Analyse de la variance des chromatides dans les endoréduplications

Résumé Une analyse de la variance est proposée pour comparer la variance entre chromatides soeurs, celle entre chromosomes d'un même doublet et celle entre doublets homologues, un doublet se composant d'um chromosome et de sa copie obtenue par endoréduplication. La variance totale des chromatides est comparée à celle due uniquement aux erreurs de mesure.

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Formulae are suggested to analyse the variance of chromatids in karyotypes with replicated chromosomes. For chromosomes 1, 2 and 3, it is possible to analyse the variance between sister chromatids, the variance between replicated chromosomes and the variance between homologous chromosomes. It is also possible to compare the total variance of chromatids (1, 2 or 3) with the variance originating only in errors of measure.

     

Comparaison des modeles de neurone de Hodgkin-Huxley et de Nelson

Le modèle de Nelson peut-être considéré comme une approximation du modèle de Hodgkin-Huxley. Moins précis, il est plus maniable. Le modèle de Nelson peut également être considéré comme une généralisation du modèle de Hodgkin-Huxley. En effet, il introduit des liaisons synaptiques localisées ou diffusantes, et un processus de facilitation. Le mécanisme des liaisons synaptiques ne se traduit pas facilement dans le langage de Hodgkin-Huxley. Par contre, le processus de facilitation s'interprète facilement. Nelson's model can be taken as an approximation of Hodgkin-Huxley's model. Its precision is lesser, but it is more usable. Nelson's model can also be taken as a generalization of Hodgkin-Huxley's one; for it introduces localized or diffusing synaptic connexions and a facilitating process. The mechanism of synaptic connexions cannot be easily translated into Hodgkin-Huxley's language. On the contrary, the facilitating process is easily interpreted.      

A Propos de la Comparaison Graphique des Matrices de Variance

We compare variance-covariance matrices considered as matrices of similarities between variables. The first part recalls the mathematical bases of the proposed method. The second part treats a set of meteorological data.     

Comparaison des performances diagnostiques de la TEP au FNa avec et sans scanner couplé dans la recherche de métastases osseuses

IntroductionPerforming a CT acquisition along with a 18F-Fluoride PET study increases the effective dose delivered to the patient. We evaluated its value in the diagnosis of bone metastases.Material and methodsThree observers retrospectively analyzed 18F-Fluoride PET images (non-attenuation corrected) without CT and attenuation corrected images fused with CT in 50 patients with a cancer. The skeleton was divided into 17 areas. A score of malignancy from 1 to 5 was attributed to each area. An area-based analysis was done as well as a patient-based analysis. For the latter, the score of the area with the highest score was given to each patient. Clinical follow-up of at least 6 months, pathology or other imaging procedures served as gold standard.ResultsFor the three observers, the areas under the ROC curve of the area-based analysis were respectively 0.79, 0.97 and 0.70 without CT and 0.98, 0.98 and 0.96 with CT. The differences were significant (P < 0.05) for observers 1 and 3. The areas under the ROC curve of the patient-based analysis were respectively 0.86, 0.96 and 0.85 without CT and 0.97, 0.98 and 0.99 with CT and there was a significant difference for observer 3.ConclusionPerforming a CT acquisition along with an 18F-Fluoride PET study increases the homogeneity of the results obtained by different observers.     

Comparaison de la dose efficace en TEP/TDM et en TDM

Hybrid imaging, particularly positron emission tomography (PET) combined with CT has emerged in the field of oncology as a modality of choice. The concomitant realization of a standard CT examination, however, raises the question of the additional dose delivered to the patient. This radiation burden could be avoided by performing a single PET/CT examination with injection of contrast media. To verify the potential dosimetric gain of this strategy, we compared the effective dose associated with each modality in a retrospective cohort of 151 patients, homogeneous in weight and size. The average effective dose for a PET/CT (injection of 5-6 MBq/kg of ¹⁸FDG) was 13.5 mSv, the CT dose representing approximately 80% of the PET dose. In our study, the average effective dose in CT thorax/abdomen/pelvis was 21.4 mSv, 60% higher than the PET/CT effective dose.     

Analyse de la structure fine des chromosomes du Gorille (Gorilla gorilla)

Summary Prometaphasic chromosomes of Gorilla, Homo and Pan are compared, using R, Q, T and H-bands techniques in complement of a previous work (Lejeune et al., 1973). Various mechanisms of chromosomal rearrangements are demonstrated with particular reference to heterochromatic segments. Some phylogenic conclusions are proposed.

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Zusammenfassung Prometaphase-Chromosomen von Gorilla, Mensch und Schimpanse werden mit hilfe der R-, Q-, T- und H-Bandentechnik verglichen; frühere Arbeiten (Lejeune et al., 1973) werden dadurch ergänzt. Verschiedene Mechanismen von Chromosomen-Rearrangements werden dargestellt; dabei finden die Heterochromatin-Segmente besondere Beachtung. Einige phylogenetische Folgerungen werden gezogen.

