than 0.05) for both calculation methods. The recommended protein intake of an adult population fed a diet based on rice and beans was 0.80 and 0.77 g/kg/day for the quadratic approach, and for the conventional method, respectively. When this diet was supplemented with 10% milk protein and with the same energy level, the calculated values were 0.64 and 0.71 g protein/kg/day for both methods, in this same order. The essential amino acid intake and absorption values were also calculated from the protein levels recommended by both methods to be in nitrogen balance, from a diet based on rice and beans. Findings revealed, in all cases, that the intakes of each and all essential amino acids met those levels indicated by FAO/WHO, with the exception of isoleucine and the sulphur-containing amino acids, which apparently limit the quality of the diet.

Adult↗
PubMed1985

[Mathematical approach to bacterial identification].

The identification of Enterobacteriaceae is examined in the context of the recent field of research assisted by multi-criteria decisions. In particular, the authors discuss the limitations of two approaches of assisted identification based on completely different mathematical concepts: the calculation of the probabilities (used in commercial centres) and the aggregation of pre-orders by a model of assisted decision such as Electra II. In order to reduce the errors of interpretation inherent in the use of any model, the authors propose the use of computer assisted systems of bacterial identification in bacteriology laboratories.

Bacteriological Techniques↗
PubMedDate not supplied

[Clinical diagnosis of dyslexia].

In 5 years of experience at the Instituto Nacional de la Comunicacion Humana, 302 clinical histories showed the diagnosis of dyslexia. The following parameters were studied: age, sex, heredofamilial history, gestation, psychomotor development, clinical picture, examination of the language (type, reading, spontaneous writing, dictation, mathematic concepts), laterality, scholarship, scholar failures, psychological study. The following results were obtained: Dyslexia was more important or frequent between 5 to 8.9 years of age. Males predominated 3:1. The heredofamilial history was important. Dyslexia prevailed in products of the first gestations. A high disturbance was found in the psychomotor development of a large percent of dyslexic patients. Examination of language was also important. Dyslexia was more frequent in right-handed patients. Scholar failures in one or more instances were found. The psychological study must be done. If dyslexia is diagnosed on time, it may be prevented and all unwanted sequelae may be avoided.

Dyslexia↗
PubMed1996

[Dynamic imaging of gastric ulcer healing using the most modern Morph-Software].

The presentation of gastric ulcer healing taken from video endoscopy as a dynamic process could not be realized till now. The documentation of the dynamic healing process shattered either on the patient's compliance or on the inconstancy of the image cut due to wobbling. The replay should be performed as a time lapse whereby the picture disturbances would become an essential part.-Instead of presenting a continuous film, instant takes of ulcer healing were processed. A dynamic effect was produced by computer-assisted production of intermediate pictures. A video was created in which short video sequences in definite time intervals were recorded endoscopically. Single stills-so-called original pictures-fitting together from each sequence were selected and spliced together. The missing intermediate pictures were made with a special computer technique according to the mathematical concept of interpolation. With this technique, the dynamic documentation of gastric ulcer healing in a 47-year-old male patient was performed. The technique enables an almost natural and real observation of ulcer healing and promises new physiological and patho-physiological knowledge in gastroenterologic endoscopy.

Amoxicillin↗
PubMed2001

University students' conceptions of first-year mathematics.

The 1998 Crawford, Gordon, Nicholas, and Prosser Conceptions of Mathematics scale was administered to 156 first-year university students at a large public university in the midwestern United States. The scale represented fragmented and cohesive conceptions of mathematics. The reliability estimated as internal consistency had a Cronbach alpha of .80 for the fragmented scale and .87 for the cohesive scale. Factor analysis of the intercorrelations indicated the same two factors of fragmented and cohesive as in the original and other replicating studies. Students' conceptions of mathematics in this study were comparable to those reported in the original study.

Adolescent↗
PubMed1980

The buffer value of weak acids and bases: origin of the concept, and first mathematical derivation and application to physico-chemical systems. The work of M. Koppel and K. Spiro (1914).

A translation is offered of a paper by M. Koppel and K. Spiro, published in 1914, and entitled: 'On the action of moderators (buffers) in the shift of the acid-base equilibrium of biological fluids'. In this work, which appeared in Vol. 65 of the Biochemische Zeitschrift, the authors introduced the modern concept of buffer value and, for the first time, quantified the buffering power of weak acids and bases, ampholytes, dibasic acids, and mixtures of buffers. The circumstances that surround the eclipse of this trailblazing research have been critically examined, and biographical details have been provided.

Acid-Base Equilibrium↗
PubMed1977

[Critical remarks on an essay by K.T. Kalveram, "Factor analysis. Critical comments on a theoretical concept and its mathematical reformulation"].

The following contribution is a critical discussion of a paper by K. T. Kalveram Uber Faktorenanalyse. Kritik eines theoretischen Konzepts und seine mathematische Neuformulierung", which was published in this journal in 1970. In the following it is shown that Kalveram's attempt of a mathematical reformulation must be considered a failure, even if mathematical misrepresentations are not taken into account.

Factor Analysis, Statistical↗