La classification numérique : principes et applications

in Notes de Statistique et d'Informatique (1996), (1), 28

The principles of some clustering techniques are described and illustrated by an example. The data consist of chemical contents for 45 types of mineral water.

The elementary reactions of energy selected 1,1-Difluoroethene ions.

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1996)

The dissociative photoionization dynamics of 1,1-difluoroethene has been investigated by TPEPICO using synchrotron radiation. The breakdown diagram has been build. The attention has been focussed on C2HF ... [more ▼]

The dissociative photoionization dynamics of 1,1-difluoroethene has been investigated by TPEPICO using synchrotron radiation. The breakdown diagram has been build. The attention has been focussed on C2HF+ (HF-loss) channel. [less ▲]

Influence des facteurs individuels et de troupeau sur les performances de reproduction bovine

in Annales de Médecine Vétérinaire (1996), 140

Through a wide review of the litterature (330 references), the authors have tried to describe the determinant or predisposing effects of factors usually involved in the reproduction problems in beef or ... [more ▼]

Through a wide review of the litterature (330 references), the authors have tried to describe the determinant or predisposing effects of factors usually involved in the reproduction problems in beef or dairy cattle. These factors have been qualified as individual or herd factors. The first ones involve the animal itself like age, genetic, milk production level, dystocia, twinning, perinatal mortality, placental retentio, milk fever, uterine involution, metritis, post-partum ovarian activity. The second ones concern the environnement of the animal i.e. first insemination policy, oestrus detection, insemination time and technic, nutrition, season, stabulation, herd size or management capacity of the farmer. The authors conclude to the multifactorial etiology of the reproduction pathologies. It also appears necessary to develop data collection systems like herd health management programs. Such systems should be able to offer to the practitionner the opportunity to be involved more efficiently in the economic health of the herd using epidemiological tools to study the different implied factors. [less ▲]

Selection of hammerhead ribozymes for optimum cleavage of interleukin 6 mRNA.

in Biochemical Journal (1996), 314 ( Pt 2)

Four GUC triplets in the coding region of the MRNA of interleukin 6 (IL-6) were examined for their suitabilty to serve as a target for hammerhead ribozome-mediated cleavage. This selection procedure was ... [more ▼]

Four GUC triplets in the coding region of the MRNA of interleukin 6 (IL-6) were examined for their suitabilty to serve as a target for hammerhead ribozome-mediated cleavage. This selection procedure was performed with the intention to downregulate IL-6 production as a potential treatment of those diseases in which IL-6 overexpression is involved. Hammerhead ribozymes and their respective short synthetic substrates (19-mers) were synthesized for these four GUC triplets. Notwithstanding the identical catalytic core sequences, the difference in base composition of the helices involved in substrate binding caused substantial variation in cleavage activity. The cleavage reactions on the 1035 nucleotide IL-6 mRNA transcript revealed that two ribozymes were able to cleave this substrate, showing a decrease in catalytic efficiency to 1/30 and 1/300 of the short substrate. This study indicates that the GUC triplet located at nucleotide 510 of the mRNA of IL-6 is the best site for hammerhead ribozyme-mediated cleavage. We suggest that in future targeting of chemically modified hammerhead ribosomes for cleavage of IL-6 RNA should be directed at this location. [less ▲]

Odours identification in the environment by means of mathematical methods

in Odours & VOC's journal (1996), 1

The aim of the present paper is to test and compare some mathematical discrimination or pattern recognition methods in order to identify one among three air pollution sources.The basic material in this ... [more ▼]

