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Sample records for etude par diffusion

  1. Contribution to the study of 14 MeV neutron scattering by {sup 12}C using a time-of-flight spectrometer (1963); Contribution a l'etude de la diffusion des neutrons de 14 MeV par {sup 12}C, a l'aide d'un spectrometre a temps de vol (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, P. [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-07-15

    Experimental measurements of 14 MeV fast neutrons scattering by {sup 12}C by time-flight spectrometer, with a 1.7 n. sec over-all resolution. The excitation of the 7.65 MeV level is observed. (author) [French] Etude experimentate de la diffusion par {sup 12}C des neutrons rapides de 14 MeV a l'aide d'un spectrometre de resolution totale de 17 n/s. Observation de l'excitation du niveau 0+ de 7,65 MeV. (auteur)

  2. Study by neutron diffusion of local order liquid sulfur around the polymerization transition; Etude par diffusion de neutrons de l`ordre local du soufre liquide autour de la transition de polymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Descotes, L.

    1994-05-01

    We studied the liquid sulfur according to the temperature. The sulfur is one of the most complicated elementary liquid. We experimented the neutron diffusion by the powder orthorhombic sulfur. The complexity at the polymerization transition are only accompanied by weak local structural transfer. 231 refs., 48 figs., 8 tabs., 3 annexes.

  3. Study of magnetic thin films by polarized neutron reflectivity. Off-specular diffusion on periodical structures; Etude de couches minces magnetiques par reflectivite de neutrons polarises. Diffusion non speculaire sur des structures periodiques

    Energy Technology Data Exchange (ETDEWEB)

    Ott, F

    1998-11-26

    Theoretical (Zeeman energy effects) and experimental (beam polarisation problems) progress have been made in the understanding of polarized neutron reflectivity with polarisation analysis. It has been shown that modelization and numerical simulations makes it possible to avoid to have to systematically measure a full set of reflectivity curves for each field and temperature condition. It has been possible to determine a magnetic profile as a function of the field in a magnetic bilayer system by using only a few points in the reciprocal space. This technique allows to considerable reduce the experiment time. In single nickel layer systems, we have shown that it is possible to induce magnetic rotation inhomogeneities when these systems are subjects to deformation strains. The effect are related to magneto-elastic constants gradients. In trilayer systems, with a ME constant modulation, we have been able to induce large magnetic rotation gradients. A new magneto-optic technique to measure the magnetization direction without rotating the magnetic field has been developed. The field of neutron reflectivity has been extended to off-specular studies. It has been possible to account quantitatively of the off-specular diffusion on 2-D model systems (prepared by optical lithography). This new technique should make it possible in the future to determine magnetic structures with a in-depth as well as lateral resolution. (author)

  4. Etude de la dynamique en régimes quasiharmonique et anharmonique de la phase basse température de la triéthylènediamine par diffusion cohérente inélastique des neutrons

    OpenAIRE

    Hedoux , A.; Sauvajol , J.L.; More , M.

    1988-01-01

    La triéthylènediamine N(CH2CH2)3N cristallise jusqu'à Tc = 351 K dans une phase solide ordonnée de symétrie hexagonale compacte. Les expériences de diffusion cohérente inélastique des neutrons réalisées dans la phase basse température s'inscrivent dans le cadre de l'étude du processus de la transition martensitique à Tc à partir de l'évolution avec la température des paramètres dynamiques. Ainsi les courbes de dispersion ont été déterminées à 190 K, 245 K et 295 K. Les mesures effectuées à te...

  5. La structure de l'eau liquide: Une etude thermique par spectroscopie infrarouge

    Science.gov (United States)

    Larouche, Pascal

    Le probleme de la structure de l'eau liquide est important car l'eau est le liquide le plus present sur Terre, et complexe, la quete d'un modele precis pour decrire comment fonctionne ce liquide ayant debute des la fin du dix-neuvieme siecle. Cette etude aborde ce probleme en etudiant l'effet de l'augmentation de la temperature sur H2O et D 2O purs a l'aide de la spectroscopie infrarouge. L'intervalle de temperatures scrute est 29--93.1°C. Les spectres enregistres sont des spectres MIR-ATR entre 650 et 6000 cm-1 . L'analyse par facteurs de ces donnees permet de montrer que deux et seulement deux facteurs principaux sont necessaires pour decomposer tous les spectres experimentaux. Ces resultats sont confirmes grace a l'analyse par facteurs de spectres de la region FIR. Par la suite, la transformation en spectres de la partie reelle n et imaginaire k de l'indice de refraction permet de combiner les donnees des regions MIR et FIR. Une fois ce calcul termine, les spectres de transmission complets de H 2O et D2O entre 25 et 90°C sont connus. Ils sont ensuite utilises pour calculer par extrapolation le spectre des especes constituant l'eau liquide, puis leur abondance en fonction de la temperature. L'extrapolation de ces abondances montre que les especes correspondent a des temperatures limites de --18 et 122°C. Par la suite, la decomposition gaussienne des spectres d'especes met en evidence la riche structure de ces objets et permet de demontrer que l'apparent deplacement du massif d'absorption OH (OD) est produit par une variation de l'intensite des bandes et non pas de leur deplacement. L'examen attentif des spectres des especes prouve qu'il n'y a pas de OH libres crees par l'augmentation de la temperature: meme a 93.1°C, chaque molecule possede quatre liens-H. Ces conclusions sont de plus confirmees par une analyse thermodynamique du passage des molecules de la phase solide a la phase gazeuse. Pour diversifier la nature des resultats experimentaux utilises, des

  6. Free diffusion of translation of macromolecules in solution with the rayleigh interferometer; Diffusion libre de translation des macromolecules en solution, par interferometrie de rayleigh

    Energy Technology Data Exchange (ETDEWEB)

    Leger, J.J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The aim of this study is to develop a rapid and accurate measurement, with the Rayleigh interferometer, of the free diffusion coefficient of translation of macromolecules in solution. After having explained the choice of a diffusion cell with laminar lateral flow, and explained the principle of the Rayleigh interferometer, a semi-automatic technique of free diffusion are then introduced. Solutions are proposed for systems composed of two or three components, such as biopolymers. The paper ends by drafting the possible treatment of recorded experimental data by means of electronic computer. (author) [French] Cette etude a ete entreprise pour mettre au point une methode precise et rapide de mesure, par interferometre de Rayleigh, du coefficient de diffusion libre de translation des macromolecules en solution. Apres avoir justifie le choix d'une cellule de diffusion a ecoulement laminaire lateral et explique le principe de l'interferometre de Rayleigh, l'auteur decrit une technique semi-automatique d'enregistrement des cliches d'interference. Il introduit ensuite les equations differentielles de diffusion libre et propose des solutions pour les systemes a deux et trois composants applicables aux biopolymeres. L'article se termine par une esquisse concernant le traitement des donnees experimentales enregistrees au moyen du calcul electronique. (auteur)

  7. The study of neutron transport by oscillation method; Etude du transport des neutrons par la methode de modulation

    Energy Technology Data Exchange (ETDEWEB)

    Raievski, V

    1959-07-01

    The oscillation method is of very general use for studying the behavior of thermal neutrons in media. The main experiments are described and a general theory of them is given. This theory, which is presented in the first part, is established using the two-group approximation which has proved its efficiency in the case of thermal neutron piles. The validity of the two-group approximation is recalled. This allows definition of the meaning of the parameters used in the theory and which are measured in these experiments. The experiments carried out by this method are described, especially those performed at the Centre d'Etudes Nucleaires de Saclay where the method has been extensively used. These experiments are interpreted by means of the general theory given previously. In this way, the identity of parameters measured by this method and those given by the theory is proved. This is particularly conclusive is the case of the mean life of neutrons in a pile. (author) [French] La methode de modulation est un procede tres general d'etude des proprietes neutroniques des milieux contenant des neutrons thermiques. Le present rapport a pour but de decrire les principales de ces experiences et d'en donner une theorie generale. Cette theorie, exposee dans la premiere partie, est etablie dons le cadre de l'approximation a deux groupes de vitesse qui a prouve son efficacite dons le cas des piles a neutrons thermiques. Le domaine de validite de l'approximation a deux groupes est rappele au debut, ce qui permet de definir avec precision la signification des parametres qui entrent dons la theorie et qui font l'objet de ces mesures. La deuxieme partie decrit les experiences realisees, en particulier celles effectuees au Centre d'Etudes Nucleaires de Saclay ou la methode a ete considerablement developpee. Ces experiences sont interpretees dans le cadre de la theorie generale exposee precedemment. On prouve ainsi l'identite des parametres mesures

  8. Correspondance Corbin-Ivanow ; Lettres échangées entre Henry Corbin et Vladimir Ivanow de 1947 à 1966. Publiées par Sabine Schmidtke, avec une préface de Christian Jambet, Paris, Travaux et mémoires de l’Institut d’Etudes Iraniennes, Diffusion

    OpenAIRE

    Lory, Pierre

    2010-01-01

    Ce volume regroupe 87 lettres échangées par C. Corbin et V. Ivanow, conservées par Mme Stella Corbin et publiées avec une annotation précise (identification des personnes, chronologie, bibliographie ) par S. Schmidtke. Le contenu est variable : échange d’information, demandes concernant des manuscrits et des livres surtout. Les débats de fond sont rares, mais transparaissent par moment entre Ivanow  agnostique caustique, pour qui le mysticisme relève du domaine de la psychiatrie  et Corbin...

  9. Etude par simulation hil des performances d'un statcom pour la ...

    African Journals Online (AJOL)

    Ce travail présente l'étude par simulation Hardware In the Loop (HIL) des performances d'un STATCOM pour la stabilisation de la tension délivrée par une génératrice asynchrone triphasée auto excitée dans un réseau autonome. Nous avons combiné l'utilisation du logiciel de simulation LABVIEW et la carte ARDUINO ...

  10. Study of cerenkov radiation. Production of {gamma} rays by electron accelerators; Etude du rayonnement de freinage. Production de rayons {gamma} par des accelerateurs d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    This study is a critical comparison of the theories of Bremsstrahlung. Experimental results obtained by the production of {gamma} radiation with electron accelerators are compared to the theoretical results in order to estimate the extent to which the various theories are valid. (author) [French] Cette etude est une synthese des theories du rayonnement de freinage. Des resultats experimentaux, obtenus par la production de rayonnements {gamma} avec des accelerateurs d'electrons, sont compares aux resultats theoriques afin d'evaluer les domaines de validite des diverses theories. (auteur)

  11. Studies of light water lattices by the homogeneous boron poisoning technique; Etude des reseaux a eau legere par la methode d'empoisonnement homogene au bore

    Energy Technology Data Exchange (ETDEWEB)

    Bailly, J.; Calament, J.; Girard, Y.; Golinelli, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    By homogeneously poisoning a critical facility with boric acid, one can balance important reactivities. Furthermore this technique is particularly interesting, due to the fact that it allows the substitution of cross sections to kinetic parameters in lattice calculations. With this use of boric acid as a poison arise important technological problems which are described in this report, the last part of which deals with the accuracy of the measurements made in these conditions. The main features of a lattice study made according to this moderator poisoning technique concern the determination of the concentration of dissolved boron which makes the multiplying assembly just critical and the determination of the reactivity factor as a function of temperature (this study has been carried out fill above 95 deg. C). (authors) [French] L'empoisonnement homogene d'une facilite critique par l'acide borique permet, outre d'effectuer des compensations de reactivites importantes, de jouer le role d'un intermediaire de mesure particulierement interessant par le fait qu'il conduit a substituer, dans le calcul des reseaux, des sections efficaces aux parametres cinetiques. Cette utilisation de l'acide borique comme poison ne va pas sans poser d'importants problemes technologiques qui sont decrits dans la presente etude, dont la derniere partie est consacree a la precision de mesures effectuees dans, ces conditions. Les points essentiels de l'etude d'un reseau suivant cette technique d'empoisonnement du moderateur, concernant la mesure de la concentration de bore dissous qui rend l'assemblage multiplicateur juste critique, ainsi que la determination du coefficient de reactivite en fonction de la temperature (l'etude a ete poussee au-dela de 95 deg. C). (auteurs)

  12. Etude par imagerie radar des pollutions pétrolières

    Directory of Open Access Journals (Sweden)

    G. Rees

    2004-06-01

    Full Text Available En Russie, chaque année, les déversements de pétrole représentent un cinquième de la production totale. Les plus importants se produisent dans le domaine périglaciaire où le milieu naturel est d’une extrême fragilité. Les pipelines sont soumis à de rudes conditions notamment à la corrosion et aux processus cryogéniques. Le risque de rupture augmente en conséquence. La surveillance des déversements d’hydrocarbures, contrainte par l’immensité et la fréquente inaccessibilité du réseau de pipelines, peut être réalisée par le recours à la télédétection. L’objectif de ce travail est de fournir, à travers l’exemple de la catastrophe d’Usinsk (Rép. de Komi survenue en 1994, des outils d’analyse des images radar. Outre leur capacité à s’affranchir du couvert nuageux, les capteurs radar apportent des informations complémentaires à celles fournies par des capteurs optiques. L’exploitation thématique de ces images est rendue difficile par un certain nombre de facteurs perturbateurs tels que les caractéristiques propres du capteur, la direction de visée, la topographie et le phénomène de chatoiement (speckle. Le travail présenté montre le rôle prépondérant joué par ces corrections qui permettent de disposer de données quantitatives comparables d’une date à une autre. La méthode mise au point ici pour le suivi temporel de l’épanchement de pétrole d’Usinsk à partir de trois images radar, est discutée notamment dans ses limites et son aspect opérationnel possible.

  13. ETUDE PAR DFT+U DE L’INTERACTION Ni-CeO2

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    Z CHAFI

    2010-12-01

    Full Text Available L’étude de l’interaction Ni-CeO2 a été entreprise en utilisant une méthode ab initio basée sur la DFT+U. Dans une première étape, les valeurs du paramètre d’Hubbard, Ueff, ont été déterminées après ajustement du paramètre de maille et de l’énergie de gap du volume de l’oxyde de cérium. Elles sont respectivement de 3 et 5 eV pour les approximations GGA et LDA. Nous avons ensuite étudié d’une part la possibilité d’insérer le nickel atomique dans le volume de CeO2. D’autre part, nous avons testé les effets de l’insertion et l’adsorption de Ni dans les surfaces les plus stables (111 et (110 de CeO2. Les résultats des calculs DFT+U sont en bon accord avec ceux que nous avons précédemment trouvé en utilisant un calcul DFT concernant les sites favorables de l’atome de nickel et le nombre de liaisons. Toutefois, l’approximation LDA+5 eV, a permis d’obtenir des énergies plus favorables ainsi que des distances comparables à celles observées expérimentalement à l’interface métal/oxyde dans les catalyseurs Ni/CeO2 synthétisés sous irradiation. Une expansion du volume est observée lors de l’insertion du nickel dans le volume de l’oxyde de cérium. Concernant l’adsorption sur les surfaces, la meilleure énergie est trouvée dans le cas où l’atome de nickel est situé en position bridge entre deux atomes d’oxygène sur la surface (110. Finalement, les calculs montrent que le nickel s’insère plus facilement dans la surface (110 avec une meilleure énergie d’insertion, obtenue par l’approximation LDA+5 eV, de 4,071 eV.

  14. Study of the artificial radioactivity of the marine medium using gamma spectrometry (1962-1966); Etude de la radioactivite artificielle du milieu marin par spectrometrie gamma (1962-1966)

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    Chesselet, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The results described in this study are relative to the artificial radioactivity of such elements as zirconium-95, niobium-95, ruthenium-103, ruthenium-106, cerium-141, cerium-144 and praseodymium-144 which were present in the atmospheric fallout between 1962 and 1964, and their incidence in superficial marine waters. Various physical, chemical or biological processes are studied by a high sensitivity gamma ray spectrometry technic, using those radioelements as 'tracers'. The change of state in sea water of an important fraction (about 50 per cent) of the radioactive particles going into the soluble phase - this phenomenon was not expected for those radioelements - controls the processes of accumulation in the planktonic biomass and the diffusion towards deeper waters. On the other hand, an 'in situ' spectrometry method is described. It enables the direct measurement in the sea of very low concentrations of some gamma ray emitters. The application of this method has made possible to carry out numerous observations in the surface waters of the Western Mediterranean sea and in the Bay of Biscay. It is shown that the mixing depth is closely connected to the depth of the thermocline. An accumulation process at this level is observed. The diffusion coefficients are similar to the thermal turbulent coefficient. The existence during several months of 'compartments' is established for the surface waters of the Bay of Biscay. From the establishment of the budget of fall-out, a comparative study shows that the rate of radioactive fallout on the maritime zone considered is always two to three times higher than on the neighbouring continental regions. Several explanations of this phenomenon are discussed. (author) [French] Les resultats decrits dans cette etude concernent la radioactivite artificielle sous forme de zirconium-95, niobium-95, ruthenium-103, ruthenium-106, cerium-141, cerium-144 et praseodyme-144 apportee par la retombee

  15. The study of some thiazinic and indaminic dye syntheses induced by ionising radiation; Etude de quelques syntheses de colorants thianziniques et indaminiques amorcees par les rayonnements ionisants

    Energy Technology Data Exchange (ETDEWEB)

    Balestic, S. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-03-15

    With a view to finding some radiochemical reactions applicable on an industrial scale for evaluating the radioactive waste from nuclear reactors, a systematic study was made of the radiochemical synthesis of thiazinic dyes such as methylene blue and Lauths' violet, on which the first tests were carried out in 1954. The first part of the study concerned the identification and the dosage, during radiolysis, of dyes by means of their absorption spectra after separation from the reaction medium by adsorption chromatography or ion-exchange; other radiolysis products such as ammonium chloride and hydrogen peroxide were also identified. During a later stage by systematically varying the physico-chemical parameters it was possible to determine the most favourable conditions for radio-synthesis; the maximum radiochemical yields obtained had the following values: G (Lauths' violet) 1,65; G (Methylene blue) = 1,75. Furthermore, the study of the influence of variously substituted aminated products on the radiochemical yield showed the possibility of synthesising Bindsehedlers green and Wursters blue by radiochemical methods. Finally the discovery of a fundamental intermediate product, Wursters red, together with the kinetic study of the chemical synthesis of methylene blue made it possible to determine the main stages of the reaction mechanism and to decide which of these stages could be attributed to ionising radiations in the case of the radiochemical synthesis. (author) [French] Dans le but de trouver des reactions radiochimiques susceptibles d'une application industrielle pour valoriser les dechets radioactifs provenant des reacteurs nucleaires, il a ete entrepris une etude systematique de la synthese radiochimique des colorants thiazimiques tels que le Bleu de Methylene et le Violet de Lauth dont les premiers essais ont ete effectues par Loiseleur en 1954. La premiere partie de l'etude a porte sur l'identification et le dosage des colorants formes

  16. Neutron scattering techniques for betaine calcium chloride dihydrate under applied external field (temperature, electric field and hydrostatic pressure); Etude par diffusion de neutrons du chlorure de calcium et de betaine dihydrate sous champ externe applique (temperature, champ electrique et pression hydrostatique)

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, O

    1997-11-17

    We have studied with neutron scattering techniques betaine calcium chloride dihydrate (BCCD), a dielectric aperiodic crystal which displays a Devil`s staircase type phase diagram made up of several incommensurate and commensurate phases, having a range of stability very sensitive to temperature, electric field and hydrostatic pressure. We have measured a global hysteresis of {delta}(T) of about 2-3 K in the two incommensurate phases. A structural study of the modulated commensurate phases 1/4 and 1/5 allows us to evidence that the atomic modulation functions are anharmonic. The relevance of the modelization of the modulated structure by polar Ising pseudo-spins is then directly established. On the basis of group theory calculation in the four dimensional super-space, we interpret this anharmonic modulation as a soliton regime with respect to the lowest-temperature non modulated ferroelectric phase. The continuous character of the transition to the lowest-temperature non modulated phase and the diffuse scattering observed in this phase are accounted for the presence of ferroelectric domains separated by discommensurations. Furthermore, we have shown that X-rays induce in BCCD a strong variation with time of irradiation of the intensity of satellite peaks, and more specifically for third order ones. This is why the `X-rays` structural model is found more harmonic than the `neutron` one. Under electric field applied along the vector b axis, we confirm that commensurate phases with {delta} = even/odd are favoured and hence are polar along this direction. We have evidenced at 10 kV / cm two new higher order commensurate phases in the phase INC2, corroborating the idea of a `complete` Devil`s air-case phase diagram. A phenomenon of generalized coexistence of phases occurs above 5 kV / cm. We have characterized at high field phase transitions between `coexisting` phases, which are distinguishable from classical lock-in transitions. Under hydrostatic pressure, our results

  17. Etude de la distribution des champs magnetostatiques dans une section d'essais de type CANDU chauffee par effet de joule

    Science.gov (United States)

    Hall, Darren

    Parmi tous les parametres physiques consideres lors de l'analyse de surete d'un reacteur nucleaire, le flux de chaleur critique (FCC) fait partie des plus importants. Afin d'etudier le FCC sous des conditions experimentales relativement securitaires, la chaleur degagee par le combustible nucleaire peut etre reproduite grâce a l'effetet de Joule. Or, afin de generer la puissance thermique necessaire pour les experiences sur le FCC des reacteurs CANDU, des courants electriques tres eleves de l'ordre de plusieurs dizaines de milliers d'amperes sont requis ce qui genere un champ magnetostatique tres intense capable d'interagir avec la section d'essais et l'instrumentation. Consequemment, l'industrie nucleaire est preoccupee par les effets de ce champ magnetique sur les donnees collectees et par les forces d'origine magnetique agissant sur le systeme. Dans ce contexte, le travail presente dans ce memoire de maitrise vise l'implementation d'une methodologie de calcul capable de fournir une information detaillee sur le champ magnetique engendre par ces courants. Toutefois, etant donne la complexitee du systeme, une etude magnetostatique appropriee requiert une methode numerique afin d'obtenir une distribution fiable du champ magnetique a travers differentes structures de la section d'essais. a cet effet, nous considerons dans le cadre de ce memoire le volume integral equation method (VIEM), une methode bien etablie basee sur les solutions integrales des equations de Maxwell. Plus precisement, nous employons le VIEM afin d'etudier la distribution du champ magetique a l'interieur de la section d'essais et pour determiner l'influence des prises concues pour le branchement des capteurs de pression sur la symetrie de cette distribution. Etant donne que les methodes integrales incluent les conditions aux limites et par consequent ne requierent pas l'emploi d'un critere de convergence, nous proposons une nouvelle technique de discretisation. L'emploi de cette procedure nous

  18. Point-of-care ultrasonography adoption in Canada: using diffusion theory and the Evaluation Tool for Ultrasound skills Development and Education (ETUDE).

    Science.gov (United States)

    Woo, Michael Y; Frank, Jason R; Lee, A Curtis

    2014-09-01

    Point-of-care ultrasonography (PoCUS) first appeared in the 1980s in North America, but the extent of the diffusion of its adoption is unknown. We characterized early PoCUS adoption by emergency physicians in Canada and its barriers to use using Rogers' diffusion of innovations theory. We developed a questionnaire based on a pilot study and literature review to assess past, current, and potential use of PoCUS and potential barriers to adoption. A Dillman technique for electronic surveys was used for dissemination. Using Rogers' diffusion of innovations theory, we developed and validated the Evaluation Tool for Ultrasound skills Development and Education (ETUDE). ETUDE scores allowed categorization of respondents into innovators, early adopters, majority, and nonadopters. Descriptive statistics, correlations, and χ² statistics were used to analyze the data. The 296 respondents (36.4% of 814 surveyed) had a median age of 40 and were 72.5% male. Adoption scores using ETUDE revealed nonadopters (18.8%), majority (28.7%), early adopters (34.5%), and innovators (18.0%). Respondents endorsed "always" using PoCUS currently and in the future for focused assessment with sonography in trauma (FAST) (current 41.8%/future 88.4%), first trimester pregnancy (current 23.3%/future 73.7%), suspected abdominal aortic aneurysm (current 32.7%/future 92.6%), basic cardiac indications (current 30.7%/future 87.5%), and central venous catheterization (current 17.0%/future 80.3%). Several barriers to PoCUS were identified for part-time emergency physicians and those working in inner-city/urban/suburban settings. This is the first study to determine the state of adoption and barriers to the introduction of PoCUS in Canadian emergency medicine practice. The novel validated ETUDE instrument should be used to evaluate the uptake of PoCUS over time.

  19. Contribution to the study of the role of diffusion in the growth of crystals from solution; Contribution a l'etude du role de la diffusion dans la croissance des cristaux a partir de solution

    Energy Technology Data Exchange (ETDEWEB)

    Quivy, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-12-01

    'un oculaire micrometrique et de chronophotographies. On a d'autre part utilise la methode interferentielle en lumiere polarisee pour determiner la distribution de la concentration au voisinage du cristal; cela a permis, ayant mesure par ailleurs le coefficient de diffusion, de calculer la vitesse de croissance et de constater un desaccord, de l'ordre de deux, avec les mesures directes. Celui-ci peut meme atteindre une valeur de dix dans le cas de substances tres solubles, lesquelles font l'objet d'une etude de R. ITTI. (auteur)

  20. Electronic temperature measurement on the deca II plasma using the Bremsstrahlung; Mesure de la temperature electronique du plasma de deca II par etude du rayonnement de freinage

    Energy Technology Data Exchange (ETDEWEB)

    Dumas, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-06-01

    The electronic temperature of the DECA II machine's plasma is determined by studying the Bremsstrahlung. Two types of detectors are used for this measurement, a set scintillator-photo-multiplicator and a photoelectric effect detector with a massive silver target. The method used is the classical 'absorbent method', The absorbents used are thin formvar foils whose thickness is between 600 and 12 500 angstrom. The measurements done in two different working conditions of the DECA II machine have given: Te {approx_equal} 200 eV in the first case and Te {approx_equal} 70 eV in the second case. (author) [French] Nous avons determine la temperature electronique du plasma de la machine DECA II par l'etude du rayonnement de freinage. Pour cette mesure nous avons utilise deux types de detecteurs: des ensembles scintillateur-photomultiplicateur et un detecteur a effet photoelectrique a cible massive en argent. La methode utilisee pour cette mesure est la classique methode des absorbants. Nous avons utilise des feuilles de format tres mince (de 600 a 12 500 angstrom) comme absorbant. Les mesures faites dans deux regimes de travail differents de la machine DECA II nous ont conduit a: Te {approx_equal} 200 eV dans un cas et Te {approx_equal} eV dans l'autre cas. (auteur)

  1. A method for estimating the diffuse attenuation coefficient (KdPAR)from paired temperature sensors

    Science.gov (United States)

    Read, Jordan S.; Rose, Kevin C.; Winslow, Luke A.; Read, Emily K.

    2015-01-01

    A new method for estimating the diffuse attenuation coefficient for photosynthetically active radiation (KdPAR) from paired temperature sensors was derived. We show that during cases where the attenuation of penetrating shortwave solar radiation is the dominant source of temperature changes, time series measurements of water temperatures at multiple depths (z1 and z2) are related to one another by a linear scaling factor (a). KdPAR can then be estimated by the simple equation KdPAR ln(a)/(z2/z1). A suggested workflow is presented that outlines procedures for calculating KdPAR according to this paired temperature sensor (PTS) method. This method is best suited for conditions when radiative temperature gains are large relative to physical noise. These conditions occur frequently on water bodies with low wind and/or high KdPARs but can be used for other types of lakes during time periods of low wind and/or where spatially redundant measurements of temperatures are available. The optimal vertical placement of temperature sensors according to a priori knowledge of KdPAR is also described. This information can be used to inform the design of future sensor deployments using the PTS method or for campaigns where characterizing sub-daily changes in temperatures is important. The PTS method provides a novel method to characterize light attenuation in aquatic ecosystems without expensive radiometric equipment or the user subjectivity inherent in Secchi depth measurements. This method also can enable the estimation of KdPAR at higher frequencies than many manual monitoring programs allow.

  2. Radio-vulcanization of natural rubber in the latex phase. Study of an experimental 1 tonne per hour production; Radio-vulcanisation du caoutchouc naturel en phase latex. Etude d'une production experimentale de 1 tonne par heure

    Energy Technology Data Exchange (ETDEWEB)

    Leveque, P.; Puig, J.R.; Roudeix, H. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    After briefly reviewing the main research carried out on the radio-vulcanization of latex and elastomers, a description is given of 4 types of cell which have been used successively with a view to industrial irradiation. They have made it possible to acquire the information necessary for resolving the main problem arising during irradiation - the formation of coagulum. The first two cell are designed for irradiation by a horizontal beam ('Dynamitron'), the two others use a vertical beam ('Circe'). The study of the properties of the rubber obtained shows it to compare favorably with 'Revultex'. In the appendix are given some characteristics of natural latex and information about its processing. (authors) [French] Apres un rappel des principales etudes sur la radio-vulcanisation du latex et des elastomeres, on decrit les quatre types de cellules successivement essayes en vue de l'irradiation industrielle. Ils ont permis d'acquerir les informations necessaires a la resolution du probleme principal pose par l'irradiation, la formation de coagulum au cours de celle,-ci. Les deux premiers sont concus pour l'irradiation par un faisceau horizontal ('Dynamitron'), les derniers par un faisceau vertical ('Circe'). L'etude des proprietes du caoutchouc obtenu montre qu'il se compare favorablement au 'Revultex'. Un apercu est donne en annexe des caracteristiques du latex naturel et de sa mise en oeuvre. (auteurs)

  3. Contribution to the study of the stability of water-cooled reactors; Contribution a l'etude de la stabilite des reacteurs refroidis par de l'eau

    Energy Technology Data Exchange (ETDEWEB)

    Coudert, C. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1969-06-01

    This work is devoted to the study of the stability of reactors cooled by water subjected only to natural convection. It is made up of two parts, a theoretical study and experimental work, each of these parts being devoted to a consideration of linear and non-linear conditions: - calculation of the transfer function of the reactor using neutronic and hydrodynamic linear equations with the determination of the instability threshold; - demonstration of the existence of the limiting oscillation cycle in the case of a linear feedback using MALKIN'S method; - measurement and interpretation of the reactor's transfer functions and of the hydrodynamic transfer functions; and - analysis of the noise due to boiling. (author) [French] Dans ce travail on etudie la stabilite des piles refroidies par de l'eau circulant en convection naturelle. Cette etude se divise en deux parties: un travail theorique et un travail experimental, chacune de ces parties comportant une etude lineaire et une etude non-lineaire: - calcul de la fonction de transfert du reacteur a partir des equations lineaires de la neutronique et de l'hydrodynamique avec determination du seuil d'instabilite; - demonstration de l'existence du cycle limite des oscillations dans le cas d'une retroaction lineaire en utilisant la methode de MALKIN; - mesure et interpretation de la fonction de transfert du reacteur et des fonctions de transfert hydrodynamiques; et - analyse du bruit d'ebullition. (auteur)

  4. Experimental study of contamination by inhalation of radioactive iodine aerosols. Biological balance; Etude experimentale de la contamination par inhalation d'aerosols d'iode radioactif bilan biologique

    Energy Technology Data Exchange (ETDEWEB)

    Marble, G. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    Several articles have been published concerning research into contamination produced by inhalation of radioactive iodine aerosols in monkeys. Results dealing with the biological balance of this contamination are presented and discussed in this report. (author) [French] L'etude experimentale de la contamination par inhalation d'aerosols d'iode radioactif effectuee chez le singe a fait l'objet de plusieurs publications. Les resultats concernant le bilan biologique de cette contamination sont presentes et discutes dans ce rapport. (auteur)

  5. Study of various processes for marking sediments with gold-198; Etude de divers procedes de marquages de sediments par l'or 198

    Energy Technology Data Exchange (ETDEWEB)

    Jeanneau, B. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-12-15

    The use of radioactive isotopes for the study of sediment deposits is based mainly on two methods: marking in the mass - a glass of an element which can be activated replaces the sediment; surface marking - a physico-chemical process is used to deposit a radio-element at the surface of the sediment. The second process is used in particular for sands when it is advantageous to have a large number of particles for statistical analysis. The aim of this work was to develop a rapid and simple method of marking which could be applied on the actual site of the experiment where equipment, may be limited. The method recommended for marking sand with gold-198 is a combination of the Petersen (treatment with tin chloride) and Campbell (treatment with silver) methods combined with prior treatments with nitric acid and caustic soda. Using this method it is possible to deposit 125 mg of gold per kilo of sediment with a yield of 95 per cent (i.e. 10 Ci/kg) using a hydrochloric acid solution containing gold. The problem of the solidity of the deposits, of their value and of their reproducibility is discussed from the point of view of the mineral constitution of the sand. (author) [French] L'utilisation d'isotopes radioactifs pour l'etude des deplacements sedimentaires fait, principalement appel a deux methodes: le marquage massique - un verre contenant un element activable remplace le sediment; le marquage superficiel - un traitement physico-chimique permet de deposer un radioelement a la surface du sediment. Le second procede est surtout employe pour les sables lorsqu'il est utile de disposer d'un grand nombre de grains pour des raisons statistiques. Le but de ce travail etait de mettre au point une methode simple et rapide de marquage pouvant etre appliquee sur le site meme de l'experience pour les utilisateurs disposant d'un equipement limite. Le procede preconise pour le marquage des sables par l'or 198 est une combinaison des methodes

  6. E. P. R. spectroscopic study of nitroxide mono- and bi-radicals; Etude par spectroscopie de resonance paramagnetique electronique de monoradicaux et de biradicaux nitroxydes

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, H. [Commissariat a l' Energie Atomique, Grenoble, 38 (France). Centre d' Etudes Nucleaires

    1967-07-01

    experimentales d'etude de produits parfaitement bien definis au point de vue structure chimique. L'etude par resonance paramagnetique electronique de monoradicaux nitroxydes conduit a la determination des axes et des elements du tenseur d'interaction hyperfine electron-noyau d'azote et du tenseur d'anisotropie du facteur de Lande: les resultats sont relies a la structure electronique des radicaux. On interprete qualitativement l'influence du solvant sur les elements des tenseurs, ainsi que les elargissements selectifs des raies hyperfines en milieu visqueux. Dans les biradicaux nitroxydes, la structure hyperfine depend non seulement des interactions magnetiques propres a chaque monomere, mais egalement de la grandeur de l'interaction d'echange separant les etats singulet et triplet du dimere; les biradicaux etudies ici sont les premiers composes organiques pour lesquels l'influence de l'echange sur la structure hyperfine est clairement mise en evidence. La presence de deux electrons non apparies introduit egalement une interaction magnetique dipolaire electron-electron, que l'on peut mettre a profit, dans le cas d'un echange intermediaire, pour determiner le signe de l'echange en etudiant le biradical dans un cristal liquide. Ces composes presentent egalement des elargissements selectifs de transitions hyperfines lorsque la viscosite du solvant croit. La theorie utilisee pour interpreter les largeurs de raie des monoradicaux est etendue au cas des biradicaux; elle rend compte des resultats experimentaux si l'on introduit simultanement les anisotropies des facteurs de Lande et des interactions dipolaires electrons-noyaux et electron-electron, en conduisant a une autre determination du signe de l'echange. (auteur)

  7. Electronic diffraction study of the chlorination of nickel; Etude par diffraction electronique de la chloruration du nickel

    Energy Technology Data Exchange (ETDEWEB)

    Vigner, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    A study has been made of the chlorination of the (100), (110) and (111) crystal faces of nickel using high energy electron diffraction and electron microscopy. Two methods have been used: bombardment with chlorine ions having an energy of between 10 and 30 keV, and direct chlorination in a diffractor at pressures of about 10{sup -4} torr. It has thus been possible to show the very special properties of nickel chloride (CdBr{sub 2} type, space group R 3-bar m) which is always formed along the (0001) plane, whatever the orientation of the substrate. It has also been possible to attain the metal-halide interface and to show the existence of two-dimensional chemisorbed films which are ordered or disordered according to the crystal orientation. (author) [French] La chloruration des faces (100) (110) et (111) du nickel a ete etudiee par diffraction des electrons de haute energie et par microscopie electronique. Deux methodes ont ete utilisees: le bombardement avec des ions chlore ayant une energie comprise entre 10 et 30 keV, et la chloruration directe dans un diffracteur pour des pressions de l'ordre de 10{sup -4} torr. Ainsi ont ete mises en evidence les proprietes tres particulieres du chlorure de nickel (type CdBr{sub 2}, groupe spatial R 3-bar m) qui s'accole toujours suivant le plan (0001), quelle que soit l'orientation du substrat. Il a ete egalement possible d'atteindre l'interface metal-halogenure et de montrer l'existence de couches chimisorbees bidimensionnelles, ordonnees ou desordonnees suivant l'orientation cristalline etudiee. (auteur)

  8. Development of black scattering coatings for space application (etude de traitements noirs diffusants pour application spatiale)

    Science.gov (United States)

    Mestreau-Garreau, Agnes; Pezant, Christian; Cousin, Bernard; Etcheto, Pierre; Otrio, Georges

    2017-11-01

    In the context of Research and Technology (R&T), studies have been performed on the coatings of vane edge in the 0.4 to 1 μm spectral range. The main purposes of the study were to improve the diffusing black coatings available on the market and to look for other diffusing black coatings. At the same time, we have also improved the machining technologies of vane edges. The characterisation (thermal tests, radiometric measurements, adhesion tests) of the most promising technologies has been carried out. The results have pointed out the stainless steel vanes with the edge obtained by polishing or by advanced grinding.

  9. Etude du déplacement de l'huile par le gaz Analysis of Oil Displacement by Gas

    Directory of Open Access Journals (Sweden)

    Delclaud J.

    2006-11-01

    Full Text Available Les ingénieurs « réservoir u prévoient avec beaucoup de difficultés l'exploitation des gisements en utilisant les relations perméabilités relatives-saturations fournies par les laboratoires. Ceci amène à se demander si le concept est valide en écoulement transitoire, si les mesures sont effectuées selon des procédures convenables, si la relation statique entre la pression capillaire et la saturation est conservée en régime variable, si enfin la méconnaissance des lois de combinaison de ces fonctions n'est pas la cause de l'insatisfaction des ingénieurs. Le travail présenté ici traite des trois premiers points. Deux séries d'expériences sont réalisées à cet effet : - d'une part, des expériences de déplacement de l'huile par le gaz, où l'on s'intéresse à l'établissement et à la caractérisation de phénomènes pseudo-stationnaires. Les échantillons poreux choisis sont de faibles dimensions. Ils permettent ainsi de réduire la durée des périodes transitoires; - d'autre part, des expériences de déplacement sur des échantillons homogènes de grandes dimensions où l'on étudie les phénomènes transitoires. On mesure, tout au long du massif, la pression dans les deux phases et la saturation. Les perméabilités relatives sont calculées en tout point et à tout instant, à partir des équations de continuité. II ressort de ces travaux que la relation perméabilité relative-saturation est la même en tout point du milieu poreux, tout au long de l'écoulement transitoire, qu'elle ne dépend pas de la vitesse d'écoulement et que la relation pression capillaire-saturation coïncide avec celle établie par la méthode des états restaurés. La validité du concept en écoulement transitoire est donc prouvée. La méthode de WELGE, JOHNSON, BOSSLER et NAUMANN conduit à des résultats différents de ceux obtenus. On montre, pour expliquer ces écarts, que les hypothèses théoriques de cette méthode sont

  10. Study of the machining of uranium carbide rods obtained by continuous casting under electronic bombardment; Etude de l'usinage de barreaux de carbure d'uranium obtenus par coulee continue sous bombardement electronique

    Energy Technology Data Exchange (ETDEWEB)

    Rousset, P.; Accary, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The authors consider the various methods of machining uranium mono-carbide and compare them critically in the case of their application to uranium carbide obtained by fusion under an electronic bombardment and continuous casting. This study leads them to propose two mechanical machining methods: cylindrical rectification and center-less rectification, preceded by a preliminary roughing out of a cylinder, the latter appearing more suitable. A study of the machining yields as a function of the diameter of the rough bars and of the diameter of the finished rods has shown that an optimum value of the rough bar diameter exists for each value of the finished rod diameter. It is found that the yield increases as the diameter itself increases, this yield rising from 45 per cent to around 70 per cent as the diameter of the rough bars increases from 25-26 mm to 37-38 mm. (authors) [French] Les auteurs envisagent les differentes methodes d'usinage du monocarbure d'uranium et se livrent a une etude critique de celles-ci, dans le cas de leur application a l'usinage de barreaux de carbure d'uranium obtenus par fusion sous bombardement electronique et coulee continue. Cette etude les conduit a proposer deux methodes d'usinage mecanique: la rectification cylindrique et la rectification 'centerless', precedee d'un ebauchage par carottage, la seconde paraissant la plus appropriee. L'etude des rendements d'usinage en fonction du diametre des barreaux bruts et du diametre des barreaux finis, a mis en evidence une valeur optimale du diametre des barreaux bruts pour chaque valeur du diametre des barreaux usines. Elle a montre que le rendement croit lorsque le diametre croit lui-meme, ce rendement passant d'environ 45 pour cent a environ 70 pour cent, lorsque le diametre des barreaux bruts passe de 25-26 mm a 37-38 mm.

  11. X-spectrographic method for plutonium detection. Application to contamination measurements in humans; Etude d'une methode de detection du plutonium par spectrographie X. Application a la mesure des contaminations sur l'homme

    Energy Technology Data Exchange (ETDEWEB)

    Michel Trouble [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    After reviewing the radio-toxicology of plutonium 239 and conventional detection methods using its {alpha}-radiation, the author considers the measurement of the X emission spectrum of plutonium 239 using a proportional counter filled with argon under pressure. This preliminary work leads to the third part of this research involving the detailed study of the possibilities of applying thin alkali halide crystal scintillators to the detection of soft plutonium X-rays; there follows a systematic study of all the parameters liable to render the detection as sensitive as possible: movement due to the photomultiplier itself and its accessory electronic equipment, nature and size of the crystal scintillator as well as its mode of preparation, shielding against external parasitic radiation. Examples of some applications to the measurement of contamination in humans give an idea of the sensitivity of this method. (author) [French] Apres un apercu de la radiotoxicologie du plutonium 239 et des methodes classiques de detection par son rayonnement {alpha}, on etudie le spectre d'emission X du plutonium 239 avec un compteur proportionnel rempli avec de l'argon sous pression. Ce travail preliminaire permet d'aborder la troisieme partie de cette etude dans laquelle nous examinons d'une fagon approfondie les possibilites d'application des cristaux scintillateurs minces d'halogenure alcalin a la detection du rayonnement X mou du plutonium; suit une etude systematique de tous les parametres susceptibles de rendre la detection aussi sensible que possible: mouvement propre du photomultiplicateur et de l'electronique associee, nature et dimensions du cristal scintillateur ainsi que son mode de fabrication, blindage contre les rayonnements parasites exterieurs. Quelques applications a la mesure des contaminations sur l'homme permettent d'apprecier la sensibilite de cette methode. (auteur)

  12. Study of catanionic systems by X-rays and neutron scattering; Etude de melanges de catanioniques par diffusion de rayonnement

    Energy Technology Data Exchange (ETDEWEB)

    Vaudrin, C.; Dubois, M.; Zemb, T

    2001-07-01

    The catanionic ternary phase diagram, myristic acid, cetyl-trimethyl-ammonium hydroxide, water is known since 1998. Many specific structures, as discs, icosahedral or extremely swollen lamellar phases, have been characterised. The work presented here is looking particularly toward lamellar domains, and its aim is to understand on one hand the organisation of each surfactant in the lamellar plane, and on the other hand to understand the influence of the excess of surfactant, i.e. the surface charge of the aggregates. DSC analyses and X-rays scattering confirmed the very importance of the head-group interactions. Indeed, the polar heads of opposite sign are closed together and induced a crystallisation of the alkyl chains. But, by the fact that the chains are physically and not chemically linked, the structure keeps a huge thermal expansion coefficient. Some kinetic experiments are also summed up in this report. The gel or fluid state of the chains appears to be an important parameter in the kinetic of formation and of destruction of the lamellar phases. (authors)

  13. Contribution to the study of the geophysical behaviour of lead-210 by application of alpha spectrometry; Contribution a l'etude du comportement geophysique du plomb 210 par application de la spectrometrie alpha

    Energy Technology Data Exchange (ETDEWEB)

    Nezami, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    A study of the changes in the lead-210 contents of rain-water and of water produced by melting polar ice has required the development of a method for dosing lead-210, an {alpha} emitter. This method is 40 times more sensitive than that which measures the lead-210 by bismuth-210, a ({beta} emitter. The first part of the report presents the study of a spectrometry using semiconductor detectors; a catalogue of a spectra shows the advantages of this method. In the second part will be found at first a new chemical separation method for polonium-210 and the results obtained with this method. The main results obtained on the geophysical behaviour of lead-210 are the following: - the monthly lead-210 and polonium-210 contents in rain water are approximately constant with time. - in the Gif-sur-Yvette region, the clean-up by 'dry fall-out' can attain 40 to 50 per cent of the total fall-out. - a study of Antarctic ice samples makes it possible to determine an annual accumulation rate equivalent to 13.8 cm of water and to show discrepancies in the periodic concentrations which correspond to the latest maxima of solar activity. - a balance is drawn up between the radon produced by the continents and the lead-210 fall-out. (author) [French] Une etude sur les variations de la teneur en plomb 210 des eaux de pluie et des eaux de fusion des glaces polaires a necessite la mise au point d'une methode de dosage du plomb 210 emetteur {alpha}. Cette methode permet d'obtenir une sensibilite quarante fois superieure a celle dosant le plomb 210 par le bismuth 210 emetteur {beta}. La premiere partie du travail presente l'etude de la spectrometrie {alpha} par detecteur a semiconducteurs, un catalogue de spectres {alpha} met en evidence les avantages de cette methode. Dans la deuxieme partie on trouvera en premier lieu une nouvelle methode chimique de separation du polonium 210 ainsi que les resultats obtenus grace a cette methode. Les principaux resultats sur le

  14. Contribution to the study of detonation initiation by shock in solid explosives (1961); Contribution a l'etude de l'initiation de la detonation par choc dans les explosifs solides (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Fauquignon, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-05-15

    When a shock wave is induced in an explosive, it can initiate chemical reactions which lead more or less rapidly to a stable detonation state. In this study more particular attention was paid to the transition phase, in which has been evaluated the increases in the wave velocity, the pressure, and the electrical conductivity. The influence of the nature of the medium in front of the wave and in contact with the explosive has also been the subject of an experimental study designed to determine the extent to which its nature can be ignored and, subsequently, to characterise the initiation conditions using only the shock intensity induced in the explosive. Finally, the results were generalized for various explosive compositions and led to the development of a possible mechanism for shock initiation. (author) [French] Lorsqu'une onde de choc est induite dans un explosif, elle peut y amorcer des reactions chimiques qui conduisent plus ou moins rapidement a un regime de detonation stable. Dans cette etude, on s'est interesse plus particulierement a la phase transitoire dans laquelle on a evalue l'accroissement de la vitesse d'onde, de la pression et de la conductibilite electrique. L'influence du milieu amont, au contact de l'explosif, a egalement fait l'objet de recherches experimentales de facon a determiner dans quelle mesure on pouvait s'affranchir de sa nature et, par suite, caracteriser les conditions d'initiation par la seule intensite du choc induit dans l'explosif. Enfin, les resultats ont ete generalises a diverses compositions explosives et ont conduit a l'elaboration d'un schema possible du mecanisme de l'initiation par choc. (auteur)

  15. Etude des polysaccharides pariétaux de la pomme extraction et caractérisation par des methodes chimiques et enzymatiques.

    NARCIS (Netherlands)

    Renard, C.M.G.C.

    1989-01-01

    La composition de la paroi de pomme et les connections entre polymeres parietaux ont ete etudies par des methodes chimiques et enzymatiques. La paroi de pomme, riche en pectines et cellulose ne contient pas d'acides phenoliques. La pectine soluble, extraite par un agent chelatant est pauvre en oses

  16. Study of the fluctuations of the partial and total radiative widths by neutron capture resonance method; Etude des fluctuations des largeurs radiatives partielles et totales par la capture des neutrons de resonance

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, V.D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    Radiative capture experiments by neutron time-of-flight methods have been made for following studies: distribution of partial radiative widths, effects of correlation between different radiative transitions, fluctuations of total radiative widths {gamma}{sub {gamma}} from resonance to resonance, variation of {gamma}{sub {gamma}} with number of mass and the search for the existence of potential capture. Also, some other experiments with the use of neutron capture gamma-rays spectra have been investigated. (author) [French] Par la capture des neutrons de resonance dont les energies sont selectionnees a l'aide de la technique du temps de vol, differents types d'experiences ont ete realisees concernant les etudes des distributions des largeurs radiatives partielles, des effets de correlation entre differentes voies de desexcitation, de la fluctuation des largeurs radiatives totales {gamma}{sub {gamma}} de resonance a resonance, de la variation de la quantite {gamma}{sub {gamma}} en fonction du nombre de masse et de la mise en evidence de l'existence du processus de capture potentielle. Quelques autres applications de l'emploi du spectre de rayons gamma ont egalement ete presentees. (auteur)

  17. Contribution to the studies on the mineral content of plant material through radioactivation analysis; Contribution a l'etude de la composition minerale des matieres vegetales au moyen de l'analyse par radioactivation

    Energy Technology Data Exchange (ETDEWEB)

    Fourcy, A. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-03-15

    Radioactivation analysis is by its great sensibility or its rapidity quite helpful in plant biology and agronomy. Specific composition of plants and results to obtain in biological experimentation have needed a practical research on analytical methods for plant materials, using for radioactivation swimming-pool reactor neutrons and 14 MeV neutrons from a generator. Dosage process for 25 elements is exposed, taking account of the interest of the analysis for each element, the average amount occurring in plants and the result obtained. Many applications are developed, concerning nutrition physiology, genetics, parasitology, toxicology, control of manufactured agricultural and pharmaceutical products industrial and pesticides residues, ecology, radioecology and biochemistry. (author) [French] L'analyse par radioactivation, par sa grande sensibilite ou sa rapidite, est susceptible de rendre de nombreux services en biologie vegetale et en agronomie. La composition particuliere des plantes et les buts recherches dans l'experimentation ont exige une etude concrete des methodes d'analyse propres a la matiere vegetale en utilisant, pour la radioactivation, soit un reacteur de type piscine a eau legere, soit un accelerateur generateur de neutrons de 14 MeV. Le mode de dosage de 25 elements est expose en tenant compte de l'interet de l'analyse de chaque element, des teneurs moyennes rencontrees dans les plantes, et du resultat atteint. De nombreuses applications sont developpees qui touchent a la physiologie de la nutrition, la genetique, la parasitologie, la toxicologie, le controle des fabrications, les pollutions industrielles, l'ecologie, la radioecologie et la biochimie. (auteur)

  18. Etude des vibrations libres d’une boite de vitesses par la méthode des éléments finis

    OpenAIRE

    BOUZIDI, IMANE

    2014-01-01

    La fonctionnalité de la boîte de vitesse est de transmettre la puissance fournie par un moteur aux roues du véhicule, Ce travail vise à prédire le comportement dynamique de la transmission par engrenage dans une boite de vitesses. On modélisera le comportement de la transmission par engrenage ; les engrenages qui sont assimilés a des cylindres rigides, les arbres qui sont introduits via des éléments finis de poutres de Timochenko, au niveau des noeuds du modèle globale. Pour fo...

  19. Study by neutrons diffusion and X-rays of structural and magnetic properties of Bi{sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n+4+{delta}} type superconductive cuprates; Etude par diffusion des neutrons et des rayons X des proprietes structurales et magnetiques des cuprates supraconducteurs de type Bi{sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n+4+{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliu-Doloc, L.

    1995-09-22

    In this work we have used inelastic and elastic neutron and X-ray scattering techniques for characterizing the incommensurate structural distortions in compounds belonging to the family Bi{sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n+4+{delta}} of high-Tc superconducting cuprates. We have searched the existence of structural instabilities specific of the CuO{sub 2} planes and of magnetic instabilities. The modulated structure of the 2212 phase has been refined from single-crystal neutron diffraction results and importance of distortion of CuO{sub 2} planes has thus been determined. It is shown that the additional oxygen is not ordered three-dimensionally within the modulated structure and that the information about it is contained in diffuse scattering results. A model of the short-range order associated with additional oxygen atoms is proposed and discussed. The temperature studies of the long-range order have shown a great stability of the amplitude and period of the incommensurate distortion wave in the one-layer, as well as in the double-layer compounds, either superconducting or insulating. We find such a behaviour to be highly incompatible with a distortion resulting from a charge-density-wave instability. The results we have obtained indicate that the bismuth-based high-Tc superconducting cuprates have essentially the same physics of the CuO{sub 2} planes as the previous two families, La{sub 2-x}Sr{sub x}CuO{sub 4} and YBa{sub 2}Cu{sub 3}O{sub 6+{delta}}, being at the proximity of three instabilities: a metal-insulator transition, an antiferromagnetic instability and a structural instability specific of the CuO{sub 2} planes. (author).

  20. Etude des erreurs d'estimation des populations par la méthode des captures successives (DeLURY, 2 captures et des captures-recaptures (PETERSEN

    Directory of Open Access Journals (Sweden)

    LAURENT M.