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Travail de l'E.R.A. n^o 47 du C.N.R.S.     

Action de l'antimycine A sur la respiration et la structure des mitochondries d'Euglena gracilis Z.

Summary Addition of antimycin A to a culture of Euglena gracilis Z growing with lactate causes an immediate increase of respiration, through a pathway not inhibited by cyanide. Several hours after antimycin addition, giant mitochondrion develop. They are easily observable in the light microscope after staining with a tetrazolium salt; and electron microscopy reveals that they have a ramified structure, with a matrix containing many cristae.     

Influence des variations expérimentales de la calcémie sur la morphologie fine des cellules C du rat et du poulet

Résumé Les expériences d'hypercalcémie aigües et chroniques provoquent chez le rat des modifications spectaculaires des cellules C. Ces résultats sont en accord avec les données physiologiques sur la sécrétion de calcitonine chez le mammifère. Chez le poulet, par contre, les mêmes expériences ne provoquent pas de modifications indiscutables des Corps ultimobranchiaux (C.U.B.). Seule, l'injection intraveineuse de calcium provoque une dégranulation d'ailleurs partielle et assez peu accusée, des cellules C. L'inertie réactionnelle des C.U.B., que nous constatons morphologiquement, ressort également des données contradictoires sur le rôle physiologique de la calcitonine chez l'oiseau.

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Influence of experimental modifications of calcemia on the fine structure of the C-cells in rat and in chicken

Summary Acute and chronic hypercalcemia in rats induce spectacular modifications of the C cells. These results are in agreement with the physiological data on calcitonin secretion in mammals. The same experiments in chickens, however fail to provide a net modification of the ultimobranchial body. Only an intravenous injection of calcium induces degranulation of the C cells, and even then, this is partial and hardly evident. The lack of the ultimobranchial body response as observed in our morphological study may be compared with the conflicting physiological data on the role of calcitonin in birds.

     

Catalogue des Vesperidae et des Cerambycidae de la faune de France (Coleoptera)

Ce catalogue des Vesperidae et Cerambycidae de la faune de France est fondé sur une vaste étude bibliographique et sur les observations des auteurs ainsi que celles, vérifiées, de nombreux amateurs. Les nombreuses modifications montrent la nécessité de la révision du dernier ouvrage de référence (Villiers 1978). Le bilan faunistique des recherches permet de dresser une liste de 251 taxa représentant 242 espèces actuellement présentes en France continentale et en Corse. Cette liste est sujette à de perpétuelles modifications liées aux fluctuations de populations, aux introductions et aux activités de recherche de nombreux amateurs. Ce travail de synthèse systématique, taxinomique et faunistique est une première étape pour la réalisation d’un atlas des Vesperidae et Cerambycidae de France et de Corse.     

Comparing children's Homo sapiens and chimpanzees' Pan troglodytes quantity judgments of sequentially presented sets of items

We presented a quantity judgment task that involved comparing two sequentially presented sets of items to preschoolers and chimpanzees using nearly identical pr...     

La symbiose du spermatozoide et de l'ovule,origine de l'ontogenese et de la phylogenese des metazoaires

The origin of metazoa implies the passage from an eukarote protozoan to a protozygote ancestor of a metazoan zygote. The most probable hypothesis is that of a symbiotic origin of the first zygote by association of two protists one signifying a spherical oocell and the other a flagellated spermatozoan; this could be the first step of the metazoan ontogenesis and therefore also of the phylogenesis. The genesis can also be explained by two haploid genomes NX NY, three gametes (two spermatozoa and one ovule), NX apparently being able to create both forms, and two zygotes. A double symbiosis, a chromosomic crossing-over and a selective expulsion can prove it.     

Comparaison paléocognitive des niveaux moustérien et magdalénien de la grotte Tournal (Bize, Aude)

We analyse the functional processing chain of large mammals acquired at the mousterian and magdalenian levels of the Tournal cave (Bize, Aude). Palethnologic results are analysed through a method from experimental psychology of goal oriented activities. The elements are the objects used by prehistoric man and their properties. Objects and properties are linked by binary relationships. These relationships are processed by software, SIMBOL, developed at the IPH, based on an algorithm initially published by the Laboratoire de psychologie expérimentale of Paris-8. SIMBOL returns the cognitive graph of the task representation for the mousterian and the magdalenian layer, allowing a rigorous comparison of the cognitive activities on both periods. The main result is that the logical structure is preserved when passing from one level to the other. This could be interpreted as a due to the noticeable cognitive similarity of the men from the different periods, along with the fact that cognitive complexity seems to be the same on both graphs. Cognitive fluidity improves from mousterian to magdalenian suggesting that cognitive mechanisms such as sense sliding and analogies could be easier at the magdalenian level. Could we interpret this result as a due to a greater creativity at the magdalenian level than at the mousterian one? Further investigations are needed to state this, as well as enhanced data volume, potentially allowed by this entirely new method.