The aim of the present paper is to test and compare some mathematical discrimination or pattern recognition methods in order to identify one among three air pollution sources.The basic material in this work are : - the standard gas chromatography/mass spectrometry analysis with concentrations values for different chemical compounds observed at about hundred sites in iron and steel industries : either coking plants, or cold rolling mills, or coil-coating plants. - the odours levels, measured by the method of dilution at the threshold. Generally speaking, coil-coating plants emit more chemical compounds than two others, however olfactive threshold is about the same in the three cases. Sums of compounds concentrations for different chemical families (e.g. alkanes, alcohol's, phenols, ...) are calculated and used for the mathematical treatments. Because the frequency histogram of the observed concentrations has a log normal distribution, logarithm of concentration is chosen as operating variable instead of concentration itself. The stepwise multiple linear regression is used in order to express the dilution factor at the olfactory perception threshold as a linear combination of the logarithm of concentrations. Results show that this factor can be estimated quite well on the basis of the concentrations of compounds belonging only to three chemical families. Nevertheless, these families differ following the emission source. To perform the optimal odour description of the three types of industrial plants a larger set of compounds families should be examined in a first step. Factor analysis is used with the aim of regrouping observed variables that are linked together in the plane of the first two factors. The representation of observation points is then superposed on this scheme. Some variable clusters are observed. The method, applied to the whole variables set, classes rather well the observations : the three emissions sources are well discriminated. Cluster analysis, discriminant analysis and neural network have also been used, but only with three variables common to all installations : concentrations of alkylbenzenes, polycyclic aromatics and alkanes. Cluster analysis is not a "supervised method". That means that it is free to create itself some groups showing similar behaviour with regard to the observed variables. Indeed, results show that cluster analysis does not allow to recognise the emission source. In discriminant analysis, target groups membership is provided for each set of variables values : it is a supervised method. The classification functions so deduced allow to discriminate quite well the three industrial plants and to predict the emission origin. A total of 87 % of the observations are correctly on the basis of the classification functions. Neural network approach, with backpropagation algorithm, is a so-called "pattern recognition technique" and is also a supervised method. It provides still better results than statistical ones. After the learning phase, the network is able to identify correctly 99.5 % of observations from 95.5 % the training set.The concentrations of compounds belonging to three chemical families, combined with a pattern recognition technique based either on discriminant analysis, or on neural network, prove to be efficient for recognising the source of odorous gaseous effluents. For the data set considered in this paper, the neural network exhibits better classification performances than discriminant analysis, but its learning phase is slower. However, applying one method or the other for further recognition of unknown patterns is quick and easy. [less ▲]

Evolution des principaux types d'aides à la décision en matière de gestion forestière.

Report (1996)

Forest planning is more and more made of activities which require to take into account a great amount of various sets of ecological, economical and social data which have to be considered in a diversity ... [more ▼]

Forest planning is more and more made of activities which require to take into account a great amount of various sets of ecological, economical and social data which have to be considered in a diversity of space and time-scales. Facing such complexity the managers need of guidance in coming to the right decision. Some decision support systems are presented and briefly described as concerns nature, objectives and possible applications to concrete situations. [less ▲]

De la patria potestas (puissance paternelle) à l'autorité parentale

in L'enfant, avenir des droits de l'homme (1996)

Pseudoaneurisma gigante del ventriculo izquierdo

in Prensa Medica Argentina (1996), 83(10), 919-924

A 85 years old patient was hospitalized because of thoracic pain, lasting since three months. He suffered of Parkinson's disease and he was a smoker. The pain increased with cough and Vansalva's test. His ... [more ▼]

A 85 years old patient was hospitalized because of thoracic pain, lasting since three months. He suffered of Parkinson's disease and he was a smoker. The pain increased with cough and Vansalva's test. His left arm was cianotic. An arterial obstruction was suspected. Dopler ultrasound of the left arm confirmed a partial obstruction of the left axillar artery. Surprisingly, thoracic scan and MRI found an important cardiomegaly. The heart was in contact with the diaphragmatic and gastric region. Ecocardiography confirmed a 7 cm pseudo aneurysm of the left ventricle. Coronarography showed extreme hypokinesia of the left ventricle. There was also an obstruction of the right coronary and 50 % stenosis of the left coronary. Pseudo aneurysm was a complication of myocardial infarction of the left ventricle. Surgery was offered to the patient, but he declined the intervention. He was dismissed with medical treatment and anticoagulation. The patient deceased three months later. [less ▲]

Incidence du martelage sur l'exploitation mécanisée des premières éclaircies résineuses

in Silva Belgica (1996), 103(6), 7-14

Fréquence et importance du charriage dans des rivières à charge de fond graveleuse

in Géomorphologie : Relief, Processus, Environnement (1996)