    1978-01-01

    Full Text Available L'estimation des populations naturelles par capture-recapture et par captures successives est souvent entachée d'erreur car, dans de nombreux cas, l'hypothèse fondamentale d'égalité des probabilités de captures pour tous les individus dans le temps et dans l'espace n'est pas respectée. Dans le cas des populations de poissons envisagés ici, les captures ont lieu par la pêche électrique. On a pu chiffrer l'ordre de grandeur des erreurs systématiques faites sur l'estimation des peuplements, en fonction des conditions particulières, biotiques et abiotiques, des différents milieux inventoriés.

  1. Etude pilote par PET/CT de la réponse à l'ipilimumab dans le traitement du mélanome métastatique.

    OpenAIRE

    Rochat, N.

    2012-01-01

    0 Abstract L'incidence du mélanome est en nette augmentation en Europe et aux Etats-Unis. La Chirurgie peut être curative au stade précoce de la maladie,la radiothérapie se pratique À visée palliative, les chimiothérapies n'ont montré que peu d'effet. Les progress actuels se font via l'immunothérapie. Des traitements par l'interleukine-2 et l'interféron-α se sont montrés efficaces chez certains patients, mais leur utilisation est limitée par leur forte toxicité. Depuis 201...

  2. Etude du mecanisme de predissociation de l'ion moleculaire de protoxyde d'azote par la mesure de l'energie cinetique des fragments de l'oxyde nitrique et de l'oxygene

    Science.gov (United States)

    Delisle, Claude

    La reaction N2 + O+ ↔ NO + + N, laquelle joue un role important dans la physique de la haute atmosphere, a ete le sujet de plusieurs etudes. Bien que cette reaction ait ete l'objet d'une quantite importante de travaux, ces derniers ne permettent toutefois pas de comprendre entierement le mecanisme d'un point de vue quantique, particulierement les niveaux d'energie excites des fragments qui permettent cette reaction. Puisque cette reaction n'est pas tres facile a reproduire en laboratoire, nous avons utilise la spectroscopie laser sur faisceaux d'ions rapides afin d'explorer les limites de dissociation de l'ion moleculaire intermediaire de cette reaction, a savoir l'ion N2O+. Le faisceau d'ions N2O+ rapides, apres excitation de l'ion moleculaire vers un niveau predissocie de l'etat A2Sigma+, se dissocie pour produire les fragments ioniques O+ et NO+. Par la mesure de la variation du nombre de fragments ioniques en fonction de l'energie cinetique des ions N2O+, nous avons enregistre les spectres de predissociation de l'ion N2O+. Lorsque c'etait possible, nous avons procede a l'analyse de ces spectres de dissociation afin d'en tirer les constantes moleculaires. Pour certaines des transitions rotationnelles intenses, nous avons mesure l'energie cinetique acquise par les fragments lors de la predissociation de l'ion N 2O+. Afin d'analyser les distributions en energie cinetique, nous avons developpe une simulation de l'experience en considerant, entre autres choses, la position des niveaux de vibration et de rotation des fragments diatomiques de chacune des limites de dissociation de N2O+. Les resultats de l'analyse sont exprimes en termes de population des niveaux de vibration des fragments diatomiques pour une distribution donnee de la population des niveaux de rotation des fragments. Les resultats ainsi obtenus, montrent que les fragments diatomiques sont produits dans des niveaux de vibration fortement excites. De tels niveaux d'excitation ne correspondent pas aux

  3. Electron paramagnetic resonance study of radicals formed by radiolysis at 77 K of nitroalkanes and of their solutions in organic glasses. Chromatography analysis of radiolysis products of nitromethane in ethanol solution in a vitreous medium; Etude par resonance paramagnetique electronique des radicaux formes par radiolyse a 77 K des nitroalcanes et de leurs solutions dans les verres organiques analyse par chromatographie des produits de la radiolyse du nitromethane en solution dans l'ethanol en milieux vitreux

    Energy Technology Data Exchange (ETDEWEB)

    Rosilio, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-05-01

    radiolyse. Notre etude porte sur la structure et la reactivite des radicaux formes par irradiation 7 des derives nitres a 77 K, et sur le mecanisme de formation et de disparition de ces radicaux dans les differentes matrices utilisees. Les radicaux resultant de l'arrachement d'un hydrogene en {alpha} du groupe NO{sub 2}, et les radicaux resultant de reactions d'addition sur le groupe nitre caracterises par un electron non apparie sur l'azote ont ete identifies, soit dans la radiolyse des nitroalcanes purs, soit dans la radiolyse a 77 K des nitroalcanes en solution dans les verres organiques. La conformation et les mouvements des radicaux dans les matrices, le mecanisme de formation des radicaux observes resultant generalement de la capture par les nitroalcanes des especes primaires de la radiolyse ont ete etudies. Les nitroalcanes en solution dans l'ethanol se manifestent a la fois comme capteurs d'electrons et de radicaux libres. L'etude de la radiolyse des nitroalcanes en solution dans un verre polaire d'ethanol a ete completee par des analyses chimiques des produits finals de la radiolyse; elle nous a permis de deduire l'efficacite de capture des electrons pieges et des radicaux libres par les nitroalcanes dans l'ethanol. Pour cela nous avons dose, pour le systeme nitro-methane - ethanol les rendements radiochimiques de-l'hydrogene, de l'acetaldehyde et du glycol en fonction de la concentration en capteur. Un mecanisme de disparition des radicaux observes a ete propose. (auteur)

  4. Study of the diffusion of iron, of silver and of carbon in beryllium using radioactive tracers; Etude de la diffusion du fer, de l'argent et du carbone dans le beryllium au moyen des traceurs radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Naik, M.Ch. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-06-01

    {sub perpendiculaire} = 1.98 exp - [45700 / RT]. L'anisotropie diminue lorsque la temperature croit. L'argent diffuse plus vite suivant l'axe C que dans le plan de base. Ce resultat ne peut etre explique par le modele propose pour la diffusion d'atomes etrangers en solution dans le zinc. Un plus grand nombre d'experiences est necessaire pour tenter de construire un modele. On a egalement tente de determiner les coefficients de diffusion du carbone dans le beryllium par traitement dans une atmosphere d'acetylene marque au carbone 14. Des coefficients de diffusion ent ete obtenus mais ceux-ci ne semblent pas devoir etre pris en consideration car une reaction chimique se produit a la surface des echantillons. (auteur)

  5. Pharmacological study of radioactive-gold colloid transport by blood and by serous exudate; Contribution a l'etude pharmacologique du transport des colloides d'or radioactif par le sang et les exsudats sereux

    Energy Technology Data Exchange (ETDEWEB)

    Rousselet, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    substances et particulierement dans le transport de l'or colloidal radioactif. Les fractions sanguines qui peuvent participer au transport de l'or colloidal sont les hematies, les leucocytes et elements histiocytaires, et le plasma. La repartition de la radioactivite dans ces elements est precisee en pratiquant des autoradiographies de coupes de culots de sang centrifuge et congele apres incubation avec de l'or colloidal. Cette etude montre l'importance du plasma dans le transport des particules radioactives. Nous avons alors recherche une fixation eventuelle de l'or colloidal 198 sur les diverses proteines seriques en appliquant certaines methodes de separation a savoir une filtration-exclusion sur colonne de gel de Sephadex G-200 et un fractionnement electrophoretique sur papier et sur acetate de cellulose gelatineux (cellogel). Nous avons etudie la liaison ''in vitro'' et ''in vivo'' des particules colloidales d'or 198 d'abord avec les proteines seriques de sujets sains puis avec les proteines des liquides d'epanchement d'origine pathologique, chez l'homme, ou du a une inflammation experimentale a la carragenine chez le rat. Les particules d'or colloidal 198 de 30 m{mu} (S-2) sont liees dans une certaine mesure aux {alpha}2 globulines sanguines ou ascitiques, celles de 5 m{mu} (S-6) sont liees aux {alpha}1 globulines de meme que les grains contenus dans l'or polydisperse. Cette liaison semble intervenir grace a la couche protectrice de macromolecules constituees par la gelatine. Seules les caracteristiques physicochimiques de grains colloidaux peuvent expliquer leur difference de localisation sur l'electrophoregramme. L'or sous forme ionique, par contre, est combine, aux seules albumines si la quantite de metal presente ne depasse pas une certaine limite. (auteur)

  6. ETUDE DE L'ACTION D'UNE ONDE ELECTROMAGNETIQUE POLARISEE CIRCULAIREMENT SUR UN ATOME A DEUX NIVEAUX PAR LE FORMALISME DES INTEGRALES DE CHEMINS

    Directory of Open Access Journals (Sweden)

    M AOUACHRIA

    2002-12-01

    Full Text Available L'action d'une onde électromagnétique polarisée circulairement sur un atome à deux niveaux est étudiée par le formalisme des intégrales de chemins. L'utilisation de l'espace des phases et de certaines rotations dans l'espace des états cohérents ont permis de simplifier énormément les calculs. Les fonctions d'onde correspondantes ont été retrouvées exactement.

  7. Etude du phénomème de vieillissement des transistors MOS microniques par l'analyse des caractéristiques DCG

    Science.gov (United States)

    Oualid, J.; Jérisian, R.

    1992-06-01

    A novel method of characterization of the micronic MOSFET degradation due to hot-carriers is proposed. It consists on the analysis of the leakage current variation with gate bias of the transistors studied as gate controlled diodes (GCD) by short circuiting the source and the drain. The GCD characteristics are plotted before and after stress. We show that the proposed method is considerably more sensitive than the usual methods which consist in the measurements of the threshold voltage, the transconductance or the subthreshold swing before and after stress. By comparison with the charge pumping method, the proposed shows that hot-carriers create not only oxide charges and interface states but also bulk traps near the drain. Our method confirm that degradation caused by a given drain bias saturates after a certain lapse of time depending on the applied gate bias. We have observed, after a stress, a slight relaxation of the defects which are created by hot-carriers. The density of these defects are not always maximum for a stress V_GS = V_DS /2 as it is currently admitted [1]. Une nouvelle méthode de caractérisation du vieillissement des transistors microniques et submicroniques est proposée. Elle est basée sur l'analyse de la variation du courant de fuite en fonction de la polarisation grille des transistors étudiés comme des diodes contrôlées par grille en reliant la source et le drain. Les caractéristiques DCG sont relevées avant et après l'opération de vieillissement qui consiste à appliquer une polarisation drain V_DS et une polarisation grille V_GS, par rapport à la source, pendant un temps plus ou moins long (contrainte). Nous montrons que cette méthode est considérablement plus sensible que les méthodes usuelles qui consistent à suivre l'évolution de la tension de seuil V_TO, de la transductance g_m ou de la pente S en régime d'inversion faible. Par rapport à la méthode de pompage de charge [2-4], elle présente l'avantage de r

  8. Etude de la desactivation des catalyseurs d'hydrotraitement par cokage. Synthèse bibliographique Study of the Deactivation of Hydrotreating Catalysts by Coking. Bibliographic Synthesis

    Directory of Open Access Journals (Sweden)

    Gualda G.

    2006-11-01

    Full Text Available Ce travail effectue la synthèse de la littérature disponible en février 1987 sur le phénomène de cokage en hydrotraitement entraînant la désactivation des catalyseurs. Il propose trois angles d'étude apportant chacun un éclairage complémentaire sur le sujet : - un angle physico-chimique qui décrit les méthodes de caractérisation du coke et des catalyseurs usés utilisées par les auteurs, et les informations qu'elles fournissent; - un angle d'observation macroscopique du phénomène de désactivation par cokage, par la confrontation de modèles et de résultats expérimentaux; - un angle plus fondamental faisant état des mécanismes proposés pour la formation du coke dans les conditions d'hydrotraitement des fractions lourdes du pétrole en particulier. Il ressort de cette étude la très grande hétérogénéité des travaux, tant du point de vue des protocoles expérimentaux que des interprétations mécanistiques. Une étude rigoureuse et systématique s'impose donc dans ce domaine. Toutefois, il semble bien établi que l'on puisse faire la différence entre un coke fatal formé par dégradation thermique des hydrocarbures, et un coke dépendant des propriétés des catalyseurs mis en oeuvre. This article makes a synthesis of the literature available in February 1987 on the coking phenomenon in hydrotreating causing catalyst deactivation. It proposes three angles of study, each giving complementary light on the subject:(a a physicochemical angle describing methods of characterizing the coke and catalysts used by the authors, and the information they provide;(b a macroscopic observation angle of the deactivation phenomenon by coking, by comparing models and experimental results;(c a more fundamental angle bearing on the mechanisms proposed for coke formation under hydrotreatment conditions of heavy oil fractions in particular. This study shows the great heterogeneity of research, from the standpoint of both experimental

  9. Etude de l'impact de la valorisation energetique de pneus hors d'usage, dans une cimenterie, sur les emissions gazeuses par modelisation de la dispersion atmospherique

    Science.gov (United States)

    Bredin, Nathalie

    La génération incéssante de déchets nécessite le développement de nouvelles technologies, telle que la valorisation énergétique, pour en disposer. Une filière appropriée pour valoriser énergétiquement les déchets est le procédé cimentier. L'industrie du ciment est une des grandes consommatrices d'énergie. La température nécessaire à la préparation du ciment se situe aux environs de 1450°C pour faire réagir la matière première (cru) qui est sous forme poudreuse et constituée principalement de roches calcaires, argileuses, schisteuses,... Les gaz de combustion ont un long temps de résidence dans les fours. De plus, le mode de fonctionnement des fours est responsable d'un effet de lessivage des gaz acides par le cru alcalin. Ces propriétés font du procédé cimentier un bon candidat pour la valorisation énergétique des déchets. Les déchets interessants pour les cimenteries sont, entre autres, les huiles usées, les solvants usés et les pneus usés qui ont un pouvoir calorifique équivalent à celui du charbon. Les rejets à l'atmosphère des cimenteries sont principalement des émissions gazeuses. Ainsi, l'impact de la valorisation de pneus usés sur les émissions gazeuses de la cimenterie Saint-Laurent de Joliette a été étudié, à l'aide de l'outil qu'est la modélisation de la dispersion atmosphérique. Le modèle utilisé ISC-ST2, Industrial Source Complex-Short Term, est de type gaussien. L'analyse des concentrations maximales horaires et moyennes sur différentes périodes de temps (1 heure, 8 heures, ..., 1 an) des émissions gazeuses dans l'air ambiant montre que celles-ci sont en deçà des normes émises par le gouvernement québécois et par la Communauté Urbaine de Montréal. L'étude de la distribution géographique des polluants, d'après les concentrations annuelles, dans un rayon de 5 km autour de la cimenterie montre que le fait d'utiliser des pneus comme combustible de substitution n'a qu'un faible impact sur la

  10. Etudes des transferts d'assimilats entre tiges de luzerne (Medicago sativa L) par l'utilisation du 14CO2

    OpenAIRE

    Dufour, L.; Faucher, M.; Lemaire, G.

    1989-01-01

    Des études antérieures ont montré que la repousse d’une plante de luzerne fait intervenir 2 types morphologiques de tiges : - les tiges 1 apparaissent les premières, à partir des bourgeons axillaires des bases des tiges laissées par la coupe; - les tiges 2 prennent naissance directement sur le collet et sont plus vigoureuses que les tiges 1. La question d’un éventuel rôle trophique des tiges 1 dans la croissance des tiges 2 s’est posée. Pour tenter d’y répondre, après une étude morpholog...

  11. Etude de l'influence du rayonnement UV sur le vieillissement des bitumes purs et modifiés par des polymères

    OpenAIRE

    KIENER, Nicolas; LABORATOIRE CENTRAL DES PONTS ET CHAUSSEES - LCPC

    2004-01-01

    Les bitumes, résidus de la distillation du pétrole, sont des mélanges complexes de composés hydrocarbonés très utilisés comme liant routier. Sur la route, le bitume subit différents types de contraintes à l'origine de son vieillissement : passage des véhicules, températures, rayonnements solaires. Le vieillissement chimique des bitumes, essentiellement dû à la température et aux radiations solaires, se traduit par des réactions d'oxydation. Ce travail porte sur l'étude du vieillissement photo...

  12. Study of damage and helium diffusion in fluoro-apatites; Etude de l'endommagement et de la diffusion de l'helium dans des fluoroapatites

    Energy Technology Data Exchange (ETDEWEB)

    Miro, S

    2004-12-15

    This work lies within the scope of the study of the radionuclides containment matrices. The choice of the fluoro-apatites as potential matrices of containment was suggested by the notable properties of these latter (thermal and chemical stability even under radioactive radiation). By irradiations with heavy ions and a helium implantation we simulated the effects related to the alpha radioactivity and to the spontaneous nuclear fission of the radionuclides. Thanks to the study of Durango fluoro-apatite single crystals and fluoro-apatite sintered ceramics, we evidenced that the damage fraction as well as the unit cell deformations increase with the electronic energy loss and with the substitution. These effects are followed at high fluences by a phenomenon of re-crystallization. The study of the helium diffusion points out that the thermal diffusion process improves with the substitution and strongly increases with heavy ions irradiation. (author)

  13. Les activités de conservation des lémuriens par le Groupe d’Etude et de Recherche sur les Primates de Madagascar (GERP Conservation activities of lemurs by the Madagascar Primate Research Group (GERP- Groupe d’Etude et de Recherche sur les Primates de Madagascar

    Directory of Open Access Journals (Sweden)

    Rose Marie Randrianarison

    2011-10-01

    Full Text Available Le Groupe d’Etude et de Recherche sur les Primates de Madagascar, une association de conservation, a été créée en 1994 grâce à l’initiative des Enseignants Chercheurs et étudiants du Département de Paléontologie et d’Anthropologie Biologique et du Département de Biologie Animale de l’Université d’Antananarivo. Le GERP regroupe actuellement des membres scientifiques multidisciplinaires Malgaches et étrangers dont la majorité d’entre eux est constituée par des primatologues. Les principales actions du GERP se focalisent sur les travaux de recherche sur les Primates Prosimiens de Madagascar, l’établissement de leur plan de conservation, la découverte de nouvelles espèces de lémuriens, la translocation et le transfert des lémuriens vivant dans des milieux défrichés ou précaires, le suivi et l’abondance des lémuriens ainsi que la révision de leurs aires de distribution. Les résultats des recherches effectuées sur la conservation ont permis de publier des articles dans des revues de renommée nationale et internationale sur la Primatologie. En outre, le renforcement de capacité et l’éducation de la communauté de base, des systèmes éducatifs primaires et supérieurs sur la conservation des lémuriens et l’appui aux activités de développement durable de la population locale s’avèrent nécessaires pour que la conservation des lémuriens soit pérenne.The Madagascar Primate Research Group (GERP - Groupe d’Etude et de Recherche sur les Primates de Madagascar is a conservation-focused association created in 1994 by the initiative of researcher lecturers and students from the Department of Paleontology and Biological Anthropology and the Department of Animal Biology of the University of Antananarivo. The GERP membership consists of multidisciplinary scientists, both Malagasy and foreign, the majority of whom are primatologists. The principle actions of the association are focused on research on the

  14. Some magnetic resonance properties of solutions of sodium in liquid ammonia; Contribution a l'etude des solutions de sodium dans l'ammoniac liquide par resonance magnetique

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-02-01

    Dilute solutions of sodium in liquid ammonia are studied by the mean of dynamic polarization techniques, and with the aid of Becker Lindquist and Alder model. Paramagnetic shifts are computed as a function of the 'average spin density', for each of the nuclear spin system. The nuclear contributions to the Overhauser shift are computed in the same way. A theoretical study of the main relaxation processes is carried out for each of the nuclear spin system and for the electronic spin system. The dynamic polarization experiments consist in classical measurement of the Overhauser enhancement for nitrogen, and in direct measurements of nitrogen Knight shift and nuclear contributions to the Overhauser shift by the mean of double irradiation techniques. The results show that, in dilute solutions, the relaxation of nitrogen arises from quadrupole interaction and from hyperfine interaction with unpaired electrons. Both interactions are of the same order of magnitude. Overhauser shift measurements show that the spin density is negative at the proton site, in agreement with Hughes results. (author) [French] Les solutions diluees de sodium dans l'ammoniac sont etudiees au moyen des techniques de la polarisation dynamique, sur la base du modele de Becker Lindquist et Aider. Les deplacements paramagnetiques des raies de resonance nucleaire des differents noyaux sont analyses en faisant appel a la notion de ''densite moyenne de spin'' introduite par l'auteur; et les differentes contributions nucleaires au deplacement d'Overhauser sont calculees en fonction de cette meme grandeur. Une etude theorique de la relaxation de chaque systeme de spin permet d'evaluer l'importance relative des differents mecanismes mis en jeu. Les experiences de polarisation dynamique effectuees au cours de ce travail consistent en mesures classiques de l'effet Overhauser sur l'azote, d'une part, et en la mise en oeuvre de techniques

  15. A study by internal friction of defects produced in iron and nickel irradiated at very low temperatures; Etude au moyen du frottement interne des defauts crees par irradiation a tres basse temperature dans le fer et le nickel

    Energy Technology Data Exchange (ETDEWEB)

    Keating-Hart, G. de [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    This work represents a contribution to the study of point defects in metals. After a brief review of the theory of internal friction we will discuss some technical innovations aimed at increasing the flexibility of the apparatus at our disposal. These innovations have allowed us to extend our range of measurements down to 20 deg. K. We will then discuss our experimental results. Firstly, we describe preliminary experiments on electron irradiated iron and the evidence for a laminar structure. Secondly, we present and account of the first measurements on nickel after neutron irradiation at 27 deg. K. We will compare the results with those obtained by other methods in this laboratory. Essentially we have observed transitory peaks at low temperature due to close Frenkel pairs and we have noticed the absence of a peak which would correspond to the magnetic after effect band of stage I{sub E}. An attempt is made to explain the disappearance of the observed peaks upon the application of an internal saturating magnetic field. (author) [French] Ce memoire constitue une contribution a l'etude des defauts ponctuels dans les metaux. Apres un bref apercu theorique sur le frottement interne, nous presenterons quelques realisations techniques destinees a accroitre les possibilites des instruments qui nous ont ete confies. Ces dernieres nous ont permis d'etendre la gamme des mesures jusqu'a 20 deg. K. Nous parlerons ensuite de nos resultats experimentaux. En premier lieu, ceux obtenus au cours de premieres experiences, sur le fer irradie aux electrons mettent en evidence des structures de laminage. En second lieu, nous exposerons les premieres mesures realisees sur du nickel irradie aux neutrons; nous comparerons ces resultats avec ceux obtenus par d'autres moyens experimentaux dans le laboratoire. Nous avons observe essentiellement des pics fugitifs a basse temperature dus aux paires proches de Frenckel et nous avons constate l'absence d'un pic

  16. Etude du Voice Onset Time (V.O.T dans des séquences VCV produites par des patients francophones souffrants de paralysies récurrentielles

    Directory of Open Access Journals (Sweden)

    Fauth Camille

    2014-07-01

    Notre étude se veut longitudinale puisque la voix des patients est enregistrée lors de différentes phases post-opératoires (post-opératoire 2, 3 et 4, ce qui devrait nous permettre de mettre au jour, non seulement les perturbations provoquées par l’immobilité laryngée, mais également les réajustements que les patients pourraient mettre en place au cours du temps et de leur rééducation orthophonique. Seul l’intervalle du VOT pour les occlusives sonores a été modifié. Pour les occlusives voisées, la transition CV implique uniquement un changement d’un état obstrué de conduit vocal à un état suffisamment dégagé de celui-ci pour permettre l’apparition d’une structure formantique claire et stable. En revanche, pour les occlusives non voisées, cette transition CV exige, outre le changement d’état du conduit vocal, une modification de la configuration de la glotte d’une position ouverte pour la consonne non voisée à une position fermée pour la voyelle subséquente. En conséquence, en raison de difficultés de maintien de vibrations laryngées, le VOT, qui est un indice de voisement, est alors généralement plus long pour les occlusives voisées que celles produites par les locuteurs contrôles. La durée du VOT de Klatt (1975 des occlusives voisées des patients reste toutefois quantitativement distincte des occlusives non voisées. En conséquence, la durée de la tenue consonantique des patients se voit également allongée dans les phases d’enregistrement précoces.

  17. reponse biochimique par les substances phénoliques des olives contre les attaques parasitaires,bacterienne et fongiques dans la region TLEMCEN (algerie).

    OpenAIRE

    Gouar.N; Beghdad C; Gaouar M; Ilias F; Mejdoub K

    2012-01-01

    l'etude de l'olivier et de la flore pathogene qui lui est associée d'une part ,l'etude phytochimique des composes phenoliques secretes par cet arbre d'autre part, ont permis d'obtenir des resultats servant a connaitre la defense de l'olivier contre les agressions par ces differents pathogenes.. l'etude de l'olivier et de la flore pathogene qui lui est associée d'une part ,l'etude phytochimique des composes phenoliques secretes par cet arbre d'autre part, ont permis d'obtenir des r...

  18. Kinetic study of the alkaline metals oxidation by dry oxygen; Etude cinetique de l'oxydation des metaux alcalins par l'oxygene sec

    Energy Technology Data Exchange (ETDEWEB)

    Touzain, Ph. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-06-15

    The oxidation of lithium, sodium, potassium, rubidium, cesium and sodium-potassium alloys by dry oxygen is studied at several temperatures and in the oxygen pressure range 40 to 400 mmHg. One distinguishes three different oxidation behaviours (inflammation, ignition and slow combustion) whose zones are precised in function of the temperature. The slow oxidation kinetic laws, the composition of oxides and the motive of oxides colorations are determined. At least, the experimental data are construed theoretically. (author) [French] L'oxydation du lithium, du sodium, du potassium, du rubidium, du cesium et des alliages sodium-potassium par l'oxygene sec est etudiee a diverses temperatures et a des pressions comprises entre 40 et 400 mmHg d'oxygene. On distingue trois processus d'oxydation differents (l'inflammation, l'ignition et la combustion lente) dont les domaines en fonction de la temperature sont precises. Les lois cinetiques d'oxydation lente, la nature des oxydes formes ainsi que les causes des colorations de ces oxydes sont determinees. Enfin les resultats obtenus sont interpretes theoriquement. (auteur)

  19. The study by means of a photomultiplier of the scintillations produced by {alpha} particles striking a zinc sulphide screen; Etude, au photomultiplicateur, des scintillations produites par les particules {alpha} dans un ecran de sulfure de zinc. Application a la numeration precise des particules {alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, J.P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-06-15

    The object of the study is the accurate counting of {alpha} particles by p-m. detection of their scintillations upon impact with a zinc sulphide screen. The main advantage of the method is the extreme simplicity of the electronics used: the possibility of obtaining a utilizable pulse from the p-m. (EMI5311) without any amplification, and in linear response, is demonstrated. The scintillation produced by an impact on Zn-S has also been studied experimentally. The decrease of light intensity in relation to time may be interpreted by the exponential relation: I = I{sub 0} exp (-t / {tau}) whereby {tau} = (39 {+-} 0,1) 10{sup -6} s. The relation between scintillation intensity and remaining trajectory after travel through a given air-space has also been determined. Possible suitable applications of this method of {alpha} counting are those where good stability and low background are necessary. Results stated bear on air contamination studies, isotopic composition variation measurement of uranium, bismuth content measurement in alloys by irradiation of specimens in a thermal neutron flux and {alpha} count on the Po formed. (author) [French] Ce travail est consacre a l'etude de la numeration precise des particules {alpha} par detection au photomultiplicateur des scintillations produites par ces particules dans un ecran de sulfure de zinc. Le principal avantage de cette methode reside dans l'extreme simplicite de l'appareillage electronique; il est en effet montre qu'il est possible, tout en convoyant une reponse lineaire, d'obtenir du photomultiplicateur (EMI5311) un signal electrique utilisable sans aucune amplification. La scintillation produite par l'impact des particules {alpha} sur un ecran de Zn-S est etudiee experimentalement. La decroissance de l'intensite lumineuse en fonction du temps est interpretable par la relation exponentielle I = I{sub 0} exp (-t / {tau}) avec {tau} = (39 {+-} 0,1) 10{sup -6} s. La relation entre l

  20. Experimental study of turbulence on Tore Supra by plasma micro-waves interaction; Etude experimentale de la turbulence sur Tore Supra par interaction plasma micro-ondes

    Energy Technology Data Exchange (ETDEWEB)

    Colas, L

    1996-09-23

    Internal small-scale magnetic turbulence is a serious candidate to explain the anomalous heat transport in tokamaks. This turbulence is badly known in the gradient region of large machines. In this work internal magnetic fluctuations are measured on Tore Supra with an original diagnostic : Cross Polarization Scattering (CPS). This experimental tool relies on the Eigenmode change of a probing polarised microwave beam scattered by magnetic fluctuations, close to a cut-off layer for the incident wave. In this work, the diagnostic is first qualified to assess its sensitivity to magnetic fluctuations, and the spatial localisation for its measurements. The magnetic fluctuation behaviour is then analysed over a wide range of plasma current, density and additional power, and interpreted with a simple 1-D scattering model. A scan of the plasma density or magnetic field is used to move the CPS measurement location from r/a = 0.3 to r/a = 0.75. A fluctuation radial profile is obtained by two means. In L-mode discharges, the relation between magnetic fluctuations, temperature profiles and local heat diffusivities is investigated. With all measurements, it is also possible to look for a local parameter correlated to the turbulence in a large domain of plasma conditions. The fluctuation-induced local heat diffusivity expected from the measured fluctuations is estimated using the non-collisional quasi-linear formula: X{sup mag}{sub e} = {pi}qRV{sub te}({delta}B / B){sup 2}. Both the absolute values and the parametric dependence of calculated X{sup mag}{sub e} are close to the electron thermal diffusivities Xe determined by transport analysis. In particular, a threshold is evidenced in the dependence of fluctuation-induced heat fluxes on local {nabla}T{sub e}, which is analogous to the critical gradient for measured heat fluxes. The experimental setup is also sensitive to the Thomson scattering of the probing wave by density fluctuations. Its measurements are analysed as the

  1. Irradiation induced surface segregation in concentrated alloys: a contribution; Contribution a l`etude de la segregation de surface induite par irradiation dans les alliages concentres

    Energy Technology Data Exchange (ETDEWEB)

    Grandjean, Y.

    1996-12-31

    A new computer modelization of irradiation induced surface segregation is presented together with some experimental determinations in binary and ternary alloys. The model we propose handles the alloy thermodynamics and kinetics at the same level of sophistication. Diffusion is described at the atomistic level and proceeds vis the jumps of point defects (vacancies, dumb-bell interstitials): the various jump frequencies depend on the local composition in a manner consistent with the thermodynamics of the alloy. For application to specific alloys, we have chosen the simplest statistical approximation: pair interactions in the Bragg Williams approximation. For a system which exhibits the thermodynamics and kinetics features of Ni-Cu alloys, the model generates the behaviour parameters (flux and temperature) and of alloy composition. Quantitative agreement with the published experimental results (two compositions, three temperatures) is obtained with a single set of parameters. Modelling austenitic steels used in nuclear industry requires taking into account the contribution of dumbbells to mass transport. The effects of this latter contribution are studied on a model of Ni-Fe. Interstitial trapping on dilute impurities is shown to delay or even suppress the irradiation induced segregation. Such an effect is indeed observed in the experiments we report on Fe{sub 50}Ni{sub 50} and Fe{sub 49}Ni{sub 50}Hf{sub 1} alloys. (author). 190 refs.

  2. Etude de quelques fonctionnelles du mouvement brownien et de certaines propriétés de la diffusion unidimensionnelle en milieu aléatoire

    Science.gov (United States)

    Monthus, Cécile

    This paper deals with functionals of Brownian motion that appear in various contexts, and with some properties of anomalous diffusion in a one-dimensional random environment. Section 2 explains why path integrals provide a powerful framework to compute probability distribution of functionals of Brownian motion. This approach is used to study winding properties of planar Brownian motion. Section 3 is devoted to an exponential functional of Brownian motion, which arise in particular in the study of transport properties of classical diffusion in a one-dimensional disordered system of finite length. This functional belongs to the field of multiplicative stochastic processes. Cet article porte sur l'étude des distributions de probabilité de quelques fonctionnelles du mouvement brownien qui interviennent dans divers contextes physiques. Le paragraphe 2 présente une méthode d'intégrale de chemin qui relieles distributions de probabilité de certaines fonctionnelles du mouvement brownien, à des fonctions de Green euclidiennes de la mécanique quantique. Cette approche permet notamment d'étudier certaines propriétés d'enroulementdu mouvement brownien plan, qu'il soit libre ou soumis à l'action d'un potentiel extérieur. Les fonctions d'échelle et les formes des lois asymptotiques à grand temps de l'enroulement autour d'un point dépendent des propriétés spectrales de basse énergied'une famille d'hamiltoniens contenant un potentiel vecteur de type Aharonov-Bohm.Le paragraphe 3 a pour l'objet l'étude de la loi de probabilité d'une fonctionnelle exponentielle du mouvement brownien qui intervient dans le cadnG de la diffusion unidimensionnelle aléatoire. Celle-ci apparaît notamment lorsque l'on s'intéresse à la distribution du flux de particules quitraverse un échantillon désordonné de taille finie, lorsque les particules diffusent classiquement, sous l'action d'une force aléatoire gelée distribuée comme un bruit blanc gaussien. Le spectre de

  3. Folds and Etudes

    Science.gov (United States)

    Bean, Robert

    2007-01-01

    In this article, the author talks about "Folds" and "Etudes" which are images derived from anonymous typing exercises that he found in a used copy of "Touch Typing Made Simple". "Etudes" refers to the musical tradition of studies for a solo instrument, which is a typewriter. Typing exercises are repetitive attempts to type words and phrases…

  4. Study of the fibrinogen - fibrin transformation kinetics and modifications caused to this reaction by irradiation (X rays) of the fibrinogen solution; Etude de la cinetique de la transformation fibrinogene-fibrine et modifications apportees dans cette reaction par irradiation (rayons X) de solution de fibrinogene

    Energy Technology Data Exchange (ETDEWEB)

    Hollard, D.; Suscillon, M.; Marcille, G.; Rambaud, F.; Baloyan, M. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1966-07-01

    The authors present a spectrophotometric method for studying the transformation fibrinogen - fibrin. This method has the advantage of drawing immediately in graph form the three, phases of this transformation: proteolysis or monomerization; polymerisation; clot stabilization. It is a simple, faithful and easily reproductive technic. Owing to this method, they studied modifications of this transformation due to irradiation of fibrinogen solution. Low doses (90 000 R/mn) prevent transverse polymerisation. To upper doses (180 000 R and more), the action of thrombin on fibrinogen does not give an organised clot but a lacteous and fragile gel. There is not here a coagulation in the physiological understanding. (author) [French] Les auteurs presentent une methode d'etude spectro-photometrique de la transformation fibrinogene - fibrine. Cette technique a l'avantage de visualiser instantanement-par le trace d'une courbe les 3 phases de cette transformation: proteolyse ou monomerisation; polymerisation; stabilisation du caillot. C'est une technique simple, fidele, reproductible; grace a cette methode les auteurs ont pu etudier les modifications apportees dans cette transformation par irradiation aux rayons X de la solution de fibrinogene. A faible dose (90 000 R) l'irradiation inhibe la polymerisation Transversale. A forte dose ( > 180 000 R) le fibrinogene n'est plus transforme par la thrombine en un caillot organise mais en un gel laiteux et fragile. Il ne s'agit plus alors de coagulation au sens physiologique du terme. (auteur)

  5. Synthesis of zirconium by zirconium tetrachloride reduction by magnesio-thermia. Experimental study and modelling; Elaboration de zirconium par reduction de tetrachlorure de zirconium par magnesothermie. Etude experimentale et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Basin, N

    2001-01-01

    This work deals with the synthesis of zirconium. The ore is carbo-chlorinated to obtain the tetrachloride which is then purified by selective condensation and extractive distillation. Zirconium tetrachloride is then reduced by magnesium and the pseudo-alloy is obtained according to the global following reaction (Kroll process): ZrCl{sub 4} + 2 Mg = 2 MgCl{sub 2}. By thermodynamics, it has been shown that the volatilization of magnesium chloride and the formation of zirconium sub-chlorides are minimized when the combined effects of temperature and of dilution with argon are limited. With these conditions, the products, essentially zirconium and magnesium chloride, are obtained in equivalence ratio in the magnesio-thermia reaction. The global kinetics of the reduction process has been studied by a thermal gravimetric method. A thermo-balance device has been developed specially for this kinetics study. It runs under a controlled atmosphere and is coupled to a vapor tetrachloride feed unit. The transformation is modelled supposing that the zirconium and magnesium chloride formation result: 1)of the evaporation of magnesium from its liquid phase 2)of the transfer of magnesium and zirconium tetrachloride vapors towards the front of the reaction located in the gaseous phase 3)of the chemical reaction. In the studied conditions, the diffusion is supposed to be the limiting process. The influence of the following parameters: geometry of the reactive zone, temperature, scanning rate of the argon-zirconium tetrachloride mixture, composition of the argon-zirconium tetrachloride mixture has been experimentally studied and confronted with success to the model. (O.M.)

  6. Study of cis- and trans-uranium elements by paper chromatography and electrophoresis; Contribution a l'etude des elements cis- et trans-uraniens par chromatographie sur papier et electrophorese

    Energy Technology Data Exchange (ETDEWEB)

    Clanet, F. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-01-01

    In this work, the field of application of paper chromatography and electrophoresis in inorganic chemistry has been extended to elements 90 to 96 in hydrochloric and nitric acid solution. Results obtained concern the following points: 1) - Characterization of the valency states of Np and of Pu using coloured reactions on chromatograms and electrophoregrams. The valency IV is characterized by alizarin, arsenazo-I and thorin-I, whilst diphenylcarbazide is used for the hexavalent state. 2) - Paper chromatography: by using as eluent, mixtures of equal parts of aqueous HCl and HNO{sub 3} solutions and of alcohols (methanol, ethanol and n-butanol), the R{sub f} values of elements 90 to 96 have been determined. It has been possible to deduce certain conclusions concerning the complexing of these elements by Cl{sup -} and NO{sub 3}{sup -} ions. 3) - We have developed an electrophoretic technique on cellulose acetate membranes in order to separate the charged species formed by the elements 90 to 96 in HCl and HNO{sub 3} solutions from 1 to 12 M. Mobility curves have been obtained. It appears from our results that the tendency for the elements considered to form anionic complexes follows the order of the ionic potentials when the valency state is four; this order is reversed for the valency three. The ions Cl{sup -} have a smaller tendency to form complexes than the NO{sub 3}{sup -} ions with respect to these elements in their oxidation state III or IV, but the reverse phenomenon is observed for U{sup VI} and Pu{sup VI}. Finally, the complexing of the cations Pu{sup 4+} and PuUO{sub 2}{sup 2+} by NO{sub 3}{sup -} follows the order of the ionic potentials but occurs in the reverse order for Cl{sup -} ions. 4) - Various analytical applications are considered: separation of the various elements from each other and separation of the valency states of Np and of Pu. (author) [French] Dans cette etude, le champ d'application de la chromatographie sur papier et de l

  7. Survey of the chemical diffusion at infinite dilution in the nickel-plutonium and aluminium-uranium systems; Contribution a l'etude de l'heterodiffusion a dilution infinie systemes nickel-plutonium et aluminium-uranium

    Energy Technology Data Exchange (ETDEWEB)

    Blechet, J.J. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-09-01

    Solubility S{sub 0} and chemical diffusion coefficients D{sub PuNi} at infinite dilution of plutonium in nickel have been determined by autoradiography {alpha} in poly-phased system by the welded couples method: S{sub 0} varies from 40 to 80.10{sup -6} (atomic concentration) and D{sub PuNi} follows an Arrhenius law D = D{sub 0} exp (-Q/RT) with 0.03 cm{sup 2}/s < D{sub 0} < 1.6 cm{sup 2}/s and 46000 cal/mole < Q < 56000 cal/mole. Diffusion of uranium in aluminium have been carried out by fissiography using the thin layer method. Frequency factor lies between 0.01 and 3.1 cm{sup 2}/s and the activation energy lies between 24000 and 34000 cal/mole. (author) [French] La solubilite S{sub 0} et les coefficients de diffusion chimique D{sub PuNi}, a dilution infinie, du plutonium dans le nickel ont ete determines par autoradiographie {alpha} sur des couples soudes en systeme polyphase. Entre 1000 et 1125 deg. C. S{sub 0} varie de 40 a 80.10{sup -6} et D obeit a une loi d'ARRHENIUS (concentration atomique) D = D{sub 0} exp (-Q/RT) avec 0.03 cm{sup 2}s{sup -1} < D{sub 0} < 1.60 cm{sup 2}s{sup -1} 46000 calories par mole < Q < 56000 calories par mole. La diffusion de l'uranium dans l'aluminium a ete etudiee par fissiographie en utilisant la technique du depot mince. Le facteur de frequence est situe entre 0.01 et 3.1 cm{sup 2}s{sup -1} et l'energie d'activation entre 24000 et 34000 calories par mole. (auteur)

  8. Magnetic and resonant X-ray scattering investigations of strongly correlated electron systems; Etude de systemes electroniques fortement correles par diffusion magnetique et resonnante des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Paolasini, L.; Bergevin, F. de [European Synchrotron Radiation Facility, 38 - Grenoble (France)

    2008-06-15

    Resonant X-ray scattering is a method which combines high-Q resolution X-ray elastic diffraction and atomic core-hole spectroscopy for investigating electronic and magnetic long-range ordered structures in condensed matter. During recent years the development of theoretical models to describe resonant X-ray scattering amplitudes and the evolution of experimental techniques, which include the control and analysis of linear photon polarization and the introduction of extreme environment conditions such as low temperatures, high magnetic field and high pressures, have opened a new field of investigation in the domain of strongly correlated electron systems. (authors)

  9. Study of betaine calcium chloride dihydrate (BCCD) by neutrons inelastic scattering; Etude du chlorure de betaine et de calcium dihydrate (BCCD) par diffusion inelastique de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Hlinka, J.

    1995-06-27

    The aim of this work is to study the betaine calcium chloride dihydrate (BCCD) lattice dynamics by neutrons inelastic and coherent scattering. In the first part are summarized the main properties of the BCCD as they are determined in some previous experimental works. It has been more particularly emphasized on the structural and dynamical properties of this compound. The theoretical concepts used in incommensurate dielectric materials physics are given in the second part. They are at first introduced generally and then applied to BCCD. In the third part is described the experimental method used in this work : the neutrons inelastic scattering. The experimental results on the BCCD normal phase dynamics are then presented. These results and their interpretation allow to build up a semi-microscopic model introduced in the fifth part. The incommensurate lattice dynamics (at 20 K under the transition temperature towards the modulated phase) is studied in the last part. It has been shown that new aspects in relation to the previous works appear in BCCD. (O.L.). 121 refs., 25 figs., 5 tabs.

  10. Contribution to the study on the flow rate adjustment for gas cooled power reactors (1964); Contributiom a l'etude de reglage du debit pour les reacteurs industriels refroidis par gaz (1964)

    Energy Technology Data Exchange (ETDEWEB)

    Milliot, B. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1961-06-15

    1. This original study firstly defines the problem of the adjustment of the coolant flow rate in a reactor channel as a function of the corresponding heat transfer equations and of the local and temporal neutron flux. The necessity of such an adjustment is pointed out and the modifying parameters are studied. An adjustment study using the envelope of the possible flux curves is developed. A short study on the technology and the economical advantage of this adjustment is presented. Some measurements, made on G-1 and G-2, show the precision one can obtain from adjustment apparatus itself as well as from the complete reactor adjustment system. 2. Evolution of nuclear properties of fuel in an heterogeneous thermal reactor. In the first port of this paper, the phenomena of fuel evolution have been mainly pointed out. Now a bibliographical study more qualitatively than quantitatively has been done. This survey specifies the present theories and relates to a real effective cross section and also yields to the bases of such a nuclear calculation. (author) [French] 1. Cette etude originale definit d'abord le probleme du reglage du debit de refrigerant dans un canal de reacteur en fonction de la formulation du calcul des performances thermodynamiques de ce canal et des variations du flux neutronique dans l'espace et le temps. La necessite du reglage est ensuite mise en evidence et les parametres le modifiant sont etudies. Une methode de reglage, basee sur l'emploi d 'une courbe enveloppe des courbes de flux possibles, est donnee. Une breve etude de la technologie et des incidences economiques du reglage est presentee. Des mesures effectuees sur les reacteurs G-1 et G-2 montrent la precision que l'on peut attendre des dispositifs de reglage comme du reglage d'ensemble du reacteur lui-meme. 2. Evolution des proprietes nucleaires du combustible dans un reacteur heterogene a neutrons thermiques. Les phenomenes d'evolution du combustible

  11. New features of nuclear excitation by {alpha} particles scattering; Nouveaux aspects de l'excitation nucleaire par diffusion de particules {alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Saudinos, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    Inelastic scattering of medium energy a particles by nuclei is known to excite preferentially levels of collective character. We have studied the scattering of isotopically enriched targets of Ca, Fe, Ni, Cu, Zn. In part I, we discuss the theoretical features of the interaction. In part II, we describe the experimental procedure. Results are presented and analysed in part III. {alpha} particles scattering by Ca{sup 40} is showed to excite preferentially odd parity levels. In odd nuclei we have observed multiplets due to the coupling of the odd nucleon with the even-even core vibrations. For even-even nuclei, a few levels are excited with lower cross-sections between the well-known first 2{sup +} and 3{sup -} states. Some could be members of the two phonon quadrupole excitation and involve a double nuclear excitation process. (author) [French] On sait que la diffusion inelastique des particules alpha de moyenne energie excite preferentiellement des niveaux de caractere collectif. Nous avons etudie la diffusion des particules alpha de 44 MeV du cyclotron de Saclay par des isotopes separes de Ca, Fe, Ni, Cu, Zn. Dans la premiere partie nous exposons les theories de cette interaction. Dans la seconde nous decrivons le systeme experimental. Les resultats sont donnes dans la troisieme partie. Nous montrons que les niveaux excites preferentiellement pour {sup 40}Ca par diffusion ({alpha},{alpha}') sont de parite negative. Dans les noyaux pair-impair nous avons observe des multiplets dus au couplage du nucleon celibataire avec les vibrations du coeur pair-pair. Pour les noyaux pair-pair nous avons pu etudier entre le premier niveau 2{sup +} et le niveau 3{sup -} deja bien connus certains etats plus faiblement excites. Il semble qu'ils sont dus a une excitation quadrupolaire a deux phonons et impliquent un processus de double excitation nucleaire. (auteur)

  12. Scattering of electromagnetic waves by an non-uniform cylindrical plasma; Diffusion coherente d'une onde electromagnetique par un cylindre de plasma inhomogene

    Energy Technology Data Exchange (ETDEWEB)

    Faugeras, P.E. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires. Groupe de recherches sur la fusion controlee

    1967-07-01

    The problem of the scattering of plane electromagnetic waves from a non-uniform, cylindrically symmetrical plasma is solved analytically, by a self-consistent field method, for a wave with the electric field parallel to the cylinder axis. Numerical results for the diffracted field are plotted for interesting ranges of the parameters involved: diameter, density on the axis, radial profile of the density, and collision frequencies. The case where the incident field is cylindric (waves surfaces parallel to the cylinder axis) is examined - this permits to connect theoretical calculations and experimental diffraction patterns, and also to explain the diffraction effects observed in a classical microwave interferometry experiment. These results, and the possibility of measuring exactly the diffracted field (showed by experiments with dielectric and metallic rods) lead to a new plasma diagnostic method, based on the diffraction, which has no theoretical limitations and it usable when the classical free-space wave methods are not (plasma diameter lower than 10 wave lengths). The feasibility of this method is tested with a plasma at atmospheric pressure and a 2 mm incident wavelength. The plasma is obtained by the laminar flow of a plasma torch, with a working gas (He or Ar) seeded by potassium (density continuously variable between 10{sup 11} and 10{sup 15} e/cm{sup 3}. Some diffraction patterns by this plasma and for various incident waves, are also given and explained with theoretical calculations. (author) [French] On etudie la diffusion coherente d'une onde electromagnetique par un cylindre de plasma inhomogene par une methode de champ self-consistant, et pour une onde de vecteur electrique parallele a l'axe du cylindre. On a calcule le champ diffracte en faisant varier le diametre du cylindre, la densite sur l'axe, le profil de densite et les frequences de collisions, et on donne ici les principaux resultats. On examine ensuite le cas d'une onde

  13. A study of the diffusion mechanisms in amorphous metallic alloys: diffusion and diffusion under high pressure in an amorphous NiZr alloy; Contribution a l`etude des mecanismes de transport dans les materiaux metalliques amorphes: diffusion et diffusion sous pression dans NiZr amorphe

    Energy Technology Data Exchange (ETDEWEB)

    Grandjean, A.

    1996-03-01

    The aim of this work is a better understanding of the diffusion mechanism in amorphous metallic alloys. Then interdiffusion and hafnium diffusion in amorphous NiZr alloy have been studied. Samples used are made by sputtering co-deposition under vacuum and are well relaxed before the diffusion measurements. The time evolution of resistivity during annealing due to the decay of a composition modulated film has been measured and from this change in resistivity interdiffusion coefficients have been determined. Dependence of Hf diffusion on temperature and pressure has been studied using (SIMS). In this two cases, the diffusion process obeys an Arrhenius law and gives an activation energy of 1.33 eV for interdiffusion, and 0.76 eV for Hf diffusion. An effect of pressure on Hf diffusion has been found leading to an activation volume of 8.5 angstrom{sup 3}. Thanks to these results, two approaches of the diffusion mechanisms in these systems have been proposed. The first comes from a comparison with the diffusion mechanisms in crystalline metals, that is to say by point defects. The second is an hypothesis of collective motions in these non crystalline alloys. (author).

  14. Etude expérimentale de la diffusion thermique dans les monocristaux d'olivine et dans les roches du manteau supérieur

    OpenAIRE

    GIBERT, Benoit

    2003-01-01

    The knowledge of the thermal structure of the Earth is a prerequisite to better understand the geological processes observed at the Earth's surface. Conductive and convective heat transport mechanisms within the mantle determine this thermal structure and are mainly controlled by heat transport properties of mantle rocks. This study proposes to investigate these properties by measuring the thermal diffusivity of olivine single-crystals and polycristalline aggregates (rocks) at high temperatur...

  15. Mesures en temps réel par diffusion de neutrons aux petits angles (DNPA) avec un appareil à ``flux stoppé'' (stopped-flow)

    Science.gov (United States)

    Grillo, I.

    2005-11-01

    La nouvelle génération de diffractomètres à haut flux pour la diffusion de neutrons aux petits angles, comme D22 à l'ILL, ouvre de nouvelles perspectives avec les expériences “temps réel” et les “cinétiques rapides”. “Temps réel” signifie un film de l'échantillon après une perturbation, par exemple un saut en température, une variation de pH, une dilution, un mélange ou encore l'application d'un champ magnétique. Par “rapide” on entend des temps d'acquisition courts, de l'ordre de quelques centaines de millisecondes pour suivre les toutes premières étapes de formation et d'organisation de l'échantillon. La connaissance d'éventuelles phases intermédiaires peut être cruciale pour comprendre les propriétés de l'échantillon dans son état d'équilibre. Pour ces expériences, un appareil à flux stoppé (Bio-Logic^TM) a été spécialement adapté pour la DNPA. Il permet de mélanger rapidement deux à trois solutions en contrôlant précisement les volumes et les temps de mélanges puis de démarrer l'observation en connaissant le délai après le début de la réaction. Cette nouvelle technique a été utilisée pour suivre la croissance de vésicules formées après dilution de micelles d'AOT par une solution saline. Le moteur de la croissance est l'écrantage des répulsions électrostatiques entre les têtes polaires tensioactives, ce qui favorise la formation d'une bicouche localement plane.

  16. Etudes Méthodologiques en Imagerie par Résonance Magnétique Nucléaire et en Cristallographie des Protéines Résolue en Temps.

    OpenAIRE

    Bourgeois, Dominique

    1999-01-01

    Le résumé des travaux présentés dans ce document ressemble assez à un "pot pourri". Il caractérise en cela la diversité des sujets scientifiques que j'ai abordé jusqu'à présent. Même si ces dix premières années de recherche ont d'une certaine façon manqué de cohérence, elles ont été guidées par un fil directeur : l'intérêt pour la méthodologie à l'interface biologie-physique. Que ce soit dans le domaine de l'imagerie par résonance magnétique nucléaire in vivo ou dans celui de la cristallograp...

  17. Contribution to the study of thermal diffusivity of solids; Contribution a l'etude de la diffusivite thermique des solides

    Energy Technology Data Exchange (ETDEWEB)

    Zankel, K. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-07-01

    Angstroem method has been reviewed for its application to measurements of thermal diffusivity and conductivity on short specimens. An apparatus and a technique have been developed for rapid and precise measurements of a large variety of materials, which might also contain heat sources. This technique allows measurements at both high and low temperatures. Stainless steel, nickel and uranium monocarbide specimens were tested and the results of the thermal diffusivity measurements between 50 deg. C and 700 deg. C are presented. (author) [French] L'application de la methode d'Angstroem pour la mesure de la diffusivite et de la conductivite thermique sur des echantillons courts est examinee. Un appareillage est decrit, qui permet non seulement des mesures sur une grande variete de materiaux, mais qui est aussi concu pour des mesures rapides, precises et ou des sources thermiques peuvent etre introduites au sein de l'echantillon. La methode s'adapte egalement aux mesures a basses et hautes temperatures. Des resultats de mesure sur un echantillon en acier inoxydable, en nickel et en carbure d'uranium pour des temperatures comprises entre 50 et 700 deg. C sont reportes. (auteur)

  18. Study of electronic heat transport in plasma through diagnosis based on modulated electron cyclotron heating; Etudes de transport de la chaleur electronique par injection modulee d'ondes a la frequence cyclotronique electronique

    Energy Technology Data Exchange (ETDEWEB)

    Clemencon, A.; Guivarch, C

    2003-07-01

    In order to make nuclear fusion energetically profitable, it is crucial to heat and confine the plasma efficiently. Studying the behavior of the heat diffusion coefficient is a key issue in this matter. The use of modulated electron cyclotron heating as a diagnostic has suggested the existence of a transport barrier under certain plasma conditions. We have determined the solution to the heat transport equation, for several heat diffusion coefficient profiles. By comparing the analytical solutions with experimental data; we are able to study the heat diffusion coefficient profile. Thus, in certain experiments, we can confirm that the heat diffusion coefficient switches from low to high values at the radius where the electron cyclotron heat deposition is made. (authors)

  19. Study of heterogeneous multiplying and non-multiplying media by the neutron pulsed source technique; Etude des milieux heterogenes multiplicateurs et non-multiplicateurs par la technique de la source pulsee de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Deniz, V. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    The pulsed neutron technique consists essentially in sending in the medium to be studied a short neutron pulse and in determining the asymptotic decay constant of the generated population. The variation of the decay constant as a function of the size of the medium allows the medium characteristics to be defined. This technique has been largely developed these last years and has been applied as well to moderator as to multiplying media, in most cases homogeneous ones. We considered of interest of apply this technique to lattices, to see if useful informations could be collected for lattice calculations. We present here a general theoretical study of the problem, and results and interpretation of a series of experiments made on graphite lattices. There is a good agreement for non-multiplying media. In the case of multiplying media, it is shown that the age value used until now in graphite lattices calculations is over-estimated by about 10 per cent. [French] La technique de la pulsation neutronique consiste essentiellement a envoyer dans le milieu a etudier une courte bouffee de neutrons et a determiner la constante de decroissance asymptotique de la population engendree. La variation de cette constante de decroissance en fonction des dimensions du milieu permet de determiner ses caracteristiques. Cette technique a connu ces dernieres annees un grand essor et a ete appliquee a des moderateurs et des milieux multiplicateurs. Il s'agissait dans la plupart des cas de milieux homogenes. Il nous a semble interessant de l'utiliser dans le cas des reseaux, afin de voir si ces experiences peuvent fournir des renseignements utiles aux calculs. Nous presentons ici une etude theorique generale du probleme, ainsi que les resultats et l'interpretation d'une serie d'experiences faites sur des reseaux a graphite. L'accord est bon dans le cas des reseaux non-multiplicateurs. Dans le cas des reseaux multiplicateurs, on montre que la valeur de l

  20. Caractérisation de la structure des membranes ionomères (NAFION^{tinytextregistered}) par diffusion de rayons X aux petits angles

    Science.gov (United States)

    Rubatat, L.; Rollet, A. L.; Diat, O.; Gébel, G.

    2002-07-01

    Ionomer membranes, like Nafion^{tinytextregistered} used in fuel cell, present a nano- phase separation between domains with different ionic concentrations. Up to now models describe the ionic domains as spheres of about 40 Å diameter. Small angles X-ray scattering studies over a large range of wave vectors, lead to a new assumption for the Nafion structure, describing the polymer aggregation as elongated objects surrounding by the ionic charges. Les membranes ionomères de type Nafion^{tinytextregistered} utilisées en pile à combustible, sont caractérisées par une nano-séparation de phases entre des domaines plus ou moins riches en sites ioniques. Les modèles proposés pour décrire ces domaines ioniques, les représentent généralement sous forme de sphères de 40 Å de diamètre. L'étude en diffusion de rayons X que nous avons menée récemment, sur une large gamme de vecteurs d'ondes, nous permet de proposer une vision différente de la structure du Nafion en considérant une agrégation de polymères sous formes d'objets très allongés, avec en surface les charges ioniques.

  1. Surface integral formulation of Maxwell's equations for simulation of non-destructive testing by eddy currents. Preliminary study on the implementation of the fast multipole method; Formulation integrale surfacique des equations de Maxwell pour la simulation de controles non destructifs par courant de Foucault. Etude preliminaire a la mise en oeuvre de la methode multipole rapide.

    Energy Technology Data Exchange (ETDEWEB)

    Lim, T.

    2011-04-28

    numeriquement un controle non destructif par courants de Foucault (CND-CF), la reponse du capteur peut etre modelisee via une approche semi-analytique par integrales de volume. Plus rapide que la methode des elements finis, cette approche est cependant limitee a l'etude de pieces planes ou cylindriques (sans prise en compte des effets de bords) du fait de la complexite de l'expression de la dyade de Green pour des configurations plus generales. Or, il existe une forte demande industrielle pour etendre les capacites de la modelisation CF a des configurations complexes (plaques deformees, bords de piece...). Nous avons donc ete amenes a formuler differemment le probleme electromagnetique, en nous fixant comme objectif de conserver une approche semi-analytique. La formulation integrale surfacique (SIE) permet d'exprimer le probleme volumique en un probleme de transmission equivalent a l'interface (2D) entre sous-domaines homogenes. Ce probleme est ramene a la resolution d'un systeme lineaire (par la methode des moments) dont le nombre d'inconnues est reduit du fait du caractere surfacique du maillage. Des lors, ce systeme peut etre resolu par un solveur direct pour de petites configurations. Cela nous a permis de traiter plusieurs seconds membres (ie. differentes positions de capteurs) pour une seule inversion de la matrice d'impedance. Les resultats numeriques obtenus au moyen de cette formulation concernent des plaques avec la prise en compte des effets de bords tels que l'arete et le coin. Ils sont en accord avec des resultats obtenus par la methode des elements finis. Pour des configurations de grandes tailles, nous avons mene une etude preliminaire a l'adaptation d'une methode d'acceleration du produit matrice-vecteur intervenant dans un solveur iteratif (methode multipole rapide, ou FMM) afin de definir les conditions dans lesquelles le calcul FMM fonctionne correctement (precision, convergence...) dans le contexte CND

  2. Contribution to the study of solid helium-3 by nuclear magnetic resonance; Contribution a l'etude de l'helium trois solide par resonance magnetique nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Landesman, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    Due to the unusually large zero point motion of helium three atoms in the solid, the overlap of the atomic wave functions is very important. As a consequence, there are exchange interactions, the theoretical calculation and the experimental measurement of which are discussed. Nuclear magnetic resonance is especially well suited for the latter.A detailed theory is given for both exchange narrowing and Zeeman-exchange cross relaxation, which phenomena are used to measure the exchange interaction as a function of molar volume. The alignment temperature is thus known; it goes down when the pressure goes up and is never higher than three milli degrees. An influence of helium four impurities on the exchange interactions between helium three atoms which are neighbours of the substitutional He is shown. (author) [French] Par suite de l'amplitude exceptionnelle des mouvements de point zero dans l'helium trois solide, le recouvrement des fonctions d'onde atomiques est tres important. Il en resulte des interactions d' echange dont on discute l'evaluation theorique et la mise en evidence experimentale. Cette derniere peut se faire par resonance magnetique; on etudie theoriquement les phenomenes de retrecissement par echange et de relaxation Zeeman-echange que l'on met a profit pour determiner les interactions d'echange en fonction du volume molaire. On en deduit que la temperature d'alignement nucleaire diminue quand on comprime le solide et est au plus de 3x10{sup -3} K. L'influence des impuretes d'helium quatre sur les interactions d'echange entre atomes {sup 3}He voisins de {sup 4}He est mise en evidence. (auteur)

  3. Contribution to the study of metallic impurities diffusion in a polymer film (KAPTON) under and out of irradiation; Contribution a l`etude de la diffusion d`impuretes metalliques dans un film polymere (KAPTON) sous et hors irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Marin, N.

    1995-12-18

    The main topic of this work is the diffusion behaviour in the polymer film Kapton, under and out of irradiation, of metallic coatings with different reactivity (copper, nickel, titanium) deposited by sputtering. The analysis of diffusion profiles has been performed by backscattering spectrometry, which, in association with cross-section microscopy, allows to connect the diffusion behaviour to the microscopic structure of the metal/Kapton interface. Generally speaking, the study under thermal annealing shows the importance of peculiarities of commercials polymers. In particular, additional elements they contain are liable to modify their surface characteristics and, as a consequence, diffusion. So, unlike observations in model polyimides, we show that even weakly reactive metals do not diffuse inside the polymer. Besides, there exists an energy threshold of Ar{sup +} used for sputtering, above which copper layers become very stable and so come up to industry`s expectation. The study under irradiation gives evidence for copper diffusion under irradiation, resulting in 15 mn mean radius spherical clusters inside the modified polymer. This fast diffusion is shown to be due to the concomitant effect of nuclear collisions and temperature. This study is also the opportunity to show dramatic radiation-induced effects in Kapton, more particularly a large modification of mechanical and optical properties with the loss of more volatile elements (H, N,O). With regard to methodology, this study shows the strong ambiguity in the RBS spectrum interpretation in the case of lateral non-uniformity, and we propose a model giving access to the statistical distribution of the non-uniform property of the target. (author). 262 refs., 99 figs., 8 appends.

  4. The structure of para-toluidine by X-ray and neutron diffraction; Etude de la structure de la para-toluidine par la diffraction des rayons X et des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Bertinotti, A.L. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-12-01

    The crystal and molecular structure of para-toluidine has been solved by X-ray and neutron diffraction counter techniques. The molecules are arranged in the form of infinite chains in the crystal, each molecule being linked to two neighbours by hydrogen bonds. The presence of the H bonds makes clear the difference in the melting points between para-toluidine and benzene hydrocarbons of related symmetry and molecular weight. Their direction accounts for the (001) cleavage and the growth anisotropy of crystals from supersaturated vapour phase. A structure-seeking method by computer has been elaborated, using lattice energy calculations applied to molecules treated as rigid bodies and making use of a simplex method for function minimization without calculation of derivatives. The way the available information is handled allows to increase the range of convergence, as shown in the case of para-toluidine. (author) [French] La structure cristalline et moleculaire de la para-toluidine a ete resolue a l'aide de la diffraction des rayons X et des neutrons. L'analyse a revele que la structure presentait un encha ement particulier des molecules, liees entre elles par des ponts hydrogene. La presence des liaisons rend compte de l'elevation du point de fusion de la para-toluidine par rapport a celui des carbures benzeniques de symetrie et de poids moleculaires voisins. La direction des liaisons explique le clivage facile (001) des cristaux obtenus par fusion et l'anisotropie de croissance des cristaux en phase vapeur. Une methode de recherche de structures par ordinateur a ete elaboree, faisant usage du concept d'energie reticulaire applique aux molecules considerees comme rigides et faisant appel a une methode de simplexe pour la minimisation des fonctions sans calcul de derivees. La maniere dont est exploitee l'information disponible permet d'accro re, comme cela est montre dans le cas de la para-toluidine, l'etendue du domaine de

  5. Contribution to the study of the evolution of radiation induced He in Be O; Etudes sur l'evolution de l'helium produit par reactions nucleaires dans l'oxyde de beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Bareau, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-11-15

    The purpose of this work in-pile investigation of He formed by (n, 2n) and (n, {alpha}) nuclear reactions, released from irradiated BeO, in the temperature range 1000 - 1350 deg. C. The experimental results show that, for an instantaneous neutron fast flux of 10{sup 13} n cm{sup -2} sec{sup -1}, an equilibrium is attempted, after several days, for a part lower than 20 per cent of the quantity of He formed, theoretically calculated from the neutron cross sections of nuclear reactions, and from the analytical form of the neutron fast flux, releases from the solid. The validity of the values of calculated helium and the gas chromatographic analytical method are also verified by dissolution of the BeO pellets in cryolite. A new fast neutron flux measuring method may be so defined. The discussion of the experimental results enables to establish that the processus of He release is characterized by two phenomena: the first one which controls the release of He atoms out of the solid and the second which reveals a capture processus, connected to the irradiation and probably due to the vacancies induced in the lattice. (author) [French] On etudie en pile le degagement de l'helium forme par reactions nucleaires (n, 2 n) et (n, {alpha}) dans l'oxyde de beryllium irradie entre 1000 et 1350 deg. C. Les resultats experimentaux montrant que, pour un flux rapide instantane de 10{sup 13} n{sub r} cm{sup -2} s{sup -1}, on aboutit, au bout de quelques jours, a un etat d'equilibre pour lequel une partie, inferieure a 20 pour cent de la quantite d'helium forme, calculee theoriquement a partir des sections efficaces des reactions nucleaires et de la forme analytique du flux rapide, s'echappe du solide. On verifie egalement par dissolution des echantillons de BeO dans la cryolithe la validite du calcul de l'helium et de la methode de dosage par chromatographie en phase gazeuse. On peut ainsi definir une methode nouvelle de mesure des flux rapides. La

  6. Etude de la qualité organoleptique de trois variétés de mangues ...

    African Journals Online (AJOL)

    Etude de la qualité organoleptique de trois variétés de mangues Amélie , Lippens , Brooks séchées au cours du stockage par technique de brunissement enzymatique des peroxydases (POD) et des polyphénoloxydases (PPO)

  7. Tritium enrichment by thermal diffusion. I. Calculation of an installation for measuring natural tritium; Enrichissement du tritium par diffusion thermique. - I. Calcul d'une installation destinee a la mesure du tritium naturel

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, M.; Ravoire, J. [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1966-07-01

    The natural content of tritium is so low that its measurement generally requires a preliminary enrichment. The thermal diffusion on hydrogen is studied as an enrichment method. The installation studied comprises two stages of columns of the hot-wire type, together with a device for transferring the tritium from the water sample into the hydrogen in the columns using catalytic exchange. A complete mathematical treatment for the operation of such a unit has been made and programmed for the IBM 7094 computer. An optimization has been effected by means of this program. It is shown that for similar performances, less hydrogen is retained in the case of hot-wire type columns than in the case of columns composed of concentric tubes. (authors) [French] La teneur naturelle du tritium est si faible que sa mesure demande generalement un enrichissement prealable. On etudie la diffusion thermique sur l'hydrogene comme moyen d'enrichissement. L'installation que l'on etudie comprend deux etages de colonnes du type fil chaud, et un dispositif de transfert du tritium de l'echantillon d'eau dans l'hydrogene des colonnes par echange catalytique. Un traitement mathematique complet du fonctionnement d'un tel ensemble a ete etabli et programme sur machine IBM 7094. Une optimisation a ete faite a l'aide du programme. On montre egalement qu'a performances egales, la retenue d'hydrogene est plus faible dans le cas des colonnes du type fil chaud que dans le cas des colonnes du type tubes concentriques. (auteurs)

  8. Self-defects and self diffusion in a silica glass: a first-principles study; Etude ab-initio des auto-defauts et des mecanismes d'auto-diffusion dans un verre de silice

    Energy Technology Data Exchange (ETDEWEB)

    Martin, L.; Colomer, S

    2004-11-15

    SiO{sub 2} and silica based compounds are key materials in a variety of scientific and technological fields as, for instance, in microelectronics or nuclear technology. In all these fields, one of the still open questions is their long term aging in a radioactive environment. Due to the complexity of the effects of radiations upon matter, the understanding of the long term aging needs the knowledge of diffusion mechanisms at the atomic scale. In that context, numerical modelling appears as a way to access this scale. We present a first principles study on self-defects and self-diffusion in a silica model. As expected, at variance with SiO{sub 2} crystalline phases, the defects formation energies are distributed, due to the non-equivalence of defects sites. We prove that the formation energy dispersion is correlated to the local stress. Concerning the equilibrium concentrations and oxygen diffusion mechanism, we discuss how the shape of the distribution, as well as impurity levels within the gap, play a main role in the dominance of defect types. Finally we present the main oxygen diffusion mechanism in homogeneous and heterogeneous defect formation regime. (author)

  9. Experimental study of columns partially filled with concrete under compressive axial loads Etude expérimentale des colonnes partiellement remplis par le béton sous charge axiale

    Directory of Open Access Journals (Sweden)

    Achoura D.

    2012-09-01

    Full Text Available Dans cette étude, on présente les résultats expérimentaux obtenus sur des poteaux mixtes béton-acier mince réalisés par soudures. Un total de 24 profilés en acier, et en forme de I a été testé sous charge de compression uni-axiale à l’âge de 28 jours. les spécimens ont été réparties comme suit: 4 à vides, 4 partiellement remplies avec un béton ordinaire sans l’addition des connecteurs, 4 renforcés par des connecteurs de cisaillements de type cornière en U, 4 autres l’ont été avec des connecteurs de cisaillements type goujons et 8 restants ont été renforcés avec des liens transversaux d’espacement 100mm, 50mm, soudés aux bouts des ailes opposées. Les principaux paramètres étudiés sont: l’élancement du profilé, le type de connecteur de renforcement. A partir des résultats d’essais obtenus, il est confirmé que les parois minces sont plus sensibles de l’apparition au voilement et la longueur des profilés a un effet considérable sur la capacité portante et le mode de rupture. L’addition des connecteurs de renforcement a confirmé l’augmentation de la charge ultime par rapport aux profilés sans connecteurs. In the present work, results of tests conducted on thin welded steel-concrete stubs are presented. A total of 24 stubs an I steel section were tested under axial compression at 28 days after the date of casting, 4 were empty, 4 filled with normal concrete, 8 columns had shear connecters welded along the centreline of the web, and 8 columns had steel rods welded between the tips of opposing flanges on both sides of the spacing of the transverse link 100 mm and 50 mm. The main parameters studied were: the heel height, and type of connector strengthening. From the test results, it is confirmed that the thin walls are more sensitive to the appearance local buckling and the length of the profiles has a significant effect on the bearing capacity and failure mode. The bearing capacity was increased

  10. ETUDE DE L'EFFET DE QUELQUES FACTEURS SUR LA CYTOTOXICITE INDUITE PAR L'AMPHOTERICINE B ASSOCIEE AUX LIPOPROTEINES DU SERUM SANGUIN CHEZ DES CELLULES DE GLOBULES ROUGES HUMAINES

    OpenAIRE

    BOUCHERIT, ATMANI Zahia

    2014-01-01

    toxiques. Dans le cadre de l'élaboration d'une stratégie de développement de cette molécule visant à augmenter l'index thérapeutique tout en réduisant la toxicité, nous avons étudié l'effet de quelques facteurs sur la cytotoxicité induite par l'amphotéricine B associée à des lipoprotéines du sérum sanguin chez le globule rouge humain (modèle universel de cellules animales supérieures). Dans notre travail nous avons abordé d'une part, les effets des caractéristiques des lipoprot...

  11. Etude de génétique des populations sur l'huître creuse de mangrove, Crassostrea gasar (Adanson, 1757), par l'apport du marqueur ITS2

    OpenAIRE

    Moreau, Dimitri

    2001-01-01

    Le genre Crassostrea regroupe de nombreuses espèces dont la répartition mondiale s'étend sur une grande partie des régions côtières des basses et moyennes latitudes. La classification des différentes espèces décrites à partir des critères morphologiques et de répartition géographique est aujourd'hui remise en cause dans de nombreux cas par les nouvelles études utilisent les techniques récentes de biologie moléculaire. C'est en particulier grâce à l'apport des séquences génomiques variables, q...

  12. Study of radio-active ions in the atmosphere; Etude des ions radioactifs de l'atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Renoux, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1965-01-01

    A comparative study is made of active, deposits of radon and thoron in suspension in the atmosphere by means of {alpha} radiation counting, using ZELENY tubes, scattering equipment, filter papers or membranes. It has been possible to show the existence of small and large ions which are negative and positive, as well as of neutral radio-active nuclei; their properties are studied. A theoretical interpretation of the results is presented. The average content of radon (using the Ra A concentration) and of Th B in the air has been determined. The radioactive equilibrium between radon and its daughter products in atmospheric air are examined. The techniques developed for active radon and thoron deposits are applied to the study of artificial radio-activity, the analyses being carried out by means of {gamma} spectrometry. (author) [French] On effectue une etude comparative entre les depots actifs du radon et du thoron en suspension dont l'atmosphere a l'aide de comptages de rayonnement {alpha}, en utilisant des tubes de ZELENY, une batterie de diffusion, des papiers filtres ou des membranes. On met ainsi en evidence la presence de petits et gros ions negatifs et positifs, ainsi que celle de noyaux neutres radioactifs, et on etudie leurs proprietes. Une Interpretation theorique des resultats obtenus est developpee. On determine la teneur moyenne de l'air en radon (a partir de la concentration en Ra A) et en Th B. L'equilibre radioactif entre le radon et ses descendants, dans l'air atmospherique, est examine. Les Techniques mises au point pour les depots actifs du radon et du thoron sont appliquees a l'etude de la radioactivite artificielle, les depouillements s'effectuant par spectrometrie {gamma}. (auteur)

  13. Study of gamma radiation between 0.1 and 1.0 MeV in the earth's atmosphere; Etude du rayonnement gamma entre 0,1 et 1 Mev dans l'atmosphere terrestre

    Energy Technology Data Exchange (ETDEWEB)

    Boclet, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-01-01

    The present work is devoted to some of the particular problems arising in the detection and localisation of sources of gamma radiation situated outside the earth's atmosphere. These weak sources can only be detected and localized if care is taken to eliminate gamma and particle radiations coming from other sources in the earth's atmosphere and in space. In order to separate the various sources of background noise, generally much stronger than the radiation under study, use is made of a directional detector whose characteristics are determined as described in the first part of the following report. The closest diffuse source considered is that constituted by the earth's atmosphere. Its detailed study will make it possible both to eliminate its effect when sources outside the earth are to be measured, and to predict the amount of secondary gamma radiation emitted by the same process in other celestial bodies, the moon in particular. This work considered in the 2. and 3. parts of the report. (author) [French] La presente etude est consacree a certains des problemes particuliers poses par la detection et la localisation des sources de rayonnement gamma situees hors de l'atmosphere terrestre. Ces sources faibles ne peuvent etre detectees et localisees que si l'on se protege des rayonnements gamma et particulaires provenant d'autres sources situees dans l'atmosphere terrestre et dans l'espace. Pour separer ces divers composants parasites, en general beaucoup plus intenses que le rayonnement a etudier, nous emploierons un detecteur directif dont nous determinons les caracteristiques dans la premiere partie de l'expose qui suit. La source diffuse la plus proche que nous considerons comme parasite est constituee par l'atmosphere terrestre. Son etude detaillee nous permettra d'une part de nous en proteger lorsque nous voudrons etudier les sources {gamma} extra-terrestres, d'autre part de prevoir le rayonnement gamma

  14. Organisation of biological research carried out in the United States by the A.E.C. or under her contract (1960); Organisation des recherches biologiques menees aux Etats-Unis par l'A.E.C. ou sous son egide. Compte-rendu sommaire d'une mission d'etude (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Pellerin, J. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    This report is based on information gathered in the course of a trip to the United States, in November and December 1958 which consisted chiefly of visits to the main biological and medical research laboratories and discussions with the heads of these establishments. A description is given of the general organisation of the Atomic Energy Commission's Division of Biology and Medicine, and of the distribution of responsibility for radiation protection work and for biological, medical and agricultural research amongst the various Services attached to it; this is followed by a more detailed account of the activities carried on in this field at the great national laboratories. Finally, the systems of collaboration set up with external research organisations in the form of research contracts are examined, together with the substantial help provided by the A.E.C. for biological, medical and agricultural research in general, owing to a systematic policy of subsidising the distribution of radioisotopes for this purpose. (author) [French] Le present rapport a ete etabli sur la base des renseignements recueillis au cours d'un voyage d'etude aux Etats-Unis, en novembre et decembre 1958, comportant notamment la visite des principaux laboratoires de recherche biologique et medicale et des entretiens avec les principaux responsables de ces laboratoires. Apres une description de l'organisation generale de la 'Division of Biology and Medicine' de l'Atomic Energy Commission et de la repartition entre les divers Services qui lui sont rattaches des responsabilites concernant la protection contre les radiations et la Recherche biologique, medicale et agronomique, des indications plus detaillees sont donnees au sujet des activites poursuivies dans ce domaine au sein des grands laboratoires nationaux. Sont examinees enfin, l'importance et les modalites de la collaboration instituee avec les Organismes de Recherche exterieurs sous la forme de

  15. Theoretical and experimental study of ions focusing systems in order to improve the ions beam brightness by suppressing aberration causes; Etude theorique et experimentale de la focalisation des ions afin d'ameliorer la brillance du faisceau ionique par la suppression des causes d'aberration

    Energy Technology Data Exchange (ETDEWEB)

    Faure, J

    1966-07-01

    It is shown that a beam brightness can be improved by an order of magnitude when the sources of aberrations are suppressed in the anode region source, as well as in the extraction region and in the electrostatic focusing system. A calculation was first set up to determine a simple focusing system. The aberration ratio due to this focusing system is smaller than 10 to 15 per cent. The experimental study was developed by using an ion source and its extraction system capable of producing an aberration free beam at an energy of 20 keV and an accelerating unit up to 190 keV that confirms that the qualities of a 35 mA beam produced by the said ion source are not spoiled when the beam goes through the focusing and accelerating system that was designed to be aberration free. (author) [French] Dans ce travail, on s'attache a demontrer que la brillance d'un faisceau peut etre amelioree d'un ordre de grandeur lorsque l'on supprime les causes d'aberration aussi bien a la sortie de la source, dans la zone d'extraction, que dans le systeme de focalisation electrostatique. Un calcul est, tout d'abord, mis au point pour determiner un systeme de focalisation simple. Cette focalisation n'entraine pas un taux d'aberrations superieur a 10 ou 15 pour cent. Puis l'etude experimentale conduit: a) a la realisation d'une source et de son systeme d'extraction fournissant un faisceau sans aberration a une energie de 20 keV. b) et a l'elaboration d'un petit accelerateur a 190 keV qui verifie que les proprietes d'un faisceau de 35 mA issu de la source ne sont pas affectees par la traversee des systemes focalisateur et accelerateur lorsque ceux-ci n'apportent pas d'aberration. (auteur)

  16. Study of the C{sub 10}-C{sub 14} paraffins separation by adsorption on 5A zeolite; Etude de la separation des paraffines en C{sub 10}-C{sub 14} par adsorption sur zeolithe 5A

    Energy Technology Data Exchange (ETDEWEB)

    Paoli, H.

    2002-11-01

    Surface-active synthesis by the way of LAB (Linear Alkyl Benzene) chain needs linear alkanes between C10 and C14. The petroleum cut used is a mixture of linear and branched paraffins, and therefore a separation is needed. It is realised using of a Simulated Counter Current process, developed and licensed by IFP. The molecular sieve employed, i.e. zeolite 5A, is obtained by ion exchange and thermal treatment from a 4A zeolite. These post synthesis operations modify the adsorbent structure and consequently its adsorption and diffusion properties. After having obtained a range as complete as possible of samples of various exchange ratios and treated in various conditions, we have characterised these adsorbent structures by X-Rays Diffraction. A limited number of structures has been refined by the Rietveld method, on the basis of anomalous diffraction experiments at the Ca K edge. Aluminium NMR was used as well. These structural data allowed to explain adsorption properties modifications of various probe molecules (H{sub 2}O, nC{sub 6}, nC{sub 10} and nC{sub 14}) studied by TPD and diffusion properties modifications studied by Quasi Elastic Neutron Scattering. (author)

  17. Electron density and temperature study of plasmas using a millimeter-wave Fabry-Perot interferometer; Etude de la densite electronique et de la temperature de plasmas a l'aide d'un interferometre Fabry-Perot en ondes millimetriques

    Energy Technology Data Exchange (ETDEWEB)

    Bize, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The contents of this article, which have been used as a basis for a State doctorate thesis, deal with research into focussing systems of the Fabry-Perot, millimetre wave type. With the help of this equipment, measurements have been made of the electronic density using interferometry in the range from 10{sup 9} to 10{sup 14} electrons/cm{sup 3}, and of the electron temperature by Thomson diffusion, of plasmas formed by laser ionisation and by high frequency. (author) [French] Le contenu de cet article, qui a fait l'objet d'une these d'Etat, se rapporte a l'etude des systemes focalisant de type Fabry-Perot en ondes millimetriques. A l'aide de ces dispositifs, on mesure la densite electronique par interferometrie dans la gamme de densites de 10{sup 9} a 10{sup 14} e/cm{sup 3} et la temperature electronique par diffusion Thomson de plasmas crees par ionisation laser et par haute frequence. (auteur)

  18. Contribution to the study of the ionization and heating of gases by laser radiation; Contribution a l'etude de l'ionisation et du chauffage des gaz par le rayonnement d'un laser declenche

    Energy Technology Data Exchange (ETDEWEB)

    Veyrie, P. [Commissariat a l' Energie Atomique, Limeil-Brevannes (France). Centre d' Etudes

    1968-01-01

    The ionization and heating of gases by the concentrated radiation of a neodymium laser is studied. The power is 300 MW, the gas studied is primarily deuterium between 300 mm and 2280 mm. The first part concerns a certain number of experimental results on the absorption of the radiation and on changes produced in the plasma as a function of time. From these results are deduced a certain number of consequences, amongst which may be mentioned the definition of a pre-ionization threshold. These experimental results are interpreted in the second part. A calculation is made of the length of the period during which the electrons multiply up to when the absorption becomes measurable. The last phase corresponds to the hydrodynamics evolution, the calculations are compared with the experiments. The agreement between theory and experiment is satisfactory for the different phases. (author) [French] On etudie l'ionisation et le chauffage des gaz par le rayonnement concentre d'un laser au neodyme. La puissance est de 300 MW, le gaz etudie est principalement le deuterium entre 300 mm et 2280 mm. La premiere partie concerne un certain nombre de resultats experimentaux. Il s'agit de l'absorption du rayonnement et de l'evolution chronologique du plasma. De ces resultats on deduit un certain nombre de consequences parmi lesquelles il faut citer la definition d'un seuil de preionisation. Ces resultats experimentaux sont interpretes dans la deuxieme partie. On calcule la duree de la phase pendant laquelle se multiplient les electrons jusqu'a ce que l'absorption soit mesurable. La derniere phase correspond a l'evolution hydrodynamique. Les calculs sont confrontes avec l'experience. L'accord entre theorie et experience est satisfaisant pour les differentes phases. (auteur)

  19. Methodological study of the diffusion of interacting cations through clays. Application: experimental tests and simulation of coupled chemistry-diffusion transport of alkaline ions through a synthetical bentonite; Etude methodologique de la diffusion de cations interagissants dans les argiles. Application: mise en oeuvre experimentale et modelisation du couplage chimie-diffusion d'alcalins dans une bentonite synthetique

    Energy Technology Data Exchange (ETDEWEB)

    Melkior, Th

    2000-07-01

    The subject of this work deals with the project of underground disposal of radioactive wastes in deep geological formations. It concerns the study of the migration of radionuclides through clays. In these materials, the main transport mechanism is assumed to be diffusion under natural conditions. Therefore, some diffusion experiments are conducted. With interacting solutes which present a strong affinity for the material, the duration of these tests will be too long, for the range of concentrations of interest. An alternative is to determine on one hand the geochemical retention properties using batch tests and crushed rock samples and, on the other hand, to deduce the transport parameters from diffusion tests realised with a non-interacting tracer, tritiated water. These data are then used to simulate the migration of the reactive elements with a numerical code which can deal with coupled chemistry-diffusion equations. The validity of this approach is tested by comparing the numerical simulations with the results of diffusion experiments of cations through a clay. The subject is investigated in the case of the diffusion of cesium, lithium and sodium through a compacted sodium bentonite. The diffusion tests are realised with the through-diffusion method. The comparison between the experimental results and the simulations shows that the latter tends to under estimate the propagation of the considered species. The differences could be attributed to surface diffusion and to a decrease of the accessibility to the sites of fixation of the bentonite, from the conditions of clay suspensions in batch tests to the situation of compacted samples. The influence of the experimental apparatus used during the diffusion tests on the results of the measurement has also been tested. It showed that these apparatus have to be taken into consideration when the experimental data are interpreted. A specific model has been therefore developed with the numerical code CASTEM 2000. (author)

  20. Etude théorique et expérimentale de la liaison de deux puits par fracturation hydraulique Theoretical and Experimental Analysis of the Linking of Two Wells by Hydraulic Fracturing

    Directory of Open Access Journals (Sweden)

    Bouteca M.

    2006-11-01

    Full Text Available La nécessité de réaliser, dans une couche mince et située à plus de 1000 m de profondeur, une communication hydraulique ou pneumatique entre deux sondages verticaux, a conduit à l'étude d'une méthode basée sur la fracturation hydraulique des puits à relier. Une telle approche suppose que l'on connaisse ou que l'on contrôle la direction des fractures développées. Les techniques actuelles ne permettant pas d'apprécier la direction de fracture avec une précision suffisante, la méthode proposée vise à influencer favorablement cette direction. Elle est basée sur une modification des contraintes effectives en place par une injection préalable de fluide dans les puits à relier. Les résultats obtenus au moyen de calculs analytiques et numériques à deux dimensions sont présentés, ainsi que les expériences réalisées sur un modèle physique en laboratoire. In a thin layer and at a depth of more than 1000 meters, the need to create a hydraulic or pneumatic communication between two vertical boreholes led to research on a method based on hydraulic fracturing in the wells to be linked. Such an approach supposes that the direction of the fractures thus created must be known or controlled. Current techniques cannot be used to assess fracture direction with sufficient accuracy. The method proposed here aims to have a favorable influence on this direction. It is based on making a change in the effective stresses in situ by the prior injection of fluid into the wells to be linked. The results obtained by two-dimensional analytical and digital computing are described together with the experiments performed on a physical model in the laboratory.

  1. Entraînement de globules d'huile par un tensio-actif. Etude de la formation du banc Mobilization of Oil Ganglia by a Surfactant Analysis of Bank Formation

    Directory of Open Access Journals (Sweden)

    Moulu J. C.

    2006-11-01

    Full Text Available Lors de l'injection d'une solution de tensio-actif dans un gisement déjà balayé par de l'eau, l'huile résiduelle, piégée sous la forme de globules discontinus, est remise en mouvement et se regroupe éventuellement sous la forme d'un banc d'huile. Le but de la présente étude est d'expliquer la formation de ce banc au cours d'un tel déplacement. Les résultats d'expériences réalisées en micromodèles de billes de verre permettent de constater que : - la récupération globale est corrélable avec le nombre capillaire Nc= uVdf/O, u et Vdf étant la viscosité et la vitesse de Darcy du fluide injecté, O la tension interfaciale avec l'huile en place ; - la vitesse des globules varie différemment avec u, Vdf, O et tend vers la même limite plus grande que la vitesse du fluide injecté pour de grandes valeurs du nombre capillaire Nc ; - le banc d'huile ne se forme que dans le cas où la vitesse des globules atteint celle du fluide injecté. L'huile déplacée reste alors groupée avec une saturation importante au niveau du front de tensio-actif. When a surfactant solution is injected into a reservoir previously waterflooded, the residual oil trapped as discontinuous ganglia is mobilized and eventually bunched together forming an oil bank. The aim of this study is to explain the formation of this bank during such a drive. The results of experiments performed in micromodels of glass beads show that: a Overall recovery can be correlated with the capillary number, Nc = uVfd/O, in which u and Vfd are the viscosity a and Darcy velocity of the injected fluid and O is the interfacial tension with the oil in place. b Ganglia velocity varies differently with u, Vfd and O, and it tends towards the same limit faster than the velocity of the injected fluid for high values of the capillary number Nc. c The oil bank is formed only in the case where globule velocity attaints that of injected fluid. the dispaced oil then remains bunched, with high

  2. Etude aerodynamique d'un jet turbulent impactant une paroi concave

    Science.gov (United States)

    LeBlanc, Benoit

    Etant donne la demande croissante de temperatures elevees dans des chambres de combustion de systemes de propulsions en aerospatiale (turbomoteurs, moteur a reaction, etc.), l'interet dans le refroidissement par jets impactant s'est vu croitre. Le refroidissement des aubes de turbine permet une augmentation de temperature de combustion, ce qui se traduit en une augmentation de l'efficacite de combustion et donc une meilleure economie de carburant. Le transfert de chaleur dans les au bages est influence par les aspects aerodynamiques du refroidissement a jet, particulierement dans le cas d'ecoulements turbulents. Un manque de comprehension de l'aerodynamique a l'interieur de ces espaces confinees peut mener a des changements de transfert thermique qui sont inattendus, ce qui augmente le risque de fluage. Il est donc d'interet pour l'industrie aerospatiale et l'academie de poursuivre la recherche dans l'aerodynamique des jets turbulents impactant les parois courbes. Les jets impactant les surfaces courbes ont deja fait l'objet de nombreuses etudes. Par contre des conditions oscillatoires observees en laboratoire se sont averees difficiles a reproduire en numerique, puisque les structures d'ecoulements impactants des parois concaves sont fortement dependantes de la turbulence et des effets instationnaires. Une etude experimentale fut realisee a l'institut PPRIME a l'Universite de Poitiers afin d'observer le phenomene d'oscillation dans le jet. Une serie d'essais ont verifie les conditions d'ecoulement laminaires et turbulentes, toutefois le cout des essais experimentaux a seulement permis d'avoir un apercu du phenomene global. Une deuxieme serie d'essais fut realisee numeriquement a l'Universite de Moncton avec l'outil OpenFOAM pour des conditions d'ecoulement laminaire et bidimensionnel. Cette etude a donc comme but de poursuivre l'enquete de l'aerodynamique oscillatoire des jets impactant des parois courbes, mais pour un regime d'ecoulement transitoire, turbulent

  3. Prise en charge du spondylolisthesis par lyse isthmique a niamey, a ...

    African Journals Online (AJOL)

    Objectif Evaluer la prise en charge chirurgicale du spondylolisthésis par lyse isthmique à Niamey. Méthode Etude prospective en série continue réalisée dans le service de Neurochirurgie de Niamey de Janvier 1999 à Janvier 2006. Etaient inclus les spondylolisthésis par lyse isthmique. Les spondylolisthésis étaient ...

  4. Study of the ANTARES detector sensitivity to a diffuse high-energy cosmic neutrino flux; Etude de la sensibilite du detecteur ANTARES a un flux diffus de neutrinos cosmiques de haute energie

    Energy Technology Data Exchange (ETDEWEB)

    Romeyer, A

    2003-04-01

    The ANTARES collaboration aims to built an underwater neutrino telescope, 2 400 m deep, 40 km from Toulon (France). This detector is constituted by 12 strings, each one comprising 90 photomultipliers. Neutrinos are detected through their charged current interaction in the medium surrounding the detector (water or rock) leading to the production of a muon in the final state. Its Cherenkov light emitted all along its travel is detected by a three dimensional array of photomultipliers. The diffuse neutrino flux is constituted by the addition of the neutrino emission of sources. Only astrophysical ones have been discussed. The different theoretical models predicting such a flux have been listed and added to the simulation possibilities. As the muon energy reconstruction was a crucial parameter in this analysis, a new energy estimator has been developed. It gives a resolution of a factor three on the muon energy above 1 TeV. Discriminant variables have been also developed in order to reject the atmospheric muon background. Including all these developments, the ANTARES sensitivity is found to be around 8.10{sup -8} GeV-cm{sup -2}-s{sup -1}-sr{sup -1} after one year of data taking for an E{sup -2} spectrum and a 10 string detector. (author)

  5. Experimental study of an oxygen-hydrogen diffusion flame laden with solid alumina particles; Etude experimentale d'une flamme de diffusion oxygene-hydrogene ensemencee en particules solides d'alumine

    Energy Technology Data Exchange (ETDEWEB)

    Labor, S.

    2003-07-15

    Monocrystalline sapphire microspheres are generated through the melting of alumina (AL{sub 2}O{sub 3}) particles in a flame. The alumina particles are injected in a very peculiar O{sub 2}/H{sub 2} confined diffusion flame as it is a downwards vertical flame having fuel in periphery of a central powdered oxygen jet. Quantitative measurements were carried out (ADL, PIV) and supplemented by a numerical study (N3S-Natur). (1) The laminar behavior of the isothermal conditions is kept through reactive flow. Therefore, particles will mainly collide due to speed gradients. (2) It has been shown that an axial particle will have a transit time int the high temperature zone very different to that of an off-line one. (3) The PIV date proved that the particle density was not homogeneous. (4) The hydrogen jet hardly influences the flame aerodynamic structure. Conversely, the central oxygen jet is at premium due to its effect on both the flame speed and temperature distribution. (author)

  6. Study of uranium (VI) in carbonate solution by potentiometric titrations and ion-exchange; Etude des solutions d'uranium (VI) en milieu carbonate par titrages potentiometriques et echange d'ions

    Energy Technology Data Exchange (ETDEWEB)

    Billon, A. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-04-01

    'ion molybdate MoO{sub 4}{sup 2-}. La separation est possible en milieu carbonate 1 M sur de petites quantites, en utilisant la technique de l'elution. Il est suggere une possibilite de separation a une echelle plus importante basee sur le deplacement du molybdene par l'uranium en milieu hydrogenocarbonate 0.5 M (le rapport des coefficients de selectivite est alors tres grand). (auteur)

  7. Dilatometric, radio crystallographic, and microstructural study of transformations produced by quenching at different rates with subsequent tempering, in zirconium-copper alloys containing less than 5 per cent copper by weight; Etude dilatometrique, radiocristallographique et microstructurale des transformations par trempe a diverses vitesses et par revenu ulterieur des alliages Zr-Cu a faibles teneurs (inferieures a 5 pour cent poids)

    Energy Technology Data Exchange (ETDEWEB)

    Couterne, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-03-01

    When {beta}-phase zirconium-copper alloys are strongly tempered, structural transformations occur leading to metastable phases which are not predicted by the equilibrium diagram. The formation mechanism is always of the martensitic type but the crystalline structures are very different according to the amount of the added element: - when the copper content is about 1 per cent by weight, a hexagonal {alpha}' phase is obtained having parameters which are very close to those of the a solid solution; its morphology is strongly acicular. - when the copper content is equal or greater than 1.6 per cent Cu by weight, a new {omega} phase has been shown to exist; this phase has a hexagonal symmetry (c/a = 0.624) and the crystals formed are of sub-microscopic size. This {omega} phase is decomposed on isothermal or an-isothermal tempering, probably by shearing, at a temperature which is practically below 550 C; an {alpha} supersaturated solid solution is first formed and there then occurs a gradual change to the a equilibrium solid solution with progressive precipitation of the compound Zr{sub 2}Cu. (author) [French] Par trempe energique depuis la phase {beta}, les alliages zirconium-cuivre sont le siege de transformations structurales conduisant a des phases metastables non prevues par le diagramme d'equilibre. Le mecanisme de formation est toujours de type martensitique, mais suivant la teneur en element ajoute les structures cristallines evoluent nettement: - lorsque la teneur en cuivre est de l'ordre de 1 pour cent Cu pds, on obtient une phase {alpha}' hexagonale, de parametres voisins de ceux de la solution solide {alpha}, et dont la morphologie est nettement aciculaire; - lorsque la teneur en cuivre est egale ou superieure a 1.6 pour cent Cu pds, une nouvelle phase {omega} a ete mise en evidence; cette phase a une symetrie hexagonale (c/a 0.624) et les cristaux formes sont de taille submicroscopique. Par revenu isotherme ou anisotherme cette phase

  8. Resolution of the time dependent P{sub n} equations by a Godunov type scheme having the diffusion limit; Resolution des equations P{sub n} instationnaires par un schema de type Godunov, ayant la limite diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Cargo, P.; Samba, G

    2007-07-01

    We consider the P{sub n} model to approximate the transport equation in one dimension of space. In a diffusive regime, the solution of this system is solution of a diffusion equation. We are looking for a numerical scheme having the diffusion limit property: in a diffusive regime, it gives the solution of the limiting diffusion equation on a mesh at the diffusion scale. The numerical scheme proposed is an extension of the Godunov type scheme proposed by L. Gosse to solve the P{sub 1} model without absorption term. Moreover, it has the well-balanced property: it preserves the steady solutions of the system. (authors)

  9. Neutron diffraction study at 0.3 K of the magnetic properties of rare-earth aluminium or gallium garnets; Etude par diffraction des neutrons a 0,3 K des proprietes magnetiques de grenats de terre rare et d'aluminium ou de gallium

    Energy Technology Data Exchange (ETDEWEB)

    Hammann, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-03-01

    In order to study ordered magnetic states below 1.5 deg. K by neutron diffraction measurements, a helium-3 cryostat has been realised in which the thermalization of a great quantity of powdered sample is performed by a helium-4 superfluid film, and which leaves the possibility of applying an external magnetic field. We thus studied essentially the magnetic phase transitions of rare-earth aluminium or gallium garnets. First we determined the antiferromagnetic structures of the erbium gallium garnet (T{sub N} = 0.79 deg. K) and of the neodymium gallium garnet (T{sub N} = 0.516 deg. K). The metamagnetic behavior of the erbium gallium garnet has been observed and compared to that of the dysprosium aluminium garnet. Second we considered the 'non-Kramers' ions Tb{sup 3+} and Ho{sup 3+} in the aluminium garnets. In this case, only two single ground states (well isolated from upper levels) have to be considered. A molecular field model with purely magnetic dipolar interactions, leads then to the existence of magnetic phase transition with antiferromagnetic ordering. This has been observed for the terbium-aluminium garnet below T{sub N} 1.35 deg. K and for the holmium-aluminium garnet below T{sub N} {approx} 0.98 deg. K. (author) [French] Afin d'acceder a l'etude par diffraction des neutrons des etats magnetiques ordonnes en-dessous de 1,5 deg. K, nous avons realise un cryostat a helium-3 qui assure la mise en temperature de la quantite importante d'echantillon en poudre a l'aide d'un film d'helium-4-superfluide, et qui laisse la possibilite d'application d'un champ magnetique exterieur. Nous avons essentiellement etudie avec cette technique les transitions de phase magnetique de grenats de terre rare et d'aluminium ou de gallium. C'est ainsi qu'on a determine l'ordre antiferromagnetique dans les grenats de gallium-erbium (T{sub N} = 0,79 deg. K) et de gallium-neodyme (T{sub N} = 0,516 deg. K). Le

  10. Contribution to the study of deformed heavy nuclei by means of nuclear reactions; Contribution a l'etude des noyaux lourds deformes au moyen de reactions nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Gastebois, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    The experimental results obtained in the study of the (d,p) reactions, at E{sub d} = 12 MeV, on the three even-even deformed nuclei {sup 170}Yb, {sup 172}Yb and {sup 174}Yb have been analysed in terms of DWBA calculations. The spectroscopic information relative to the odd final nuclei have been compared with the predictions of the collective model and of the Nilsson's model. The effect of various parameters used in the DWBA analysis (form factors, optical wave functions) has been carefully studied. The observed differences between the three final nuclei are qualitatively reproduced in the experimental study of resonances, seen in excitation functions of elastically and inelastically scattered protons on the same target nuclei, and corresponding to analogue states in the three nuclei {sup 171}Lu, {sup 173}Lu and {sup 175}Lu. (author) [French] Les resultats experimentaux de l'etude des reactions (d.p) a E{sub d} = 12 MeV, sur les noyaux deformes pairs-pairs {sup 170}Yb, {sup 172}Yb et {sup 174}Yb ont ete interpretes dans le cadre de l'approximation de Born des ondes deformees. Les informations spectroscopiques relatives aux noyaux impairs finals ont ete comparees aux predictions du modele collectif et du modele de Nilsson, apres avoir examine avec soin l'influence des differents parametres (facteurs de forme, fonctions d'onde 'optiques') utilises lors de l'analyse. Les differences observees entre les trois noyaux finals sont qualitativement reproduites par les resultats experimentaux de l'etude de resonances dans les fonctions d'excitation de diffusion elastique et inelastique de protons sur les memes noyaux-cibles, lors de la recherche d'etats analogues dans les noyaux {sup 171}Lu, {sup 173}Lu et {sup 175}Lu. (auteur)

  11. Etude de la qualité organoleptique de trois variétés de mangues ...

    African Journals Online (AJOL)

    Etude de la qualité organoleptique de trois variétés de mangues Amélie , Lippens , Brooks séchées au cours du stockage par technique de brunissement enzymatique des peroxydases (POD) et des ... Les activités les plus élevées en polyphénoloxydase et en peroxydase étaient respectivement de 19.75×10-3 ± 0.01 et 52.

  12. New logarithmic technique of diffusivity identification using the flash method; Nouvelle technique logarithmique d`identification de la diffusivite par la methode flash

    Energy Technology Data Exchange (ETDEWEB)

    Thermitus, M.A.; Laurent, M. [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France)

    1997-12-31

    Using a logarithmic transformation, the thermogram of a flash experiment can be interpreted as the sum of the adiabatic model solution with a term representative of the losses. Two methods based on this transformation are proposed in this study. They are based on the identification of a parameter that depends on the thickness of the sample and on its diffusivity and not on the experimental conditions. They allow to identify the diffusivity with a high precision even for materials with a low conductivity at high temperatures. (J.S.) 12 refs.

  13. Structural and dynamical study about denatured states of yeast phosphoglycerate kinase by neutrons scattering and X-rays; Etude structurale et dynamique des etats denatures de la phosphoglycerate kinase de levure par diffusion des neutrons et des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Receveur, V

    1997-04-28

    During a long time, the neutron scattering and X-rays techniques have not been used for the studies bearing on the folding of proteins. The compactness and the globularness of a protein are two structural characteristics describing the denatured states and the intermediate states of folding, and the neutrons and x-rays scattering are probably the two techniques the most appropriate to give this kind of information; they are sensible to the spatial extent and to the molecules compactness, and to their general shape. For these three or four last years, the works using these techniques are increasing, giving precious knowledge on the different steps of folding and on the interactions stabilizing the denatured or intermediate states. This thesis falls into this category. (N.C.).

  14. Conformation and arrangement of polyelectrolytes in semi-diluted solution. A study by small angle neutrons scattering; Conformation et arrangement des polyelectrolytes en solution semi-diluee. Etude par diffusion des neutrons aux petits angles

    Energy Technology Data Exchange (ETDEWEB)

    Spiteri, M.N.

    1997-03-25

    Polyelectrolytes have particular physical and chemical properties and can thus be used for instance for petroleum production. Some of their microscopic properties have been studied in this work. With the particular zero average contrast technique, the small angle neutron scattering allows to directly know the form factors in semi-diluted solutions of polyelectrolytes where the chains are mixed. Another measure leads to the crystal structure. The electrostatic screen effects when salt is added in aqueous solutions of completely charged PSSNa solutions (f=1) (sodium polystyrene sulfonate) are studied. It seems that the chains take a vermiform conformation. Their persistence length varies as I{sup -1/3} (I is the ionic force). The hydrophobicity effects in partially charged PSSNa solutions (f<1) are given too. They lead to a progressive collapse of the chains when their charge rates decrease. The screen and condensation effects when the charge rate f of the PSSNa (f>f(Manning)) varies in a polar solvent (DMSO) are studied. The vermiform chains have the same persistence length (for each f) which varies as I{sup -1/4}. Lastly, the f variation effects in the case of a weakly charged hydrophilic poly-ion (f

  15. Étude des matrices sol-gel en film mince par détection de molécule unique en champ large : diffusion moléculaire et agrégation photo-induite

    Science.gov (United States)

    Nutarelli, D.; Débarre, A.; Jaffiol, R.; Julien, C.; Richard, A.; Tchénio, P.; Chaput, F.; Boilot, J. P.

    2004-11-01

    La fluorescence de molécules de colorant dans des matrices sol-gel en film mince a été étudiée par détection de molécule unique. Outre les phénomènes de photo-blanchiment et de clignotement, un processus de photo-agrégation a été observé. Ce phénomène, dont la dynamique dépend de la présence d'oxygène, de l'intensité du laser d'excitation et de la température, montre l'existence de deux classes de molécules dans l'échantillon. Des molécules immobiles et d'autres qui diffusent. L'analyse de la dynamique d'agrégation permettra de dégager certaines caractéristiques du mécanisme de photo-agrégation et d'appréhender le rôle joué par la matrice sol-gel dans ce processus.

  16. Etude de la réaction $\\pi^{-}$p $\\to$ $\\pi^{-}$ $\\pi^{o}$p à 2,77 GeV/c pour de faibles impulsions du proton diffusé. Application de la méthode d'extrapolation de Chew et Low à la diffusion élastique $\\pi^{-}$ $\\pi$°

    CERN Document Server

    Baton, Jean-Pierre

    Dans le cas actuel de nos connaissances sur les interactions fortes, il peut paraître inutile d'entreprendre une nouvelle expérience du type pour vérifier la validité du modèle périphérique exposé par CHEW et LOW en 1959 et, cela , en toute rigueur, à l'étude de la diffusion pion pion. *?Tv l°rS> 6n 6ffet) Un trèS grand n° mbre d' exP érien ' es [2 - 56]' portant sur la réaction (I) raooe ±00" pOUr/°nfirmer ce modèle da • ! f^ d obtenir dans des ûé ^ raisonnables un nombre d'événements qu'a Ta rlacuon ?*" ^^ ^ CSM d6S e*P^ences précitées nous a conduit à ne regarder pour de faibles impulsions du proton diffusé. Dans le Chapitre I, nous décrivons les conditions expérimentales de cette étude et les mé- thodes employées pour l'obtention des données. Il est fait état en détail des précautions prises pour éviter l'introduction de biais dans nos données expérimentales. Le Chapitre II traite de la détermination de la section efficace de production de la réaction (1) à parti...

  17. Contribution to the study of molecular movements in cyclohexane by electron spin resonance and electron-nuclear double resonance using a radical probe; Contribution a l'etude des mouvements moleculaires dans le cyclohexane par resonance paramagnetique electronique et double resonance electronique-nucleaire a l'aide d'une sonde radicalaire

    Energy Technology Data Exchange (ETDEWEB)

    Volino, F. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Solutions of stable free radicals of the nitroxide type have been studied as a function of temperature. In the plastic or globular state, the cyclohexane molecules have rapid rotational and diffusional movements. They transmit this movement to dissolved free radicals. Conversely, measurements by electron spin resonance of the absolute movement of the radicals, and by electron nuclear double resonance of their movement relative to the cyclohexane molecules give very precise methods for local analyses of the movement present in the cyclohexane matrix. The principle of these techniques makes up the 'radical probe method'. (author) [French] Des solutions de radicaux libres stables, du type nitroxyde dans le cyclohexane ont ete etudiees, en fonction de la temperature. Les molecules de cyclohexane, dans l'etat plastique ou globulaire, sont animees de mouvements rapides de rotation sur elles-memes et de diffusion. Elles transmettent leur mobilite aux radicaux libres dissous. Reciproquement, la mesure du mouvement absolu des radicaux, a l'aide de la resonance paramagnetique electronique, et celle du mouvement relatif des radicaux et des molecules de cyclohexane par double resonance electronique-nucleaire, constituent des methodes tres precises pour analyser localement les mouvements presents dans la matrice de cyclohexane. Ce principe et ces techniques constituent la 'methode de la sonde radicalaire'. (auteur)

  18. Generalities on the dynamic behaviour of rapid reactors. Preliminary studies on Rapsodie; Generalites sur le comportement dynamique des piles rapides. Etudes preliminaires de rapsodie

    Energy Technology Data Exchange (ETDEWEB)

    Campan, J.L.; Chaumont, J.P.; Clauzon, P.P.; Ghesquiere, G.; Leduc, J.; Schmitt, A.P.; Zaleski, C.P. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1963-07-01

    The study of the dynamic behaviour of fast reactors may be divided into three section: 1. Stability studies around equilibrium power only the linear case was examining. S. Transient studies in the case of usual reactor operation (shut down, scram, etc.) with thermal shocks evaluation, for instance. 3. Explosion studies, for the maximum credible accidents. This report presents the status of the studies performed at the 'Physics Research Department' at Cadarache. Methods used are detailed and illustrated with the results obtained on a preliminary metallic core of the Rapsodie Reactor. (authors) [French] Le comportement dynamique des piles rapides, se presente tout naturellement sous trois aspects: 1. Etude de stabilite autour d'un regime d'equilibre (nous nous sommes bornes ici au cas lineaire). 2. Etude de regimes transitoires lors des operations normales de pile (arret, arret d'urgence, etc.) avec evaluation des chocs thermiques par exemple. 3. Etude des regimes transitoires de caractere explosif lors des accidents les plus graves possibles. Ce rapport presente l'etat des etudes a la date du 20 decembre 1961 a la Section d'Etudes de Piles Rapides a CADARACHE. Les methodes employees ont ete detaillees et illustrees a partir des resultats obtenus sur une premiere version 'combustible metallique' de Rapsodie. (auteurs)

  19. Simulation of anions diffusion in Callovo-Oxfordian argillite by description of the rock microstructure; Modelisation de la diffusion des anions dans l'argilite du Callovo-oxfordien par description de la microstructure de la roche

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, N. [CEA Saclay, Dept. de Physico-Chimie (DEN/DANS/DPC/SECR), 91 - Gif sur Yvette (France)

    2008-07-01

    The Callovo-Oxfordian argillite has been proposed as host rock for deep underground radioactive wastes storage. The aim of this study is to determine the report of effective diffusion coefficients De(anion)/De(water) at the micrometer scale considering the spatial distribution of minerals in the rock. (A.L.B.)

  20. Etat des lieux et profil de l'imagerie par resonance magnetique dans ...

    African Journals Online (AJOL)

    Objectif: Faire l'état des lieux de la prescription de l'Imagerie par Résonance Magnétique (IRM) et de décrire les aspects IRM des cancers de la prostate au Togo. Matériel et Méthode: Etude rétrospective, descriptive des IRM prostatiques dans le service de radiologie de la clinique Autel d'ELIE sur une période de 5 ans.

  1. Protease-activated receptor (PAR)-2 is required for PAR-1 signalling in pulmonary fibrosis

    NARCIS (Netherlands)

    Lin, Cong; von der Thüsen, Jan; Daalhuisen, Joost; ten Brink, Marieke; Crestani, Bruno; van der Poll, Tom; Borensztajn, Keren; Spek, C. Arnold

    2015-01-01

    Idiopathic pulmonary fibrosis is the most devastating diffuse fibrosing lung disease of unknown aetiology. Compelling evidence suggests that both protease-activated receptor (PAR)-1 and PAR-2 participate in the development of pulmonary fibrosis. Previous studies have shown that bleomycin-induced

  2. Structure physico-chimique et résistance à la fissuration des bitumes routiers : Thèse de Malo Le Guern au Laboratoire Central des Ponts et Chaussées en partenariat avec Total : Etude des bitumes purs : Influence du vieillissement en laboratoire par 25 heures de PAV

    OpenAIRE

    LE GUERN, Malo

    2008-01-01

    Le bitume peut être caractérisé par différentes méthodes physico-chimiques. Lors du cycle d'utilisation (stockage, enrobage, sur site), le liant subit des vieillissements physiques et chimiques. Dans ce rapport, nous étudions les différences entre les caractéristiques physicochimiques des bitumes purs de natures différentes, sélectionnés pour la thèse, ainsi que les modifications induites par un vieillissement de 25 heures de vieillissement par l'essai de « Pressure Aging Vessel » (PAV), e...

  3. Uranium prospecting using radon (1963); La prospection de l'uranium par le radon (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Pradel, J.; Billard, F.; Miribel, J.; Gangloff, A.; Puybaraud, Y.; Tayeb, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The radon which diffuses in the ground and which migrates in the atmosphere is a natural radioactive tracer. The study of its production can give useful information on the uranium content and structure of the rocks from which it comes. Numerous authors have therefore suggested that uranium deposits be prospected by means of this radon. Three analytic methods have been used successively by the C.E.A.: the method of accumulation in a hole, the method of instantaneous sampling in the ground, and the method of sampling by scanning. Only the last has proved interesting and has been the object of systematic studies. It consists in purging the measurement recipient with air drawn from the probe and in measuring the variations in activity with time and with the volume drawn up, using a portable apparatus producing scintillations in a sulphurated flask. The first series of measurements made it possible to develop an apparatus (flow rate, hole depth, scintillating probe) and to distinguish between tbe activities of the thoron and of the radon by making two measurements at an interval of 54 seconds. A campaign of systematic sampling was then carried out. It made It possible to show the good reproducibility of the results obtained and tbe good agreement with conventional methods. This method is the best one for areas having large overlap. In the appendix the detector and its mode of use are briefly described, and the first results of an emanometric prospecting test in the Vendee mining division are given. (authors) [French] Le radon qui diffuse dans le sol et migre dans l'atmosphere constitue un traceur radioactif naturel. L'etude de son degagement peut apporter de precieux renseignements sur la teneur en uranium et la structure des roches dont il est issu. De nombreux auteurs ont donc propose la prospection des gisements d'uranium par le radon. Trois methodes d'analyse ont ete successivement utilisees au C.E.A.: la methode d'accumulation dans un trou

  4. Etude de l'impact des procédés de transformation sur la diffusion des caroténoïdes : cas du lycopène de la tomate

    OpenAIRE

    Degrou, Antoine

    2013-01-01

    Les caroténoïdes sont une famille de molécules lipidiques que l’on trouve en particulier dans les végétaux, et qui ont pour caractéristique visuelle d’être colorés, du jaune au rouge. Ils ont été identifiés comme nutritionnellement actifs par des études épidémiologiques. Afin de pouvoir jouer un rôle dans l’organisme les caroténoïdes doivent être absorbés. Pour ce faire ils doivent être libérés de la matrice alimentaire afin de passer après plusieurs étapes dans la circulation sanguine. Or le...

  5. Sources d'hétérogénéité d'un assemblage par soudage par diffusion homogène de tôles en acier austénitique inoxydable Heterogeneity sources during homogeneous HIP-bonding of austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Bouquet Nicolas

    2013-11-01

    Full Text Available Ce document présente un aperçu des hétérogénéités de microstructure aux interfaces qui peuvent être rencontrées lors du soudage par diffusion homogène d'un assemblage de tôles. Un assemblage homogène a finalement été réalisé avec l'obtention de propriétés mécaniques très satisfaisantes. Pour finir, une piste de réflexion est apportée afin d'améliorer les propriétés des assemblages. This document deals with the structural sources of heterogeneity during homogeneous HIP-bonding of austenitic stainless steel. An homogeneous microstructure was finally obtained with very good mechanical properties comparable to those of the base material. To conclude, a way to further improve the assembly properties is discussed.

  6. Etude sur les tendons en materiaux composites et leur application aux ancrages postcontraints

    Science.gov (United States)

    Chennouf, Adil

    L'objectif general de la presente these est d'evaluer le comportement a l'arrachement et au fluage d'ancrages injectes constitues de tendons en materiaux composites afin d'etablir des recommandations plus appropriees et realistes pour le dimensionnement et la conception. Quatre types de tendons en materiaux composites, deux a base de fibres d'aramide et deux a base de fibres de carbone, ont ete utilises dans l'etude. Les travaux de recherche de cette these ont porte notamment sur: (I) Une caracterisation physique et mecanique des tendons en materiaux composites utilises dans l'etude. (II) Une etude en laboratoire sur les coulis de scellement. La premiere etape de cette etude a concerne le developpement d'un coulis de scellement performant adapte aux tendons en materiaux composites et a differentes situations d'injection. La seconde etape a traite des essais de caracterisations physique et mecanique du coulis de scellement developpe comparativement a trois coulis de scellement usuels d'un meme rapport E/L de 0,4. (III) Une etude sur des modeles reduits d'ancrages injectes. (IV) Une etude sur des modeles d'ancrages a grande echelle. La synthese de ces etudes a permis d'enoncer les principales conclusions suivantes: (1) Les valeurs moyennes des charges de rupture des tendons en materiaux composites ont ete de 1% a 29% superieures a celles specifiees par les manufacturiers. (2) L'etude sur les coulis de scellement a permis le developpement de coulis de ciment repondant aux criteres fixes, soient une grande stabilite, une bonne fluidite, une legere expansion et de bonnes caracteristiques mecaniques. (3) Les tendons en materiaux composites ont montre des contraintes d'adherence maximum superieures a celles des tendons en acier. (4) Le type de fibre, la configuration et le fini de surface des tendons en materiaux composites gouvernent leur resistance a l'adherence. (5) L'introduction de sable et d'autres ajouts comme les fines de silice et la poudre d'aluminium au coulis

  7. Developpement de techniques de diagnostic non intrusif par tomographie optique

    Science.gov (United States)

    Dubot, Fabien

    Que ce soit dans les domaines des procedes industriels ou de l'imagerie medicale, on a assiste ces deux dernieres decennies a un developpement croissant des techniques optiques de diagnostic. L'engouement pour ces methodes repose principalement sur le fait qu'elles sont totalement non invasives, qu'elle utilisent des sources de rayonnement non nocives pour l'homme et l'environnement et qu'elles sont relativement peu couteuses et faciles a mettre en oeuvre comparees aux autres techniques d'imagerie. Une de ces techniques est la Tomographie Optique Diffuse (TOD). Cette methode d'imagerie tridimensionnelle consiste a caracteriser les proprietes radiatives d'un Milieu Semi-Transparent (MST) a partir de mesures optiques dans le proche infrarouge obtenues a l'aide d'un ensemble de sources et detecteurs situes sur la frontiere du domaine sonde. Elle repose notamment sur un modele direct de propagation de la lumiere dans le MST, fournissant les predictions, et un algorithme de minimisation d'une fonction de cout integrant les predictions et les mesures, permettant la reconstruction des parametres d'interet. Dans ce travail, le modele direct est l'approximation diffuse de l'equation de transfert radiatif dans le regime frequentiel tandis que les parametres d'interet sont les distributions spatiales des coefficients d'absorption et de diffusion reduit. Cette these est consacree au developpement d'une methode inverse robuste pour la resolution du probleme de TOD dans le domaine frequentiel. Pour repondre a cet objectif, ce travail est structure en trois parties qui constituent les principaux axes de la these. Premierement, une comparaison des algorithmes de Gauss-Newton amorti et de Broyden- Fletcher-Goldfarb-Shanno (BFGS) est proposee dans le cas bidimensionnel. Deux methodes de regularisation sont combinees pour chacun des deux algorithmes, a savoir la reduction de la dimension de l'espace de controle basee sur le maillage et la regularisation par penalisation de Tikhonov

  8. Mixed-hybrid finite element method for the transport equation and diffusion approximation of transport problems; Resolution de l'equation du transport par une methode d'elements finis mixtes-hybrides et approximation par la diffusion de problemes de transport

    Energy Technology Data Exchange (ETDEWEB)

    Cartier, J

    2006-04-15

    This thesis focuses on mathematical analysis, numerical resolution and modelling of the transport equations. First of all, we deal with numerical approximation of the solution of the transport equations by using a mixed-hybrid scheme. We derive and study a mixed formulation of the transport equation, then we analyse the related variational problem and present the discretization and the main properties of the scheme. We particularly pay attention to the behavior of the scheme and we show its efficiency in the diffusion limit (when the mean free path is small in comparison with the characteristic length of the physical domain). We present academical benchmarks in order to compare our scheme with other methods in many physical configurations and validate our method on analytical test cases. Unstructured and very distorted meshes are used to validate our scheme. The second part of this thesis deals with two transport problems. The first one is devoted to the study of diffusion due to boundary conditions in a transport problem between two plane plates. The second one consists in modelling and simulating radiative transfer phenomenon in case of the industrial context of inertial confinement fusion. (author)

  9. Le changement comme tradition dans la recherche et la formation a la recherche en biotechnologie et en peripherie Etude de cas en sciences de la sante, sciences naturelles et genie

    Science.gov (United States)

    Bourque, Claude Julie

    Le champ de la recherche scientifique et de la formation a la recherche est traverse depuis quelques dizaines d'annees par plusieurs courants et discours associes au changement, mais peu de travaux empiriques permettent de comprendre ce qui change concretement. C'est la contribution originale de cette these au champ de l'education, plus specifiquement a l'etude sociologique de l'enseignement superieur ou sont concentrees les activites liees a la triade thematique du programme doctoral dans lequel elle a ete produite : recherche, formation et pratique. L'enquete-terrain a ete realisee en 2009 et 2010 aupres de 808 repondants affilies a 60 etablissements au Quebec et a produit un vaste materiau de nature mixte (donnees quantitatives et qualitatives). Un portrait de la nebuleuse biotechnologique qui touche les secteurs des sciences de la sante, des sciences naturelles et du genie a ete realise. Ce domaine concerne des dizaines de disciplines et se revele de nature transdisciplinaire, mais les pratiques n'y sont pas davantage marquees par le changement que celles d'autres domaines connexes. Les dynamiques sociales ont fait l'objet d'analyses comparatives dans quatre contextes: le choix des programmes, des objets et des methodes, le financement, la diffusion et la planification de la carriere. Les resultats indiquent que les echanges entre les agents traditionnellement situes au coeur des activites de recherche dominent ces dynamiques dans tous les contextes etudies. L'etude des representations au fondement des pratiques a revele l'existence de trois ecoles de pensee qui coexistent dans le champ scientifique: academique, pragmatique et economiste. Ces ecoles permettent de categoriser les agents en fonction des zones de fractures qui marquent leurs oppositions tout en identifiant ce qu'ils ont en commun. Les representations et les pratiques liees a la formation temoignent d'un habitus plutot homogene, alors que les contradictions semblent plus souvent ancrees dans des

  10. Etude des propriétés magnéto-optiques des couches minces à base ...

    African Journals Online (AJOL)

    Etude des propriétés magnéto-optiques des couches minces à base de ferrite de cobalt obtenues par voie sol-gel. ... Les courbes obtenues à la longueur d'onde de 820 nm présentent des cycles d'hystérésis avec des rotations rémanentes de 40, 60 et 81°/cm. Ces résultats présentent une excellente rotation Faraday de ...

  11. PAR-TERRA directs homologous sex chromosome pairing.

    Science.gov (United States)

    Chu, Hsueh-Ping; Froberg, John E; Kesner, Barry; Oh, Hyun Jung; Ji, Fei; Sadreyev, Ruslan; Pinter, Stefan F; Lee, Jeannie T

    2017-08-01

    In mammals, homologous chromosomes rarely pair outside meiosis. One exception is the X chromosome, which transiently pairs during X-chromosome inactivation (XCI). How two chromosomes find each other in 3D space is not known. Here, we reveal a required interaction between the X-inactivation center (Xic) and the telomere in mouse embryonic stem (ES) cells. The subtelomeric, pseudoautosomal regions (PARs) of the two sex chromosomes (X and Y) also undergo pairing in both female and male cells. PARs transcribe a class of telomeric RNA, dubbed PAR-TERRA, which accounts for a vast majority of all TERRA transcripts. PAR-TERRA binds throughout the genome, including to the PAR and Xic. During X-chromosome pairing, PAR-TERRA anchors the Xic to the PAR, creating a 'tetrad' of pairwise homologous interactions (Xic-Xic, PAR-PAR, and Xic-PAR). Xic pairing occurs within the tetrad. Depleting PAR-TERRA abrogates pairing and blocks initiation of XCI, whereas autosomal PAR-TERRA induces ectopic pairing. We propose a 'constrained diffusion model' in which PAR-TERRA creates an interaction hub to guide Xic homology searching during XCI.

  12. ETUDE - European Trade Union Distance Education.

    Science.gov (United States)

    Creanor, Linda; Walker, Steve

    2000-01-01

    Describes transnational distance learning activities among European trade union educators carried out as part of the European Trade Union Distance Education (ETUDE) project, supported by the European Commission. Highlights include the context of international trade union distance education; tutor training course; tutors' experiences; and…

  13. Study of recombination processes for 'electron-hole' pairs in germanium irradiated by {gamma} rays from {sup 60}Co using the photovoltaic effect in P-N junctions; Etude du processus de recombinaison des paires ''electron-trou'' dans le germanium irradie par les rayons {gamma} du cobalt 60 a l'aide de l'effet photovoltaique dans les jonctions P-N

    Energy Technology Data Exchange (ETDEWEB)

    Zahedi-Mochadam, A.A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-10-01

    trouve a 0,25 eV au-dessous de la bande de conduction et les sections efficaces de capture des trous et des electrons ont respectivement pour valeurs: {sigma}{sub p} = 4 x 10{sup -15} cm{sup 2} et {sigma}{sub n} = 3 x 10{sup -15} cm{sup 2}. La valeur de {sigma}{sub n} semble sous-estimee, du fait que le nombre des defauts dans les echantillons de type P parait plus faible que dans ceux de type N. Ces resultats laissent a penser que les interstitiels sont responsables de la recombinaison. A 80 K, nous avons trouve dans les echantillons de type N, un niveau peu profond situe a 0,05 eV au-dessous de la bande de conduction avec la section de capture des trous {sigma}{sub p} {>=} 10{sup -14} cm{sup 2}. Nous pensons que dans ce cas, la recombinaison des porteurs de charge est controlee par des paires 'lacune-instertitiels' proches. Dans les echantillons de type P a basse temperature, la duree de vie reste pratiquement constante au cours de l'irradiation. Ce fait est attribue a une guerison spontanee des defauts d'origine purement electrique. Dans la derniere partie du travail, l'etude de l'effet photovoltaique applique au probleme de la dosimetrie des rayons gamma est consideree. On montre que de tels dosimetres bases sur ce principe permettent de mesurer l'intensite des rayons gamma dans une gamme tres etendue.

  14. Study of the background noise generated by the accelerator PEP-2 with a CsI(Na) scanning ring. Study of mass difference between B neutral mesons by using BABAR detector and DI-leptons events; Etude du bruit de fond engendre par l'accelerateur PEP-2 avec un anneau de cristaux de CsI(Na). Etude des oscillations des mesons B neutres avec le detecteur BaBar en utilisant les evenements DI-Leptons

    Energy Technology Data Exchange (ETDEWEB)

    Domenico, G. de

    2000-06-14

    The first part of this report is dedicated to the CP-violation in the sector of B quarks and to its experimental proof through 2 major equipment: the B meson factory PEP-2 and the detector BABAR. The second part deals with the background noise generated by PEP-2. The third part presents the study of the oscillations of neutral B mesons with the detector BABAR. The study of the background noise shows important differences between the experimental data and the simulation. These differences are thought to be due on one hand to the lack of accuracy of pressure models that set the normalisation of the simulated background noise, and on the other hand to the absence of simulation of particles that undergo Coulomb diffusion and do more than a lap before bumping into the void tube. The second hypothesis is backed by the evaluation of the collimation effect of the beam that appears to be more important in experimental data than in the simulation. Among the main results given by the BABAR collaboration, the measurement of the oscillation frequency of the neutral B meson is very important. This measurement is based on semi-leptonic decays of B mesons in order to tag the favour of neutral B mesons at the very moment of their decay. The data analysis was performed over 2.3 10{sup 6} decays of B meson pairs and we obtained: {delta}m{sub d} = (0.495 {+-} 0.026 {+-} 0.023) {Dirac_h}ps{sup -1}. The accuracy on the value of {delta}m{sub d} could be improved by using tagging methods based on the semi-exclusive then exclusive reconstruction of neutral B mesons. (A.C.)

  15. Contribution to the theoretical and experimental study of the electron-volt effect in N-P junctions; Contribution a l'etude theorique et experimentale de l'effet electronvoltaique dans les jonctions N-P

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Van, Dong [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-07-15

    , taking into account other phenomena which occur at low temperature. In the fourth part, results concerning the healing of the defects and protection measures against too energetic {beta} rays are described. A healing difference was observed between the lifetime and the conductivity. Finally, interesting results were obtained from experiments using a cadmium sulphide film to transform the {beta} particles of {sup 90}Sr-{sup 90}Y into photons. (author) [French] Le but propose dons le cadre de ce travail est d'etudier le comportement d'une jonction semi-conductrice sous l'action des rayons {beta}. L'etude a porte d'une part sur la conversion directe de l'energie rayonnee par une source radioactive en energie electrique utilisable a l'aide des jonctions N-P, et d'autre part sur la cinetique des defauts produits dans les cristaux de semi-conducteur par les rayons {beta} de grande energie. Dans la premiere partie du travail, on a essaye de completer les theories anterieures de l'effet electron-voltaique dans les jonctions en faisant une analyse mathematique de l'effet. Ceci a permis d'atteindre une equation unique dans laquelle figurent les parametres electriques et geometriques du semi-conducteur, de la jonction et les proprietes du rayonnement incident. D'autre part, on a etudie d'une maniere plus approfondie le courant de diffusion des porteurs de charge crees par le bombardement en tenant compte de tous les facteurs intervenant dans l'expression de l'efficacite de collection de charge d'une jonction. Dans la deuxieme partie, ou des experiences d'irradiation des jonctions N-P ont ete effectuees avec une source de {sup 90}Sr- {sup 90}Y, on a signale l'interet particulier d'une jonction d'arseniure de gallium susceptible de travailler a des temperatures relativement elevees (voisines de 100 deg. C). La troisieme partie presente l'etude des defauts crees dans un cristal de

  16. Influence of diffusion on extraction kinetics in porous bodies. The case of uranium oxides; Influence de la diffusion sur la cinetique d'extraction dans un corps poreux. Cas des oxydes de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Tinturier, B. [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

    1966-12-01

    The study of the leaching of heaped uranium ore can be considered theoretically as the problem of the diffusion of liquids in porous bodies and in particular as that of its influence on the chemical reaction rates of conventional uranium oxides. Below a certain value of the pore diameter, it is diffusion which is responsible for mass transfer. The porous structure can be characterized by various physical constants which modify the free diffusion equation and, as long as the pores have a diameter greater than a few microns, it can be shown that the pore walls have a negligible effect on the diffusion. The diffusion coefficients for the nitrate, the sulfate, the chloride, the acetate and the perchlorate of uranium have been determined. In the case of the reaction of uranium trioxide with acids in a porous body, the reaction kinetics are governed by the arrival of the reagent by diffusion. The attack of uranium dioxide by an acid ferric iron solution has been studied under the same conditions and it has been found that the diffusion modifies the influence of the ferrous and ferric iron concentrations on the reaction kinetics. The same is true for the oxide U{sub 3}O{sub 8}. All the results concerning these reactions studied in the absence of the influence of diffusion should be modified to take this factor into account when it intervenes in an extraction process. (authors) [French] L'etude de la lixiviation en tas d'un minerai d'uranium peut se ramener theoriquement au probleme de la diffusion des liquides dans les corps poreux et en particulier a celui de son influence sur les vitesses de reaction chimique des oxydes classiques de l'uranium. En dessous d'une certaine limite de diametre des pores la diffusion est responsable du transfert de masse. La structure poreuse peut se caracteriser par differentes constantes physiques qui modifient l'equation de la diffusion libre et tant que les pores ont un diametre superieur a quelques microns

  17. Accouchement par césarienne et mortalité maternelle du postpartum

    OpenAIRE

    Deneux-Tharaux , Catherine; Carmona , Elodie; Bouvier-Colle , Marie-Hélène; Bréart , Gérard

    2006-01-01

    Objectifs Une augmentation continue du taux d'accouchements par césarienne (CS)est observée dans la plupart des pays depuis 20 ans. Cette évolution a suscité l'émergence d'un débat controversé sur les risques et les bénéfices associés à la CS. L'objectif de cette étude était d'estimer le risque de mort maternelle du postpartum lié directement à la CS par comparaison à l'accouchement par voie basse, globalement et en distinguant les CS pre- ou intra- partum . Méthode Etude cas/témoins. Les cas...

  18. Texture study of divided solids by gas adsorption: application to beryllia, alumina and to gels and oxides; Contribution a l'etude, par adsorption gazeuse, de la texture des solides divises. Application a l'alumine, a la glucine et a differents gels et oxydes

    Energy Technology Data Exchange (ETDEWEB)

    Rouquerol, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-12-01

    particulier dans le cas des solides mtcroporeux) pour la determination du volume de gaz adsorbe dans une couche monomoleculaire et que l'azote est sensible aux interactions chimiques ou electriques avec l'adsorbant: il convient de le remplacer par l'argon. Les methodes de calcul de la distribution de taille des pores sont analysees et discutees. Nos resultats experimentaux ont montre que l'epaisseur de la couche multimoleculaire doit etre calculee a partir du nombre de couches donne par Shull et d'une epaisseur de 3,6 angstrom par couche. Enfin, nous proposons une nouvelle methode d'analyse de la branche de desorption. Nous montrons que certains systemes lamellaires, non poreux, tels que Be(OH){sub 2}, donnent une hysteresis sur une isotherme d'adsorption du type I ou II. En nous basant sur les resultats numeriques fournis par notre methode ainsi que sur des observations obtenues par microscopie electronique, nous concluons que cette hysteresis est due au manque de rigidite du solide. Inversement, nous avons caracterise des solides poreux qui ne donnent pas lieu au phenomene d'hysteresis. C'est le cas des echantillons de glucine de texture microporeuse (r < 20 A). Les conclusions precedentes nous permettent de decrire l'evolution de texture subie par deux series d'echantillons (glucine et alumine) au cours de leur deshydratation progressive (traitement thermique allant de 150 a 1100 C). (auteur)

  19. Study of contamination by 100 {mu}Ci of Sr 90 in the rat: clinical, hematological and osseous effects (appearance of osteosarcomas); Etude d'une contamination par 100 {mu}Ci de Sr 90 chez le rat: consequences cliniques, hematologiques et osseuses (apparition d'osteosarcomes)

    Energy Technology Data Exchange (ETDEWEB)

    Graf, B.; Lafuma, J.; Parmentier, C.; Parmentier, N. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    Clinical, hematological and osseous effects following an intramuscular injection of 100 {mu}Ci 90 Sr were studied in the rat. In spite of the magnitude of the injection and the resulting damage, the elimination of strontium could compare with what occurs after an injection at tracer doses. Comparing with the controls at the outcoming time, clinical monitoring mainly brought out a loss of body weight. Fairly early (20. - 30. day) there occurred severe hematological damage, especially on lymphocyte line, which subsided spontaneously. As foreseen, the anatomo-pathological survey of the early period showed bone and medullar lesions in the areas of enchondral ossification. In the late period, bone sarcomas occurred in nine animals out of ten. The outstanding histological type was osteogenic osteosarcomas; besides, two animals experienced bilateral tumors. (authors) [French] Les auteurs etudient les consequences cliniques, hematologiques et osseuses d'une contamination par 100 microcuries de Sr 90 injectes par voie intramusculaire chez le rat. Malgre l'importance de la contamination et les lesions consequentes, l'elimination du Sr 90 est comparable a celle que l'on observe apres injection de doses traceuses. La surveillance clinique ne met essentiellement en evidence, a la periode terminale, qu'une diminution du poids par rapport aux temoins. Les lesions hematologiques sont importantes, predominant sur la lignee lymphocytaire. Elles sont relativement precoces (20e - 30e jours) et regressent spontanement. La surveillance anatomo-pathologique de la periode precoce a montre, comme il etait previsible, des lesions osseuses et medullaires dans les zones d'ossification enchondrale. A la periode tardive, la survenue de sarcomes osseux a ete observee chez neuf animaux sur dix. Le type histologique predominant est l'osteosarcome osteogenique et il faut signaler egalement les tumeurs bilaterales observees chez deux animaux. (auteurs)

  20. Etude de la réactivité hydraulique d’un ciment bélitique synthétisé à basse température par la méthode sèche en utilisant un minéralisateur

    Directory of Open Access Journals (Sweden)

    Mazouzi Wafaa

    2014-04-01

    Full Text Available Pour des raisons écologiques (réduction des émissions de CO2, les ciments bélitiques à faible teneur en alite ont fait l’objet de beaucoup de recherches ces dernières années afin de substituer le clinker Portland ordinaire. Ces recherches ont concernées la production du ciment bélitique à basse temperature et l’amélioration de son activité hydraulique, ainsi que l’étude de la durabilité des matériaux à base de ce ciment. Dans ce travail, le mélange cru des matières premières (calcaire et argile du ciment bélitique a été substitué par un autre mélange composé de poussière de chaux hydraulique des ateliers d’ensachage et de boue de forage des puits de pétrole en Algérie. Le procédé de cuisson par voie sèche en utilisant 2% de sulfate de zinc (ZnSO4 comme minéralisateur a été adopté pour la fabrication de ce ciment bélitique (éco-ciment à basse température (1100°C. L’analyse par diffraction des rayons X (DRX a montré que la phase fortement réactive de la bélite (άL-C2S a été stabilisée, ce qui montre la forte réactivité hydraulique de ce ciment bélitique. Les analyses par DRX, effectuées sur des pâtes du ciment bélitique synthétisé, et les essais physiques (temps de prise et mécaniques sur des pâtes et mortiers, ont confirmé la réactivité hydraulique de ce ciment qui demeure similaire à celle du ciment de type CEM I 42,5.

  1. Contribution a l'etude et au developpement de nouvelles poudres de fonte

    Science.gov (United States)

    Boisvert, Mathieu

    L'obtention de graphite libre dans des pieces fabriquees par metallurgie des poudres (M/P) est un defi auquel plusieurs chercheurs se sont attardes. En effet, la presence de graphite apres frittage ameliore l'usinabilite des pieces, permettant donc de reduire les couts de production, et peut aussi engendrer une amelioration des proprietes tribologiques. L'approche utilisee dans cette these pour tenter d'obtenir du graphite libre apres frittage est par l'utilisation de nouvelles poudres de fontes atomisees a l'eau. L'atomisation a l'eau etant un procede de production de poudres relativement peu couteux qui permet de grandes capacites de production, le transfert des decouvertes de ce doctorat vers des applications industrielles sera donc economiquement plus favorable. En plus de l'objectif d'obtenir du graphite libre apres frittage, un autre aspect important des travaux est le controle de la morphologie du graphite libre apres frittage. En effet, il est connu dans la litterature des fontes coulees/moulees que la morphologie du graphite influencera les proprietes des fontes, ce qui est aussi vrai pour les pieces de M/P. Les fontes ductiles, pour lesquelles le graphite est sous forme de nodules spheroidaux isoles les uns des autres, possedent des proprietes mecaniques superieures aux fontes grises pour lesquelles le graphite est sous forme lamellaire et continu dans la matrice. Les resultats presentes dans cette these montrent qu'il est possible, dans des melanges contenant des poudres de fontes, d'avoir un controle sur la morphologie du graphite et donc sur les proprietes des pieces. Le controle de la morphologie du graphite a principalement ete realise par le type de frittage et le phenomene de diffusion " uphill " du carbone cause par des gradients en silicium. En effet, pour les frittages en phase solide, tous les nodules de graphite sont presents a l'interieur des grains de poudre apres frittage. Pour les frittages en phase liquide, l'intensite de la diffusion

  2. Elaboration of fiber-reinforced metallic materials; Elaboration des materiaux metalliques renforces par des fibres

    Energy Technology Data Exchange (ETDEWEB)

    Martin, J.M. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-08-01

    A bibliographic study on the elaboration of fiber reinforced metallic materials is presented in three parts: the theory of fiber reinforcement of metals in summarized, with emphasis on the mechanical and geometric factors which govern the behaviour and the performances to be expected from a given composite material; a second part is devoted to the study of the physical and chemical factors related to the structural stability of the material. Finally, the various processes of fabrication of such composites are presented and discussed. (author) [French] Cette etude bibliographique de l'elaboration des materiaux metalliques renforces par des fibres, comprend trois parties. Dans la premiere partie, la theorie du renforcement des metaux par des fibres est resumee de maniere a mettre en lumiere les facteurs mecaniques et geometriques qui determinent le comportement et les performances que l'on peut attendre d'un composite donne. La seconde partie est consacree a l'etude des facteurs physico-chimiques qui determinent la stabilite structurale d'un composite. Enfin, la troisieme partie est constituee par l'expose des differentes methodes d'elaboration des composites. (auteur)

  3. Contribution to the study of defects created by {alpha} particles in uranium at 4.2 K; Contribution a l'etude des defauts crees par irradiation a l'aide de particules {alpha} dans l'uranium a 4.2 K

    Energy Technology Data Exchange (ETDEWEB)

    Raharinaivo, A.L. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    A device is described for the irradiation, in liquid helium, of metallic strips with {alpha} particles produced by radioactive sources. It has thereby been possible to measure changes in resistivity of variously treated uranium samples (cold- worked, annealed, previously exposed to neutrons, etc. ) as a function of the irradiation flux. The annealings carried out after irradiation compare favorably to those effected after a quenching from 100 to 4 K (JOUSSET experiments). The results are discussed; it is concluded that a defect, very probably of the interstitial type, is mobile in uranium at temperatures below 5 K. (author) [French] On decrit un dispositif permettant d'irradier, dans l'helium liquide, des lames metalliques par des particules {alpha} issues de sources radioactives. On a ainsi mesure les variations de resistivite, en fonction du flux d'irradiation, d'uranium diversement traite (ecroui, recuit, prealablement irradie par des neutrons...). Les recuits apres irradiation se comparent bien aux recuits apres trempe de 100 a 4 K (experiences de JOUSSET). L'ensemble des resultats est discute et il conduit a la conclusion qu'un defaut, tres vraisemblablement interstitiel, est mobile dans l'uranium a des temperatures inferieures a 5 K. (auteur)

  4. Etude métallurgique du soudage par friction malaxage sur un acier à haute limite élastique destiné à la construction navale : le 80 HLES Metallurgical study of friction stir welding on a steel high yield for shipbuilding: The 80 HLES

    Directory of Open Access Journals (Sweden)

    Allart Marion

    2013-11-01

    Full Text Available Le soudage par friction malaxage est un procédé de soudage relativement récent (début des années 90. Il est aujourd'hui utilisé couramment sur des alliages légers mais ne l'est que depuis peu sur les aciers. L'objectif de nos travaux est de chercher à caractériser la microstructure métallurgique et l'état de déformation et de contrainte après soudage par friction malaxage sur des échantillons d'aciers à haute limite élastique utilisés dans l'industrie navale. Nous chercherons à comprendre les phénomènes métallurgiques qui interviennent en cours de soudage. The friction stir welding is a welding process relatively recent (early 90s. It is now commonly used on light alloys but is only recently on steels. The objective of our work is to try to characterize the metallurgical microstructure and state of stress and strain after friction stir welding on samples of high strength steels used in the shipbuilding industry. We seek to understand the metallurgical phenomena that occur during welding.

  5. Creating Pedagogical Etudes for Interactive Instruments

    OpenAIRE

    Butler, Jennifer

    2008-01-01

    In this paper I discuss the importance of and need forpedagogical materials to support the development of newinterfaces and new instruments for electronic music. I describemy method for creating a graduated series of pedagogicaletudes composed using Max/MSP. The etudes will helpperformers and instrument designers learn the most commonlyused basic skills necessary to perform with interactiveelectronic music instruments. My intention is that the finalseries will guide a beginner from these init...

  6. Diffusion in the uranium - plutonium system and self-diffusion of plutonium in epsilon phase; Diffusion dans le systeme uranium-plutonium et autodiffusion du plutonium epsilon

    Energy Technology Data Exchange (ETDEWEB)

    Dupuy, M. [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    A survey of uranium-plutonium phase diagram leads to confirm anglo-saxon results about the plutonium solubility in {alpha} uranium (15 per cent at 565 C) and the uranium one in {zeta} phase (74 per cent at 565 C). Interdiffusion coefficients, for concentration lower than 15 per cent had been determined in a temperature range from 410 C to 640 C. They vary between 0.2 and 6 10{sup 12} cm{sup 2} s{sup -1}, and the activation energy between 13 and 20 kcal/mole. Grain boundary, diffusion of plutonium in a uranium had been pointed out by micrography, X-ray microanalysis and {alpha} autoradiography. Self-diffusion of plutonium in {epsilon} phase (bcc) obeys Arrhenius law: D = 2. 10{sup -2} exp -(18500)/RT. But this activation energy does not follow empirical laws generally accepted for other metals. It has analogies with 'anomalous' bcc metals ({beta}Zr, {beta}Ti, {beta}Hf, U{sub {gamma}}). (author) [French] Une etude du diagramme d'equilibre uranium-plutonium conduit a confirmer les resultats anglo-saxons relatifs a la solubilite du plutonium dans l'uranium {alpha} (15 pour cent a 565 C) et de l'uranium dans la phase {zeta} (74 pour cent a 565 C). Les coefficients de diffusion chimique, pour des concentrations inferieures a 15 pour cent ont ete determines a des temperatures comprises entre 410 et 640 C. Ils se situent entre 0.2 et 6. 10{sup 12} cm{sup 2} s{sup -1}. L'energie d'activation varie entre 13 et 20 kcal/mole. La diffusion intergranulaire du plutonium dans l'uranium a a ete mise en evidence par micrographie, microanalyse X et autoradiographie {alpha}. L' autodiffusion du plutonium {beta} cubique centree obeit a la loi d'Arrhenius D = 2. 10{sup -2} exp - (18500)/RT. Son energie d'activation n'obeit pas aux lois empiriques generalement admises pour les autres metaux. Elle possede des analogies avec les cubiques centres ''anormaux'' (Zr{beta}, Ti{beta}, Hf{beta}, U{gamma}). (auteur)

  7. Déclenchement du travail à terme par le misoprostol: expérience d ...

    African Journals Online (AJOL)

    Evaluer l'efficacité et l'innocuité de l'utilisation du misoprostol par voie vaginale pour le déclenchement du travail à terme. Etude prospective réalisée au service de gynécologie obstétrique B de l'hôpital Charles Nicolle de Tunis sur une durée de 4 mois. La population sélectionnée concernait les patientes à terme devant ...

  8. R7T7 glass alteration mechanism in an aqueous closed system: understanding and modelling the long term alteration kinetic; Etude des mecanismes d'alteration par l'eau du verre R7T7 en milieu confine: comprehension et modelisation de la cinetique residuelle

    Energy Technology Data Exchange (ETDEWEB)

    Chave, T

    2007-10-15

    The long term alteration rate of the French R7T7 nuclear glass has been investigated since many years because it will define the overall resistance of the radionuclide containment matrix. Recent studies have shown that the final rate remains constant or is slightly decreasing with time. It never reaches zero. Though this residual rate is very low, only 5 nm per year at 50 C, it would be the dominant alteration phenomenon in a geological repository. Two mechanisms are suggested for explaining such behaviour: diffusion in solution of elements from glass through an amorphous altered layer and precipitation of neo-formed phases. The diffusion processes are in agreement with a solid state diffusion mechanism and can lead to secondary phase precipitation due to solution concentration increases. Observed phases are mainly phyllosilicates and zeolites, in specific conditions. Phyllosilicates are expected to maintain the residual kinetic rate whereas alteration resumption could be observed in presence of zeolites at very high pH or temperature (10.5 at 90 C or temperature above 150 C). Both diffusion and neo-formed phase precipitation have been investigated in order to better understand their impact on the residual alteration rate and have then been modelled by a calculation code, coupling chemistry and transport, in order to be able to better anticipate the long term behaviour of the glass R7T7 in an aqueous closed system. (author)

  9. Etude par résonance paramagnétique électronique des ions lanthanides et autres impuretés paramagnétiques dans la fluorite naturelle : exemples d'application à la prospection minière et à la géochimie.

    OpenAIRE

    Chatagnon, Bruno

    1981-01-01

    La fluorite, ses gisements en milieu hydrothermal, ses défaut cristallins ponctuels, centres colorés, géochimie des terres rares (lanthanides). La RPE permet l'étude des terres rares en sites dans les cristaux de fluorite, déterminant l'état de charge, la substitution. La RPE déterminant les centres colorés créés par irradiation peut servir à la prospection des minerais uranifères en particulier dans les morts-terrains. En géochimie théorique, l'existence ou l'absence de centres paramégnétiqu...

  10. Preparation and study of dialkyl nitroxide radicals; Preparation et etude de radicaux nitroxydes diacyles

    Energy Technology Data Exchange (ETDEWEB)

    Chenavas, P. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    These radicals are obtained by oxidation of N-hydroxy-imides with lead tetracetate or p-nitro-perbenzoic acid. These imides are prepared by heating dicarboxylic acids anhydrides with benzyloxy-amine followed by catalytic hydrogenation of N-benzyloxy-imides so obtained. Two series of radicals have mainly been studied, the first concerning five-membered cyclic imides, the second six-membered cyclic imides, these molecules having methyls substituents or no on the carbon ring. N. M. R. spectra of some O-benzyl-imides have been analysed. These different results have made it possible to study the conformation and stereochemistry of these imides. (author) [French] Ces radicaux sont obtenus par oxydation d'imides N-hydroxyles par le tetracetate de plomb ou l'acide p-nitroperbenzoique; ces imides sont prepares par chauffage d'anhydrides de diacides en presence de benzyloxyamine suivie d'une hydrogenation catalytique des N-benzyloxyimides ainsi obtenus. Deux series de radicaux ont principalement ete etudies: la premiere relative a des imides cycliques a cinq chainons, la seconde a des imides cycliques a six chainons, ces molecules ayant des substituants methyles ou non sur la chaine carbonee. Les derives O-benzyles de quelques-uns de ces imides ont ete analyses en R. M. N. Ces differents resultats ont permis une etude de la conformation et de la stereochimie de ces imides. (auteur)

  11. Analysis of electronic circuits using digital computers; L'analyse des circuits electroniques par les calculateurs numeriques

    Energy Technology Data Exchange (ETDEWEB)

    Tapu, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    Various programmes have been proposed for studying electronic circuits with the help of computers. It is shown here how it possible to use the programme ECAP, developed by I.B.M., for studying the behaviour of an operational amplifier from different point of view: direct current, alternating current and transient state analysis, optimisation of the gain in open loop, study of the reliability. (author) [French] Differents programmes ont ete proposes pour l'etude des circuits electroniques a l'aide des calculateurs. On montre comment on peut utiliser le programme ECAP, mis au point par I. B. M., pour etudier le comportement d'un amplificateur operationnel, a differents points de vue: analyse en courant continu, courant alternatif et regime transitoire, optimalisation du gain en boucle ouverte, etude de la fiabilite. (auteur)

  12. FooPar

    DEFF Research Database (Denmark)

    Hargreaves, F. P.; Merkle, D.

    2013-01-01

    We present FooPar, an extension for highly efficient Parallel Computing in the multi-paradigm programming language Scala. Scala offers concise and clean syntax and integrates functional programming features. Our framework FooPar combines these features with parallel computing techniques. Foo...

  13. suPAR

    DEFF Research Database (Denmark)

    Hodges, Gethin W; Bang, Casper N; Wachtell, Kristian

    2015-01-01

    The fundamental role of inflammation in cardiovascular disease (CVD) has prompted interest in numerous biomarkers that detect subclinical levels of inflammation. Soluble urokinase plasminogen activator receptor (suPAR) is a novel biomarker that correlates significantly with cardiovascular events...... comprehensive review of suPAR in CVD and explore its function and usefulness in predicting cardiovascular events....

  14. Study of the behaviour of artificial radioactive aerosols. Applications to some problems of atmospheric circulation (1963); Etude du comportement dcs aerosols radioactifs artificiels. Applications a quelques problemes de circulation atmospherique (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-11-15

    The aim of this work, consists in the examination of the behaviour of radioactive aerosols produced in the atmosphere by nuclear explosions, in order to deduce the most general laws governing atmospheric circulation and diffusion. After having given a general table of the radioactive aerosols present the authors consider the validity and the precision of the measurement methods and the concentration of the aerosols at ground level and in the upper atmosphere, as well as their deposition on the ground. The existence is thus demonstrated of a tropospheric equatorial barrier and of discontinuous and seasonal aspects of stratosphere-troposphere transfers. The role is shown of precipitations and dry auto-filtration in the lower atmosphere cleaning processes. This work makes it possible to describe the general behaviour of dust from the stratosphere, and to improve the total radioactive contamination of the globe. (author) [French] L'objectif de ce travail consiste a examiner le comportement des aerosols radioactifs introduits dans l'atmosphere par les explosions nucleaires, pour en deduire les lois les plus generals de la circulation et diffusion atmospheriques. Apres avoir dresse un tableau d'ensemble des aerosols radioactifs presents, on examine la validite et la precision des methodes de mesure de leur concentration, au niveau du sol et en haute atmosphere, ainsi que de leur depot a la surface du sol. On met ainsi en evidence l'existence d'une barriere equatoriale tropospherique; l'aspect discontinu et saisonnier des transferts stratosphere-troposphere; le role des precipitations et de l'auto-filtration seche, dans les processus de nettoyage de la basse atmosphere. Ces etudes permettent de decrire le comportement general des poussieres d'origine stratospherique et d'ameliorer le bilan de la contamination radioactive du globe. (auteur)

  15. Contribution to the study of the sintering of finely divided alumina; Contribution a l'etude du frittage de l'alumine finement divisee

    Energy Technology Data Exchange (ETDEWEB)

    Vergnon, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-07-01

    Two crystalline forms of alumina, delta and alpha, were used to prepare compacts. The shrinkage of these compacts was investigated at different temperatures. The samples of alumina are composed of non porous, spherical particles, of a very high purity. Their mean diameter varies between 160 and 1 200 Angstrom for the delta alumina samples and between 400 and 1 200 Angstrom for the alpha alumina samples. The shrinkage of compacts, heated at a linearly increasing temperature (300 deg. C/h, slow heating) was studied in a A.D.A.M.E.L. dilatometer, modified to be used as a retractometer. The kinetics of the isothermal shrinkage of compacts after their rapid introduction (a few seconds, flash heating) in the high temperature zone of the furnace were followed with a photographic technique. It is shown that the heating rate influences the shrinkage of the compacts when they are heated at temperatures over 1 000 deg. C. The kinetics of the isothermal shrinkage, at temperature between 1000 deg. C and 1600 deg. C were thoroughly studied. Values of the apparent activation energy for the different classes of compacts are given. An interpretation of the results is proposed. It takes into account two different but interdependent mechanisms of sintering: the disappearance of porosity as a result of vacancy diffusion and the grain growth as a result of boundary migration. (author) [French] Deux formes cristallines de l'alumine, la forme delta et la forme alpha, ont ete utilisees pour confectionner des comprimes en vue d'une etude cinetique du frittage. Ces alumines d'une tres grande purete sont constituees de particules spheriques non poreuses, sensiblement homodispersees dont le diametre moyen varie entre 160 et 1200 Angstrom pour les echantillons de l'alumine delta et entre 400 et 1200 Angstrom pour ceux de l'alumine alpha. Le retrait des comprimes chauffes a temperature linerairement croissante (300 deg. C/h: chauffage lent) a ete suivi a l'aide du

  16. Par Pond water balance

    International Nuclear Information System (INIS)

    Hiergesell, R.A.; Dixon, K.L.

    1996-06-01

    A water budget for the Par Pond hydrologic system was established in order to estimate the rate of groundwater influx to Par Pond. This estimate will be used in modeling exercises to predict Par Pond reservoir elevation and spillway discharge in the scenario where Savannah River water is no longer pumped and discharged into Par Pond. The principal of conservation of mass was used to develop the water budget, where water inflow was set equal to water outflow. Components of the water budget were identified, and the flux associated with each was determined. The water budget was considered balanced when inflow and outflow summed to zero. The results of this study suggest that Par Pond gains water from the groundwater system in the upper reaches of the reservoir, but looses water to the groundwater system near the dam. The rate of flux of groundwater from the water table aquifer into Par Pond was determined to be 13 cfs. The rate of flux from Par Pond to the water table aquifer near the dam was determined to be 7 cfs

  17. Study of the nuclear graphite contact with the eutectic liquid (ZrF{sub 4} - NaF-LiF) and its protection by the vitreous carbon; Etude du contact du graphite nucleaire avec le liquide eutectique (ZrF{sub 4} -NaF-LiF) et sa protection par le carbone vitreux

    Energy Technology Data Exchange (ETDEWEB)

    Bernardet, V.; Duclaux, L. [Universite de Savoie, LCME, Polytech Savoie, 73 - Le Bourget du Lac (France); Renaudin, G.; Dubois, M.; Guerin, K.; Avignant, D. [LMI, CNRS, 63 - Aubiere (France); Renaudin, S.; Delpeux, S. [CRMD, CNRS, 45 - Orleans (France)

    2008-07-01

    In the reactors of fourth generation called molten slats reactors, the graphite core is on contact with liquid fluoride salts used as fuel and coolant. The aim of the study is to better understand the interaction between the graphite and the molten salt and to determine methods to protect the graphite to limit its corrosion by the fuel. The molten salts of this study is composed of NaF and LiF and ZrF{sub 4}. The fluoride salts reactivity and diffusion have been characterized for the nuclear graphite. Microscopy and spectroscopy Raman have been used to characterize the adhesion. (A.L.B.)

  18. Etude des comportements rheologiques des melanges de farine ble ...

    African Journals Online (AJOL)

    Etude des comportements rheologiques des melanges de farine ble/sorgho sans tanins issue de trois nouvelles varietes cultivees au Senegal et mise au point de pains a base de farines composees (ble/sorgho)

  19. Instrumental performance of an etude after three methods of practice.

    Science.gov (United States)

    Vanden Ark, S

    1997-12-01

    For 80 fifth-grade students three practice conditions (mental, mental with physical simulation, and physical with singing) produced significant mean differences in instrumental performance of an etude. No significant differences were found for traditional, physical practice.

  20. A study of the aptitude of soils under natural conditions to retain radiostrontium; Etude de la vocation des sols en place a la retention du radiostrontium

    Energy Technology Data Exchange (ETDEWEB)

    Bovard, P.; Grauby, A. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    Independently of the theoretical study of the propagation of radioactivity in the soil as a result of submersions or of radioactive rain, the authors have studied directly and practically how this radioactivity can vary in the actual soil. To this end a simple, rapid method has been perfected; it makes it possible to maintain for each soil sample the natural parameters (structure, humidity, etc.) without introducing boundary effects. In the laboratory, after charging the soil samples, part of the study of the propagation of radioactivity is done by autoradiography; finally, as a practical application, the study of an atomic site illustrates the methods described. (author) [French] Independamment de l'etude theorique de la propagation de la radioactivite dans le sol a la suite de submersions ou de pluies radioactives, les auteurs ont etudie directement et pratiquement comment pourrait evoluer cette radioactivite dans les sols en place. Pour cela, une methode simple et rapide a ete mise au point; elle permet de conserver pour chaque echantillon de sol, les parametres naturels (structure, humidite, etc...), sans introduire d'effets de paroi. En laboratoire, apres mise en charge des massifs preleves, une partie de l'etude de la propagation des radioelements est realisee par autoradiographie; enfin, une application pratique, l'etude d'un site atomique, illustre l'expose. (auteur)

  1. Diffused zircaloy 2/stainless steel junctions; Jonctions diffusees zircaloy 2 - acier inoxydable

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The diffusion permits to realize joints between two different materials, in fact of the formation of a liquid phase at the contact face. The study of the tensile properties allowed the determination of the ideal conditions for the diffusion treatment which are, within 2 and 3 minutes for a temperature within 1020 C and 1030 C. The characteristics of the so obtained joints were, studied: mechanical properties, tightness, resistance to thermal cycling. Analysis of the thermal stress, owing to the differential dilatation of the two materials mode the object of a particular study. The investigation on the diffusion zone, includes specially, an analysis of the constituents distribution formed during the diffusion treatment. (author) [French] La diffusion permet de realiser des joints entre deux materiaux differents, du fait de la formation d'une phase liquide a l'interface de contact. L'etude de la resistance a la traction a permis de determiner les conditions optimum du traitement de diffusion: une duree de 2 a 3 minutes pour une temperature comprise entre 1020 C et 1030 C. Les caracteristiques des jonctions ainsi obtenues ont ete etudiees: proprietes mecaniques, etancheite, resistance au cyclage thermique. L'analyse des contraintes thermiques dues a la difference de dilatation des deux materiaux, a fait l'objet d'une etude particuliere. L'etude metallurgique de la zone diffusee comporte en particulier une analyse de la repartition des constituants formes lors du traitement de diffusion. (auteur)

  2. The magnetic diffusion of neutrons; La diffusion magnetique des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, W.C. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    The purpose of this report is to examine briefly the diffusion of neutrons by substances, particularly by crystals containing permanent atomic or ionic magnetic moments. In other words we shall deal with ferromagnetic, antiferromagnetic, ferrimagnetic or paramagnetic crystals, but first it is necessary to touch on nuclear diffusion of neutrons. We shall start with the interaction of the neutron with a single diffusion centre; the results will then be applied to the magnetic interactions of the neutron with the satellite electrons of the atom; finally we shall discuss the diffusion of neutrons by crystals. (author) [French] Le but de ce rapport est d'examiner, brievement, la diffusion des neutrons par les substances, et surtout, par des cristaux qui contiennent des moments magnetiques atomiques ou ioniques permanents. C'est-a-dire que nous nous interesserons aux cristaux ferromagnetiques, antiferromagnetiques, ferrimagnetiques ou paramagnetiques; il nous faut cependant rappeler d'abord la diffusion nucleaire des neutrons. Nous commencerons par l'interaction du neutron avec un seul centre diffuseur; puis les resultats seront appliques aux interactions magnetiques du neutron avec les electrons satellites de l'atome; enfin nous discuterons la diffusion des neutrons par les cristaux. (auteur)

  3. Contribution to the study of physico-chemical properties of surfaces modified by laser treatment. Application to the enhancement of localized corrosion resistance of stainless steels; Contribution a l'etude des proprietes physico-chimiques des surfaces modifiees par traitement laser. Application a l'amelioration de la resistance a la corrosion localisee des aciers inoxydables

    Energy Technology Data Exchange (ETDEWEB)

    Pacquentin, W.

    2011-11-25

    integrite sur des periodes de plus en plus longues. L'objectif de ce travail de these est d'evaluer le potentiel d'un traitement de refusion laser pour ameliorer la resistance a la corrosion d'un acier inoxydable de type 304L; l'utilisation du laser dans le domaine des traitements de surface constituant un procede en pleine evolution a cause des changements recents dans la technologie des lasers. Dans le cadre de ce travail, le choix du laser s'est porte sur un laser nano-impulsionnel a fibre dopee ytterbium dont les caracteristiques permettent la fusion quasiinstantanee sur quelques microns de la surface traitee, immediatement suivie d'une solidification ultra-rapide avec des vitesses de refroidissement pouvant atteindre 1011 K/s. La combinaison de ces processus favorise l'elimination des defauts surfaciques, la formation de phases hors equilibre, la segregation d'elements chimiques et la formation d'une nouvelle couche d'oxyde dont les proprietes sont gouvernees par les parametres laser. Afin de les correler avec la reactivite electrochimique de la surface, l'influence de deux parametres laser sur les proprietes physicochimiques de la surface a ete etudiee: la puissance du laser et le taux de recouvrement des impacts laser. Pour clarifier ces relations, la resistance a la corrosion par piquration des surfaces traitees a ete determinee par des tests electrochimiques. Pour des parametres laser specifiques, le potentiel de piquration d'un acier inoxydable de type 304L augmente de plus de 500 mV traduisant ainsi une meilleure tenue a la corrosion localisee en milieu chlorure. L'interdependance des differents phenomenes resultant du traitement laser a rendu complexe la hierarchisation de leur effet sur la sensibilite de l'alliage teste. Cependant, il a ete montre que la nature de l'oxyde thermique forme au cours de la refusion laser et ses defauts sont du premier ordre pour l'amorcage des

  4. Characterization of junctions produced by medium-energy ion implantation in silicon; Caracterisation de jonctions obtenues par implantation d'ions de moyenne energie dans le silicium

    Energy Technology Data Exchange (ETDEWEB)

    Monfret, A. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1970-07-01

    Characteristics of diodes made by implanting 20 keV boron and phosphorus ions into silicon are reviewed. Special features of theses diodes are presented, and correlation with technology is studied. This paper includes three parts: - in the first part, the theory of range distribution is considered for both amorphous and single-crystal targets, - In the second part, a brief description of the experimental conditions is given. - In the third part, the experimental results are presented. The results lead to a schematic model of the component. They also show the influence of cleaning and annealing treatments from which optimized process of fabrication can be determined. In this study, the influence of a two stage annealing process is shown. For phosphorus and boron implants, the first stage is performed at 150 deg. C while the second stage is 450 deg. C for phosphorus and 550 deg. C for boron implants. The implanted diodes are found to exhibit good electrical characteristics. Comparisons with standard diffused diodes are quite favourable. (author) [French] On examine les caracteristiques de diodes obtenues par implantation d'ions bore et phosphore de 20 keV dans le silicium. On met en evidence le comportement particulier de ces diodes et on presente certaines correlations avec la technologie. L'expose comprend trois parties: - la premiere partie est consacree au calcul du profil de dopage en mode canalise ou non. - Dans la deuxieme partie, on decrit l'appareillage et les conditions experimentales d'implantation. - Dans la troisieme partie, on presente les resultats experimentaux. On propose un modele schematique pour expliquer le comportement des tenues en tension des diodes. L'etude des courants de fuite en fonction de la preparation des echantillons et des traitements thermiques permet de determiner des conditions optimales d'elaboration. Au cours de cette etude on met en evidence l'influence de deux stades de recuit: le premier a

  5. Scanning electron microscopy and X-ray photoelectron studies of high temperature oxidation mechanism of a Fe-Cr-Al alloy; Etude par microscopie electronique a balayage et spectroscopie de photoelectrons des mecanismes d'oxydation a haute temperature d'un alliage Fe-Cr-Al

    Energy Technology Data Exchange (ETDEWEB)

    Delaunay, F.; Berthier, C.; Lameille, J.M. [CEA Saclay, Dept. d' Entreposage et de Stockage des Dechets (DCC/DPE/SPCP), 91 - Gif-sur-Yvette (France)

    2000-07-01

    5 show continuous, uniform and adherent scale, in good agreement with Mennicke and al, who also observed that yttrium in Fe{sub 20}Cr{sub 5}Al improves the adherence and uniformity of the protective alumina scale. However, these small islands, when located at the surface, offer oxygen a diffusion path towards the underlying alloy. Figure 5 confirms that titanium and magnesium, present in low concentrations in the alloy, can diffuse across the alumina scale to be oxidized at the surface. In conclusion, oxide scale initially mainly consists of thermodynamically stable {alpha}-Al{sub 2}O{sub 3}, and after longer exposure, titanium and magnesium diffuse towards the surface to form TiO{sub 2} and MgAl{sub 2}O{sub 4}. The addition of yttrium improves the adhesion and uniformity of alumina scale. Little islands of yttrium, zirconium and titanium are present in the alloy, probably due to low solubility, and they may play a role in improving scale adherence by acting as anchoring points. (authors)

  6. Study of the excited {Delta} resonance ways of decay in {sup 4}He and other nuclei with the ({sup 3}He,T) reaction at 2 GeV; Etude des voies de decroissance de la resonance {Delta} excitee dans l`{sup 4}He et d`autres noyaux par la reaction ({sup 3}He,T) a 2 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Tarle-Rousteau, S.

    1995-05-10

    This thesis describes the ({sup 3}He,t) experiment carried out at 2 GeV at the Saturne National Laboratory (CEA Saclay, France) on {sup 1}H, {sup 2}H, {sup 4}He, {sup 12}C and {sup 208}Pb targets. The charged particles (pions and/or protons) from the {Delta} resonance deexcitation are detected in coincidence with triton using the Diogene large angle detector. New informations are obtained on the ways of {Delta} resonance decay in nuclei. Three modes of decay are investigated: the quasi-free decay, the {Delta}N into NN absorption and the coherent pions production. Modifications of {Delta} resonance properties in nuclei with respect to those of free {Delta} are analysed using the experimental results about pions diffusion, photons absorption, charge exchange reaction and {Delta}-hole model conclusions. The quasi-deuteron absorption process on {sup 4}He is studied using a Monte-Carlo simulation. Coherent pions production is also analysed in detail on {sup 4}He and {sup 12}C target nuclei. The process is very sensitive to {Delta}-hole correlations involved in the longitudinal spin canal which shifts the nucleus response in the {Delta} resonance region towards the low transferred energies. (J.S.). 85 refs., 72 figs., 10 tabs., 1 annexe.

  7. Study of extraction kinetics of lanthanides(III) and actinides(III) nitrates by the molecule N, N'-dimethyl-N, N'-dibutyl, tetradecylmalonamide; Etude des cinetiques d'extraction des nitrates de lanthanides (III) et d'actinides (III) par le malonamide N, N'-dimethyl-N, N'-dibutyl, tetradecylmalonamide

    Energy Technology Data Exchange (ETDEWEB)

    Daldon, M

    1999-07-01

    The kinetics of extraction of lanthanides (III) and actinides (III) nitrates by the molecule N, N'-dimethyl - N, N'-dibutyl tetra-decyl malonamide has been investigated. This study was realised with a new constant interfacial-area-stirred cell. During the qualification step of the device it appears that the reduction of the device can lead to hydrolytic perturbations. The main conclusions are: - after the determination of conditions which provide kinetics regime (diffusion of species neglectable), partial orders of the kinetics law have been obtained and lead to the establishment of the law J = k [Nd{sup 3+}] [NO{sub 3}{sup -}]{sup 3} [diamide]{sup 1}, - interfacial tension measurements and kinetics study in presence of surface-active compounds proved that the chemical limiting reaction for Nd(III) is interfacial, - the results allow to propose an adsorption-desorption reaction mechanism, - a comprehensive study of the extraction kinetics of the lanthanides(III) series and also Am(III) and Cm(III) nitrates has been realised. The lighter lanthanides (La, Ce and Pr) exhibit higher kinetics rate of extraction than the others, which differs from the tendency observed with distribution coefficients which exhibit tetrad effect. The kinetics rate of extraction of Am(III) and Cm(III) is closed to the value of Eu(III). (author)

  8. Comparative study by infrared spectrometry of the behaviour of Y-H and Y-D groups. Valencies frequency and molecular association constants; Etude comparee par spectrometrie infrarouge du comportement de groupements YH et YD. Frequences de valence et constantes d'association moleculaires

    Energy Technology Data Exchange (ETDEWEB)

    Leicknam, J.P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-02-01

    et N-deuteries montre que le phenomene est complexe. Dans une seconde partie, on examine quantitativement une centaine d'associations moleculaires formees en solution dans un solvant inerte par pont hydrogene et pont deuterium. Les auto-associations des donneurs de proton et de deuton sont tout d'obord etudiees, puis on determine les constantes d'association K{sub H} des donneurs de proton avec divers accepteurs et les rapports K{sub D}/K{sub R} obtenus apres substitution partielle du deuterium a l'hydrogene dans ces donneurs. Les resultats montrent qu'il faut distinguer des effets thermodynamiques (qui seront calculables lorsque toutes les frequences des molecules libres et complexees seront connues) et des effets chimiques lies a la nature des donneurs et des accepteurs; parmi ces derniers, la formation eventuelle de 'paires ioniques' a, sans doute, une grande importance sur le sens de l'effet isotopique. (auteur)

  9. Contribution to the densification study of silicon and zirconium carbides by an innovating process: the Spark Plasma Sintering; Contribution a l'etude de la densification des carbures de silicium et de zirconium par un procede innovant: le spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Allemand, A. [CEA Saclay, Dept. des Materiaux pour le Nucleaire (DEN/DMN/SRMA/LTMEx), 91 - Gif-sur-Yvette (France); Guillard, F.; Galy, J. [Centre d' Elaboration de Materiaux et d' Etudes Structurales (CEMES-CNRS), 31 - Toulouse (France)

    2007-07-01

    In the framework of the CPR ISMIR, the works presented here take up the results of the thesis of F. Guillard defended on december 2006. This thesis has dealt with the Spark Plasma Sintering (SPS) technique and more particularly have been studied: 1)the {beta}SiC and ZrC sintering 2)the modelling of ZrC sintering by the SPS technique and 3)the studies of the carbides/oxides interfaces carried out by SPS. Concerning the {beta}SiC and ZrC sintering: the two carbides have been sintered between 1450 and 1950 C with times periods of 10 minutes and pressures between 50 and 150 MPa. These experiments have shown that the way to apply the pressure is of major importance. Moreover, 92% of densification can be reached after 5 minutes in 1850 C for SiC. For ZrC, 95% of densification is reached as soon as 5 minutes in 1750 C. Different correlations between grains size, density and the way to apply pressure are presented. For the SPS modelling of ZrC, two existing models, taking into account the diffusion laws, are used to try to model the SPS. The results are presented and discussed. At last, the SPS allows to make interfaces starting from powders or materials previously sintered. The SiC/ZrC and ZrO{sub 2}/SiC interfaces have been studied. A microstructural study is presented as well as a technique which allows the assembling with no cracks of SiC and ZrC. (O.M.)

  10. Elastic and plastic properties of iron-aluminium alloys. Special problems raised by the brittleness of alloys of high aluminium content; Proprietes elastiques et plastiques des alliages fer-aluminium. Problemes particuliers poses par la fragilite des alliages a forte teneur en aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Mouturat, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    considerablement reduite par des conditions appropriees d'elaboration et de transformation. II) Les etudes de module d'elasticite sont en rapport avec les diagrammes fer-aluminium; les temperatures de transformation sont bien mises en evidence. La formation de liaisons covalentes a partir de 25 atomes pour cent se traduit par des valeurs plus elevees du module. III) L'analyse des variations de la limite elastique en fonction de la-temperature fait apparaitre certaines relations avec les structures ordonnees, la presence de domaines anti-phases et l'existence de dislocations de surstructure. IV) Dans le domaine Fe Al ordonne, la cinetique du phenomene Portevin-le- Chatelier reposerait sur un mecanisme de diffusion lacunaire; nous avons precise leur role par l'influence qu'elles ont sur les dislocations, ce qui nous a conduit a l'ordre inhomogene de Rudman qui pourrait expliquer les crochets observes sur les courbes de traction. (auteur)

  11. Etude des etats electroniques en champ magnetique dans le niveau de Landau N=0 de la tricouche ABC de graphene

    Science.gov (United States)

    Rondeau, Maxime

    Dans cet ouvrage nous etudions les phases du gaz d'electrons bidimensionnel dans la tricouche de graphene en empilement ABC. En partant du modele des liaisons fortes et en faisant l'approximation du continuum autour des vallees K +, K-, nous obtenons un modele effectif a deux bandes qui permet de decrire la physique de basse energie des electrons en champ magnetique dans cette structure. Ce modele contient trois orbitales degenerees dans le niveau de Landau N = O. Ce dernier est donc 12N φ, fois degeneres en incluant les degres de liberte de spin et de vallee. En ajoutant l'interaction de Coulomb au systeme et en considerant seulement les remplissages v = -5, -4, -4, 5 afin d'avoir un systeme a trois niveaux, nous etudions le diagramme de phase du gaz d'electrons en fonction d'un biais electrique entre les couches externes. Nous trouvons une phase d'onde de densite de charge bidimensionnelle (ODC2D) comme etat fondamental du systeme. Cette ODC2D se nomme cristal dans ce memoire et nous derivons ses proprietes de transports et ses modes collectifs. Nous discutons egalement du caractere topologique de ce cristal. Notre etude englobe aussi les phases liquides avec ou sans coherence orbitale. Nous concluons notre memoire par l'etude de quelques signatures experimentales des phases du gaz d'electrons dans la tricouche.

  12. La formation de l'oxyde azotique dans les flammes de diffusion de gaz naturel Nitrogen. Oxyde Formation in Natural-Gas Diffusion Flams

    Directory of Open Access Journals (Sweden)

    Portrait L. M.

    2006-11-01

    Full Text Available L'étude de la formation de l'oxyde azotique dans des flammes de diffusion de ga naturel est effectuée depuis deux ans sur le four expérimental du Groupe d'Etude des Flammes de Gaz Naturel situé à Toulouse. Un certain nombre de variables ont été explorées : type de flamme, excès d'air, préchauffage de l'air, teneur en oxygène du comburant, puissance calorifique, et débit de moment cinétique. L'étude a mis en évidence une corrélation générale, quelle que soit la variable considérée, entre la quantité maximale d'oxyde d'azote formé et la température maximale de la flamme. Certains des résultats précédents ont été exploités à l'Institut Français du Pétrole, en vue d'établir une équation de vitesse de formation de NO applicable aux flammes axiales de diffusion de gaz naturel. Les calculs s'appuient sur les connaissances obtenues lors de l'étude cinétique de formation de NO effectuée au Laboratoire d'Aérothermique Fondamentale. Les résultats du calcul théorique confirment ceux de l'étude sur le four expérimental en ce qui concerne l'influence prépondérante de la température sur la formation de l'oxyde azotique. Par ailleurs, le calcul théorique retrouve bien les résultats obtenus lors de l'étude fondamentale, selon lesquels la cinétique de formation de NO évolue le long de la flamme depuis le front de flamme jusqu'aux gaz brûlés. La généralisation à un grand nombre de flammes de l'équation cinétique expérimentale obtenue nécessite maintenant de prendre en compte certains phénomènes de diffusion négligés jusqu'à présent. Research on the formation of nitrogen oxide in natural-gas diffusion flammes has been going on for two years in the experimental furnace of the Groupe d'Etude des Flammes de Gaz Naturel located in Toulouse. Different variables have been investigoted such as type of flamme, air excess, air preheating, oxygen content in the oxidant, heating power and kinetic moment output

  13. Cooperative photo-induced effects: from photo-magnetism under continuous irradiation to ultra-fast phenomena - study through optical spectroscopy and X-ray diffraction; Effets photo-induits cooperatifs: du photomagnetisme sous irradiation continue aux phenomenes ultrarapides - etude par spectroscopie optique et diffraction X

    Energy Technology Data Exchange (ETDEWEB)

    Glijer, D

    2006-12-15

    The control with ultra-short laser pulses of the collective and concerted transformation of molecules driving a macroscopic state switching on an ultra-fast time scale in solid state opens new prospects in materials science. The goal is to realize at the material level what happens at the molecular level in femto-chemistry. These processes are highly cooperative and highly non-linear, leading to self-amplification and self-organization within the material, a so-called photo-induced phase transition with a new long range order (structural, magnetic, ferroelectric,...). Two families of molecular compounds have been studied here: first of all, spin transition materials changing from a diamagnetic state over to a paramagnetic state under the effect of temperature or under continuous laser excitation. It concerns photo-active molecular bi-stability prototype materials in solid state, whose switching has been studied during X-ray diffraction, optical reflectivity and magnetism experiments. Then we have studied charge-transfer molecular systems, prototype compounds for ultrafast photo-induced phase transitions: insulator-metal, neutral-ionic....As well as ultrafast optical experiments, time-resolved X ray crystallography is a key technique in order to follow at the atomic level the different steps of the photo-induced transformation and thus to observe the involved mechanisms. We have underlined a process of photo-formation of one-dimensional nano-domains of lattice-relaxed charge-transfer excitations, governing the photo-induced phase transition of the molecular charge-transfer complex TTF-CA by the first time-resolved diffuse scattering measurements. Moreover, a new femtosecond laser-plasma source and a optical pump-probe spectroscopy set-up with a highly sensitive detecting system have been developed in this work. The results presented here will be an illustration of the present scientific challenges existing on the one hand with the development of projects of major

  14. Contribution to the study of the biological properties of compounds labeled with radio-chromium {sup 51}Cr; Contribution a l'etude des proprietes biologiques des composes marques au radiochrome {sup 51}Cr

    Energy Technology Data Exchange (ETDEWEB)

    Ingrand, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-15

    Among the radioisotopes commonly used in biology and medicine which are controlled Individually in the Radioelement Departement of the Saclay Nuclear Research Centre before being sent to the users, the author has chosen chromium 51 incorporated in inorganic salts or in organic substrates for a study of the biological properties of the compounds. In the first part, he has compared the pathways followed by the radioactive sodium chromate and chromic chloride mixed with blood or given to the whole animal, the object being to determine whether a reduction of hexavalent chromium occurs, both in vitro and in vivo. In the second part, the author has tried to show the validity of using, various substrates labeled with chromium 51, red cells, haemoglobin, plasma proteins and cytochrome c. The results obtained have contributed to underline the interest of using such compounds for biological applications. (author) [French] Parmi les radioisotopes d'utilisation courants en biologie et en medecine qui sont l'objet d'un controle particulier dans le Departement des Radioelements du Centre d'Etudes Nucleaires de Saclay avant leur diffusion aux utilisateurs, l'auteur a choisi le chrome 51 incorpore a des sels mineraux ou a des substrats organiques, afin d'en etudier les proprietes biologiques. Dans la premiere partie, il a compare le sort du chromate de sodium et du chlorure chromique radioactifs melanges a du sang ou administres a l'animal entier en s'efforcant de mettre en evidence une reduction du chrome hexavalent aussi bien in vitro qu'in vivo. Dans la deuxieme partie, il a cherche a etablir la validite de l'emploi de differents substrats marques au chrome 51, l'hematie, l'hemoglobine, les proteines plasmatiques et le cytochrome c. Les resultats obtenus ont permis de souligner le reel interet des applications biologiques des composes marques par le radioisotope. (auteur)

  15. Coalescence of organic solutions in acid and metal extraction by tri-alkylamines; Demixtion des solutions organiques lors de l'extraction des acides et des metaux par les trialcoylamines

    Energy Technology Data Exchange (ETDEWEB)

    Blain, J. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1970-07-01

    The formation of two layers with tri-alkylammonium salts solutions in low polarity diluents could be explained on the basis of settling of micelles. Light scattering and viscosity measurements reveal that micelles size increases rather sharply before coalescence. The existence of micelles in the solution has been confirmed by ultracentrifuge experiments. The behaviour of these solutions, in general, is similar to that of colloidal soap solutions. The various parameters which promote third phase formation are: anion size in the order of Cl{sup -} {approx} Br{sup -} < NO{sub 3} < ClO{sub 4}{sup -}; extraction of excess acid; metal cation size in the order of UO{sub 2}{sup ++} < Pu{sup 4+} {approx} Th{sup 4+}; decreasing in the length of the n-alkyl chain in the alkyl-ammonium salts; decreasing in diluent polarity. The above phenomenon could be explained on the basis of the affinity between alkylammonium salts and organic solvent. The composition of the three phases is independent of the initial amine concentration for a fixed acid and metal concentration. This has been verified experimentally and is in conformity with phase rule. (author) [French] La demixtion des solutions organiques de sels de trialcoyl-ammonium dans les solvants peu polaires est provoquee par la decantation des micelles presentes dans la solution. Nous avons montre par viscosimetrie et surtout par diffusion de la lumiere que les micelles grossissent de facon importante juste avant demixtion. Des experiences d'ultracentrifugation nous ont permis de confirmer la presence de micelles. Le comportement de ces solutions est analogue a celui des solutions colloidales de savons dans l'eau. Ainsi tous les parametres qui font decroitre la compatibilite du sel d'ammonium R{sub 3}NH+ oooX{sup -} avec le solvant organique favorisent l'agregation du sel et par consequent la demixtion, soient: l'extraction des anions de taille croissante Cl{sup -} {approx} Br{sup -} < NO{sub 3} < Cl

  16. Effets secondaires cutanes de l'imatinib :etude portant sur 36 patients

    African Journals Online (AJOL)

    évolution était fatale chez un patient. Conclusion : Les effets secondaires cutanés de l'imatinib chez le noir africain sont dominés par les hypopigmentations diffuses et les oedèmes périorbitaires. Mots-clés : Imatinib, Effets secondaires, Togo.

  17. 186 Etude théorique du transport électronique par la simulation ...

    African Journals Online (AJOL)

    youness

    intervalles, piezoelectric as well as the interactions of alloy and on ionized ... déterminent ce comportement en température des lasers InGaAsP-InP. .... Choukria SAYA et al. 191 l'énergie [4,14,15]. Les interactions sont l'ingrédient indispensable de toute simulation Monte Carlo. Ce sont elles qui régissent les phénomènes ...

  18. Etude de l'oscillateur de van der pol generalise par la methode du ...

    African Journals Online (AJOL)

    La méthode du groupe de renormalisation est l'une des méthodes de perturbation singulière utilisée dans la recherche des comportements asymptotiques de solution des équations différentielles ordinaires. Dans ce papier, l'équation de l'oscillateur de VAN der Pol généralisé qui modélise beaucoup de phénomènes ...

  19. ETUDE DES OXYDES ANODIQUES OBTENUS SUR InP PAR CORRELATION DE SPECTRES XPS ET ELLIPSOMETRIQUES

    Directory of Open Access Journals (Sweden)

    A MAHDJOUB

    2003-12-01

    L’oxyde anodique inhomogène (de structure complexe obtenu sur InP constitue un exemple d’étude très intéressant qui met en évidence les possibilités qu’offrent ces deux méthodes. Si l’ellipsométrie spectroscopique (méthode  non destructive est un moyen de caractérisation très puissant, l’exploitation des spectres mesurés nécessite l’utilisation de modèles bien adaptés pour extraire l’information. Ce travail a permis d’étudier la nature complexe de l’oxyde électrochimique obtenu sur InP. Les résultats obtenus permettront une meilleure compréhension du comportement des composants électroniques à base de phosphure d’indium.

  20. Apprentissage Guidé par les Emotions: Etude d'une Architecture Multi-Agent Apprenante

    OpenAIRE

    Chapelle, Jacques

    2005-01-01

    Dans ce papier nous présentons une architecture multi-agent permettant à un robot mobile autonome d'apprendre de manière non supervisée. L'apprentissage autonome est réalisé grâce à l'utilisation d'émotions qui représentent les besoins primaires de l'apprenant. Le processus d'apprentissage que nous proposons est inspiré de l'organisation en colonnes corticales du cerveau chez les espèces vivantes. L'architecture multi-agent de type organisationnelle est utilisée pour décrire les interactions ...

  1. Apprendre et maîtriser LabVIEW par ses applications

    CERN Document Server

    Martaj, Nadia

    2014-01-01

    Cet ouvrage traite de l'apprentissage du langage LabVIEW a travers ses applications dans des domaines industriels et academiques, qui permettront a l'ingenieur, technicien ou etudiant d'apprehender rapidement et efficacement ce langage. L'ouvrage commence, dans la partie I, par traiter les differents types de donnees du langage LabVIEW (tableaux, clusters, complexes, chaines de caracteres...), leur manipulation dans des structures d'execution (boucles While, For, la structure Condition, etc.), le langage textuel MathScript, des scripts Matlab, la boite de calcul utilisant la syntaxe du langage C ainsi que les nœuds de propriete qui permettent d'obtenir ou definir la propriete d''un VI. Cette etude est menee a travers des applications d'ingenierie.La partie II est consacree a l'etude de l'outil « Conception de controle et simulation » avec lequel nous pouvons simuler des systemes analogiques ou discrets.La partie III contient differentes applications qui traitent de nombreux themes comme la regulation (diff...

  2. suPAR: the molecular crystal ball

    DEFF Research Database (Denmark)

    Thunø, Maria; Macho, Betina; Eugen-Olsen, Jesper

    2009-01-01

    soluble urokinase Plasminogen Activator Receptor (suPAR) levels reflect inflammation and elevated suPAR levels are found in several infectious diseases and cancer. suPAR exists in three forms; suPAR(I-III), suPAR(II-III) and suPAR(I) which show different properties due to structural differences. ...

  3. PENULISAN ETUDE-ETUDE MUSIK TALEMPONG UNGGAN (Sebuah Usaha Pembelajaran Musik Tradisi Berbasis Literatur

    Directory of Open Access Journals (Sweden)

    Asri MK

    2014-12-01

    Full Text Available “Talempong unggan”, a traditional music from Minangkabau community particularly in Unggan, Sumpur Kudus, Sijunjung Regency, West Sumatera Indonesia is classified into genre of “talempong duduak” (rea. Due to its special musical concept and the playing technics, this traditional music is selected as a practising course in the Karawitan Department of Indonesian Institute of Art (ISI Padang Panjang since 1993 till now. In a system of class learning with many students, Talempong Unggan definitely needs supporting methods and learning technics suitable for the course where the students can reach their maximum skills. All the melody of “talempong unggan” that has been made as a material of practice is transcribed to the system of numeric notation and rhythm motive of “gendang” and “aguang” which is written into signs and special notation. All of qualitative data is formulated into finding methods, technics and etude of learning ensamble of Talempong Unggan the traditional music that learned in Karawitan Department of ISI Padang Panjang. Key words: Talempong Unggan, Methods, Technics, Etude

  4. Conservation of an ion beam brightness. Study of a non brightness disturbing lens; Conservation de la brillance d'un faisceau ionique. Etude d'une lentille ne deteriorant pas cette brillance

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-11-01

    Experimental studies of ion sources prove that large initial brightnesses can be obtained by using the plasma expansion principle. However these brightnesses are usually spoiled by the beam focusing and accelerating systems. A high intensity focusing set up is first theoretically studied, then numerically determined by use of a 7094 IBM computer. Aberrations have been minimized. It has then been possible to construct a set up conserving the source initial brightness. For a 100 mA beam the focusing voltage is 150 kV, the beam study has been done for 350 keV beam final energy. Given is a discussion of results. (author) [French] L'etude experimentale des sources d'ions, montre que de grandes brillances initiales peuvent etre atteintes en utilisant le principe de l'expansion du plasma. Mais generalement ces brillances sont alterees par la focalisation et l'acceleration du faisceau. Nous presentions une etude theorique, suivie d'une determination numerique utilisant l'ordinateur IBM 7094, d'un montage capable de focaliser des intensites elevees. Nous nous efforcons de reduire au minimum les aberrations. Nous avons pu realiser un systeme conservant la brillance initiale de la source. Pour une intensite de 100 mA la tension de focalisation doit etre de 150 kV. L'etude du faisceau a ete faite a 350 keV. Nous discutons enfin des resultats obtenus. (auteur)

  5. Etude des interactions entre les differents acteurs des interventions ...

    African Journals Online (AJOL)

    Etude des interactions entre les differents acteurs des interventions sous directives communautaires et changements obtenus au Benin et au Togo. P.V. Malou Adom, Ch. P. Makoutode, T Gnaro, A.R. Ouro-Koura, E.M. Ouendo, G Napo-Koura, M Makoutode ...

  6. Protection des ions organiques contre les dommages induits a l'ADN par les electrons de basse energie

    Science.gov (United States)

    Dumont, Ariane

    Il a ete demontre que les electrons de basse energie (EBE) peuvent induire des cassures simple brin (CSB) a l'ADN, via la formation d'anions transitoires qui decroissent par attachement dissociatif, ou dans d'autres etats electroniques dissociatifs menant a la fragmentation. Afin d'effectuer une etude complete des effets des electrons de basse energie sur la matiere biologique, il est necessaire de comprendre leur mecanismes d'interaction non seulement avec l'ADN, mais avec les constituants de son environnement. Les histones sont une composante importante de l'environnement moleculaire de l'ADN. Leur charge positive leur permet de s'associer aux groupements phosphate anionique de l'ADN. Le role principal de ces proteines basiques consiste a organiser l'ADN et l'empaqueter afin de former la chromatine. Les cations sont une autre composante importante de la cellule; ils jouent un role dans la stabilisation de la conformation B de l'ADN in vitro par leurs interactions avec les petits et grands sillons de l'ADN, ainsi qu'avec le groupement phosphate charge negativement. Avec les histones, ils participent egalement a la compaction de l'ADN pour former la chromatine. Cette etude a pour but de comprendre comment la presence d'ions organiques (sous forme de Tris et d'EDTA) a proximite de l'ADN modifie le rendement de cassures simple brin induit par les electrons de basse energie. Le Tris et l'EDTA ont-ete choisis comme objet d'etude, puisqu'en solution, ils forment le tampon standard pour solubiliser l'ADN dans les experiences in vitro (10mM Tris, 1mM EDTA). De plus, la molecule Tris possede un groupement amine alors que l'EDTA possede 4 groupements carboxyliques. Ensembles, ils peuvent se comporter comme un modele simple pour les acides amines. Le ratio molaire de 10 :1 de Tris par rapport a l'EDTA a pour but d'imiter le comportement des histones qui sont riches en arginine et lysine, acides amines possedant un groupement amine charge positivement additionnel. Des films d

  7. Proton scattering on unstable nuclei: study of {sup 40}S(p,p`) and {sup 43}Ar(p,p`) reactions, development of detection system MUST; Diffusion de protons par des noyaux instables: Etudes des reactions {sup 40}S(p,p`) et {sup 43}Ar(p,p`), developpement du systeme de detection MUST

    Energy Technology Data Exchange (ETDEWEB)

    Marechal, F

    1998-02-06

    We measured for the first time the elastic and inelastic proton scattering on the {sup 40}S unstable nucleus. The experiment was performed in inverse kinematics at the NSCL AT Michigan State University with a {sup 40}S secondary beam bombarding a CH{sub 2} target at 30 MeV/A. We obtained the elastic scattering angular distribution and two points of the inelastic distribution to the first 2{sup +} excited state found to be located at 860{+-}90 KeV. With a coupled channel analysis, the {beta}{sub 2} quadrupolar deformation parameter is found to be equal to 0.35{+-}0.05. This value can be compared to 0.28{+-}0.02 obtained by coulomb excitation. A macroscopic analysis allowed us to extract the neutron and proton transition matrix element ratio M{sub n}/M{sub p} which is equal to 1.88{+-}0.38. This value, greater than N/Z, could indicate an isovector effect in the first 2{sup +} state excitation which could be due to a difference between the neutron and proton vibrations. The microscopic analysis gives the possibility to test the densities and the transition densities to the first 2{sup +} state. The calculated densities for the {sup 40}S nucleus show a neutron skin. However the microscopic analysis yields a M{sub n}/M{sub p} ratio of 1.40{+-}0.20. A similar elastic and inelastic proton scattering experiment allowed us to get a deformation parameter of 0.25{+-}0.03 for the {sup 43}Ar nucleus. To develop the study of direct reactions induced by radioactive beams at GANIL, we have developed and built, in collaboration with the CEA-Saclay and the CEA-Bruyeres, the new detector MUST.It is based on the silicon strip technology, and is dedicated to the measurement of recoiling light particles emitted in these reactions. The results obtained with a {sup 40}Ar beam at 77 Me V/A, have shown the good performances of the detector for the particle identification as well as for the resolutions, and allow us to consider now a large experimental programme concerning these direct reactions induced by radioactive beams. These tests allowed us to establish a reference procedure to calibrate the detector and to analyse the data. We have also developed a simulation code in order to determine the best use conditions of MUST in the future experiments. (author) 103 refs.

  8. Parálisis cerebral :

    OpenAIRE

    Giral Lamenca, Mónica

    2015-01-01

    Se aborda el tema de la parálisis cerebral definiendo qué es, clasificando los tipos de parálisis dependiendo de la afectación y las características principales. Se explican algunos de sus tratamientos, se dan sistemas alternativos y/o aumentativos de comunicación para un alumno con PC (parálisis cerebral).

  9. F{sup 19} relaxation in non-magnetic hexafluorides; Contribution a l'etude de la relaxation des fluors dans les hexafluorures non magnetiques

    Energy Technology Data Exchange (ETDEWEB)

    Rigny, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-12-01

    The interesting properties of the fluorine magnetic resonance in the hexafluorides of molybdenum, tungsten and uranium, are very much due to large anisotropies of the chemical shift tensors. In the solid phases these anisotropies, the values of which are deduced from line shape studies, allow one to show that the molecules undergo hindered rotations about the metal atom. The temperature and frequency dependence of the fluorine longitudinal relaxation times shows that the relaxation is due to the molecular motion. The dynamical parameters of this motion are then deduced from the complete study of the fluorine relaxation in the rotating frame. In the liquid phases, the existence of anisotropies allows an estimation of the different contributions to the relaxation. In particular, the frequency and temperature dependence of the relaxation shows it to be dominated by the spin-rotation interaction. We have shown that the strength of this interaction can be deduced from the chemical shifts, and the angle through which the molecule rotates quasi-freely can be determined. In the hexafluorides, this angle is roughly one radian at 70 C, and with the help of this value, the friction coefficients which describe the intermolecular interactions are discussed. (author) [French] Les proprietes de la resonance magnetique des fluors dans les hexafluorures de molybdene, tungstene et uranium sont influencees par l'existence de deplacements chimiques tres anisotropes. Dans les phases solides, la valeur de cette anisotropie peut etre determinee par l'analyse des formes de raies et son existence permet de montrer que les molecules sont en rotation empechee autour de leur atome central. L'etude du temps de relaxation longitudinal en fonction de la temperature et de la frequence montre que la relaxation est due aux mouvements moleculaires, aux plus hautes temperatures. Les proprietes dynamiques du mouvement sont obtenues par l'etude complete de la relaxation spin

  10. Implementing Formative Assessment in Engineering Education: The Use of the Online Assessment System Etude

    Science.gov (United States)

    Dopper, Sofia M.; Sjoer, Ellen

    2004-01-01

    This article describes the possibilities offered by the online assessment system Etude to achieve the benefits of formative assessment. In order to find out the way this works in practice, we carried out an experiment with the use of Etude for formative assessment in the course on collaborative report writing. Results show that online formative…

  11. Elements Optiques Holographiques Generes Par Ordinateur a Fonction de Phase Semi-Continue et Distribuee

    Science.gov (United States)

    Lemelin, Guylain

    Occupant une place grandissante dans la conception optique, les elements optiques holographiques (EOH) peuvent accomplir des taches qui seraient difficilement rendues par un groupe d'elements optiques conventionnels. Dans plusieurs systemes optiques utilisant une source laser, ces elements holographiques permettent d'imaginer des systemes optiques jusqu'ici impossibles a construire. Par consequent, ce type d'hologramme permet aux concepteurs la fabrication d'elements optiques speciaux. Nous presentons une etude d'EOH a fonction de phase semi-continue et distribuee qui augmente la capacite d'operation de ces elements optiques. Point tournant de notre developpement, nous avons mis au point une methode de fabrication par defocalisation simulee tres efficace, peu couteuse et facile a controler. Nous presentons des EOH simples qui demontrent les caracteristiques de base et des EOH plus complexes mettant en oeuvre des capacites speciales en fonction de leur utilisation specifique. Cette approche de conception optique holographique nous permet d'obtenir des EOH offrant une flexibilite d'optimisation et d'utilisation inegalee, augmentant ainsi les capacites de la conception optique.

  12. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    1Institut Sénégalais de Recherches Agricoles, Centre National de Recherches Forestières (ISRA-CNRF),. BP 2312 Sénégal ... La gomme sterculia est produite par Sterculia setigera en Afrique. Elle est largement .... recommandation scientifique pour améliorer leurs pratiques et la qualité de la gomme. Dans beaucoup de ...

  13. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    à la conclusion que non seulement les variations climatiques comportent deux variantes dont l'une est la variabilité climatique d'origine naturelle et les changements climatiques d'origine anthropique. Outre ces deux aspects, ils constatent que les changements climatiques provoqués par l'émission abusive de gaz à l'effet ...

  14. Contribution to the study of the vertical molten zone process (1963); Contribution a l'etude du procede de la zone fondue verticale (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Lenzin, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    Construction and use of several molten zone apparatuses operating either vertically or horizontally. Efficient purification of uranyl nitrate hexahydrate but less successful in the case of other hydrated double salts and of zirconyl chloride in the hydrochloric gel form. Demonstration and study of the dissymmetry in the direction of the transport of the impurity during, the purification by a vertical molten zone process. (author) [French] Construction et utilisation de plusieurs appareils de zone fondue travaillant soit en vertical, soit en horizontal. Purification efficace du nitrate d'uranyle hexahydrate mais peu significative dans le cas des autres couples de sels hydrates et du chlorure de zirconyle a l'etat de gel chlorhydrique. Mise en evidence et etude de la dissymetrie sur le sens de transport de l'impurete au cours de la purification par zone fondue verticale. (auteur)

  15. 98 Etude Comparative du Systeme Phonematique et Tonal des ...

    African Journals Online (AJOL)

    98. Etude Comparative du Systeme Phonematique et Tonal des. Deux Parlers: Le Yoruba du Nigeria et L'itsa Parle en. Republique du Benin. Ajani Akinwumi Lateef et Ayuba G. Ajibabi http://dx.doi./org/10.4314/ujah.v18i3.5. Résume. En ce début de l'époque ou la mondialisation et la coexistence des peuples dans le ...

  16. Preparation, definition and stabilisation of an inorganic sol by an organic macromolecule: case of an aluminium hydroxide colloid; Preparation, definition et stabilisation par une macromolecule organique d'un sol mineral: cas d'un colloide d'hydroxyde d'aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Hurbin-Faucon, A. [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1966-07-01

    et les limites de certaines techniques de physico-chimie colloidale. Le colloide d'aluminium est obtenu par peptisation d'un precipite d'hydroxyde d'aluminium. La caracterisation physique de la micelle est fuite a l'aide de la methode de la diffusion lumineuse qui permet de definir le colloide du point de vue taille et forme. Une particularite interessante, due a la faible valeur de l'indice de refraction du colloide en etude, nous a amene a utiliser, non seulement les methodes generales du MIE, mais aussi les methodes habituellement employees en chimie macromoleculaire, qui demandent moins d'hypotheses et permettent ainsi une analyse plus complete du sol. Le colloide d'hydroxyde d'aluminium ne resistant pas a une force ionique elevee, nous avons aborde a ce sujet le probleme de sa stabilisation par une macromolecule: la gelatine. Apres avoir caracterise cette macromolecule par des mesures potentiometriques et de diffusion lumineuse, nous avons mis en evidence l'interaction de nature chimique qui se produit lorsqu'on met en presence l'hydrosol d'aluminium et la gelatine; cette interaction conduit a l'obtention d'une entite organo-minerale resistant a une augmentation de force ionique. Nous avons etabli quelques caracteristiques du complexe ainsi forme, notamment son domaine de formation en fonction du pH de la solution, sa stabilite en presence d'electrolytes, hypotheses sur sa taille et sa forme. Nous avons enfin tente de definir l'influence de la masse moleculaire et des dimensions respectives de chaque constituant sur la formation du complexe et de la sur la stabilisation. (auteur)

  17. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    L'agarophyte Gelidium sesquipedale est une rhodophycée très commune sur les côtes marocaines, son exploitation et sa transformation locale ont précédé toute étude scientifique. L'étude de la croissance de cette espèce en milieu naturel a montré que son rythme d'élongation est faible avoisinant 9cm par an.

  18. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    chaque composant dans le circuit (oscillateur pilote quartz, l'oscillateur contrôlé par tension, les diviseurs de fréquence, comparateur de phase) [2] et les raies de référence sur les performances du système. 2. Théorie et Conception. La Figure 1 présente l'architecture classique d'un synthétiseur de fréquence utilisant.

  19. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    1Département de Physique, Faculté des Sciences, Université de Douala. B. P. 24157 Douala, Cameroun. 2Département de Géographie, Faculté des ...... grande longueur d'onde zonale favorisant ainsi le transport par un flux d'ouest, de la vapeur d'eau de l'Océan Atlantique jusqu'au Lac Tchad. Pour les régimes, il y a une ...

  20. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    déterminé les pourcentages en silice et carbonates. Nous avons aussi mis au point la présence des ions chlorures en pourcentage assez important pouvant être responsable de la corrosion des aciers de frettage des tuyaux en béton précontraint et par conséquent des dégradations affectant ces tuyaux. La présence d'un.

  1. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    pollution. L'objectif du présent travail est l'étude de la qualité des eaux superficielles et souterraines pour évaluer le degré de pollution provenant des lixiviats de la décharge et des cours d'eaux dans lesquels les ..... Les métaux lourds dosés ont montré une pollution métallique des eaux souterraine par rapport à la norme.

  2. Etudes phytochimique et pharmacologique de Bridelia ferruginea ...

    African Journals Online (AJOL)

    L'extrait aqueux de Bridelia ferruginea provoque entre 10-5mg/mL et 10-1mg/mL une augmentation des contractions rythmiques de muscle lisse Taenia coli de cobaye. Ces effets inotropes positifs antagonisés par l'Atropine (10-6mg/mL) sont totalement abolis en milieu pauvre (0Ca2+) et dépourvus de calcium (0Ca2++ ...

  3. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    D'autre part, à cause de la corrélation directe entre l'étendue des inondations et les quantités de poissons et de pâturages fournies par la plaine, il y a eu dégradation des ... aux changements climatiques en zone sahélienne du Cameroun. Un des objectifs de notre étude était de préciser le comportement des agriculteurs ...

  4. Datation par thermoluminescence

    Directory of Open Access Journals (Sweden)

    1976-01-01

    Full Text Available Depuis 1953, de nombreux chercheurs se sont intéressés à la datation par thermoluminescence de minéraux anciennement brûlés ou cuits. Dans ce travail, après avoir rappelé quelques principes physiques de la thermoluminescence, on présente cette méthode de datation en mettant l'accent sur le mécanisme thermoluminescent dans une poterie. Ainsi la dose d'irradiation reçue par le matériau étant proportionnelle au temps écoulé depuis le 'zéro archéologique', il est possible de déterminer 'la dose archéologique' et d'en déduire l'âge de l'échantillon après avoir calculé la dose d'irradiation annuelle. La réalisation pratique d'un tel ensemble de mesure est cependant très ardue. Dans un prochain article, E. A. Decamps et A. Roman montreront des résultats relatifs à la thermoluminescence d'échantillons de quartz naturels, purs et dopés et la mise au point d'une nouvelle méthode de datation. Desde 1953, muchos investigadores se han interesado en la datación por termoluminiscencia de minerales antiguamente quemados o cocidos. Dentro de este trabajo, luego de haber recordado algunos principios físicos de la termoluminiscencia, se presenta este método de datación poniendo mayor atención en el mecanismo termoluminescente en una vasija de metal o de barro. Siendo proporcional la dosis de irradiación recibida al tiempo transcurrido desde el 'cero arqueológico', es posible determinar 'la dosis arqueológica', y deducir la edad de la muestra luego de haber calculado la dosis de irradiación anual. La realización práctica de un trabajo de tal dimensión es sin embargo muy ardua. En un próximo artículo, E. A. Decamps y A. Román presentarán los resultados relativos a la termoluminiscencia de muestras de cuarzo naturales, puras y dopadas y la elaboración de un nuevo método de datación. Since 1953, a number of scientists have been concerned with the use of thermoluminescence for the dating of burned or fired minerals

  5. Solution volumes finis polynomiale par morceaux pour les ...

    African Journals Online (AJOL)

    Nous présentons dans ce papier un concept de solution volumes finis continue pour des problèmes de diffusion-convection avec des données régulières. Nous comparons dans certains cas particuliers la solution proposée avec la solution volumes finis classiques (qui est une fonction constante par morceaux) et la ...

  6. Contribution to the study of a method for measuring continuously the isotopic effect. The search for an isotopic effect during the reduction of cuprous oxide by a {sup 12}CO - {sup 14}CO mixture (1962); Contribution a l'etude d'une methode de mesure continue de l'effet isotopique. Recherche d'un effet isotopique dans la reduction de l'oxyde cuivreux par le melange {sup 12}CO - {sup 14}CO (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Richard, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-15

    The determination of an isotopic effect between the two reactions: {sup 12}CO + Cu{sub 2}O {yields} {sup 12}CO{sub 2} + 2 Cu 'light' reaction {sup 14}CO + Cu{sub 2}O {yields} {sup 14}C{sub O}2 + 2 Cu 'heavy' reaction is possible if the respective kinetics are known. The condensation, during the reaction, of the carbon dioxide formed, and the measurement as a function of time of the residual carbon monoxide pressure, makes it possible to deduce, uninterruptedly, the 'light' reaction kinetics. The 'heavy' reaction kinetics are obtained by measuring continuously, in situ, the radioactivity of the residual reactant gas as a function of the time. The apparatus used for this is a plastic scintillator counter. A calibration curve of the measured radioactivity as a function of the reactant gas pressure in the absence of reaction makes it possible to compare the kinetics of the 'light' and 'heavy' reactions. The reaction temperature is chosen such that the reaction rate is sufficiently slow, so that the variation of the radioactivity during unit counting time is negligible. (author) [French] La determination d'un effet isotopique entre les deux reactions: {sup 12}CO + Cu{sub 2}O {yields} {sup 12}CO{sub 2} + 2 Cu reaction 'legere' {sup 14}CO + Cu{sub 2}O {yields} {sup 14}C{sub O}2 + 2 Cu reaction 'lourde' est rendue possible par la connaissance de leurs cinetiques respectives. La condensation, au cours de la reaction, du gaz carbonique forme et la mesure en fonction du temps de la pression de l'oxyde de carbone residuel, permet d'obtenir, de facon continue, la cinetique de la reaction 'legere'. La cinetique de la reaction lourde est determinee par la mesure continue, in situ, du taux de radioactivite du reactif gazeux residuel en fonction du temps. Le dispositif employe dans ce but est un compteur a scintillateur plastique. Une courbe d'etalonnage, du taux mesure de

  7. Etude theorique et experimentale des evaporateurs de dioxyde de carbone operant dans des conditions de givrage

    Science.gov (United States)

    Bendaoud, Adlane Larbi

    Les evaporateurs de refrigeration sont surtout du type tube a ailettes, appeles serpentins, et fonctionnent dans l'une des conditions suivantes: seche, humide ou avec formation de givre. Il a ete demontre que la formation du givre sur la paroi exterieure de l'echangeur engendre une surconsommation energetique a cause des operations de degivrage puisque 15 a 20% seulement de la chaleur produite sert au degivrage tandis que le reste est dissipee dans l'environnement [1]. Avec l'avenement des nouveaux refrigerants, moins nocifs envers l'environnement, l'industrie du froid se trouve penalisee du fait que peu ou pas de composantes mecaniques (compresseur, pompe, echangeur...etc.) adaptees sont disponibles [3]. Il s'agit pour la communaute des frigoristes de combler ce retard technologique en redeveloppant ces composantes mecaniques afin qu'elles soient adaptees aux nouveaux refrigerants. Dans cette optique, et afin de mieux comprendre le comportement thermique des evaporateurs au CO2 fonctionnant dans des conditions seches, qu'un groupe de chercheurs du CanmetENERGIE avaient lance, en 2000, un programme de R & D. Dans le cadre de programme un outil de simulation des evaporateurs au CO2 a ete developpe et un banc d'essai contenant une boucle secondaire de refrigeration utilisant le CO2 comme refrigerant a ete construit. Comme continuite de ce travail de recherche, en 2006 ce meme groupe de recherche a lance un nouveau projet qui consiste a faire une etude theorique et experimentale des evaporateurs au CO2 operants dans des conditions de givrage. Et, c'est exactement dans le cadre de ce projet que se positionne ce travail de these. Ce travail de recherche a ete entrepris pour mieux comprendre le comportement thermique et hydrodynamique des serpentins fonctionnant dans des conditions de givrage, l'effet des circuits de refrigerant ainsi que celui des parametres geometriques et d'operation. Pour cela, un travail theorique supporte par une etude experimentale a ete effectue

  8. Mapping diffuse photosynthetically active radiation from satellite data in Thailand

    Science.gov (United States)

    Choosri, P.; Janjai, S.; Nunez, M.; Buntoung, S.; Charuchittipan, D.

    2017-12-01

    In this paper, calculation of monthly average hourly diffuse photosynthetically active radiation (PAR) using satellite data is proposed. Diffuse PAR was analyzed at four stations in Thailand. A radiative transfer model was used for calculating the diffuse PAR for cloudless sky conditions. Differences between the diffuse PAR under all sky conditions obtained from the ground-based measurements and those from the model are representative of cloud effects. Two models are developed, one describing diffuse PAR only as a function of solar zenith angle, and the second one as a multiple linear regression with solar zenith angle and satellite reflectivity acting linearly and aerosol optical depth acting in logarithmic functions. When tested with an independent data set, the multiple regression model performed best with a higher coefficient of variance R2 (0.78 vs. 0.70), lower root mean square difference (RMSD) (12.92% vs. 13.05%) and the same mean bias difference (MBD) of -2.20%. Results from the multiple regression model are used to map diffuse PAR throughout the country as monthly averages of hourly data.

  9. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Sols minéraux brutes d'érosion 8 89 ,62 9,24 77,05 14,8. 8. 58,2. 1. 5,77. 4. Résultats et discussion. Le résultat de la classification supervisée de l'image satellite est une image mono-bande qui représente la carte des ressources en sols dont les classes sont prédéfinies par les régions d'intérêts. La matrice de confusion de ...

  10. Magnetic study of solid uranium-fluorine complexes; Contribution a l'etude magnetique de composes fluores solides de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Dianoux, A.J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-06-01

    fluor. Nous montrons les difficultes d'interpretation du paramagnetisme des fluorures d'uranium, dans lesquels l'ion uranium est place dans un site de basse symetrie. L'etude theorique du magnetisme de l'ion U{sub V} dans les fluorures complexes du type M{sub 3}UF{sub 8} (M = NH{sub 4}, Na, Rb, Cs) conduit a interpreter les resultats experimentaux par une deformation trigonale de l'entourage a huit fluors de l'uranium. L'utilisation du formalisme de l'hamiltonien de spin et un emploi systematique de la theorie des groupes permettent de presenter les calculs de la susceptibilite d'une maniere concise. L'etude de la resonance et de la relaxation des fluors, dans des fluorures complexes d'uranium VI pulverulents, suggere un modele structural pour le compose NaUF{sub 7}. Nous montrons que la forme des raies d'absorption de resonance magnetique est dominee par la presence d'importants deplacements chimiques anisotropes. Dans le modele que nous proposons, six fluors sont lies a l'uranium par des liaisons a fort caractere de covalence, dans un octaedre UF{sub 6} deforme, le septieme fluor restant ionique. L'etude de la relaxation longitudinale des fluors confirme l'existence d'un mouvement de rotation de l'octaedre, l'energie d'activation etant de 0.46 eV. (auteur)

  11. The origin of cholesterol in chyle demonstrated by nuclear indicator methods; Origines du cholesterol du chyle mises en evidence par la methode des indicateurs nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, M

    1962-07-01

    In order to obtain information about the mechanism of the intestinal absorption of cholesterol, rats having a lymphatic abdominal fistula are used. The animals receive either 4-{sup 14}C- cholesterol subcutaneously or orally, or the 1-{sup 14}C acetate. The study of the specific radio-activities of the cholesterol in chyle, in serum, in the lining, and in the intestinal contents makes it possible to define the roles played by the transfer cholesterol from the serum, by the cholesterol synthesised intestinally, and by the absorption cholesterol, in the formations of the lymph and of the chylomicrons. A new theory is proposed for the mechanism of cholesterol absorption. (author) [French] Pour obtenir des renseignements concernant le mecanisme de l'absorption intestinale du cholesterol, on utilise des rats porteurs d'une fistule lymphatique abdominale. Les animaux recoivent soit du cholesterol 4-{sup 14}C par voie sous-cutanee ou par voie orale, soit de l'acetate 1-{sup 14}C. L'etude des radioactivites specifiques du cholesterol du chyle, du serum, de la paroi et du contenu intestinal permet de preciser les roles joues par le cholesterol de transfert d'origine serique, par le cholesterol de synthese intestinale et par le cholesterol d'absorption, dans la formation de la lymphe et des chylomicrons. Une theorie nouvelle concernant le mecanisme de l'absorption du cholesterol est proposee. (auteur)

  12. The ParB-parS Chromosome Segregation System Modulates Competence Development in Streptococcus pneumoniae

    NARCIS (Netherlands)

    Attaiech, Laetitia; Minnen, Anita; Kjos, Morten; Gruber, Stephan; Veening, Jan-Willem

    UNLABELLED: ParB proteins bind centromere-like DNA sequences called parS sites and are involved in plasmid and chromosome segregation in bacteria. We previously showed that the opportunistic human pathogen Streptococcus pneumoniae contains four parS sequences located close to the origin of

  13. A crystal chemistry approach for high-power ytterbium doped solid-state lasers: diffusion-bonded crystals and new crystalline hosts; Relations structures-proprietes dans les lasers solides de puissance a l'ytterbium: elaboration et caracterisation de nouveaux materiaux et de cristaux composites soudes par diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Gaume, R

    2002-11-15

    This work deals with ytterbium based crystals for high-power laser applications. In particular, we focus our interest in reducing crystal heating and its consequences during laser operation following two different ways. First, we review the specific properties of ytterbium doped solid-state lasers in order to define a figure-of-merit which gives the evaluation of laser performances, thermo-mechanical and thermo-optical properties. Bearing in mind this analysis, we propose a set of theoretical tools, based on the crystallographic structure of the crystal and its chemical composition, to predict thermo-mechanical and optical potentials. This approach, used for the seek of new Yb{sup 3+}-doped materials for high-power laser applications, shows that simple oxides containing rare-earths are favorable. Therefore, the spectroscopic properties of six new materials Yb{sup 3+}:GdVO{sub 4}, Yb{sup 3+}:GdAlO{sub 3}, Yb{sup 3+}:Gd{sub 2}O{sub 3}, Yb{sup 3+}:Sc{sub 2}SiO{sub 5}, Yb{sup 3+}:CaSc{sub 2}O{sub 4} and Yb{sup 3+}:SrSc{sub 2}O{sub 4} are described. The second aspect developed in this work deals with thermal properties enhancement of already well characterized laser materials. Two different ways are explored: a) elaboration by diffusion bonding of end-caps lasers with undoped crystals (composite crystals). Thus, different composites were obtained and a fairly lowering of thermal lensing effect was observed during laser operation. b) strengthening of crystalline structures by ionic substitution of one of its constituents. We demonstrate how crystal growth ability can be improved by a cationic substitution in the case of Yb{sup 3+}:BOYS, a largely-tunable laser material which is of great interest for femtosecond pulses generation. (author)

  14. Vision par ordinateur: outils fondamentaux

    OpenAIRE

    Horaud, Radu; Monga, Olivier

    1995-01-01

    National audience; Cet ouvrage présente les outils fondamentaux de la vision par ordinateur dans un langage mathématique accessible aux étudiants de niveau DEUG en mathématiques ou informatique. Il donne également de nombreux exemples d'utilisation de la vision par ordinateur dans deux domaines de technologie de pointe : la robotique et l'imagerie médicale. Cette deuxième édition largement augmentée est un manuel de référence. Les outils fondamentaux sont présentés dans un langage mathématiqu...

  15. Etudes sur l'histoire de la pauvreté (Moyen Age — XVIe siècle

    Directory of Open Access Journals (Sweden)

    Hilário Franco Júnior

    1977-09-01

    Full Text Available MOLLAT, Michel (dir..  Etudes sur l'histoire de la pauvreté (Moyen Age — XVIe siècle. 2 vols. Paris Publications de la Sorbonne, 1974. 855p. (primeiro parágrafo do artigo Esta obra reúne alguns dos trabalhos desenvolvidos nos seminários sobre pobres e pobreza na Idade Média, que o professor Michel Mollat coordena desde 1962 na Sorbonne. Após um rápido e excelente ensaio introdutório, assinado pelo organizador da obra, no qual se colocam alguns dos problemas relativos ao estudo da pobreza medieval, seguem-se 35 estudos, devidos a diferentes colaboradores. O primeiro volume, correspondente à primeira parte da obra ("Pobreza e caridade, valores individuais" agrupa 21 estudos, e o segundo ("Desenvolvimento da pobreza e organização da assistência". Uma bibliografia de cerca de 160 títulos, uma lista de palavras-chaves latinas de uso mais comum na documentação da Idade Média e algumas gravuras extra-texto de boa qualidade completam o livro.

  16. Etude energetique et modelisation d'un Systeme Hybride Eolien-Diesel avec stockage d'Air Comprime (SHEDAC)

    Science.gov (United States)

    Martinez, Nicolas

    Actuellement le Canada et plus specialement le Quebec, comptent une multitude de sites isoles dont !'electrification est assuree essentiellement par des generatrices diesel a cause, principalement, de l'eloignement du reseau central de disuibution electrique. Bien que consideree comme une source fiable et continue, 1 'utilisation des generatrices diesel devient de plus en plus problematique d'un point de vue energetique, economique et environnemental. Dans le but d'y resoudre et de proposer une methode d'approvisionnement plus performante, mains onereuse et plus respectueuse de l'environnement, l'usage des energies renouvelables est devenu indispensable. Differents travaux ont alors demontre que le couplage de ces energies avec des generauices diesel, formant des systemes hybrides, semble etre une des meilleures solutions. Parmi elles, le systeme hybride eolien-diesel avec stockage par air comprime (SHEDAC) se presente comme une configuration optimale pour 1 'electrification des sites isoles. En effet, differentes etudes ont permis de mettre en avant l'efficacite du stockage par air comprime, par rapport a d'autres technologies de stockage, en complement d'un systeme hybride eolien-diesel. Plus precisement, ce systeme se compose de sous-systemes qui sont: des eoliennes, des generatrices diesel et une chaine de compression et de stockage d'air comprime qui est ensuite utilisee pour suralimenter les generatrices. Ce processus permet ainsi de reduire Ia consommation en carburant tout en agrandissant la part d'energie renouvelable dans Ia production electrique. A ce jour, divers travaux de recherche ont pennis de demontrer I' efficacite d 'un tel systeme et de presenter une variete de configurations possibles. A travers ce memoire, un logiciel de dimensionnement energetique y est elabore dans le but d'unifom1iser !'approche energetique de cette technologie. Cet outil se veut etre une innovation dans le domaine puisqu'il est actuellement impossible de dimensionner un

  17. Pilot study on diffusive ground heat storage in the SUVA 'D4' building complex in Root, Switzerland; Etude pilote pour le stockage diffusif des batiments du centre D4 de la SUVA a Root, Lucerne. Analyse de 2 tests de reponse geothermique et integration du stockage diffusif dans le systeme

    Energy Technology Data Exchange (ETDEWEB)

    Pahud, D.

    2001-07-01

    This report for the Swiss Federal Office of Energy (SFOE) presents, in a first part, the results of two thermal response tests made on a geothermal heat storage system that forms part of a heating and cooling system for a complex of buildings comprising the 'D4' centre of the Swiss Accident Insurance Institution (SUVA) in Root, near Lucerne, Switzerland. These in situ response tests on two borehole heat exchangers confirmed the laboratory measurements, indicating that no significant ground water flow is present. In a second part the heat storage dimensioning and the heating/cooling system evaluation by means of computerized simulation are described, which used simulated data for the heating and cooling requirements of the new buildings and the ground heat storage parameters. The PILESIM thermal simulation tool is described, a computer code used to simulate heating and cooling systems that use heat-exchanger piles or borehole heat exchangers. The evaluations made on three system concepts are discussed that permitted the optimal design of the diffusive ground storage system. The construction of the actual system is also described.

  18. Developpement d'algorithmes de reconstruction statistique appliques en tomographie rayons-X assistee par ordinateur

    Science.gov (United States)

    Thibaudeau, Christian

    de geometrie d'acquisition. Le present memoire se consacre a l'etude de ces algorithmes statistiques en imagerie TDM et a leur implantation logicielle. Le prototype d'imageur TEP/TDM base sur la technologie LabPET(TM) de l'Universite de Sherbrooke possede tous les pre-requis pour beneficier de ces nombreux avantages. Mot-cles : tomodensitometrie (TDM), reconstruction statistique, reconstruction iterative, scanner, rayons-z, tomographie d'emission par positrons (TEP), TEP/TDM

  19. Decontamination tests on tritium-contaminated materials; Essais de decontamination de materiel contamine par du tritium

    Energy Technology Data Exchange (ETDEWEB)

    Boutot, P.; Schipfer, P. [Commissariat a l' Energie Atomique, Chusclan (France). Centre de Production de Plutonium de Marcoule

    1967-07-01

    These tests are designed to try out various processes liable to be applied to the decontamination of a material contaminated with tritium. The samples are thin stainless- steel slabs contaminated in the laboratory with elements extracted from industrial installations. The measurement of the initial and residual activities is carried out using an open-window BERTHOLD counter. The best results are obtained by passing a current of pre-heated (300 deg. C) air containing water vapour. This process makes it possible to reach a decontamination factor of 99.5 per cent in 4 hours. In a vacuum, the operation has to be prolonged to 100 hours in order to obtain a decontamination factor of 99.2 per cent. Wet-chemical or electrolytic treatments are efficient but their use is limited by the inherent corrosion risks. A study of the reappearance of the contamination has made it possible to observe that this phenomenon occurs whatever the process used. (authors) [French] Ces essais ont pour but d'experimenter divers procedes susceptibles d'etre appliques a la decontamination du materiel contamine par du tritium. Les echantillons sont constitues par des plaquettes d'acier inoxydable contamines en laboratoire et par des elements extraits d'installations industrielles. Les mesures d'activites initiales et residuelles sont effectuees au moyen d'un compteur BERTHOLD a fenetre ouverte. Les meilleurs resultats sont obtenus par balayage d'air prechauffe a 300 deg. C et additionne de vapeur d'eau. Ce procede permet d'atteindre en 4 heures un facteur de decontamination de 99,5 pour cent. Sous vide, l'operation doit etre poursuivie pendant 100 heures pour porter le facteur de decontamination a 99,2 pour cent. Les traitements par voie chimique humide et par voie electrolytique sont efficaces mais la corrosion qu'ils risquent d'engendrer limite considerablement leur champ d'application. Une etude sur la resurgence de la

  20. Systematic study of plasma and serum proteins in the pig; Etude systematique des proteines plasmatiques et seriques du porc

    Energy Technology Data Exchange (ETDEWEB)

    Daburon, F.; Nizza, P.; Hatchikian, C.; Schmidt, J.-P. [Commissariat a l' Energie Atomique (France)

    1966-07-01

    This work has been carried out in the framework of the determination of the physiological constants of a normal pig. The aim was to study the serum and plasma proteins of this animal species, the ultimate object being to discover whether the qualitative and quantitative changes in these proteins can make a significant contribution to the establishment of a biological dosimetry for irradiated pigs. The serum and plasma from a normal pig were analyzed first by various simple electrophoretic methods and then by immuno-electrophoresis. As a result of the particular characteristics of pig serum we have gradually been led to make numerous modifications to the techniques used for human serums or for those of small laboratory animals. Much careful work and patience were required in order to obtain reproducible results. (authors) [French] Ce travail se situe dans le cadre de la determination des constantes physiologiques du porc normal. il s'agissait de proceder a l'etude des proteines seriques et plasmatiques de cette espece animale, le but ulterieur etant de savoir si les modifications qualitatives et quantitatives de ces proteines pourront representer une contribution valable a l'etablissement d'une dosimetrie biologique chez le porc irradie. Le serum et le plasma du porc normal ont ete analyses d'abord par diverses methodes electrophoretiques simples puis par immunoelectrophorese. Les caracteristiques particulieres du serum de porc nous ont conduits a apporter progressivement de nombreuses modifications aux techniques utilisees pour des serums humains ou de petits animaux de laboratoire. L'obtention de resultats reproductible a exige beaucoup de patience et de minutie. (auteurs)

  1. Etude thermo-hydraulique de l'ecoulement du moderateur dans le reacteur CANDU-6

    Science.gov (United States)

    Mehdi Zadeh, Foad

    importante, se traduisant par l'accroissement de la puissance du reacteur. Ceci peut avoir des consequences majeures pour la surete nucleaire. Une modelisation CFD (Computational Fluid Dynamics) detaillee tenant compte des effets locaux s'avere donc necessaire. Le but de ce travail de recherche est de modeliser le comportement complexe de l'ecoulement du moderateur au sein de la cuve d'un reacteur nucleaire CANDU-6, notamment a proximite des tubes de calandre. Ces simulations servent a identifier les configurations possibles de l'ecoulement dans la calandre. Cette etude consiste ainsi a formuler des bases theoriques a l'origine des instabilites macroscopiques du moderateur, c.-a-d. des mouvements asymetriques qui peuvent provoquer l'ebullition du moderateur. Le defi du projet est de determiner l'impact de ces configurations de l'ecoulement sur la reactivite du reacteur CANDU-6.

  2. Modelisation numerique et validation experimentale d'un systeme de protection contre le givre par elements piezoelectriques

    Science.gov (United States)

    Harvey, Derek

    Le degivrage au moyen d'actuateurs piezoelectriques est considere comme une avenue prometteuse pour le developpement de systemes a faible consommation d'energie applicables aux helicopteres legers. Ce type de systeme excite des frequences de resonances d'une structure pour produire des deformations suffisantes pour rompre l'adherence de la glace. Par contre, la conception de tel systeme demeure generalement mal comprise. Ce projet de maitrise etudie l'utilisation de methodes numeriques pour assister la conception des systemes de protection contre le givre a base d'elements piezoelectriques. La methodologie retenue pour ce projet a ete de modeliser differentes structures simples et de simuler l'excitation harmonique des frequences de resonance au moyen d'actuateurs piezoelectriques. Le calcul des frequences de resonances ainsi que la simulation de leur excitation a ensuite ete validee a l'aide de montages experimentaux. La procedure a ete realisee pour une poutre en porte-a-faux et pour une plaque plane a l'aide du logiciel de calcul par elements finis, Abaqus. De plus, le modele de la plaque plane a ete utilise afin de realiser une etude parametrique portant sur le positionnement des actuateurs, l'effet de la rigidite ainsi que de l'epaisseur de la plaque. Finalement, la plaque plane a ete degivree en chambre climatique. Des cas de degivrage ont ete simules numeriquement afin d'etudier la possibilite d'utiliser un critere base sur la deformation pour predire le succes du systeme. La validation experimentale a confirme la capacite du logiciel a calculer precisement a la fois les frequences et les modes de resonance d'une structure et a simuler leur excitation par des actuateurs piezoelectriques. L'etude revele que la definition de l'amortissement dans le modele numerique est essentiel pour l'obtention de resultats precis. Les resultats de l'etude parametrique ont demontre l'importance de minimiser l'epaisseur et la rigidite afin de reduire la valeur des frequences

  3. Fabrication par injection flexible de pieces coniques pour des applications aerospatiales

    Science.gov (United States)

    Shebib Loiselle, Vincent

    Les materiaux composites sont presents dans les tuyeres de moteurs spatiaux depuis les annees soixante. Aujourd'hui, l'avenement des tissus tridimensionnels apporte une solution innovatrice au probleme de delamination qui limitait les proprietes mecaniques de ces composites. L'utilisation de ces tissus necessite toutefois la conception de procedes de fabrication mieux adaptes. Une nouvelle methode de fabrication de pieces composites pour des applications aerospatiales a ete etudiee tout au long de ce travail. Celle-ci applique les principes de l'injection flexible (procede Polyflex) a la fabrication de pieces coniques de fortes epaisseurs. La piece de validation a fabriquer represente un modele reduit de piece de tuyere de moteur spatial. Elle est composee d'un renfort tridimensionnel en fibres de carbone et d'une resine phenolique. La reussite du projet est definie par plusieurs criteres sur la compaction et la formation de plis du renfort et sur la formation de porosites de la piece fabriquee. Un grand nombre d'etapes ont ete necessaires avant la fabrication de deux pieces de validation. Premierement, pour repondre au critere sur la compaction du renfort, la conception d'un outil de caracterisation a ete entreprise. L'etude de la compaction a ete effectuee afin d'obtenir les informations necessaires a la comprehension de la deformation d'un renfort 3D axisymetrique. Ensuite, le principe d'injection de la piece a ete defini pour ce nouveau procede. Pour en valider les concepts proposes, la permeabilite du renfort fibreux ainsi que la viscosite de la resine ont du etre caracterisees. A l'aide de ces donnees, une serie de simulations de l'ecoulement pendant l'injection de la piece ont ete realisees et une approximation du temps de remplissage calculee. Apres cette etape, la conception du moule de tuyere a ete entamee et appuyee par une simulation mecanique de la resistance aux conditions de fabrication. Egalement, plusieurs outillages necessaires pour la fabrication

  4. Contribution to the study of french pitchblendes; Contribution a l'etude des pechblendes francaises

    Energy Technology Data Exchange (ETDEWEB)

    Geffroy, J. [Commissariat a l' Energie Atomique, Lab. de Mineralogie, Centre de Chatillon (France). Centre d' Etudes Nucleaires; Sarcia, J.A. [Commissariat a l' Energie Atomique, Div. de la Crouzille, Haute Vienne (France). Centre d' Etudes Nucleaires

    1955-07-01

    The authors first review the characteristics of uraninite-pitchblende, as deduced of present literature. They set apart from typical pitchblende a black oxide aspect, which probably corresponds to neo-formations, and a 'para-pitchblende' aspect, which they relate to deep sur-oxidation of normal pitchblende. They insist on the easy replacement of pitchblende by silica. and give indications as to changes in vein stones (fluorite, quartz, etc...). A detailed study of paragenesis and successions in french uranium districts follows (including discussion of uranium of uranium-bearing coals). The authors attempt to classify french pitchblende veins. They are chiefly epithermal and poor in satellite ores. Three types of deposits are identified: massive - pitchblende type, silica type, fluorite type. These deposits, as those of Portugal, are included in granite, Central-European peri-batholitic types where uranium associates which Ni, Co, Bi and Ag, are in France both rare and poor. Finally, the authors attempt to bring out in the european Hercynian area a particular distribution of paragenetic types. (authors) [French] Les auteurs recapitulent d'abord les caracteres et les occurences de l'uraninite - pechblende, tels qu'ils peuvent etre degages de l'actuelle bibliographie. Ils exposent ensuite les faits qui du point de vue mineralogique seulement ressortent de l'etude mineralogique et chalcographique des pechblendes francaises et de leurs satellites. Ils distinguent de la pechblende-type un facies oxyde noir; correspondant probablement a une neoformation, et un facies parapechblende, qui est rapporte a une sur oxydation hypogene de la pechblende proprement dite. Ils insistent sur le facile remaniement de la pechblende par la slice; et donnent quelques precisions sur les modifications des gangues (fluorine, quartz, etc...). Suit l'etude detaillee des parageneses et des successions dans les districts uraniferes francais: Divisions du

  5. Etude d'un systeme de recuperation et de stockage de chaleur pour un systeme eolien-diesel avec stockage d'air comprime

    Science.gov (United States)

    Remillon, Thibaut

    La recherche presentee dans ce memoire porte sur les systemes hybrides eolien-diesel avec stockage d'air comprime (SHEDAC) adaptes a la production d'electricite en sites isoles, et plus precisement sur l'apport d'un systeme de recuperation et de stockage de chaleur (TES) au fonctionnement de ces systemes. Le principe de fonctionnement est le suivant. Quand la puissance eolienne est excedentaire par rapport aux besoins de la charge, le surplus d'energie est utilise pour comprimer de l'air. De ce processus resulte un rechauffement de l'air, on choisit d'extraire et de stocker la chaleur separement. Lors de la phase de restitution d'energie, l'air comprime utilise pour suralimenter le moteur thermique est rechauffe en utili sant la chaleur stockee precedemment. Tout au long de l'etude, nous avons seulement pris en compte la chaleur provenant du processus de compression de l'air, et neglige en tous points du systeme les echanges de chaleur avec le milieu exterieur. Pour quantifier l'apport du systeme de stockage de chaleur, nous avons tout d'abord mene une etude bibliographique sur ces systemes, pour identifier les meilleures solutions disponibles. Ensuite, on a modelise une de ces solutions sous Simulink pour etudier son fonctionnement de maniere plus precise. D'autre part, on a modelise un systeme de stockage de chaleur ideal pour quantifier l'apport maximal d'un TES sur les performances du SHEDAC. Nous avons conclu que les TES les plus adaptes aux systemes SHEDAC etaient les solutions actives directes a deux reservoirs, et que, pour beneficier au maximum du systeme de stockage de chaleur, il etait interessant de realiser la detente de l'air comprime stocke dans un moteur a air comprime, pour maximiser la recuperation d'energie mecanique.

  6. Par Pond Fish, Water, and Sediment Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Paller, M.H. [Westinghouse Savannah River Company, AIKEN, SC (United States); Wike, L.D.

    1996-06-01

    The objectives of this report are to describe the Par Pond fish community and the impact of the drawdown and refill on the community, describe contaminant levels in Par Pond fish, sediments, and water and indicate how contaminant concentrations and distributions were affected by the drawdown and refill, and predict possible effects of future water level fluctuations in Par Pond.

  7. Par Pond Fish, Water, and Sediment Chemistry

    International Nuclear Information System (INIS)

    Paller, M.H.; Wike, L.D.

    1996-06-01

    The objectives of this report are to describe the Par Pond fish community and the impact of the drawdown and refill on the community, describe contaminant levels in Par Pond fish, sediments, and water and indicate how contaminant concentrations and distributions were affected by the drawdown and refill, and predict possible effects of future water level fluctuations in Par Pond

  8. Etude, consolidation et protection de caoutchouc naturel

    Directory of Open Access Journals (Sweden)

    François Duboisset

    2010-11-01

    Full Text Available Un exemplaire d’un fauteuil MAA de George Nelson produit en 1958 a été restauré dans l’atelier mobilier du département des restaurateurs de l’Institut National du Patrimoine. Ce fauteuil est un exemple très représentatif du modernisme américain par sa simplicité des formes et  son esthétisme recherché. Les articulations du dossier en caoutchouc naturel sont fortement fissurées suite à une exposition à la lumière couplée à l’utilisation du fauteuil. Un protocole technico-scientifique a permis d’établir une méthode de comblement réversible des fissures à l’aide d’éthylène vinyle acétate, résine thermoplastique souple. Ce procédé a été appliqué sur les caoutchoucs du fauteuil afin de redonner une cohérence mécanique aux pièces.A MAA chair of George Nelson dating of 1958 was restored in the workshop of furniture in the department of restoration at the National institute of heritage. This chair is a very representative example of American modernism by its simplicity of form and its refine style. The articulation of the back is composed with natural rubber. These are highly cracked due to exposure to light and coupled with the use of the chair. A protocol on scientific-technical established a reversible method of filling cracks with ethylene vinyl acetate with anti-oxidant, soft thermoplastic resin. This method has been applied on the rubber chair to give mechanical coherence to the parts and to the chair.

  9. Development of an analogue multiplexed regulation for periodic 1. order delayed processes; Etude et realisation d'une regulation analogique multiplexee pour processus aperiodiques du 1. ordre avec retard pur

    Energy Technology Data Exchange (ETDEWEB)

    Amblard, J.C. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-07-15

    The present note deals with the study regulations of the sampled type, for 1. order process with simple delay. In order to obtain a good stability in such regulations, together with acceptable performances, it is interesting to use polynomial type correctors acting directly on the sampled error signals. The active elements of these correctors can be shared by all the channels to be controlled. Furthermore, the determination of the correction parameters results from an optimal study of the system. In the second part is described the construction of a multiplexed regulation for diffusion ovens. (author) [French] La presente note concerne l'etude des regulations de type echantillonne, pour processus du 1. ordre avec retard pur. Pour obtenir une bonne stabilite de telles regulations, ainsi que des performances correcte il est interessant d'utiliser des correcteurs de type polynomial, agissant directement sur les signaux d'erreur echantillonnes. Les elements actifs de ces correcteurs peuvent etre pris communs a toutes les voies a controler. D'autre part, la determination des parametres de correction decoula d'une etude optimale du systeme. Dans une seconde partie on decrit la realisation d'une regulation multiplexee de fours a diffusion. (auteur)

  10. Diffusion libre du droit est-elle acquise... pour de bon? | CRDI ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Par exemple, la diffusion libre du droit devrait stimuler les investissements, favoriser l'émergence de petites entreprises et permettre une gestion plus efficace des risques. Le mouvement de la diffusion libre du droit a connu bien du succès, mais on comprend encore mal comment s'opère la diffusion du droit un peu partout ...

  11. Etudes optiques de nouveaux materiaux laser: Des orthosilicates dopes a l'ytterbium: Le yttrium (lutetium,scandium) pentoxide de silicium

    Science.gov (United States)

    Denoyer, Aurelie

    La decouverte et l'elaboration de nouveaux materiaux laser solides suscitent beaucoup d'interet parmi la communaute scientifique. En particulier les lasers dans la gamme de frequence du micron debouchent sur beaucoup d'applications, en telecommunication, en medecine, dans le domaine militaire, pour la, decoupe des metaux (lasers de puissance), en optique non lineaire (doublage de frequence, bistabilite optique). Le plus couramment utilise actuellement est le Nd:YAG dans cette famille de laser, mais des remplacants plus performants sont toujours recherches. Les lasers a base d'Yb3+ possedent beaucoup d'avantages compares aux lasers Nd3+ du fait de leur structure electronique simple et de leur deterioration moins rapide. Parmi les matrices cristallines pouvant accueillir l'ytterbium, les orthosilicates Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5 se positionnent tres bien, du fait de leur bonne conductivite thermique et du fort eclatement de leur champ cristallin necessaire a l'elaboration de lasers quasi-3 niveaux. De plus l'etude fine et systematique des proprietes microscopiques de nouveaux materiaux s'avere toujours tres interessante du point de vue de la recherche fondamentale, c'est ainsi que de nouveaux modeles sont concus (par exemple pour le champ cristallin) ou que de nouvelles proprietes inhabituelles sont decouvertes, menant a de nouvelles applications. Ainsi d'autres materiaux dopes a l'ytterbium sont connus pour leurs proprietes de couplage electron-phonon, de couplage magnetique, d'emission cooperative ou encore de bistabilite optique, mais ces proprietes n'ont encore jamais ete mises en evidence dans Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5. Ainsi, cette these a pour but l'etude des proprietes optiques et des interactions microscopiques dans Yb:Y2SiO 5, Yb:Lu2SiO5 et Yb:Sc2SiO5. Nous utilisons principalement les techniques d'absorption IR et de spectroscopie Raman pour determiner les excitations du champ cristallin et les modes de vibration dans le materiau

  12. Etude par microscopie electronique a balayage de l'endommagement par fatigue du cuivre apres implantation de divers elements (de He à Xe)

    Science.gov (United States)

    Mendez, J.; Violan, P.; Fayoux, C.

    1983-05-01

    The effect of ion implantation of the surface fatigue damage in polycrystalline copper has been studied. Several elements were employed, from He to Xe, which induce different defect structures. Implanted and non-implanted specimens were cycled up to rupture in tension-compression conditions under two cyclic stress levels. Fatigue tests were conducted at room temperature in laboratory air or in vacuum. Fatigue life is only modified on the He-implanted specimen cycled at the lower stress level; other implanted specimens do not show measurable changes in the fatigue lives. Scanning electron microscopy was used to characterize the effect of the implantations of the cyclic slip behaviour at the specimens surface. While Al or Cu implantations induce no changes and Xe implantation has a small effect, on the other hand, the implantation of He, B, C, N, O or Ar causes a strong inhibition of slip bands at the specimen surface. This inhibition is correlated with the nonsolubility of the elements in thermodynamic equilibrium conditions.

  13. Spectrophotometric study of neptunium (VI) complexation by nitrate ions; Etude par spectrophotometrie de la complexation du neptunium au degre d'oxydation (VI) par les ions nitrates

    Energy Technology Data Exchange (ETDEWEB)

    Pochon, P. [CEA/VALRHO - site de Marcoule, Dept. de Recherche en Retraitement et en Vitrification (DRRV), 30 - Marcoule (France)]|[Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)]|[Centre Regional Associe de Lyon, 69 (France)

    2000-07-01

    Neptunium(VI) complexation by nitrate ions was investigated by visible and near-infrared spectrophotometry, a technique suitable for observing the appearance and evolution of the species in solution. In the absence of reference spectra for Np(VI) nitrate- complexes, mathematical (factor analysis) tools were used to interpret the spectra. These chemo-metric techniques were first tested and validated on a simpler chemical system: Np(VI)complexation by the SiW{sub 11}O{sub 39}{sup 8-} anion. The test media used to investigate Np(VI) nitrate- complexes generally contain nitrate and perchlorate salts at high concentrations (high ionic strength). Media effects arising from the presence of cations, acidity or the perchlorate ion concentration are therefore significant, and no doubt account for the scattered values of the complexation constants published in the literature. The evolution of the neptunium spectra according to the parameters of the reaction medium illustrated these effects and allowed them to be quantified by a global 'perturbation constant'. In order to minimize the spectrum modifications due to media effects, the neptunium nitrate-complexes were studied at constant ionic strength in weak acidic media (2 mol.kg{sup -1}{sub H2O}) in the presence of sodium salts. The bulk formation constants and the spectrum of the NpO{sub 2}(NO{sub 3}){sup +} complex were determined for ionic strength values of 2.2, 4, 6 and 8 mol.kg{sup -1}{sub H2O}. The constants remained on the same order of magnitude regardless of the ionic strength; the thermodynamic constant {beta}{sub 1}{sup 0} determined from them according to specific interaction theory is thus probably of little significance. Conversely, the bulk constants can be corrected for the effects of the perchlorate ions by taking the global 'perturbation constant' into account. (author)

  14. Etudes par spectroscopie Raman et par RMN des verres du système B 2O 3SiO 2Li 2O

    Science.gov (United States)

    Brethous, Jean-Claude; Levasseur, Alain; Villeneuve, Gerard; Echegut, Patrick; Hagenmuller, Paul; Couzi, Michel

    1981-09-01

    A structural approach of glasses belonging to the B 2O 3SiO 2Li 2O system has been carried out by Raman spectroscopy. A complementary study of the boron environment by RMN was also realized. The glasses are formed by two separate phases containing respectively a borate and a silicate framework. This phenomenon has been confirmed by some SEM investigations. No presence of borosilicate chains has been established.

  15. Etude par modélisation des nanoparticules formées par séparation de phase dans les verres dopés terres rares

    OpenAIRE

    Bidault , Xavier

    2015-01-01

    Optical fibers with tailored spectral response are doped with luminescent ions, rare-earth ions (re), embedded in nanoparticles (np) formed in situ in silica glass through a phase separation process. This engineering requires to understand the relation between the np composition and the re environment. In molecular dynamics, the existing interatomic potentials fail to reproduce the phase separation as experimentally observed. The system xmgo-(1-x)sio2 exhibits a domain inside of which two mix...

  16. Chrono-potentiometry in molten chlorides. Application to the study of the electrochemical properties of uranium and plutonium in the LiCl-KCl eutectic; Chronopotentiometrie dans les chlorures fondus. Application a l'etude des proprietes electrochimiques de l'uranium et du plutonium dans l'eutectique LiCl-KCl

    Energy Technology Data Exchange (ETDEWEB)

    Leseur, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-05-01

    Using solutions of cadmium chloride in the eutectic LiCl-KCl, a chrono-potentiometric method has been developed with a view to its application to the study of molten solutions. Particular attention has been paid to the choice of the indicator electrodes. The method makes it possible to analyze molten solutions quantitatively and to determine diffusion coefficients and their activation energies; it yields furthermore information about the nature and the behaviour of ionic species in solution. The method has been applied to the study of solutions of uranium and plutonium chloride in the eutectic LiCl-KCl. Linear chrono-amperometry has been used for studying these solutions quantitatively, but chrono-potentiometry, of which the theory is better developed, is better suited to a quantitative study. The results obtained have made it possible to determine the diffusion coefficients of the ions Cd{sup 2+}, U{sup 3+}, U{sup 4+} and U(IV) in the presence of F{sup -} and Pu{sup 3+} ions, as well as the activation energy of the diffusion coefficients. (author) [French] La mise au point de la chronopotentiometrie comme moyen d'etude des solutions fondues a ete effectuee avec des solutions de chlorure de cadmium dans l'eutectique LiCl-KCl. Le probleme du choix des electrodes indicatrices a ete particulierement etudie. La methode permet l'analyse quantitative des solutions fondues ainsi que la determination des coefficients de diffusion et de leurs energies d'activation: elle donne en outre des renseignements sur la nature et le comportement des especes ioniques en solution. Elle a ete appliquee a l'etude des solutions des chlorures d'uranium et de plutonium dans l'eutectique LiCl-KCl. La chronoamperometrie lineaire a ete utilisee pour l'etude qualitative de ces solutions, mais la chronopotentiometrie, dont la theorie est plus complete, convient mieux pour l'etude quantitative. Les resultats obtenus ont permis de determiner les

  17. Treatment of effluent at the Saclay Centre d'Etudes Nucleaires (1960); Le traitement des effluents du Centre d'Etudes Nucleaires de Saclay (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Wormser, G. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    The Centre d'Etudes Nucleaires at Saclay possesses several installations from which liquid radioactive effluent is rejected, and it has thus been found necessary to construct a station for the purification of radioactive liquids and to settle various chemical, analytical and technological problems. This report describes, in the following order: - the disposal possibilities at the Centre d'Etudes Nucleaires, Saclay, - the effluents produced at the centre, - the set-up for collecting effluent, - treatment of the effluent, - results of these treatments. (author) [French] La presence, au Centre d'Etudes Nucleaires de Saclay, de plusieurs installations susceptibles de rejeter des effluents liquides radioactifs a necessite la construction d'une station d'epuration d'eaux radioactives et la mise au point de differents problemes chimiques, analytiques et technologiques. Dans ce rapport, nous exposerons successivement: - les possibilites de rejet du Centre d'Etudes Nucleaires de Saclay, - les effluents du centre, - le dispositif de collecte des effluents, - le traitement de ces effluents, - les resultats de ces traitements. (auteur)

  18. L'etude de l'InP et du GaP suite a l'implantation ionique de Mn et a un recuit thermique

    Science.gov (United States)

    Bucsa, Ioan Gigel

    Cette these est dediee a l'etude des materiaux InMnP et GaMnP fabriques par implantation ionique et recuit thermique. Plus precisement nous avons investigue la possibilite de former par implantation ionique des materiaux homogenes (alliages) de InMnP et GaMnP contenant de 1 a 5 % atomiques de Mn qui seraient en etat ferromagnetique, pour des possibles applications dans la spintronique. Dans un premier chapitre introductif nous donnons les motivations de cette recherche et faisons une revue de la litterature sur ce sujet. Le deuxieme chapitre decrit les principes de l'implantation ionique, qui est la technique utilisee pour la fabrication des echantillons. Les effets de l'energie, fluence et direction du faisceau ionique sur le profil d'implantation et la formation des dommages seront mis en evidence. Aussi dans ce chapitre nous allons trouver des informations sur les substrats utilises pour l'implantation. Les techniques experimentales utilisees pour la caracterisation structurale, chimique et magnetique des echantillons, ainsi que leurs limitations sont presentees dans le troisieme chapitre. Quelques principes theoriques du magnetisme necessaires pour la comprehension des mesures magnetiques se retrouvent dans le chapitre 4. Le cinquieme chapitre est dedie a l'etude de la morphologie et des proprietes magnetiques des substrats utilises pour implantation et le sixieme chapitre, a l'etude des echantillons implantes au Mn sans avoir subi un recuit thermique. Notamment nous allons voir dans ce chapitre que l'implantation de Mn a plus que 1016 ions/cm 2 amorphise la partie implantee du materiau et le Mn implante se dispose en profondeur sur un profil gaussien. De point de vue magnetique les atomes implantes se trouvent dans un etat paramagnetique entre 5 et 300 K ayant le spin 5/2. Dans le chapitre 7 nous presentons les proprietes des echantillons recuits a basses temperatures. Nous allons voir que dans ces echantillons la couche implantee est polycristalline et les

  19. Recherche documentaire par titrage automatique

    OpenAIRE

    Lopez , Cédric; Prince , Violaine; Roche , Mathieu

    2011-01-01

    Nous proposons dans cet article un système facilitant la recherche d'information dans un ensemble de documents textuels, basé sur le titrage (et sous-titrage) automatique. Ce dernier peut se révéler crucial, par exemple, dans le cadre de la problématique de l'accessibilité des pages web (norme W3C). Notre processus de titrage automatique consiste à extraire des syntagmes nominaux pertinents dans les textes, pouvant constituer des titres ou sous-titres candidats. Une approche originale combina...

  20. Digestibilidade dos nutrientes e parâmetros ruminais de bovinos de corte alimentados com rações contendo bagaço de cana-de-açúcar obtido pelo método de extração por difusão ou por moagem convencional Digestibility of nutrients and ruminal characteristics in beef cattle fed rations containing sugarcane bagasse obtained by diffusion or conventional milling extraction method

    Directory of Open Access Journals (Sweden)

    Mário Márcio Arakaki Rabelo

    2008-09-01

    Full Text Available Objetivou-se com este trabalho avaliar o efeito da utilização do bagaço de cana-de-açúcar in natura (BIN, obtido pelo método de extração do açúcar por difusão (BINdif ou moagem convencional (BINmoa como fonte de fibra íntegra, associado ao bagaço tratado sob pressão e vapor (BTPV sobre a digestibilidade dos nutrientes e os parâmetros ruminais de bovinos de corte. Quatro machos da raça Nelore, não-castrados, com fístulas ruminais e peso vivo médio inicial de 380 kg, foram distribuídos em delineamento experimental quadrado latino 4 × 4. Os tratamentos foram compostos das combinações dos bagaços: 5% BINmoa + 45% BTPV; 5% BINdif + 45% BTPV; 10% BINdif + 40% BTPV; 15% BINdif + 35% BTPV. A utilização do BIN obtido por difusão, mesmo no nível mais elevado, não teve efeito sobre a digestibilidade dos nutrientes (MS, MO, PB, FDN, FDA e EE da dieta. Entretanto, o fornecimento do bagaço obtido por difusão provocou redução nos consumos de MS, MO, PB e FDN em relação ao bagaço obtido por moagem. A produção total de ácidos graxos voláteis no rúmen, a porcentagem molar dos ácidos acético, propiônico e butírico, a relação acético/propiônico, o pH ruminal e a concentração ruminal de nirogênio amoniacal não diferiram entre os bagaços fornecidos. A utilização do bagaço obtido pelo processo de difusão ou de moagem convencional como fonte de fibra íntegra associado ao bagaço tratado sob pressão e vapor não prejudicou a digestibilidade dos nutrientes e os parâmetros ruminais de bovinos de corte alimentados com rações contendo 50% de concentrado.The objective of this study was to evaluate the effects of feeding sugarcane bagasse, obtained by extraction of sugar using diffusion (BINdif or conventional milling (BINmoa method, as a fiber source associated with bagasse treated under pressure and steam (BTPV on nutrient digestibility and ruminal characteristics in beef cattle. Four Nellore young bulls (380 kg

  1. Diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kostorz, G. [Eidgenoessische Technische Hochschule, Angewandte Physik, Zurich (Switzerland)

    1996-12-31

    While Bragg scattering is characteristic for the average structure of crystals, static local deviations from the average lattice lead to diffuse elastic scattering around and between Bragg peaks. This scattering thus contains information on the occupation of lattice sites by different atomic species and on static local displacements, even in a macroscopically homogeneous crystalline sample. The various diffuse scattering effects, including those around the incident beam (small-angle scattering), are introduced and illustrated by typical results obtained for some Ni alloys. (author) 7 figs., 41 refs.

  2. La modélisation par Reverse Monte Carlo (RMC)

    Science.gov (United States)

    McGreevy, R. L.

    2003-09-01

    La technique de modélisation par Reverse Monte Carlo (RMC) est une méthode générale de modélisation structurale à partir d'un ensemble de données expérimentales. Cette méthode étant très souple, elle peut s'appliquer à de nombreux types de données. Jusqu'à présent ces applications comprennent : la diffraction des neutrons (y compris la substitution isotopique), la diffraction des rayons X (y compris la diffusion anomale), la diffraction des électrons, la RMN (les techniques d'angle magique et de 2ème moment) et l'EXAFS. Les systèmes étudiés sont également d'une grande variété : liquides, verres, polymères, cristaux et matériaux magnétiques, par exemple. Ce cours présente les bases de la méthode RMC en signalant certaines des idées fausses répandues. L'accent sera mis sur le fait que les modèles structuraux obtenus par RMC ne sont ni'uniques' ni 'exacts' ; cependant ils sont souvent utiles à la compréhension soit de la structure du système, soit des relations entre structure et autres propriétés physiques.

  3. Etude de production et de caracterisation de biocharbons de panic erige (Panicum virgatum L.) obtenus par pyrolyse

    Science.gov (United States)

    Pilon, Guillaume

    This research aimed at the production of biomass char under pyrolytic conditions, targeting biochar as soil amendment, while also considering its application as biocoal, either for bioenergy or subsequent upgrading. The production of biomass char was performed using two bench-scale, batch-type, fixed-bed reactors, each with an operating capacity of 1 and 25 gw.b. /batch, respectively. Switchgrass (Panicum virgatum) has been used for the tests. Production conditions studied implied temperatures of 300, 400 and 500 °C with short residence times (2.5 and 5 min). As well, the effect of using CO2 as vector gas has been compared to a common inert environment of N2. The effects of the previously mentioned parameters were correlated with some important physicochemical characteristics of biomass char. Analyses were also performed on complementary pyrolytic products (bio-oil and gas). The biomass char extraction was performed using a Soxhlet and dichloromethane was used as extracting solvent. The extracts were then characterized by GC-MS thus allowing the identification of several compounds. Specific pyrolysis conditions used at 300 °C - N2 with the 1 g/batch reactor, such as high heating rates as well as high convection conditions, presented advantegeous biomass char yields and properties, and, possible torrefaction process productivity improvement (in comparison to reported literature, such as Gilbert et al. [2009]). The char extracts as well as the bio-oils analysis (also performed using GC-MS), all generated from the 25 g/batch reactor, showed major differences among the compounds obtained from the CO2 and N2 environments, respectively. Several compounds observed in the char extracts appeared less concentrated in the CO2 environment vs N2, for the same reaction temperatures. As an example, at 400 °C, furfural was found only in char extracts from N2 environment as compared to the CO2 environment. Among all studied conditions (for both reactors), only naphthalene and naphthalene derivatives constituted the PAHs content, which was only detected for the chars produced at 500 °C. The use of CO2 as pyrolysis vector gas led to a significant difference for every temperature conditions studied for the biomass char as well as for the liquid and gas products. At 300 °C, in CO 2 environment, it is possible to observe a bio-oil production significantly lower than within a N2 environment (18.0 vs 24.6 %; CO2 vs N2 for Pchar volatile content that was shown to be significantly higher under the same conditions (0.29 vs 0.35 gchar volatiles content/graw biomass; P=0.1). In addition, at 500 °C, the char ash content was observed to be significantly lower in CO 2 than in N2 (Pchar, biochar, biocoal, CO 2, Soxhlet extractions, characterization.

  4. Etude, réalisation et caractérisation du transistor à ionisation par impact (I-MOS)

    OpenAIRE

    Mayer, Frédéric

    2008-01-01

    The impact ionization transistor (I-MOS) is a new architecture enabling subthreshold slope smaller than 60mV/dec at room temperature, which is the intrinsic limit of the MOSFET architecture. The I-MOS is composed of a PiN diode, whose intrinsic area is partially covered by a gate. The target of this thesis is the performance evaluation of this new transistor from the single device to the circuit, as a potential post CMOS candidate. This device has been studied by the mean of TCAD simulations ...

  5. Study of {sup 19}C by breakup reactions; Etude du {sup 19}C par reactions de cassure

    Energy Technology Data Exchange (ETDEWEB)

    Liegard, Emmanuel [Lab. de Physique Corpusculaire, Caen Univ., 14 Caen (France)

    1998-01-07

    To date studies of halo nuclei have been principally focussed on the A 11 systems {sup 11}Li and {sup 11}Be. The evolution of the properties of the halo with the mass of the system and the binding energy and angular momentum of the halo nucleons is a question of fundamental importance. It was in this spirit that the present study of {sup 19}C (S{sub n} = 240 {+-} 100 keV) was undertaken. The experiment was performed at GANIL using a secondary {sup 19}C beam ({approx_equal} 15 pps at 36 MeV/nucleon) produced via fragmentation. The experimental setup which included the neutron array DEMON, provided for identification of the core-breakup and dissociation reaction channels. In the first case, a very narrow single neutron angular distribution (FWHM = 64 {+-} 17 MeV/c) was observed for {sup 19}C, in contrast to that found for three `reference` nuclei {sup 21}N, {sup 22}O and {sup 24}F (FWHM {approx_equal} 165 MeV/c). This result could be interpreted within the framework of the core-breakup reaction model of a one-neutron halo nucleus. The results obtained for dissociation, while supporting the existence of the halo, indicated that it is not well developed. In addition, a comparison between the present results, the parallel momentum distributions for the core ({sup 18}C) and theoretical predictions have allowed conclusions to be drawn regarding the configuration of the valence neutron. In particular, a purely 2s{sub 1/2} of 1d{sub 5/2} configuration is excluded and mixing, possible with core excited states, must be considered. A probable ground state spin-parity assignment of 3{sup +}/2 or 5{sup +}/2 is suggested. (author) 150 refs., 278 figs., 28 tabs.

  6. MODULATION DE L’INSULINO-SECRETION PAR LES CYTOKINES CHEZ LE RAT DES SABLES ET LE RAT WISTAR: ETUDE INTERSPECIFIQUE

    Directory of Open Access Journals (Sweden)

    A HADDAR

    2001-12-01

    Dans cette étude, nous avons comparé l’activité insulinosécrétoire des îlots de Langerhans isolés du rat Wistar et du rat des sables, afin de déterminer les variation interspécifiques. Nos résultats préliminaires indiquent que l'effet le plus probant est observé en présence de l’IL-1b. En effet, cette cytokine stimule la sécrétion d’insuline de manière dose-dépendante également chez le rat des sables; toutefois, l'amplitude de la réponse est plus prononcée chez le rongeur désertique, avec une augmentation du taux de l’insuline libérée de l’ordre de 147%, en présence d’une concentration de 20 UI/ml de l’IL-1b, comparée à la sécrétion basale. Quant à l’IL-2, nous n’avons enregistré aucune modification dans l’activité insulinosécrétoire des 2 espèces.

  7. Soil clean up by vapour extraction: parametrical study; Depollution des sols par extraction sous pression reduite: etude de quelques parametres

    Energy Technology Data Exchange (ETDEWEB)

    Dutheil, C.

    2003-05-15

    Soil vapour extraction is a treatment process for soils polluted by volatile organic compounds. Its principle relies on the circulation of gaseous flow in soil by the application of a depression of some hundreds milli-bars. A parametrical study has been led on a soil artificially polluted by tri-chloro-ethene. It shows that the gaseous flow rate has a slight influence on pollutants extraction yield. This is due to rate limited mass transfer processes. Soil moisture plays a negative role on treatment efficiency because of the reduction of the porosity available for the gas circulation. Tests have been performed on a soil polluted by a complex mixture of organic pollutants to elaborate a methodology of technical feasibility assessment. This methodology aims at identifying and limiting risks of site rehabilitation failure. Tests results show that soil vapour extraction was inadequate to treat the soil tested in this study because of the strong affinity between a dense organic phase (grease) and chlorinated solvents. (author)

  8. Etude de l'oxydation d'un colorant organique AO7, par H2O2, en ...

    African Journals Online (AJOL)

    Well type catalyst ... The main objective of this work was to study the degradation of Acid Orange 7 (AO7) dye in an aqueous solution by a homogeneous ... Key words: oxidation, heteropolyanions, acid orange 7, azo dye. *. Auteur correspondant ...

  9. OUTILS DE GESTION ET MANAGEMENT PUBLIC : ETUDE DU DEPLOIEMENT DU SYSTEME DE MANAGEMENT PAR LA QUALITE A POLE EMPLOI

    OpenAIRE

    Capitolin, Marie-Dominique,

    2014-01-01

    The public service organizations are particularly concerned with the intensive instrumentation management. To this end, the public management mobilizes tools from the private sector while dealing with organizations Weber.In 2008, the creation of a new agency, Pôle emploi, in charge of employment, resulting from the merger of a private organization (Assedic) and a public one (ANPE).After the merger, Pôle emploi faces numerous upheavals of identity, cultural and organizational order. They conce...

  10. Preliminary study on seasonal solar energy storage by geothermal wells; Etude preliminaire sur le stockage solaire saisonnier par puits geothermique

    Energy Technology Data Exchange (ETDEWEB)

    Chapuis, S.; Bernier, M. [Ecole Polytechnique, Montreal, PQ (Canada). Dept. de Genie Mecanique

    2008-08-15

    The feasibility of storing solar energy in the summer and using it to heat homes in the winter was examined using the TRNSYS simulation software. Following a literature review of the principles regarding energy storage, this paper described the Okotoks demonstration project which involves the latest advances in solar heating technology for creating an energy-efficient community of 52 homes. The TRNSYS simulation software was used to study the environmental conditions, technical system design and hydrogeological study of the site proposed for underground thermal storage. In solar seasonal storage systems, energy is transferred from rooftop collectors, by means of a heat transfer fluid, to be stored underground in an aquifer or in rock. The system studied was unique since it used 2 U-shaped pipe networks that simultaneously recharged and unloaded seasonally stored solar energy in geothermal wells without using a buffer tank. The TRNSYS simulation results indicated that heat loss is a large limiting factor for this technology.17 refs., 4 tabs., 12 figs.

  11. Electron spin resonance studies of gamma irradiated saccharides. Etudes par resonance paramagnetique electronique de saccharides soumis a un rayonnement gamma

    Energy Technology Data Exchange (ETDEWEB)

    Raffi, J.; Thiery, C.; Battesti, C.; Agnel, J.P.; Triolet, J.; Vincent, P. (CEA Centre d' Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Physiologie Vegetale et Ecosystemes)

    1993-04-01

    The radiolysis mechanism of several saccharides was studied in order to understand the radiolysis mechanism of starches. Electron Spin Resonance first performed in powder state did not allow determination of the chemical structure of the induced radicals. The spin-trapping method combined with HPLC however, followed by ESR spectra analysis with the 'Voyons' simulation program was applied to the study of glucose, glucose oligomers and disaccharides. We were thus able to further our understanding of the radiolysis mechanism of starches. 2 tabs., 4 figs.

  12. Etude de l'oxydation d'un colorant organique AO7, par H 2 O 2 , en ...

    African Journals Online (AJOL)

    English Title: Oxidation study of an organic dye AO7 by H2O2, in the presence of a Dawson-Well type catalyst. English Abstract. The main objective of this work was to study the degradation of Acid Orange 7 (AO7) dye in an aqueous solution by a homogeneous catalytic system based on hydrogen peroxide and a recyclable ...

  13. Study of critical adsorption by neutron reflectivity; Etude de l`adsorption critique par reflexion de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Sibille, P

    1998-02-26

    The presence of an interface between the 2 phases of a binary mixing adds a new force to the interactions between molecules. The phase equilibrium near the interface is then modified, one phase whose molecules are repelled more strongly is desorbed, this phenomenon is called adsorption. Contrary to the optical techniques, the neutron reflectivity allows us to get the needed resolution to investigate this phenomenon. The Fisher and De Gennes model foresees a concentration profile decreasing following first a square root law then an exponential law. The purpose of this work is to check this law experimentally. A binary mixing of deuterated cyclohexane with methanol has been used. A preliminary result analysis shows a linear behaviour followed by an exponential decrease. The neutron reflectivity technique is presented and the difficulties raised by its setting are described. (A.C.) 56 refs.

  14. NMR study of hydrated calcium silicates; Etude par RMN de la structure des silicates de calcium hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Klur, I

    1996-02-26

    Radioactive wastes storage methods are developed by the CEA. As cements are important materials as well for hours living radioisotopes than for years living radioisotopes, a better knowledge of this material will allow to anticipate its behaviour and to obtain safer storage methods. The structure of calcium silicates (C-S-H) (main constituent of cements) have then been determined in this thesis by nuclear magnetic resonance. This method has allow to explain in structural terms, the different calcium rates that can be measured in the C-S-H too. (O.M.) 101 refs.

  15. Model parameterization to simulate and compare the PAR absorption potential of two competing plant species.

    Science.gov (United States)

    Bendix, Jörg; Silva, Brenner; Roos, Kristin; Göttlicher, Dietrich Otto; Rollenbeck, Rütger; Nauss, Thomas; Beck, Erwin

    2010-05-01

    Mountain pastures dominated by the pasture grass Setaria sphacelata in the Andes of southern Ecuador are heavily infested by southern bracken (Pteridium arachnoideum), a major problem for pasture management. Field observations suggest that bracken might outcompete the grass due to its competitive strength with regard to the absorption of photosynthetically active radiation (PAR). To understand the PAR absorption potential of both species, the aims of the current paper are to (1) parameterize a radiation scheme of a two-big-leaf model by deriving structural (LAI, leaf angle parameter) and optical (leaf albedo, transmittance) plant traits for average individuals from field surveys, (2) to initialize the properly parameterized radiation scheme with realistic global irradiation conditions of the Rio San Francisco Valley in the Andes of southern Ecuador, and (3) to compare the PAR absorption capabilities of both species under typical local weather conditions. Field data show that bracken reveals a slightly higher average leaf area index (LAI) and more horizontally oriented leaves in comparison to Setaria. Spectrometer measurements reveal that bracken and Setaria are characterized by a similar average leaf absorptance. Simulations with the average diurnal course of incoming solar radiation (1998-2005) and the mean leaf-sun geometry reveal that PAR absorption is fairly equal for both species. However, the comparison of typical clear and overcast days show that two parameters, (1) the relation of incoming diffuse and direct irradiance, and (2) the leaf-sun geometry play a major role for PAR absorption in the two-big-leaf approach: Under cloudy sky conditions (mainly diffuse irradiance), PAR absorption is slightly higher for Setaria while under clear sky conditions (mainly direct irradiance), the average bracken individual is characterized by a higher PAR absorption potential. (approximately 74 MJ m(-2) year(-1)). The latter situation which occurs if the maximum daily

  16. Relativistic diffusion.

    Science.gov (United States)

    Haba, Z

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  17. Etude des phenomenes de penetration des especes chimiques dans les revetements cathodiques des cuves d'electrolyse de l'aluminium

    Science.gov (United States)

    Brisson, Pierre-Yves

    Cette these decrit l'etude effectuee sur les phenomenes d'insertion du sodium et de penetration du bain electrolytique dans les revetements cathodiques des cuves d'electrolyse de l'aluminium. L'etude fut effectuee a l'aide d'un montage permettant d'effectuer l'electrolyse en laboratoire. Trois types de revetement cathodiques furent etudies : des blocs semi-graphitique, des blocs graphitiques et des blocs graphitises. L'insertion du sodium dans les trois differents types de blocs fut etudiee a l'aide de la spectrometrie des photoelectrons X (XPS). L'analyse a permis de mettre en evidence deux formes de sodium dans l'anthracite et la phase liante des materiaux semi-graphitiques et graphitiques, indiquant qu'une fraction du sodium se retrouve sous forme adsorbee dans les micropores des materiaux alors que l'autre fraction est inseree dans la structure cristalline du carbone. Dans les phases graphitiques (materiaux graphitises et graphitiques), seuls les micropores sont occupes par le sodium Ce resultat explique la tendance observee selon laquelle l'ajout de graphite dans les blocs permet d'abaisser le gonflement sodique. Les mecanismes de penetration du bain dans le reseau poreux des materiaux furent etudies en microscopie electronique et en diffraction des rayons X sur des echantillons apres differents temps d'electrolyses et en variant l'atmosphere (soit sous argon ou sous azote). Ces analyses ont permis d'identifier le mecanisme conduisant a la mouillabilite du bain sur le carbone en fonction de l'atmosphere entourant l'electrolyse. Ainsi, sous azote, la formation de NaCN dans les pores des materiaux par reactions entre le sodium et l'azote permet une mouillabilite accrue du bain alors qu'en absence d'azote (sous argon), le carbure d'aluminium, formes a la surface des pores, joue un role similaire. Dans ce dernier cas, la penetration du bain est moins rapide etant donnee la necessite de toujours amener des especes contenant de l'aluminium en tete du front de

  18. Croissance epitaxiale de GaAs sur substrats de Ge par epitaxie par faisceaux chimiques

    Science.gov (United States)

    Belanger, Simon

    de confirmer l'efficacite du procede de preparation de surface et d'identifier les conditions de croissance optimales. Les resultats de caracterisation indiquent que les materiaux obtenus presentent une tres faible rugosite de surface, une bonne qualite cristalline et un dopage residuel relativement important. De plus, l'interface GaAs/Ge possede une faible densite de defauts. Finalement, la diffusion d'arsenic dans le substrat de germanium est comparable aux valeurs trouvees dans la litterature pour la croissance a basse temperature avec les autres procedes d'epitaxie courants. Ces resultats confirment que la technique d'epitaxie par faisceaux chimiques (CBE) permet de produire des couches de GaAs sur Ge de qualite adequate pour la fabrication de cellules solaires a haute performance. L'apport a la communaute scientifique a ete maximise par le biais de la redaction d'un article soumis a la revue Journal of Crystal Growth et la presentation des travaux a la conference Photovoltaics Canada 2010 . Mots-cles : Epitaxie par jets chimiques, Chemical beam epitaxy, CBE, MOMBE, Germanium, GaAs, Ge

  19. SECHAGE DE PRODUITS GRANULAIRES PAR DESHYDRATATION PAR DETENTES SUCCESSIVES (DDS)

    OpenAIRE

    Abdulla , Galal; Mellouk , Hamid; Belghit , Abdelhamid; Allaf , Karim

    2009-01-01

    International audience; Dans cette étude, nous avons évalué les performances d'un nouveau procédé de séchage dans le cas du liège en granulés. Ce procédé (La déshydratation par détentes successives : DDS) consiste à soumettre le matériau liège dans une chambre hermétique aux variations cycliques de la pression. Chaque cycle est composé d'une compression et d'une décompression. La phase de compression est réalisée en injectant de l'air comprimé à température ambiante provenant d'un compresseur...

  20. Treatment of effluent at the Saclay Centre d'Etudes Nucleaires (1960)

    International Nuclear Information System (INIS)

    Wormser, G.

    1960-01-01

    The Centre d'Etudes Nucleaires at Saclay possesses several installations from which liquid radioactive effluent is rejected, and it has thus been found necessary to construct a station for the purification of radioactive liquids and to settle various chemical, analytical and technological problems. This report describes, in the following order: - the disposal possibilities at the Centre d'Etudes Nucleaires, Saclay, - the effluents produced at the centre, - the set-up for collecting effluent, - treatment of the effluent, - results of these treatments. (author) [fr

  1. MUNU: study of the neutrino-electron scattering; MUNU: etude de la diffusion neutrino-electron

    Energy Technology Data Exchange (ETDEWEB)

    Cerna, C

    2000-11-01

    MUNU is an experiment dedicated to electron-neutrino scattering studies and in particular to neutrino magnetic moment search at a nuclear power plant in Bugey (France). MUNU is based on a gaseous time projection chamber (TPC) immersed in 8 tons of liquid scintillator acting as an active anti-Compton shielding. A preliminary analysis of the first results of this experiment corresponding to about 24 days of data collecting draws a line on the value of the neutrino magnetic moment: {mu}{sub {nu}}-bar{sub {sub e}} {<=} 1.97 10{sup -10} {mu}{sub B} (68% confidence level). All along this work, it is shown that the combined use of a TPC and of a light detection system is valuable for discriminating particles and for discarding signals from background noise.

  2. Synthese, etude structurale et electrochimique des materiaux d'electrode positive d'oxydes mixtes lithium cobalt nickel oxide (0 /= 1) pour les batteries rechargeables au lithium

    Science.gov (United States)

    Grincourt, Yves

    Depuis une dizaine d'annees, on observe un interet grandissant pour les batteries rechargeables au lithium de tension superieure a 4 volts. La commercialisation de ces batteries pour l'electronique grand marche tend de plus en plus a supplanter celle des accumulateurs Ni-Cd et Ni-MH, de tension nominate 1,2 V. Ces batteries au lithium font appel a des materiaux d'electrode positive (cathode a la decharge) du type oxydes mixtes de metaux de transition LiMnO 2, LiMn2O4, LiNiO2 ou LiCoO2. Si le compose LiCoO2 est relativement aise a synthetiser, il n'en demeure pas moins que le cobalt reste un metal plus couteux compare au nickel et au manganese. La synthese de LiNiO2, quart a elle, demeure un probleme du point de vue stoechiometrique. Un defaut de lithium (5 a 10% molaire) conduira a des proprietes electrochimiques mediocres de la batterie. Dans cette etude nous nous proposons donc de preparer par voie humide et par voie seche les materiaux d'electrode positive de la famille LiCoyNi1-yO2 aver (0 ≤ y ≤ 1) et d'etudier en detail l'influence du pourcentage de nickel et de cobalt sur les proprietes electrochimiques des oxydes mixtes Li-Ni-Co. Une des caracteristiques est la morphologie plus fine des poudres de materiaux, observes par microscopie electronique a balayage (MEB). Un traitement thermique a plus basse temperature (750°C) que pour LiCoO2 (850°C) ainsi qu'un leger exces de lithium dans la preparation, ont permis d'aboutir a un materiau de stoechiometrie quasi parfaite. Neanmoins, le role de pilfer joue par 2 a 4% de moles de Ni2+ presents sur les sites lithium, permet de conserver intacte la structure hexagonale de la maille entre deux cycles consecutifs. Afin de mieux comprendre l'influence du vieillissement dune demi-pile Li/LiMeO2 (Me = Ni, Co) a temperature ambiante, des etudes electrochimiques et d'impedance spectroscopique ont ete menees en parallele. Le vieillissement de la cellule s'accompagne seulement dune chute de son potentiel due a son auto

  3. Diffusion bonding

    International Nuclear Information System (INIS)

    Anderson, R.C.

    1976-01-01

    A method is described for joining beryllium to beryllium by diffusion bonding. At least one surface portion of at least two beryllium pieces is coated with nickel. A coated surface portion is positioned in a contiguous relationship with another surface portion and subjected to an environment having an atmosphere at a pressure lower than ambient pressure. A force is applied on the beryllium pieces for causing the contiguous surface portions to abut against each other. The contiguous surface portions are heated to a maximum temperature less than the melting temperature of the beryllium, and the applied force is decreased while increasing the temperature after attaining a temperature substantially above room temperature. A portion of the applied force is maintained at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions

  4. Composes inter-halogenes sous pression: etude des transformations structurales dans le monobromure d'iode sous forme dense

    Science.gov (United States)

    Bouchard, Alexandre

    La famille des composes halogenes et inter-halogenes representent des solides moleculaires adoptant des phases denses communes avec des solides moleculaires diatomiques comme l'azote et l'hydrogene. Parmi les transformations structurales et electroniques induites sous haute pression et observees dans ces solides, on note, entre autres, la dissociation moleculaire et la metallisation. De plus, l'etude des phases denses de l'iode a permis recemment l'observation d'une structure cristalline possedant une modulation dite incommensurable, c'est-a-dire une modulation possedant une periodicite differente de celle de la structure cristalline, jetant ainsi une lumiere nouvelle sur le processus de dissociation moleculaire dans les solides halogenes. Dans ce memoire, on propose d'etudier les changements structuraux dans monobromure d'iode (IBr), un compose inter-halogene possedant des proprietes structurales semblables a celles de deux composes halogenes, soit l'iode (I 2) et le brome (Br2) sous leur forme solide. Des experiences de diffraction des rayons X de poudres en utilisant un rayonnement synchrotron ont ete realisees a temperature ambiante sur l'IBr en variant la pression jusqu'aux environs de 60 GPa. La nature chimique particuliere du compose IBr a necessite la mise au point de techniques de chargement d'echantillon destinees a preserver l'integrite chimique de la substance utilisee. On rapporte egalement l'observation d'une phase de l'IBr presentant une modulation incommensurable. Les phases observees dans l'IBr permettent d'etablir des paralleles avec les phases denses rapportees dans I2 et Br2 par le biais d'un modele phenomenologique decrivant la sequence structurale des solides halogenes sous forme condensee.

  5. La preuve par le nombre

    Directory of Open Access Journals (Sweden)

    Hélène Verdier

    2012-04-01

    Full Text Available S’il en était besoin, la question des usages et de la finalité des résultats de l’inventaire général pourrait être abordée par le nombre : nombre d’œuvres répertoriées, de communes inventoriées, de clichés photographiques réalisés, de dossiers, de consultations des notices dans les bases de données… Les additions aujourd’hui sont éloquentes, mais elles laissent dans l’ombre le rôle de l’inventaire qui, en mettant en œuvre une démarche systématique de connaissance, participe à l’ identificatio...

  6. Contribution to the study of uranyl salts in butyl phosphate solutions; Contribution a l'etude des solutions de sels d'uranyle dans les phosphates butyliques

    Energy Technology Data Exchange (ETDEWEB)

    Coulon, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1965-06-01

    A spectroscopic study in the normal infrared region and involving the following associations: tri-alkyl phosphates (tri-butyl, tri-ethyl, tri-methyl), uranyl salts (nitrate, chloride, acetate) has confirmed the existence of an interaction between the phosphoryl group and the uranium atom, as shown by a movement of absorption band for the valency P = 0 from {approx} 1270 cm{sup -1} to {approx} 1180 cm{sup -1}. A study of the preparation, analysis and spectroscopy of the solids obtained by the precipitation of uranyl salts by acid butyl phosphates has been carried out. By infrared spectrophotometry it has been shown that the tri-butyl and di-butyl phosphates are associated in non-polar diluents even before the uranium is introduced. The extraction of uranyl salts from acid aqueous solutions by a diluted mixture of tri-butyl and di-butyl phosphates proceeds by different mechanisms according to the nature of the ion (nitrate or chloride). (author) [French] Une etude spectroscopique dans l'infrarouge moyen portant sur les associations: - phosphates trialcoyliques (tributylique - triethylique - trimethylique) - sels d'uranyle (nitrate, chlorure, acetate) a confirme l'existence d'une interaction entre le groupement phosphoryle et l'atome d'uranium, se manifestant par un deplacement de la bande d'absorption de la vibration de valence P = 0 de {approx} 1270 cm{sup -1} a {approx} 1180 cm{sup -1}. Une etude preparative, analytique et spectroscopique des solides obtenus par precipitation de sels d'uranyle par les phosphates butyliques acides a ete effectuee. La spectrophotomerie infrarouge met en evidence l'association, anterieure a toute introduction d'uranium, des phosphates tributylique et dibutylique dans des diluants non polaires. L'extraction de sels d'uranyle, d'une solution aqueuse acide par un melange dilue de phosphates tributylique et dibutylique, s'effectue suivant des processus differents a la

  7. Measurement of the spin asymmetry of the beam in the polarized virtual Compton scattering on the proton. Study of the nucleon's energy spectra through the QCD-type potential model; Mesure de l'asymetrie de spin de faisceau en diffusion compton virtuelle polarisee sur le proton. Etude du spectre d'energie du nucleon par le modele de potentiel de type QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bensafa, I.K

    2006-05-15

    The first part of this work presents the analysis and results of the VCS-SSA (virtual Compton scattering - single spin asymmetry) experiment at MAMI (Mainz). It was carried out with beam energy 883 MeV and longitudinal polarization (about 80%), at virtual photon four-momentum transfer squared (Q{sup 2} = 0.35 GeV{sup 2}) to measure the beam asymmetry in the ep {yields} ep{gamma} and ep {yields} ep{pi}{sup 0} reactions. The asymmetry obtained in photon (resp. pion) electro-production is between 0-15% (resp. 0-2%). The dispersion relation model for virtual Compton scattering and MAID model (for {pi}{sup 0}) reproduce the amplitude globally but not completely the shape of the asymmetry. Perhaps this discrepancy is due to an imperfect parameterization of some pion production multipoles ({gamma}{sup *}N {yields} {pi}N). The second part is dedicated to the study of the nucleon energy spectrum in ground-state L=0 and excited-state L=1 in the quark model, using the Coulomb + linear potential type (CL) and a relativistic correction. The hyperfine correction is applied to discriminate the nucleon masses. The values of the mass found for the proton and the {delta}(1232) are respectively equal to (968 MeV, 1168 MeV), and the masses of the excited states are between 1564 - 1607 MeV. This part is completed by an application of the CL model to an approximate calculation of generalized polarizabilities of the proton. (author)

  8. Investigation of the core-halo structure of the neutron-rich nuclei {sup 6}He and {sup 8}He by intermediate-energy elastic proton scattering at high momentum transfer; Etude de la structure coeur-halo des noyaux riches en neutron {sup 6}He et {sup 8}He par la diffusion elastique de protons aux energies intermediaires etendue a la region du premier minimum de diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Aksouh, F

    2002-12-01

    The elastic proton scattering from the halo nuclei {sup 6}He and {sup 8}He was investigated in inverse kinematics at energies around 700 MeV/u with the aim to deduce the differential cross sections for the region of high momentum transfer, covering the first diffraction minimum. For this purpose, a liquid-hydrogen target was specially developed and used for the first time allowing to obtain low-background data as compared to commonly used targets made from C-H compounds. Previous data taken in the region of small momentum transfer were sensitive to the size and the peripheral shape of the total nuclear matter density distribution but not to the inner part. The present data allow for a more detailed insight in the structure of the alike core in {sup 6,8}He through a better determination of the matter density distributions. Several density distributions calculated from different microscopic models were used to derive elastic scattering cross sections which are compared with the obtained data. (author)

  9. Mesure des stades de developpement du sapin baumier (Abies balsamea [L.] Mill.) par teledetection des maxima locaux sur images a tres haute resolution

    Science.gov (United States)

    Demers, Alain

    L'objectif principal de cette these est d'identifier les parametres cles pour lier le developpement morphologique de la cime du sapin baumier (Abies balsamea [L.] Mill.) aux patrons de reflectance qu'elle genere sur une image aerienne a haute resolution. La quantite et la distribution spatiale des aiguilles dans le sapin dependent de la structure des branches. Un mecanisme de ramification particulier (la reiteration) ressort comme le parametre cle pour lier l'augmentation de la biomasse foliaire et la forme de la branche. Les reiterats forment des agglomerats de feuillage qui engendrent des inegalites dans les patrons de reflectance de la cime. La reflectance est plus elevee ou il y a une forte concentration de reiterats (maximum local). On demontre que le developpement du sapin baumier se mesure au moyen de l'analyse des maxima locaux de la cime sur une image. La biomasse de l'arbre se mesure par la teledetection et l'analyse des patrons de reflectance de la cime, c'est-a-dire la mesure du niveau de reiteration par le decompte des maxima locaux de la cime. Cette etude demontre qu'il est possible de proceder a l'inventaire du volume de bois d'un peuplement par la teledetection de l'architecture des arbres.

  10. Multipassage diffuser

    International Nuclear Information System (INIS)

    Lalis, A.; Rouviere, R.; Simon, G.

    1976-01-01

    A multipassage diffuser having 2p passages comprises a leak-tight cylindrical enclosure closed by a top cover and a bottom end-wall, parallel porous tubes which are rigidly assembled in sectors between tube plates and through which the gas mixture flows, the tube sectors being disposed at uniform intervals on the periphery of the enclosure. The top tube plates are rigidly fixed to an annular header having the shape of a half-torus and adapted to communicate with the tubes of the corresponding sector. Each passage is constituted by a plurality of juxtaposed sectors in which the mixture circulates in the same direction, the header being divided into p portions limited by radial partition-walls and each constituting two adjacent passages. The diffuser is provided beneath the bottom end-wall with p-1 leak-tight chambers each adapted to open into two different portions of the header, and with two collector-chambers each fitted with a nozzle for introducing the gas mixture and discharging the fraction of the undiffused mixture. By means of a central orifice formed in the bottom end-wall the enclosure communicates with a shaft for discharging the diffused fraction of the gas mixture

  11. Etude phenomenologique sur la convection naturelle au dessus d ...

    African Journals Online (AJOL)

    Parmi toutes les méthodes expérimentales, l'optique a toujours occupé une place de choix grâce à son caractère non intrusif : la traversée d'un écoulement par un faisceau lumineux n'entraine pas de perturbation dans les conditions requises par la visualisation ou la mesure. C'est ce qui explique l'importance de la ...

  12. Using a simple apparatus to measure direct and diffuse photosynthetically active radiation at remote locations.

    Directory of Open Access Journals (Sweden)

    Michael J Cruse

    Full Text Available Plant canopy interception of photosynthetically active radiation (PAR drives carbon dioxide (CO2, water and energy cycling in the soil-plant-atmosphere system. Quantifying intercepted PAR requires accurate measurements of total incident PAR above canopies and direct beam and diffuse PAR components. While some regional data sets include these data, e.g. from Atmospheric Radiation Measurement (ARM Program sites, they are not often applicable to local research sites because of the variable nature (spatial and temporal of environmental variables that influence incoming PAR. Currently available instrumentation that measures diffuse and direct beam radiation separately can be cost prohibitive and require frequent adjustments. Alternatively, generalized empirical relationships that relate atmospheric variables and radiation components can be used but require assumptions that increase the potential for error. Our goal here was to construct and test a cheaper, highly portable instrument alternative that could be used at remote field sites to measure total, diffuse and direct beam PAR for extended time periods without supervision. The apparatus tested here uses a fabricated, solar powered rotating shadowband and other commercially available parts to collect continuous hourly PAR data. Measurements of total incident PAR had nearly a one-to-one relationship with total incident radiation measurements taken at the same research site by an unobstructed point quantum sensor. Additionally, measurements of diffuse PAR compared favorably with modeled estimates from previously published data, but displayed significant differences that were attributed to the important influence of rapidly changing local environmental conditions. The cost of the system is about 50% less than comparable commercially available systems that require periodic, but not continual adjustments. Overall, the data produced using this apparatus indicates that this instrumentation has the

  13. Par Pond vegetation status Summer 1995 -- Summary

    International Nuclear Information System (INIS)

    Mackey, H.E. Jr.; Riley, R.S.

    1996-01-01

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the newly emergent, shoreline aquatic plant communities of Par Pond began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level. These surveys continued in July, September, and late October, 1995. Communities similar to the pre-drawdown, Par Pond aquatic plant communities are becoming re-established. Emergent beds of maidencane, lotus, waterlily, and watershield are extensive and well developed. Cattail occurrence continued to increase during the summer, but large beds common to Par Pond prior to the drawdown have not formed. Estimates from SPOT HRV, remote sensing satellite data indicated that as much as 120 hectares of emergent wetlands vegetation may have been present along the Par Pond shoreline by early October, 1995. To track the continued development of macrophytes in Par Pond, future surveys throughout 1996 and 1997, along with the continued evaluation of satellite data to map the areal extent of the macrophyte beds of Par Pond, are planned

  14. Etude de la Dynamique de la Transition de Phase Ferroelectrique dans un Cristal de Potassium TANTALE(.93) NIOBIUM(.07) OXYGENE(3) a L'aide D'une Technique de Melange a Quatre Ondes Resolu dans le Temps

    Science.gov (United States)

    Grenier, Paul

    Dans ce travail, nous presentons une etude de la dynamique de la transition de phase d'un echantillon de KTa_{.93}Nb_ {.07}O_3. Cette etude est basee principalement sur la mesure des caracteristiques de la branche polaritonique, associee au mode mou, en fonction de la temperature a l'aide d'une technique de melange a quatre ondes resolu dans le temps. De ces mesures, nous deduisons les caracteristiques du mode mou en fonction de la temperature, du vecteur d'onde et de la frequence. Les resultats obtenus pour la "self-energie" du mode mou dans la region du polariton presentent deux caracteristiques importantes. Premierement, la presence d'un pic a cq/n ~eq 1100 cm^{ -1} que nous interpretons comme etant du a une interaction anharmonique a quatre corps. Deuxiemement, la partie imaginaire de la "self-energie" s'avere etre plus elevee d'un facteur de l'ordre de deux que la valeur obtenue en diffusion Raman. L'interpretation la plus plausible relie cette difference a la presence de domaines ferroelectriques. De plus, l'evolution en temperature des tenseurs Raman et electro-optique, associee au mode mou, montre la predominance de ce dernier pres de T_{c}. Ces differents resultats abondent dans le sens d'un modele microscopique ou se sont les interactions electromagnetiques inter-i lots qui importent pour la dynamique des transitions de phase ferroelectrique dans ces systemes.

  15. Etude comparative de deux produits de neem (huile et poudre) sur ...

    African Journals Online (AJOL)

    Etude comparative de deux produits de neem (huile et poudre) sur les stades préimaginaux du moustique Culex quinquefasciatus(Diptera : Culicidae) ... for nymphs only contact effects are showed. Neem oil formulated 1 % appears more effective than neem powder 0.3 % for mosquitoes control in aquatic environment.

  16. Etude morphologique d'un cas de femme XY avec dysgénésie ...

    African Journals Online (AJOL)

    Mots clés : Etude morphologique, femme XY, dysgénésie gonadique pure. The authors describe the morphological features of a twenty years old female, without ambiguous genitalia, presenting a 46,XY karyotype, normal female external genitalia and gonadal dysgenesis. She has an android type of morpho dysplasia and ...

  17. English Department Reforms at the Hautes Etudes Commerciales: Entering the Nineties.

    Science.gov (United States)

    Shanahan, Daniel

    1993-01-01

    Discusses the reforms made in the fall of 1990 in the English department at the Ecole Hautes Etudes Commerciales (Paris, France), which were based on the basis of a combination of literature-culture and second- and foreign-language acquisition pedagogical biases. (four references) (VWL)

  18. Contribution a l'etude des plantes alimentaires mineures dans la ...

    African Journals Online (AJOL)

    Contribution a l'etude des plantes alimentaires mineures dans la prefecture de Dankpen (Togo). AB Kebenzikato, S Akpavi, K Batawila, K Wala, M Dourma, K Kossi-Titrikou, KS Amouzou, I Butare, H Dantsey-Barry, K Akpagana ...

  19. 152 Etude de cas sur l'impact des amendements organiques vis-à ...

    African Journals Online (AJOL)

    john mukalay

    Etude de cas sur l'impact des amendements organiques vis-à-vis de la salinité en culture de bananier. Michel Mazinga KWEY1, Séverin Kalala BANZE2 et John Banza MUKALAY2*. 1Laboratoire des cultures in vitro, Département de phytotechnie, Faculté des sciences agronomiques,. Université de Lubumbashi, BP 1825, ...

  20. Etude de l'influence des modes de transformation sur les teneurs en ...

    African Journals Online (AJOL)

    Etude de l'influence des modes de transformation sur les teneurs en lycopène de quatre variétés de tomates de la région du nord du Burkina Faso. I Sawadogo, M Koala, C Dabire, LP Ouattara, VBEJT Bazie, A Hema, C Gnoula, E Pale, RHC Nebie ...

  1. Etude comparée des paramètres agromorphologiques de dix (10 ...

    African Journals Online (AJOL)

    Etude comparée des paramètres agromorphologiques de dix (10) variétés de patate douce ( Ipomoea batatas (L.) Lam cultivées au champ dans deux (2) conditions climatiques au Tchad et au Burkina Faso.

  2. Etude comparative de la flore aux abords des cours d'eau dans les ...

    African Journals Online (AJOL)

    Etude comparative de la flore aux abords des cours d'eau dans les zones hypo et hyper endémiques d'ulcère de Buruli en Côte d'Ivoire. C. Cisse Boni, E. Ehouman, D. Soro, M.W. Kone, A. Bakayoko, F. Dembele, K. Bauthire, M Dosso ...

  3. Study and achievement of a digital-analog-divider; Etude et realisation d'un diviseur-analogique-numerique

    Energy Technology Data Exchange (ETDEWEB)

    Petin, A. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1969-04-01

    This apparatus is designed to give directly, in digital form, the value of the ratio Vt1/V2 two analog voltages. It consists essentially of an analog-digital coder operating by successive weighing; the comparison voltage is made proportional to the divider V2 in the coder. The input dynamics are such that the voltages Vi and V2 are all in the range -50 mV to -5 V. Each of the circuits has an input impedance of about 10 K{omega}. As for the quotient, it is a binary number given in series and parallel form; it is made up of 8 bits, this giving a change of 1/16 to 16 per jump of 1/16 in the zone where the accuracy is highest (V2 {>=} 800 mV). The time required for a division is, at best, 15 {mu}sec. During the time of calculation, the voltages V{sub 1} and V{sub 2} should not vary by more than 1 per cent and 0.5 per cent respectively. The theory of the system and the investigation of a synoptic diagram, the study of the circuits and the actual construction are presented. (author) [French] Cet appareil est destine a fournir directement sous forme numerique la valeur du rapport V1/V2 de deux tensions analogiques. Il est constitue essentiellement d'un codeur analogique-numerique fonctionnant par pesees successives dans lequel la tension de reference est rendue proportionnelle au diviseur V2. La dynamique d'entree est telle que les tensions V1 et V2 peuvent etre comprises dans l'intervalle -50 mV a -5 V. Chacune des voies presente une impedance d'entree d'environ 10 K{omega}. En ce qui concerne le quotient, c'est un nombre binaire delivre sous les formes serie et parallele ; il est compose de 8 bits, ce qui donne une variation de 1/16 a 16 par bond de 1/16 dans la zone de meilleure precision (V2 {>=} 800 mV). Le temps necessaire pour effectuer la division est au mieux de 15 {mu}s. Durant le temps de calcul les tensions V{sub 1} et V{sub 2} ne doivent pas varier respectivement de plus de 1 pour cent et 0.5 pour cent. Apres avoir etabli la

  4. Solar UV-B and visible radiation in tropical forest gaps: measurements partitioning direct and diffuse radiation

    International Nuclear Information System (INIS)

    Flint, S.D.; Caldwell, M.M.

    1998-01-01

    Solar ultraviolet-B (UV-B) radiation penetrates plant canopies to a different degree than photosynthetically active radiation (PAR) because UV-B is diffused to a greater degree by the atmosphere. We measured both global (total) and diffuse solar radiation in canopy gaps of a semideciduous tropical forest in Panama. Measurements were simultaneously made in the UV-B and PAR wavebands. Compared to unobstructed measurements taken outside the forest, the sunlit portions of gaps were depleted in the proportion of UV-B relative to PAR, especially at midday. Shaded areas, in contrast, were always richer in UV-B relative to PAR, but the magnitude of the change varied greatly. Presumably this variation was due to the differences in the directional nature of diffuse solar UV-B radiation as compared to diffuse PAR. Measurements in the gaps showed substantial reductions in the proportion of radiation in the diffuse components of both the UV-B and PAR wavebands. However, because of the greater proportion of UV-B which is diffuse, it tended to predominate in shaded areas. Similar patterns were seen in measurements taken at temperate latitudes. Response of shade- and gap-dwelling plants to these high UV-B:PAR ratios has received little attention. (author)

  5. Regulatory cross-talk in the double par locus of plasmid pB171

    DEFF Research Database (Denmark)

    Ringgaard, Simon; Ebersbach, Gitte; Borch, Jonas

    2007-01-01

    The double par locus of Escherichia coli virulence factor pB171 consists of two adjacent and oppositely oriented par loci of different types, called par1 and par2. par1 encodes an actin ATPase (ParM), and par2 encodes an oscillating, MinD-like ATPase (ParA). The par loci share a central cis...

  6. Contribution to research on the metabolism of fission product. Studies on the physico-chemical state and the metabolic fate of radio-cerium solution; Contribution a l'etude du metabolisme des produits de fission. Recherches sur l'etat physico-chimique et le devenir metabolique des solutions de radiocerium

    Energy Technology Data Exchange (ETDEWEB)

    Aeberhardt, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    This paper describes a study of the physico-chemical state of radio-cerium in dilute solutions on the tracer scale, as a function of the pH of the solution. The way in which this radioelement is transported in the blood is studied in vitro and in vivo, with reference to the ionic or colloidal state of the radio-cerium used. The distribution of cerium amongst the various components of the blood is studied by a new method of blood fractionation and by paper electrophoresis. Evidence of a cerium globulin connection is shown in the case of ionic cerium. A study of the initial distribution of radio-cerium in rats, after intravenous administration of ionic or colloidal solutions, shows considerable differences according to the physico-chemical state of the cerium injected. (author) [French] Ce travail presente une etude de l'etat physico-chimique du radiocerium en solutions diluees a l'echelle des indicateurs, en fonction du pH de la solution. En fonction de l'etat ionique ou colloidal du radiocerium utilise, le mode de transport de ce radioelement dans le sang est etudie in vitro et in vivo. La distribution du cerium entre les differents constituants du sang est etudiee par une methode nouvelle de fractionnement du sang et par electrophorese sur papier. L'existence d'une liaison cerium-globuline est mise en evidence dans le cas du cerium ionique. L'etude de la distribution initiale du radiocerium, chez le rat apres administration par voie veineuse de solutions ionique ou colloidale, montre des differences importantes en fonction de l'etat physico-chimique du cerium injecte. (auteur)

  7. ¡París!

    Directory of Open Access Journals (Sweden)

    Beatriz Caballero

    2003-01-01

    Full Text Available El día no le alcanzaba para caminarlo. Conocía cada puente, cada calle,plaza, museo, rincón, iglesia, café, y la mesa con el mejor ángulo para mirar siempre una iglesia, ojalá Saint-Germain-des-Pres, o Notre-Dame. Siempre contaba la impresión que le había causado a Bolívar ver allí cuando el papa coronó a Napoleón. Él se iba para la oficina todos los días, Luis a un taller a pintar, Antonio a estudiar ciencias políticas, yo al colegio y mamá hacía las cosas prácticas. Aprendíamos francés todos al tiempo y por la noche nos contábamos lo nuevo que cada uno había aprendido. Mamá después, cuando ya se quería volver, decía que París nos había maleado a todos. Estaba en pleno furor el cine francés de la "nueva ola", pero ella sólo me llevaba a ver películas de vaqueros pues no se fiaba de la clasificación de los periódicos.

  8. Diffusion coefficient in photon diffusion theory

    NARCIS (Netherlands)

    Graaff, R; Ten Bosch, JJ

    2000-01-01

    The choice of the diffusion coefficient to be used in photon diffusion theory has been a subject of discussion in recent publications on tissue optics. We compared several diffusion coefficients with the apparent diffusion coefficient from the more fundamental transport theory, D-app. Application to

  9. SEPA (Service d'etudes, de Procedes et Analyses)

    International Nuclear Information System (INIS)

    2017-01-01

    The SEPA (Service d'etudes, de Procedes et Analyses), is an engineering department specializing in the analysis and processing of uranium ore. It comes from a long tradition of mining in France that began sixty-five years ago with the French Atomic Energy Commission (CEA) and that has been carried on by COGEMA and then Areva. SEPA brings a combination of experience and excellence to its activities thanks to its multidisciplinary staff (mineralogists, chemists, mechanical engineers, instrumentation specialists...), who come from diverse cultural backgrounds. Today, the SEPA draws on its wealth of know-how and expertise to devise and develop new methods for processing and valorizing ores everywhere in the world. Its mission is to: - Develop and conduct laboratory tests on methods for processing uranium and other valuable elements such as molybdenum, vanadium, rare earths, niobium, tantalum and thorium; - Analyze ores obtained during prospecting at locations all over the world; -Serve as an advisor in the commissioning of Areva industrial units and ore processing plants; -Perform environmental analyses during the full period of mining operations; -Conduct audits and provide advice on processes and analysis methods; -Carry out research and development in all aspects of minerals treatment (including the filing of patents). The SEPA combines experience, skills and a global approach to technologies used in ore processing. Its role is to continually improve the processes for extracting, processing and valorizing ores while protecting the environment

  10. Concerning the study of the irreversible magnetic behaviour of superconductivity; Contribution a l'etude du comportement magnetique irreversible des supraconducteurs

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, G. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-03-01

    The influence of the presence of extended lattice defects on the magnetic behaviour has been studied for the case of type I superconductors, such as Re and Ta, and in a more quantitative manner for the type II superconductor niobium. In this case, measurements of the thermal conductivity have given an estimate of the relative concentration of lattice defects in each specimen. These measurements show that the larger the number of lattice defects, the more irreversible becomes the magnetization curve, and the larger becomes the values of the critical current, which is related by a simple model to the magnetization values. Finally, a study by transmission electron microscopy has confirmed on the one hand the diversity of the extended lattice defects and on the other hand has allowed the formulation of several hypothesis on their respective influence. [French] L'influence de la presence de defauts etendus sur le comportement magnetique a ete etudie pour des supraconducteurs de premiere espece, tels que le rhenium et le tantale, et plus quantitativement pour un supraconducteur de deuxieme espece, le niobium. Dans ce cas, des mesures de conductibilite thermique ont permis d'estimer la concentration relative des defauts du reseau dans chaque echantillon. Ces mesures montrent que plus les defauts du reseau sont nombreux, plus la courbe d'aimantation est irreversible, et plus les valeurs du courant critique, reliees par un modele simple aux valeurs de l'aimantation, sont elevees. Enfin une etude par microscopie electronique en transmission - a permis d'une part de constater la diversite des defauts etendus et d'autre part de formuler quelques hypotheses sur leurs influences respectives.

  11. La diffusion du tourisme dans l'archipel comorien

    Directory of Open Access Journals (Sweden)

    Jean-Christophe Gay

    2001-12-01

    Full Text Available Des considérations politiques ont largement influencé la diffusion du tourisme dans l'archipel comorien. Sa balkanisation explique que deux îles sont concernées par le tourisme, en dépit d'un flux réduit.

  12. Preliminary studies on the closed cycle magneto aerodynamic converter; Etudes preliminaires sur les convertisseurs magnetohydrodynamiques fonctionnant hors d'equilibre thermodynamique

    Energy Technology Data Exchange (ETDEWEB)

    Ricateau, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    electron heating in argon-potassium can be achieved by magnetic fields from 1 to 2 Ts. Plans are being made to build an important facility which will work on the principle of hot shots. The gas generator will deliver cesium-seeded helium shots at a temperature of 2100 deg. K. The shot will last 1/ 10 s and the instantaneous thermal power will reach 1 MW. (author) [French] A cote des convertisseurs magnetoaerodynamiques a cycle ouvert qui transforment l'energie thermique contenue dans les gaz de combustion on etudie tres attentivement le convertisseur a cycle ferme qui peut tirer son energie de toute source de chaleur a haute temperature et tout particulierement des sources nucleaires. Avant une etude pratique de l'ensemble de la centrale les performances du convertisseur lui-meme doivent etre bien delimitees. Ces performances sont largement fonction de la conductivite du gaz utilise. Mais cette conductivite ne doit pas etre payee par une temperature techniquement inadmissible pour l'echangeur de chaleur. Dans le fluide de conversion on est amene a associer un gaz porteur, helium ou argon, et une semence facilement ionisable cesium ou potassium. L'ionisation purement thermique n'est efficace qu'a partir de 2500 deg. K, par contre le champ electrique developpe par induction dans le convertisseur peut, sous certaines conditions, accroitre la temperature electronique et developper une ionisation bien superieure a la valeur d'equilibre. Il devient alors possible d'ioniser le gaz a temperature moderee. Des travaux en cours ont pour but de preciser les conditions permettant de creer cette ionisation hors d'equilibre dans les gaz rares ensemenses. Des mesures ont ete faites a l'aide d'un plasmatron triphase do 500 kVA alimente a l'argon ensemence de potassium. On a fait debiter cet appareil dans une cellule permettant de mesurer les composantes tensorielles de la conductivite en presence de champ magnetique. Les valeurs

  13. ETUDE DE LA FERTILITE FEMELLE DE CINQ CLONES CULTIVES ...

    African Journals Online (AJOL)

    USER

    source de caoutchouc naturel. C'est une espèce monoïque à allogamie chez laquelle l'auto fécondation est aussi observée (Sunderasan et al., 1994). A l'état spontané en Amazonie, la pollinisation naturelle chez l'hévéa est généralement réalisée par des insectes et parfois par le vent. Après la pollinisation de la fleur.

  14. Etude de la magnetoresistance du compose supraconducteur YB a2 ...

    African Journals Online (AJOL)

    00 ;0,01 ; 0,03 ; 0,06 ; 0,10 ; 0,20 ; 0,25) ont été élaborés par la méthode de réaction à l'état solide. L'effet de différents cycles de recuit sur la substitution du cuivre par le titane dans l'YBCO a été faite à travers des mesures de résistivité ...

  15. étude par AFM dynamique.

    African Journals Online (AJOL)

    user

    Rwanda Journal Volume 20, Series C, 2011 : Mathematical Sciences, Engineering and Technology. 53. - un tube piézoélectrique assurant le déplacement relatif, dans les trois directions x, y, z de l'espace, de la pointe par rapport à l'échantillon. L'acquisition des données s'effectue par asservissement de la position de la.

  16. Row orientation effect on UV-B, UV-A and PAR solar irradiation components in vineyards at Tuscany, Italy

    Science.gov (United States)

    Grifoni, D.; Carreras, G.; Zipoli, G.; Sabatini, F.; Dalla Marta, A.; Orlandini, S.

    2008-11-01

    Besides playing an essential role in plant photosynthesis, solar radiation is also involved in many other important biological processes. In particular, it has been demonstrated that ultraviolet (UV) solar radiation plays a relevant role in grapevines ( Vitis vinifera) in the production of certain important chemical compounds directly responsible for yield and wine quality. Moreover, the exposure to UV-B radiation (280-320 nm) can affect plant-disease interaction by influencing the behaviour of both pathogen and host. The main objective of this research was to characterise the solar radiative regime of a vineyard, in terms of photosynthetically active radiation (PAR) and UV components. In this analysis, solar spectral UV irradiance components, broadband UV (280-400 nm), spectral UV-B and UV-A (320-400 nm), the biological effective UVBE, as well as the PAR (400-700 nm) component, were all considered. The diurnal patterns of these quantities and the UV-B/PAR and UV-B/UV-A ratios were analysed to investigate the effect of row orientation of the vineyard in combination with solar azimuth and elevation angles. The distribution of PAR and UV irradiance at various heights of the vertical sides of the rows was also studied. The results showed that the highest portion of plants received higher levels of daily radiation, especially the UV-B component. Row orientation of the vines had a pronounced effect on the global PAR received by the two sides of the rows and, to a lesser extent, UV-A and UV-B. When only the diffused component was considered, this geometrical effect was greatly attenuated. UV-B/PAR and UV-A/PAR ratios were also affected, with potential consequences on physiological processes. Because of the high diffusive capacity of the UV-B radiation, the UV-B/PAR ratio was significantly lower on the plant portions exposed to full sunlight than on those in the shade.

  17. Experimental study of an ion cyclotron instability in a magnetic well confined plasma; Etude experimentale d'une instabilite cyclotronique ionique dans un plasma confine dans un puits magnetique

    Energy Technology Data Exchange (ETDEWEB)

    Brossier, P. [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    This report is a contribution to the study of microinstabilities in macroscopically stable plasmas, in the low-{beta} limit. Ion cyclotron instabilities, with k{sub ||} = 0, have been numerically studied in detail; the computation of the density thresholds and growth rates of the different harmonics showed the relative role played by the following energy sources: density gradient, perpendicular distribution function and cold plasma component. This theoretical model has been compared with the results of a detailed study (density thresholds, wave structure, frequency spectrum, wavelengths, growth rate, amplitude of the electric field) of the instability observed in the DECA II device. This comparison gave a good agreement which shows the destabilising role played by the cold plasma component on a hot plasma with a loss cone distribution function. (author) [French] Ce rapport est une contribution a l'etude des microinstabilites dans les plasmas macroscopiquement stables, dans la limite des {beta} << 1. Les instabilites cyclotroniques ioniques, a k{sub ||} = 0, ont ete etudiees numeriquement en detail; le calcul des seuils de densite et taux de croissance des differents harmoniques a permis de preciser l'importance relative des facteurs destabilisants suivants: gradient de densite, fonction de distribution perpendiculaire, presence de plasma froid. Ce modele theorique a ete confronte avec les resultats d'une etude detaillee (seuils de densite, structure de l'onde, spectres de frequence, longueurs d'onde, taux de croissance, amplitude du champ electrique) de l'instabilite observee dans l'experience DECA II, Cette confrontation aboutit a un accord satisfaisant qui montre le role destabilisant joue par le plasma froid sur un plasma chaud presentant une distribution de cone de pertes. (auteur)

  18. C9.A/14 steelwork joints de poutres par plaque frontale : assemblages par gousset

    CERN Document Server

    2015-01-01

    Les Tables de résistances ultimes des assemblages boulonnés par plaque frontale et par gousset, complétées par une description des modèles de calcul et des exemples d’application, ont pour but de faciliter la tâche de l'ingénieur et du constructeur. Cette première partie C9.A/14 contient les chapitres suivants: - Joints de poutres par plaque frontale en acier S235 et S355 - Assemblages par gousset en acier S235 et S355 Les Tables contiennent des données relatives à la géométrie ainsi que les valeurs de calcul correspondantes des résistances ultimes des assemblages ; elles remplacent le chapitre « Assemblages par plaques frontales et boulons HR » des anciennes Tables C9.1 de 1983 / 2002. Le calcul de ces assemblages par plaque frontale est basé sur les hypothèses du modèle de la méthode des composants décrite dans la norme SN EN 1993-1-8. Les vérifications sont effectuées selon la norme SIA 263:2013. Les assemblages par gousset remplacent les assemblages par double cornière, (telle...

  19. Pratiques de grh et climat organisationnel : une etude exploratoire ...

    African Journals Online (AJOL)

    ... objectif de mesurer l'influence des pratiques GRH sur le climat organisationnel dans les entreprises publiques béninoises. L'enquête par questionnaire et les entrevues auprès des responsables ressources humaines ont permis d'affirmer que les pratiques de rémunération, de formation, de promotion, de recrutement, de ...

  20. Iodine-131 production by a dry method using reactor-irradiated elementary tellurium. Part 1 - Conditions for obtaining iodine emanation and its capture. Part 2 - comparative study of preparation conditions using Pyrex, stainless steel and alumina equipment. Part 3 - production on a semi-industrial scale; Production de l'iode 131 par voie seche a partir de tellure elementaire irradie a la pile. 1ere partie - Etudes des conditions pour obtenir l'emanation de l'iode et le capter. 2eme partie - Etude comparee des conditions pour effectuer cette preparation avec des appareils en Pyrex, en acier inoxydable et en alumine. 3eme partie - production a l'echelle semi-industrielle

    Energy Technology Data Exchange (ETDEWEB)

    Bardy, A.; Beydon, J.; Murthy, T.S.; Doyen, J.B.; Lefrancois, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-04-15

    A previous report has described how iodine 131 can be prepared from elementary tellurium by a dry method which consists in treating irradiated tellurium at 400 degrees in argon. The possibility of carrying out this treatment in a stainless steel or alumina apparatus has been considered. The behavior of gaseous iodine 131 towards these materials has thus been studied. If the adsorption of iodine on stainless steel is superficial desorption is rapid at 250 degrees in oxygen or 400 degrees in argon. If the adsorption is chemical in nature it becomes necessary to heat to higher temperatures. Adsorption of iodine on alumina is very weak and the iodine can be desorbed rapidly. With these materials tests have been carried out on 300 gms of tellurium containing 41 curies of iodine 131; the yields were very satisfactory ( 98 per cent). (author) [French] La methode de preparation de l iode 131 par voie seche a partir de tellure elementaire decrite dans un precedent rapport consiste a traiter le tellure irradie a 400 degres sous argon. Nous avons examine la possibilite d effectuer ce traitement dans un appareil en acier inoxidable ou en alumine. Le comportement de l iode 131 gazeux vis a vis de ces materiaux a donc ete etudie. Si l adsorption de l iode sur l acier inoxidable est superficielle la desorption est rapide a 250 degres sous oxygene ou 400 degres sous argon. Si la fixation est de nature chimique il est necessaire de chauffer a des temperatures plus elevees. L adsorption de l iode sur l alumine est res faible et l iode peut etre desorbe rapideemnt. En employant ces materiaux des essais ont ete obtenus sur 300 g de tellure contenant 41 curies d iode 131 avec un bon rendement (98 pour cent). (auteur00.

  1. COMPLIANCE OF KÖHLER OP:33 NO I-II-III ETUDE BOOKS THAT ARE USED IN HIGH SCHOOLS OF FINE ARTS WITH FLUTE CONCERTOS

    Directory of Open Access Journals (Sweden)

    Yucan EKE

    2015-09-01

    Full Text Available This research is done for attesting the compliance of the etudes in German composer Ernesto Köhler’s op:33 no I-II-III books that are used in high schools of fine arts, with ability to play the flute concertos in high schools of fine arts 12 grade program, in terms of the knowledge – skills and musical functions they cover and also for contributing to learning by matching the etudes and works which are relevant. Etudes and the chosen concertos are analyzed and separated into templates in terms of melody, rhythm and tone for this research. Opinions are taken from the flute lesson instructors of various universities of Turkey to define the melody, technique and rhythm patterns. As a result of the analysis, Köhler op: 33, Book I, Etudes: 2,3,6,7,8,9,10,11,12; Köhler op: 33, Book II, Etudes:1,3,4,5,8,9,10,11; Köhler op: 33, Book III, Etudes: 1, 2, 4, 5, 6, 8; It is determined that the etudes given above in Köhler books are qualified enough to be preparative and instructive for the ability of playing the flute concertos. Some suggestions are given about which etude(s is instructive for which concerto and what kind of benefits could be gained, by this study. Based on the observed results, various suggestions are made about defining and studying the etudes which meet the technical, rhythmic and melodic features of the target concerto.

  2. Diffusion archeology for diffusion progression history reconstruction.

    Science.gov (United States)

    Sefer, Emre; Kingsford, Carl

    2016-11-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring - perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial diffusion data. Here, we tackle the problem of reconstructing a diffusion history from one or more snapshots of the diffusion state. This ability can be invaluable to learn when certain computer nodes are infected or which people are the initial disease spreaders to control future diffusions. We formulate this problem over discrete-time SEIRS-type diffusion models in terms of maximum likelihood. We design methods that are based on submodularity and a novel prize-collecting dominating-set vertex cover (PCDSVC) relaxation that can identify likely diffusion steps with some provable performance guarantees. Our methods are the first to be able to reconstruct complete diffusion histories accurately in real and simulated situations. As a special case, they can also identify the initial spreaders better than the existing methods for that problem. Our results for both meme and contaminant diffusion show that the partial diffusion data problem can be overcome with proper modeling and methods, and that hidden temporal characteristics of diffusion can be predicted from limited data.

  3. Parálisis criptogénica del III par craneal

    Directory of Open Access Journals (Sweden)

    Albia Josefina Pozo Alonso

    Full Text Available La parálisis aislada del tercer par craneal no es frecuente en los niños. Entre las causas que la originan se encuentran las congénitas, traumáticas, infecciosas, tumorales, vasculares, tóxicas y desmielinizantes. Se presenta un paciente de 3 años de edad con el diagnóstico de una oftalmoplejía aguda dolorosa del tercer par craneal, cuya etiología no se pudo demostrar. El cuadro clínico desapareció de forma espontánea y no ha presentado recurrencias después de 3 años de seguimiento. Se concluye que ante un paciente con parálisis del tercer par craneal es necesario realizar una exhaustiva evaluación con el propósito de precisar las diversas causas que la provocan.

  4. Etude exploratoire des conceptions de la circulation sanguine aupres d'eleves de l'ordre collegial

    Science.gov (United States)

    Robitaille, Jean-Marc

    Il existe peu d'etudes sur les conceptions touchant les domaines de la biologie, notamment sur les conceptions de la circulation sanguine Nous avons observe egalement l'absence de recherche menee aupres d'eleves de l'ordre collegial sur cette question. Nous avons voulu combler une lacune en menant une recherche sur les conceptions de la circulation sanguine aupres d'eleves de l'ordre collegial. Pour mener cette recherche nous nous sommes inspires d'une methode developpee par Treagust (1988). Le premier niveau de formulation didactique etablit l'architecture du systeme et la fonction nutritive de la circulation. Le second niveau de formulation didactique decrit et relie les parametres de la dynamique de la circulation et leur relation: Pression, Debit et Resistance. Le troisieme niveau de formulation didactique s'interesse au controle de la circulation du sang dans un contexte d'homeostasie qui implique la regulation de la pression arterielle. Nous avons construit un questionnaire en nous guidant sur les niveaux de formulation didactique et l'analyse des entrevues menees aupres de dix-huit eleves, representatifs de la population cible. Ce questionnaire fut administre a un echantillon de 2300 eleves disperses dans six colleges de la region de Montreal. Notre echantillon comprend des eleves inscrits a des programmes de l'ordre collegial en Sciences de la nature et en Techniques de la sante et qui n'ont pas suivi le cours sur la circulation sanguine. Notre analyse des reponses des eleves de notre echantillon aux questions sur le premier niveau de formulation didactique revele que la majorite des eleves considerent que le systeme circulatoire relie les organes les uns aux autres dans un circuit en serie. Notre analyse revele egalement que la majorite des eleves estiment que les nutriments sont extraits du sang par les organes selon un processus de selection base sur les besoins determines par la fonction de l'organe. Ces besoins sont differents selon les organes qui ne

  5. Excess Entropy and Diffusivity

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. Excess Entropy and Diffusivity. Excess entropy scaling of diffusivity (Rosenfeld,1977). Analogous relationships also exist for viscosity and thermal conductivity.

  6. Pré-dimensionnement par simulations dynamiques d’un réacteur de stockage thermochimique assurant l’autonomie d’un système solaire combiné.

    OpenAIRE

    Hennaut, Samuel; Thomas, Sébastien; Andre, Philippe; Courbon, Emilie; Le Berigot, Tangi; Frère, Marc

    2011-01-01

    Etude du stockage de l’énergie solaire thermique sous forme thermochimique comme moyen d’assurer l’autonomie thermique d’une habitation basse énergie. La surface de capteurs nécessaire et les caractéristiques du stockage sont étudiées par simulation dynamique (TRNSYS), de manière générale et pour des couples adsorbant/adsorbat particuliers (CaCl2/H2O et Charbon actif/Méthanol). Un système solaire combiné avec 14,4 m² de capteurs plans et un stockage thermochimique de 12,35 m³ de CaCl2 permet ...

  7. Health problems raised by the elimination of radioactive wastes and nuclear accidents; Problemes sanitaires poses par l'elimination des dechets radioactifs et par les accidents nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Jammet, H.; Mechali, D.; Dousset, M. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-07-01

    residus radioactifs produits par les installations nucleaires. L'evaluation du risque encouru par les populations et la fixation des limites admissibles pour les rejets ne peuvent resulter que d'une connaissance exacte du cheminement des radioelements rejetes, depuis leur source d'emission jusqu'a l'homme. L'incorporation des radioelements dans les chaines alimentaires constitue le premier risque a prendre en consideration. Les facteurs de passage doivent etre envisages, dans toutes les etapes de cette transmission, qu'elles interessent les milieux physiques ou les milieux proprement biologiques, du fait de leur continuite et de leur interdependance. Enfin, les donnees de caractere socio-economique et dietetique doivent etre recueillies pour conduire a une evaluation des risques et des niveaux admissibles reposant non sur des donnees theoriques mais sur des bases concretes et experimentales. Le risque d'accidents nucleaires dans l'industrie atomique, bien que de probabilite tres reduite, doit etre pris en consideration du fait de la gravite de leurs consequences. Les problemes sanitaires se posent d'une part dans le domaine de l'hygiene professionnelle, d'autre part dans celui de l'hygiene publique. Le premier domaine implique un risque double: d'irradiation et de contamination. Le domaine public n'est soumis essentiellement qu'au risque de contamination par les substances radioactives liberees accidentellement dans le milieu. Les etudes sanitaires a mener dans ce domaine comprennent, de ce fait, les recherches sur la therapeutique des irradiations ou des contaminations mais aussi celles relatives au transfert des radioelements depuis l'installation accidentee jusqu'a l'homme, principalement a travers les chaines alimentaires, dans leurs composantes physiques comme dans leurs composantes biologiques. De telles etudes sont a la base des decisions d'ordre sanitaire qu

  8. Etude écologique du Parc National de Mozogo-Gokoro (Cameroun ...

    African Journals Online (AJOL)

    Etude écologique du Parc National de Mozogo-Gokoro (Cameroun): prospections préliminaires de la flore ligneuse et du sol pour sa conservation et son aménagement. ... d'aménagement. Mots clés : Pré-inventaire, diversité compositionnelle, structure, écosystème de référence, menaces anthropiques, aire protégée ...

  9. Etude des boues résiduaires de la station de traitement des eaux de ...

    African Journals Online (AJOL)

    Etude des boues résiduaires de la station de traitement des eaux de Ziga et examen de leur possible valorisation pour la confection de barrières étanches. ... pour caractériser la cohérence et la capacité de faire couler la matière dans les procédés industriels et sur les mesures de filtration de la perméabilité du gâteau

  10. Etude de conception d'un simulateur de commande numérique en ...

    African Journals Online (AJOL)

    or Register. DOWNLOAD FULL TEXT Open Access DOWNLOAD FULL TEXT Subscription or Fee Access. Etude de conception d'un simulateur de commande numérique en tournage. K. A. Kasségné, AS Ajavon, C Carton, A Pouyo. Abstract. (J. de la Recherche Scientifique de l'Université de Lomé, 2000, 4(2): 169-180) ...

  11. Diffusion-controlled intergranular penetration and embrittlement of copper by liquid bismuth between 300 and 600 Celsius degrees; Penetration intergranulaire fragilisante du cuivre par le bismuth liquide: identification de la cinetique et du mecanisme de type diffusionnel entre 300 et 600 deg

    Energy Technology Data Exchange (ETDEWEB)

    Laporte, V

    2005-02-15

    Hybrid reactors are a new concept for energy production and nuclear waste treatment. Among other requirements, structural materials have to withstand liquid metal embrittlement. This thesis aimed therefore to identify the controlling mechanism for the intergranular embrittlement of copper in contact with liquid bismuth. Scanning electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy have been used to analyze fracture surfaces of both copper polycrystals and a copper bicrystal (symmetric tilt boundary 50 degrees <100>). These analyses reveal both parabolic intergranular penetration kinetics and a maximal intergranular bismuth concentration that is less than two monolayers equivalent. These two results allow us to identify grain boundary diffusion as the controlling mechanism for the intergranular penetration of copper by liquid bismuth between 300 and 600 Celsius degrees, showing the absence of perfect grain boundary wetting. (author)

  12. Contribution to the activation analysis of the rare gases. Contribution to the analysis of carbon monoxide and water vapour in gases (1963); Contribution a l'analyse par activation des gaz rares. Contribution a l'analyse de l'oxyde de carbone et de la vapeur d'eau dans les gaz (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Diebolt, J. [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-07-15

    In the present work, we have applied radioactive analysis to the general technique of rare gas separation. This separation is carried out on active charcoal, at constant pressure. The desorption of the gas is caused by an increase in the initial temperature of adsorption. These separations are quantitative and can be confirmed by chemical analysis. The volumes of desorbed gas are measured by radioactive counting. We have also used radioactivation to study the reduction of palladous chloride by carbon monoxide. Since this reduction is quantitative, we can have a knowledge of the mass of palladium reduced by measuring its activity. We have used the property which have organic chlorides of being hydrolysed by water vapour and of liberating hydrochloric acid to study quantitatively the amount of water vapour which a gas contains. The hydrochloric acid formed is measured by activation of the chlorine in the acid. (author) [French] Dans les travaux que nous presentons, nous avons applique l'analyse par radioactivation, a la technique generale de separation des gaz rares. Cette separation est faite sur charbon active, a pression constante. La desorption des gaz est provoquee par une augmentation de la temperature initiale d'adsorption. Ces separations sont quantitatives, et peuvent etre exploitees par l'analyse chimique. Les volumes de gaz dedorbes sont mesures par comptage de la radioactivite. Nous avons egalement utilise la radioactivation pour l'etude de la reduction du chlorure palladeux par l'oxyde de carbone. Cette reduction etant quantitative, nous pouvons connaitre la masse de palladium reduit par la mesure de son activite. Nous avons exploite la propriete que possede un chlorure organique d'etre hydrolise par la vapeur d'eau et de liberer de l'acide chlorhydrique pour etudier quantitativement la vapeur d'eau contenue dans un gaz. L'acide chlorhydrique forme est mesure par l'activation du chlore de l

  13. Photoreflectance et Photoconductivite des Couches Minces de Antimoinure de Indium Deposees Sur Arsenure de Gallium Par Pulverisation Cathodique avec Magnetron

    Science.gov (United States)

    Beaulieu, Yves

    L'attrait d'un systeme d'imagerie infrarouge integre, ou les detecteurs et l'electronique peuvent etre construits sur la meme gaufre, a motive l'etude de couches minces d'antimoniure d'indium (InSb) deposees sur des substrats d'arseniure de gallium (GaAs). La croissance epitaxiale de ces couches minces a ete realisee par pulverisation cathodique avec magnetron, en utilisant une approche multi -cibles (MSE) ou sous atmosphere d'un organometallique (MOMS). Malgre la grande difference des mailles cristallines des deux semiconducteurs, la qualite des couches minces est bonne et s'ameliore avec l'epaisseur, comme le demontrent les mesures de diffraction des rayons-X, d'effets Raman et Hall, et de microscopie electronique a transmission et a balayage. Les spectres de photoconductivite resolus en energie et en temps des couches deposees par MOMS ont demontre la coexistence de deux phenomenes de photoconduction en presence d'absorption interbande. Pour les energies de photon inferieures a environ 0.35 eV, la photoconductivite usuelle, due au piegeage rapide du porteur minoritaire excedentaire, est observee. Cependant, pour les energies superieures, une composante negative plus lente coexiste avec la composante positive. Elle est due au piegeage d'electrons chauds generes optiquement, dans les echantillons de type n, par des centres situes a haute energie, principalement dans la region de l'interface. Les mesures de photoreflectance dans la region des transitions E_1 et E _1 + Delta_1 ont ete realisees sur des couches deposees par MSE et des echantillons massifs de InSb. Les variations des elargissements de lignes spectrales ont confirme l'amelioration des couches avec l'epaisseur. De plus, l'analyse des lignes spectrales indique la presence d'effets excitoniques. La photoreflectance dans les echantillons massifs de haute purete de InSb a mis en evidence la presence d'une resonance sous les transitions etudiees. L'allure de la ligne spectrale, la position en energie et l

  14. Etude physicochimique et microbiologique de l'huile essentielle de ...

    African Journals Online (AJOL)

    Thymus fontanesii (thym) est une plante aromatique, répandue en Algérie et très utilisée par les populations locales pour ses vertus médicinales. L'huile essentielle de cette plante originaire de l'ouest algérien, fait l'objet dans cet article d'une étude physicochimique et microbiologique. L'extraction de l'huile essentielle a ...

  15. Etude epidemiologique de la carie dentaire en milieu scolaire a ...

    African Journals Online (AJOL)

    La fréquentation du cabinet dentaire était faible (20,7%) et motivée par la douleur dans 93% des cas. Le type d'alimentation, sa fréquence, les habitudes d'hygiène buccodentaire avaient une influence sur l'état des dents. A Libreville, en milieu scolaire, la carie dentaire est une pathologie préoccupante. Ainsi la mise en ...

  16. Etude RICH Nursing. Plus de connaissances et de preuves scientifiques.

    Science.gov (United States)

    Schubert, Maria

    2008-01-01

    L'importance et la validité des résultats de l'étude RICH-Nursing ont été récemment mises en cause par certains milieux, ce qui a provoqué certaines incertitudes chez les infirmières. Les auteurs reviennent sur l'impact actuel de cette étude et évoquent les perspectives d'avenir.

  17. 67 Etude physicochimique de l'huile essentielle de Ruta ...

    African Journals Online (AJOL)

    AKA BOKO

    identification de la plupart des molécules a été confirmée par comparaison de leurs indices de rétention avec ceux connus dans la littérature [15-22]. 3. Résultats et discussion. 3-1. Influence de la partie de la plante étudiée sur le rendement et la.

  18. Etudes des mecanismes de dissolution des phosphates naturels de ...

    African Journals Online (AJOL)

    Dans le cadre de la recherche sur la dissolution du phosphate calcique apatitique, une étude du mécanisme de cette dissolution basé sur la complexation des ions métalliques du minerai par deux acides humiques extraits d'un sol (AHS) et d'un compost (AHC) a été réalisée. L'ion calcium (Ca2+), ion majoritaire dans les ...

  19. Singing as a Therapeutic Agent, inThe Etude, 1891-1949.

    Science.gov (United States)

    Hunter

    1999-01-01

    The Etude music magazine, founded by Theodore Presser, was one of a number of popular music magazines published in the years prior to the establishment of the music therapy profession in 1950. During its publication run from 1883 to 1957, over 100 music therapy related articles appeared, including 13 on the health benefits of singing published between 1891 and 1949. Written by authors with diverse backgrounds, such as the famous Battle Creek, Michigan physician John Harvey Kellogg and Boston music critic Louis C. Elson, the articles contained consistent and adamant support regarding the health benefits of singing. The advantages described were both physical and psychological, and were recommended prophylactically for well persons and therapeutically for ill persons. Although the articles varied in perspective, from philosophical to theoretical to pedagogical, there is a consistent holistic medicine theme that appeared almost ahead of its time and no doubt linked to the push for vocal music education in that era. The importance of The Etude in promulgating ideas that helped shape the early practice of music therapy should not be underestimated. For much of its publication run The Etude was the largest music periodical in print, reaching its peak circulation of 250,000 copies per month in 1924.

  20. Restauration adaptative des contours par une approche inspiree de la prediction des performances

    Science.gov (United States)

    Rousseau, Kami

    En teledetection, les cartes de contours peuvent servir, entre autres choses, a la restitution geometrique, a la recherche d'elements lineaires, ainsi qu'a la segmentation. La creation de ces cartes est faite relativement tot dans la chaine de traitements d'une image. Pour assurer la qualite des operations subsequentes, il faut veiller a obtenir une carte de contours precise. Notre problematique est de savoir s'il est possible de diminuer la perte de temps liee au choix d'algorithme et de parametre en corrigeant automatiquement la carte de contours. Nous concentrerons donc nos efforts sur le developpement d'une methode de detection/restauration de contours adaptative. Notre methode s'inspire d'une technique de prediction des performances d'algorithmes de bas niveau. Elle consiste a integrer un traitement par reseau de neurones a une methode " classique " de detection de contours. Plus precisement, nous proposons de combiner la carte de performances avec la carte de gradient pour permettre des decisions plus exactes. La presente etude a permis de developper un logiciel comprenant un reseau de neurones entraine pour predire la presence de contours. Ce reseau de neurones permet d'ameliorer les decisions de detecteurs de contours, en reduisant le nombre de pixels de fausses alarmes et de contours manques. La premiere etape de ce travail consiste en une methode d'evaluation de performance pour les cartes de contours. Une fois ce choix effectue, il devient possible de comparer les cartes entre elles. Il est donc plus aise de determiner, pour chaque image, la meilleure detection de contours. La revue de la litterature realisee simultanement a permis de faire un choix d'un groupe d'indicateurs prometteurs pour la restauration de contours. Ces derniers ont servi a la calibration et a l'entrainement d'un reseau de neurones pour modeliser les contours. Par la suite, l'information fournie par ce reseau a ete combinee par multiplication arithmetique avec les cartes d

  1. Diffusion in solids

    International Nuclear Information System (INIS)

    Tiwari, G.P.; Kale, G.B.; Patil, R.V.

    1999-01-01

    The article presents a brief survey of process of diffusion in solids. It is emphasised that the essence of diffusion is the mass transfer through the atomic jumps. To begin with formal equations for diffusion coefficient are presented. This is followed by discussions on mechanisms of diffusion. Except for solutes which form interstitial solid solution, diffusion in majority of cases is mediated through exchange of sites between an atom and its neighbouring vacancy. Various vacancy parameters such as activation volume, correlation factor, mass effect etc are discussed and their role in establishing the mode of diffusion is delineated. The contribution of dislocations and grain boundaries in diffusion process is brought out. The experimental determination of different types of diffusion coefficients are described. Finally, the pervasive nature of diffusion process in number of commercial processes is outlined to show the importance of diffusion studies in materials science and technology. (author)

  2. Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering; Dynamique de l'eau et des ions dans des argiles de type montmorillonite par simulation microscopique et diffusion quasi-elastique des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Malikova, N

    2005-09-15

    Montmorillonite clays in low hydration states, with Na{sup +} and Cs{sup +} compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na{sup +} and C{sup +} counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

  3. Diffusion, electrical mobility and ionic interactions in molten Salts; Diffusion, mobilite electrique et interactions ioniques dans les sels fondus

    Energy Technology Data Exchange (ETDEWEB)

    Lantelme, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-05-01

    The diffusion and the electrical migration of ions in the molten alkali nitrates LiNO{sub 3}, NaNO{sub 3} and KNO{sub 3} and in their mixtures have been examined using stable or radio-active isotope indicators. This experimental works shows that there are large differences in the diffusion coefficients and the electric mobilities when they are compared using the Nernst-Einstein formula. An interpretive model has been put forward which shows the role played by poly-ionic displacements: in a salt AC the particles moving are not only the free ions A{sup -} and C{sup +} but also the groups [A{sub n}C{sub m}]{sup (m-n)+}... These results confirm the importance of electrostatic attraction and of the polarizability of the ions. This mechanisms, furthermore, explains the inversions of electrical mobilities often observed in liquid ionic media. (author) [French] La diffusion et la migration electrique des ions dans les nitrates alcalins fondus LiNO{sub 3}, NaNO{sub 3} et KNO{sub 3} et dans leurs melanges ont ete examinees a l'aide d'indicateurs isotopiques stables et radioactifs. Cette etude experimentale fait apparaitre des ecarts importants entre les coefficients de diffusion et les mobilites electriques compares au moyen de la formule de Nernst-Einstein. Un modele d'interpretation a pu etre propose mettant en evidence l'existence de deplacements polyioniques: dans un sel AC les particules en mouvement sont non seulement les ions libres A{sup -} et C{sup +} mais aussi des groupes [A{sub n}C{sub m}]{sup (}m{sup -n)+}. Ces resultats precisent l'importance des attractions electro-statiques et de la polarisabilite des ions. D'autre part, ce mecanisme permet de rendre compte des renversements des mobilites electriques souvent observes en milieu ionique liquide.

  4. Automatic inspection of electron beam weld for stainless steel using phased array method; Controle automatique par ultrasons multielements de soudures inox realisees par faisceau d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bleuze, A. [Metalscan - Groupe Tecnatom, 71100 Saint-Remy (France); Schwartz, C. [Commissariat a l' Energie Atomique, Centre de Valduc - 21120 Is-Sur-Tille - (France)

    2007-07-01

    en partenariat avec la societe METALSCAN une technique d'imagerie ultrasonore multielements dediee au controle complet et automatique de soudures homogenes d'aciers Inox realisees par faisceau d'electrons. Pour atteindre cet objectif, une etude acoustique par simulation avec le logiciel CIVA a ete menee afin de determiner les caracteristiques optimales des sondes multielements (leur nombre et leur emplacement). Au final, la methode developpee permet, d'une part, de localiser des manques de fusion de soudure equivalents a des trous a fond plats de 0,5 mm de diametre, et d'autre part, de detecter des manques de penetration de 0,1 mm. Afin d'assurer une parfaite reproductibilite des controles, un systeme mecanique assurant la mise en rotation de la piece, permet d'inspecter l'ensemble de la soudure. Les resultats sont alors analyses automatiquement a l'aide d'un logiciel specifique assurant la tracabilite des controles. La methode a tout d'abord ete validee a l'aide de pieces etalons, puis elle a ete mise en service apres confrontation des resultats obtenus sur des defauts reels avec d'autres techniques (radiographie et caracterisations metallographiques). (auteurs)

  5. Le stockage thermique par chaleur latente

    OpenAIRE

    Martin, F.; Nicolas, Jacques

    1988-01-01

    L'article présente le principe du stockage d'énergie par transformation de phase ainsi que les matériaux employés (composés organiques, sels hydratés et matériaux à transformation solide-solide) et les différents types d'échangeurs. Peer reviewed

  6. Coinfection pulmonaire par pneumocystis jirovecii et pseudomonas ...

    African Journals Online (AJOL)

    Sous traitement, l'évolution a été favorable. Les coinfections morbides sont relativement fréquentes chez les patients vivant avec le VIH. Devant une symptomatologie respiratoire du sujet vivant avec le VIH, il faut savoir rechercher en plus du Bacille de Koch, Pneumocystis jirovecii et Pseudomonas aeruginosa par un ...

  7. Study of the age of uranium-containing mineral deposits in the Limouzat, the bois-noir mountains (12963); Etude des ages des mineralisations uraniferes du gisement du Limouzat, Massif des bois-noirs (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Durand, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    famille du radium, alors que tous les chercheurs ont considere que les teneurs en plomb des mineraux uraniferes etaient negligeables et n'avaient aucune importance dans l'etude du spectre {gamma} des echantillons. Il est bien evident qu'une etude interessante doit etre entreprise sur les effets d'ecran des differents cations se trouvant au sein des mineraux. Nous pensons qu'on peut meme aboutir a la mise en evidence de certains elements directement par la spectrometrie {gamma}. Les ages mesures au spectrometre de masse presentent deux types de discordance mais ceux-ci ont pu etre expliques en considerant une premiere venue de plomb suivie d'un rearrangement et dans certains points d'une deuxieme venue a cette date. Enfin le gisement etudie subit une circulation d'uranium et de radon. (auteur)

  8. Diffusion archeology for diffusion progression history reconstruction

    OpenAIRE

    Sefer, Emre; Kingsford, Carl

    2015-01-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring — perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial d...

  9. Theoretical and Experimental Methods in Hypersonic Flows (Les Methodes Theoriques et Experimentales pour l’Etude Des Ecoulements Hypersoniques)

    Science.gov (United States)

    1993-04-01

    eropaceReserchIngenieros Aeronauticos InRC.ut Bldg M-osac 10eac Departamento de Mecanica de Fluidos MntrealdgRoad Plaza del Cardenal Cisneros 3 Ottawa K I A 1)R6...PROCEEDINGS 514 OELECTE f Theoretical and A U Experimental Methods in A Hypersonic Flows (Les Methodes Th6oriques et Experimentales pour 1’Etude des ...CONFERENCE PROCEEDINGS 514 Theoretical and - Experimental Methods in Hypersonic Flows .... t ,Z (Les Mthodes Th~oriques et Exp6rimentales pour I’Etude des

  10. Centromere pairing by a plasmid-encoded type I ParB protein

    DEFF Research Database (Denmark)

    Ringgaard, Simon; Löwe, Jan; Gerdes, Kenn

    2007-01-01

    The par2 locus of Escherichia coli plasmid pB171 encodes two trans-acting proteins, ParA and ParB, and two cis-acting sites, parC1 and parC2, to which ParB binds cooperatively. ParA is related to MinD and oscillates in helical structures and thereby positions ParB/parC-carrying plasmids regularly...

  11. Pars plana Baerveldt tube insertion with pars plana vitrectomy for refractory glaucoma

    Directory of Open Access Journals (Sweden)

    Anton M Kolomeyer

    2012-01-01

    Conclusions: Pars plana Baerveldt tube implantation with PPV can preserve vision, reduce IOP, and decrease the number of glaucoma medications necessary to achieve target IOP in patients with recalcitrant glaucoma.

  12. Detection of atmospheric tritium by scintillation. Variations in its concentration in France; Detection du tritium atmospherique par scintillation. Evolution de sa concentration en France

    Energy Technology Data Exchange (ETDEWEB)

    Bibron, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-06-01

    The tritium released into the atmosphere as a result of the explosion of thermonuclear devices is a useful radioactive tracer for the study of certain geophysical problems. The low concentrations found however call for the use of extremely sensitive detectors. Two detection methods using liquid scintillators are described. In the first method, the sample is introduced into the scintillator in liquid form, after prior concentration of the tritium by electrolysis. In the second method the tritium is incorporated into the scintillator solvent molecule by chemical synthesis. In the last part of the report are examined the variations in the tritium concentration in rain-water and of the free hydrogen in the air in France. A discussion is then made of the seasonal variations in the case of rain-water and these are compared to the variations in the strontium-90 concentrations. (author) [French] Le tritium introduit dans l'atmosphere par les explosions d'armes thermonucleaires est un traceur radioactif Interessant pour l'etude de certains problemes de geophysique. Les faibles concentrations rencontrees obligent toutefois a utiliser des detecteurs extremement sensibles. On decrit deux methodes de detection utilisant des scintillateurs liquides. Dans la premiere methode, l'echantillon est introduit dans le scintillateur, sous forme aqueuse, apres une concentration prealable du tritium par electrolyse. Dans la seconde methode, le tritium est incorpore a la molecule du solvant du scintillateur par synthese chimique. Dans la derniere partie du rapport, on examine l'evolution de la concentration du tritium dans les eaux de precipitation et l'hydrogene libre de l'air en France. On discute ensuite les variations saisonnieres dans le cas des eaux de precipitation et on les compare aux variations du strontium 90. (auteur)

  13. Histopathologie Des Biopsies Gastriques En Milieu Africain: Etude ...

    African Journals Online (AJOL)

    Aucune prédominance par rapport au sexe n\\'était relevée. La tranche d\\'âge la plus représentée quelque soit la pathologie gastrique a été celle de 40-60 ans. Il ressort de notre étude que les lésions inflammatoires de la muqueuse gastrique constituent la pathologie la plus fréquente de l\\'estomac. Cet état inflammatoire ...

  14. Etude du confort vibro-acoustique automobile en simulateur

    OpenAIRE

    Amari , Maël

    2009-01-01

    to be available soon....; L'intégration des facteurs humains dans la conception automobile est aujourd'hui un enjeu majeur de l'innovation. De par l'utilisation de plus en plus urbaine des véhicules, le confort de roulage à basse vitesse est au cœur des préoccupations industrielles. Dans cette situation, le confort dépend essentiellement de l'environnement vibro-acoustique de l'habitacle. Les évaluations de confort d'une telle situation constituent le cadre de ce travail de recherche. En comp...

  15. SAFARI 2000 PAR Measurements, Kalahari Transect, Botswana, Wet Season 2000

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Ceptometer data from a Decagon AccuPAR (Model PAR-80) were collected at four sites in Botswana during the SAFARI 2000 Kalahari Transect Wet Season Campaign...

  16. Copenhagen uPAR prostate cancer (CuPCa) database

    DEFF Research Database (Denmark)

    Lippert, Solvej; Berg, Kasper D; Høyer-Hansen, Gunilla

    2016-01-01

    AIM: Urokinase plasminogen activator receptor (uPAR) plays a central role during cancer invasion by facilitating pericellular proteolysis. We initiated the prospective 'Copenhagen uPAR Prostate Cancer' study to investigate the significance of uPAR levels in prostate cancer (PCa) patients. METHODS......: Plasma samples and clinical data from patients with newly diagnosed PCa have been collected prospectively. The uPAR forms have been measured in plasma using time-resolved fluorescence immunoassays. RESULTS: The level of intact uPAR(I-III) did not differ. Plasma uPAR(I-III) + uPAR(II-III) levels and u......PAR(I) levels were significantly higher in hormone-naive and castrate-resistant patients compared with patients with localized disease (both: p PCa....

  17. SAFARI 2000 PAR Measurements, Kalahari Transect, Botswana, Wet Season 2000

    Data.gov (United States)

    National Aeronautics and Space Administration — Ceptometer data from a Decagon AccuPAR (Model PAR-80) were collected at four sites in Botswana during the SAFARI 2000 Kalahari Transect Wet Season Campaign (March,...

  18. Experimental contamination of margaritana margaritifera (L) (a Fresh water bivalve) by caesium 137; Contamination experimentale de margaritana margaritifera (L) (bivalve d'eau douce) par le cesium 137

    Energy Technology Data Exchange (ETDEWEB)

    Foulquier, L.; Bovard, P.; Grauby, A. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1966-07-01

    The hydro biological research carried out in the Radio-Ecology Section has led the authors to study some Margaritana sampling stations situated down-stream from the Monts d'Arree nuclear power station. They describe the preservation and contamination methods used for fixing the {sup 137}Cs concentration factors in the case of Margaritana Margaritifera (L). The results of experiments carried out over a period of one hundred days show that the specific activity of the various organs is stabilized after thirty to thirty-five days. The authors have noticed a relatively low adsorption on the shell through the intermediary of micro-organisms, and a strong and rapid absorption in the soft parts. The concentration factors have values, at equilibrium, of around: 9 for the shell, 300 for all the organs, and 38 for the whole animal. A comparison of these results with work published by other authors makes it possible to draw general conclusions concerning the mechanism of {sup 137}Cs fixation by lamellibranch, as well as their capacity of fixation. (author) [French] Les etudes hydrobiologiques effectuees au sein de la Section de Radio-Ecologie ont amene les auteurs a etudier des stations de prelevement de Margaritana en aval de la Centrale Nucleaire des Monts d'Arree. Ils decrivent les methodes de conservation et de contamination utilisees pour l'etablissement des facteurs de concentration du {sup 137}Cs par Margaritana margaritifera (L). Les resultats des experimentations menees pendant cent jours montrent que les activites specifiques de la coquille et des differents organes se stabilisent au bout de trente a trente-cinq jours. Les auteurs constatent une adsorption relativement faible sur la coquille par l'intermediaire des micro-organismes et une absorption forte et rapide dans les parties molles. Les facteurs de concentration se situent, a l'equilibre, autour de: 9 pour la coquille, 300 pour l'ensemble des organes et 38 si l'on considere

  19. Mise au point du rheometre a cisaillement annulaire pour l'etude de rheologie d'un mastic bitumineux avec verre incorpore =

    Science.gov (United States)

    El Mansouri, Souleimane

    Dans le domaine viscoelastique lineaire (VEL, domaine des petites deformations), le comportement thermomecanique du bitume et du mastic bitumineux (melange uniforme de bitume et de fillers) a ete caracterise au Laboratoire des Chaussees et Materiaux Bitumineux (LCMB) de l'Ecole de technologie superieure (ETS) avec l'appui de nos partenaires externes : la Societe des Alcools du Quebec (SAQ) et Eco Entreprises Quebec (EEQ). Les proprietes rheologiques des bitumes et des mastics ont ete mesurees grâce a un nouvel outil d'investigation appele, Rheometre a Cisaillement Annulaire (RCA), sous differentes conditions de chargement. Cet appareil permet non seulement de solliciter des eprouvettes de tailles importantes par rapport a celles utilisees lors des essais classiques, mais aussi d'effectuer des essais en conditions quasi-homogenes, ce qui permet de donner acces a la loi de comportement des materiaux. Les essais sont realises sur une large gamme de temperatures et de frequences (de -15 °C a 45°C et de 0,03Hz a 10 Hz). Cette etude a ete menee principalement pour comparer le comportement d'un bitume avec celui d'un mastic bitumineux dans le domaine des petites deformations. neanmoins, dans une seconde perspective, on s'interesse a l'influence des fillers de verre de post-consommation sur le comportement d'un mastic a faibles niveaux de deformations en comparant l'evolution des modules complexes de cisaillements (G*) d'un mastic avec fillers de verre et un mastic avec fillers conventionnels (calcaire). Enfin, le modele analogique 2S2P1D est utilise pour simuler le comportement viscoelastique lineaire des bitumes et des mastics bitumineux testes lors de la campagne experimentale.

  20. Propagation and diffusion of a plasma column in a magnetic field; Propagation et diffusion d'une colonne de plasma dans un champ magnetique

    Energy Technology Data Exchange (ETDEWEB)

    Bottiglioni, F.; Coutant, J.; Gadda, E.; Prevot, F. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-12-01

    A plasma column is created in a magnetic field by longitudinal diffusion from a low-pressure pulsed discharge in hydrogen. Depending on the discharge conditions, two regimes are obtained in which the gas pumping speed has a different effect upon the plasma density in the column. Calculations are presented which can explain this effect by a difference in the transverse diffusion coefficient. (authors) [French] On forme une colonne de plasma dans un champ magnetique par diffusion longitudinale a partir d'une decharge puisee dans l'hydrogene a basse pression. Selon les conditions de la decharge on observe deux regimes differents pour lesquels le pompage du gaz neutre a un effet different sur la densite resultante du plasma dans la colonne. On presente des calculs qui peuvent expliquer cet effet par une difference dans la diffusion transversale du plasma. (auteurs)

  1. Spin-diffusions and diffusive molecular dynamics

    Science.gov (United States)

    Farmer, Brittan; Luskin, Mitchell; Plecháč, Petr; Simpson, Gideon

    2017-12-01

    Metastable configurations in condensed matter typically fluctuate about local energy minima at the femtosecond time scale before transitioning between local minima after nanoseconds or microseconds. This vast scale separation limits the applicability of classical molecular dynamics (MD) methods and has spurned the development of a host of approximate algorithms. One recently proposed method is diffusive MD which aims at integrating a system of ordinary differential equations describing the likelihood of occupancy by one of two species, in the case of a binary alloy, while quasistatically evolving the locations of the atoms. While diffusive MD has shown itself to be efficient and provide agreement with observations, it is fundamentally a model, with unclear connections to classical MD. In this work, we formulate a spin-diffusion stochastic process and show how it can be connected to diffusive MD. The spin-diffusion model couples a classical overdamped Langevin equation to a kinetic Monte Carlo model for exchange amongst the species of a binary alloy. Under suitable assumptions and approximations, spin-diffusion can be shown to lead to diffusive MD type models. The key assumptions and approximations include a well-defined time scale separation, a choice of spin-exchange rates, a low temperature approximation, and a mean field type approximation. We derive several models from different assumptions and show their relationship to diffusive MD. Differences and similarities amongst the models are explored in a simple test problem.

  2. Microfabricated diffusion source

    Science.gov (United States)

    Oborny, Michael C [Albuquerque, NM; Frye-Mason, Gregory C [Cedar Crest, NM; Manginell, Ronald P [Albuquerque, NM

    2008-07-15

    A microfabricated diffusion source to provide for a controlled diffusion rate of a vapor comprises a porous reservoir formed in a substrate that can be filled with a liquid, a headspace cavity for evaporation of the vapor therein, a diffusion channel to provide a controlled diffusion of the vapor, and an outlet to release the vapor into a gas stream. The microfabricated diffusion source can provide a calibration standard for a microanalytical system. The microanalytical system with an integral diffusion source can be fabricated with microelectromechanical systems technologies.

  3. Distillation simulée par chromatographie en phase gazeuse sur des coupes lourdes de pétrole Simulated Distillation of Heavy Oil Cuts by Gas Chromatography

    Directory of Open Access Journals (Sweden)

    Petroff N.

    2006-11-01

    Full Text Available Ce travail est le fruit d'une action concertée entre Institut Français du Pétrole (IFP, Compagnie Française de Raffinage (CFR et Société Nationale Elf Aquitaine (Production (SNEA (P au sein du GEC (Groupe d'Etudes Concertées sur l'analyse des fractions lourdes du pétrole. On décrit dans cette étude une méthode de chromatographie gazeuse permettant de caractériser par une courbe de distillation simulée, des coupes lourdes 370-535 °C, obtenues par distillation sous vide des résidus atmosphériques. Un mode opératoire détaillé est fourni, contenant des indications précises sur la préparation des colonnes, leur conditionnement, leurs conditions optimales d'emploi et sur les précautions d'exploitation quantitative des chromatogrammes obtenus. Des essais de répétabilité et de reproductibilité ont été réalisés sur différentes coupes de produits lourds. La qualité des résultats obtenus a conduit à une tentative de normalisation de la méthode au sein du Bureau de Normalisation du Pétrole. This article reports on the research done by a GEC (Groupe d'Etudes Concertées committee made up of scientists from the Institut Français du Pétrole (IFP, Compagnie Française de Raffinage (CFR and Société Nationale Elf Aquitaine (Production (SNEA(P who worked on joint research on heavy petroleum fractions. A gas chromatography method is described wich leads to characterize heavy cuts (370-535°C obtained by the vacuum distillation of atmospherie residues, by the simulated distillation curve. Detailed operating instructions are given, including specific recommendations for preparing and conditioning columns, optimum operating conditions, and precautions for the quantitative use of chromatograms. Repeatability and reproducibility tests were performed on several heavy cuts by four independent laboratories. The quality of the results obtained led to an attempt to have the method standardized by the Bureau de Normalisation du Pétrole.

  4. Methodologie de modelisation aerostructurelle d'une aile utilisant un logiciel de calcul aerodynamique et un logiciel de calcul par elements finis =

    Science.gov (United States)

    Communier, David

    Lors de l'etude structurelle d'une aile d'avion, il est difficile de modeliser fidelement les forces aerodynamiques subies par l'aile de l'avion. Pour faciliter l'analyse, on repartit la portance maximale theorique de l'aile sur son longeron principal ou sur ses nervures. La repartition utilisee implique que l'aile entiere sera plus resistante que necessaire et donc que la structure ne sera pas totalement optimisee. Pour pallier ce probleme, il faudrait s'assurer d'appliquer une repartition aerodynamique de la portance sur la surface complete de l'aile. On serait donc en mesure d'obtenir une repartition des charges sur l'aile beaucoup plus fiable. Pour le realiser, nous aurons besoin de coupler les resultats d'un logiciel calculant les charges aerodynamiques de l'aile avec les resultats d'un logiciel permettant sa conception et son analyse structurelle. Dans ce projet, le logiciel utilise pour calculer les coefficients de pression sur l'aile est XFLR5 et le logiciel permettant la conception et l'analyse structurelle sera CATIA V5. Le logiciel XFLR5 permet une analyse rapide d'une aile en se basant sur l'analyse de ses profils. Ce logiciel calcule les performances des profils de la meme maniere que XFOIL et permet de choisir parmi trois methodes de calcul pour obtenir les performances de l'aile : Lifting Line Theory (LLT), Vortex Lattice Method (VLM) et 3D Panels. Dans notre methodologie, nous utilisons la methode de calcul 3D Panels dont la validite a ete testee en soufflerie pour confirmer les calculs sur XFLR5. En ce qui concerne la conception et l'analyse par des elements finis de la structure, le logiciel CATIA V5 est couramment utilise dans le domaine aerospatial. CATIA V5 permet une automatisation des etapes de conception de l'aile. Ainsi, dans ce memoire, nous allons decrire la methodologie permettant l'etude aerostructurelle d'une aile d'avion.

  5. The inflammatory marker suPAR after cardiac arrest

    DEFF Research Database (Denmark)

    Rundgren, Malin; Lyngbaek, Stig; Fisker, Helle

    2015-01-01

    . This pilot study aimed at investigating suPAR levels in relation to outcome after CA and mild induced hypothermia. METHODS: suPAR levels were measured at 6, 36, and 72 hours in patients treated with hypothermia after CA. suPAR levels were analyzed in relation to survival after 6 months. Receiver operating...

  6. Molecular Mechanisms of Par-4-Induced Apoptosis in Prostate Cancer

    National Research Council Canada - National Science Library

    Ladias, John A

    2007-01-01

    .... Phosphorylation of Par-4 by Akt1 results in inhibition of apoptosis. To obtain insights into the mechanisms of Par-4 selective killing of prostate cancer cells, we expressed the human Par-4 SAC domain in bacteria and purified it to homogeneity...

  7. Macrophage Migration Inhibitory Factor Mediates PAR-Induced Bladder Pain.

    Directory of Open Access Journals (Sweden)

    Dimitrios E Kouzoukas

    Full Text Available Macrophage migration inhibitory factor (MIF, a pro-inflammatory cytokine, is constitutively expressed in urothelial cells that also express protease-activated receptors (PAR. Urothelial PAR1 receptors were shown to mediate bladder inflammation. We showed that PAR1 and PAR4 activator, thrombin, also mediates urothelial MIF release. We hypothesized that stimulation of urothelial PAR1 or PAR4 receptors elicits release of urothelial MIF that acts on MIF receptors in the urothelium to mediate bladder inflammation and pain. Thus, we examined the effect of activation of specific bladder PAR receptors on MIF release, bladder pain, micturition and histological changes.MIF release was measured in vitro after exposing immortalized human urothelial cells (UROtsa to PAR1 or PAR4 activating peptides (AP. Female C57BL/6 mice received intravesical PAR1- or PAR4-AP for one hour to determine: 1 bladder MIF release in vivo within one hour; 2 abdominal hypersensitivity (allodynia to von Frey filament stimulation 24 hours after treatment; 3 micturition parameters 24 hours after treatment; 4 histological changes in the bladder as a result of treatment; 5 changes in expression of bladder MIF and MIF receptors using real-time RT-PCR; 6 changes in urothelial MIF and MIF receptor, CXCR4, protein levels using quantitative immunofluorescence; 7 effect of MIF or CXCR4 antagonism.PAR1- or PAR4-AP triggered MIF release from both human urothelial cells in vitro and mouse urothelium in vivo. Twenty-four hours after intravesical PAR1- or PAR4-AP, we observed abdominal hypersensitivity in mice without changes in micturition or bladder histology. PAR4-AP was more effective and also increased expression of bladder MIF and urothelium MIF receptor, CXCR4. Bladder CXCR4 localized to the urothelium. Antagonizing MIF with ISO-1 eliminated PAR4- and reduced PAR1-induced hypersensitivity, while antagonizing CXCR4 with AMD3100 only partially prevented PAR4-induced hypersensitivity

  8. Diffuse-Illumination Systems for Growing Plants

    Science.gov (United States)

    May, George; Ryan, Robert

    2010-01-01

    Agriculture in both terrestrial and space-controlled environments relies heavily on artificial illumination for efficient photosynthesis. Plant-growth illumination systems require high photon flux in the spectral range corresponding with plant photosynthetic active radiation (PAR) (400 700 nm), high spatial uniformity to promote uniform growth, and high energy efficiency to minimize electricity usage. The proposed plant-growth system takes advantage of the highly diffuse reflective surfaces on the interior of a sphere, hemisphere, or other nearly enclosed structure that is coated with highly reflective materials. This type of surface and structure uniformly mixes discrete light sources to produce highly uniform illumination. Multiple reflections from within the domelike structures are exploited to obtain diffuse illumination, which promotes the efficient reuse of photons that have not yet been absorbed by plants. The highly reflective surfaces encourage only the plant tissue (placed inside the sphere or enclosure) to absorb the light. Discrete light sources, such as light emitting diodes (LEDs), are typically used because of their high efficiency, wavelength selection, and electronically dimmable properties. The light sources are arranged to minimize shadowing and to improve uniformity. Different wavelengths of LEDs (typically blue, green, and red) are used for photosynthesis. Wavelengths outside the PAR range can be added for plant diagnostics or for growth regulation

  9. Deltagerinvolveret organisationsudvikling med PAR som metode

    DEFF Research Database (Denmark)

    Sparre, Mogens

    2017-01-01

    about the organization in an management group with a Participatory Action Research (PAR) case study? The article deals with a Phenomenological case study, where the researcher, with a PAR approach method, creates a research design with the purpose to influence the participant’s “Subjective perception......When a leader wants to initiate or influence some necessary changes in the organization, he must be aware of the fact that the subjects that form the organization create their own meaning about actions the manager wants implemented. This article confronts the assumption that people are by nature...... resistant to change. The quite widespread narrative of resistance to change, is believed to originate from the many top-down driven change projects implemented by the top management or/and external consultants. Is it possible to create a desired change in the form of the inter-subjective perception building...

  10. Les Brulures Chimiques Par Le Laurier Rose

    OpenAIRE

    Bakkali, H.; Ababou, M.; Nassim Sabah, T.; Moussaoui, A.; Ennouhi, A.; Fouadi, F.Z.; Siah, S.; Ihrai, H.

    2010-01-01

    Le laurier rose ou Nerium oleander est un arbuste qui pousse naturellement dans les régions méditerranéennes. Au Maroc on le trouve dans les lieux humides. Il est réputé par ses risques de toxicité systémique en cas d'empoisonnement à cause de la présence de deux alcaloïdes, surtout l'oléandrine. La littérature illustre des cas d'utilisation locale des feuilles de cette plante contre la gale, les hémorroïdes et les furoncles. Nous rapportons deux cas de brûlures chimiques par le laurier rose ...

  11. [Ambroise Paré in French literature].

    Science.gov (United States)

    Dumaitre, P

    1995-01-01

    The 16th century by its passionate side has been the favourite one of authors of historical novels in which among the heroes of "cloak and dagger stories" appears sometime Ambroise Paré. Alexandre Dumas (the father) has shown him at the court of Charles IX in La Reine Margot (1845) where he does not however play a great role. On the contrary, Balzac in Le Martyr calviniste (1842) has given him a capital part close to the dying François II, whom he intended to trepanize but had to give up this idea as a consequence of the opposition of the queen-mother Catherine de Médicis. In the present century, Robert Merle in Paris ma bonne ville (Fortune de France, 3, 1980) shows Paré at the time of the Saint Barthélemy.

  12. Par Pond refill water quality sampling

    Energy Technology Data Exchange (ETDEWEB)

    Koch, J.W. II; Martin, F.D.; Westbury, H.M.

    1996-08-01

    This study was designed to document anoxia and its cause in the event that the anoxia caused a fish kill. However, no fish kill was observed during this study, and dissolved oxygen and nutrient concentrations generally remained within the range expected for southeastern reservoirs. Par Pond water quality monitoring will continue during the second summer after refill as the aquatic macrophytes become reestablished and nutrients in the sediments are released to the water column.

  13. Lung diffusion testing

    Science.gov (United States)

    ... medlineplus.gov/ency/article/003854.htm Lung diffusion testing To use the sharing features on this page, please enable JavaScript. Lung diffusion testing measures how well the lungs exchange gases. This ...

  14. Nonlinear ambipolar diffusion waves

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, J.T.; Rowlands, G.

    1985-07-01

    The evolution of a plasma perturbation in a neutral gas is considered using the ambipolar diffusion approximation. A nonlinear diffusion equation is derived and, in the one-dimensional case, exact solutions of shock type are obtained.

  15. Etude Irm Des Sequelles Lesionnelles Post - Traumatisme Cranien ...

    African Journals Online (AJOL)

    Hemosiderin and encephalomalacia atrophy are common signs. Diffuse Axonal Injury were found in 11 cases, focal sequella of brain sterm in 10 cases. Conclusion We concluded that RMI is an excellent technic of imaging cerebral sequella. Keywords: Brain trauma, Head injuries, Head trauma, Cerebral sequella, MRI.

  16. Etude de la diversité, de l'endémisme et de la distribution spatiale ...

    African Journals Online (AJOL)

    Etude de la diversité, de l'endémisme et de la distribution spatiale des Rubiaceae de Côte d'Ivoire. Fatou Nanou Tuo, Kouao Jean Koffi, Akossoua Faustine Kouassi, Moussa Kone, Bakayoko Adama, Jan Bogaert ...

  17. Etude de l'impact de la variation de la température sur les activités ...

    African Journals Online (AJOL)

    Etude de l'impact de la variation de la température sur les activités microbiennes : application à une population de Listeria monocytogenes CIP 7831, Listeria monocytogenes Scott A CIP 103575 et Escherichia coli ATCC 25922.

  18. Data processing in gamma spectrometry. Application to the decay schemes study; Traitement des informations en spectrometrie gamma application a l'etude de schemas de desintegration

    Energy Technology Data Exchange (ETDEWEB)

    Boulanger, J.P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, departement d' electronique generale, service d' instrumentation nucleaire

    1968-06-01

    The purpose of this thesis is the processing of the data issued from a gamma spectrometer, and its applications to the decay schemes study. The mathematical analysis of the full energy peaks, in connection with the very good resolution of semi-conductor detectors, leads to a very accurate determination of the energies. The resolution of complex spectra by the least squares method, completed by a spectra generating process, allows the calculation of branching ratios. Then, the handling of the two dimensional experiments permits the coincidence exam. For each of these methods, the calculation principle, then the systematics tests realized in order to prove their validity and to determine their application ranges as well as some experimental results appropriate to illustrate their possibilities, are presented. The energies of some nuclides, frequently used as standards have been thus measured and the decay schemes of {sup 134}Cs and {sup 110m}Ag determined precisely. (author) [French] Cette these est consacree aux methodes de traitement des informations issues d'un spectrometre {gamma}, et a leur application a l'etude des schemas de desintegration: l'analyse mathematique des pics d'absorption totale, conjuguee avec l'excellent pouvoir de resolution des detecteurs semi-conducteurs, conduit a une determination tres precise des energies. La decomposition des spectres complexes par la methode des moindres carres, completee par un procede de generation de spectres, autorise le calcul des rapports de branchement. Enfin le depouillement des experiences biparametriques permet l'examen des coincidences. Pour chacune de ces methodes, on expose le principe des calculs et les essais systematiques effectues afin d'eprouver leur validite et de definir leurs domaines d'application, ainsi que quelques resultats experimentaux propres a illustrer leurs possibilites. Les energies de quelques isotopes utilises couramment comme etalons ont ainsi ete

  19. Regulatory cross-talk in the double par locus of plasmid pB171

    DEFF Research Database (Denmark)

    Ringgaard, Simon; Ebersbach, Gitte; Borch, Jonas

    2007-01-01

    The double par locus of Escherichia coli virulence factor pB171 consists of two adjacent and oppositely oriented par loci of different types, called par1 and par2. par1 encodes an actin ATPase (ParM), and par2 encodes an oscillating, MinD-like ATPase (ParA). The par loci share a central cis-actin...... well with the observed transcriptional regulation of the par operons in vivo and in vitro. Integration host factor (IHF) was identified as a novel factor involved in par2-mediated plasmid partitioning....

  20. Study of allotropic transformations in plutonium; Etude des transformations allotropiques du plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Spriet, B. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-06-01

    The allotropic transformations in plutonium have been studied by different methods: metallography, dilatometry, thermal analysis, resistivity measurements, examination with a hot stage microscope. In order to study the importance of the purity, purification process such as zone-melting or electro-diffusion have been developed. The characteristics of the {alpha} {r_reversible} {beta} transformation can be explained in terms of the influence of internal stresses on the transition temperature and on the transformation kinetics. Some particular characteristics of {delta} {yields} {gamma}, {gamma} {yields} {alpha}, {delta} {r_reversible} {epsilon}, {beta} {r_reversible} {gamma} and {delta} {yields} {alpha} transformations are also given. (author) [French] Les transformations, allotropiques du plutonium ont ete etudiees a l'aide de differentes methodes: metallographie, dilatometrie, analyse thermique, mesure de resistivite, examen au microscope a platine chauffante. Pour preciser l'influence de la purete, des procedes de purification comme la fusion de zone ou l'electrodiffusion ont ete mis au point. Les caracteres de la transformation {alpha} {r_reversible} {beta} s'expliquent par le role des contraintes internes sur la temperature de transition et la cinetique de transformation. Quelques particularites des transformations {delta} {yields} {gamma}, {gamma} {yields} {alpha}, {delta} {r_reversible} {epsilon}, {beta} {r_reversible} {gamma} et {delta} {yields} {alpha} sont egalement presentees. (auteur)

  1. etude de pouvoir antimicrobiene et antioxydants des huilles essentielles

    OpenAIRE

    Mohammedi, zohra

    2014-01-01

    ensemble. - Résumé Les extraits naturels issus des végétaux contiennent une variété de composés phénoliques et des huiles essentielles auxquelles on attribue un pouvoir inhibiteur des microorganismes et des capacités antioxydantes. Les huiles essentielles de L. stoechas L et S. olusairum L ont été analysées par CPG et RÎvIIN du carbone-13. Les constituants majeurs sont : fenchone, cinéole et camphre pour la Lavande. Le fiiranodiène/furanoélémène (46 1/0) pour la partie aé...

  2. Etude numerique du sillage tourbillonnaire d'une eolienne

    Science.gov (United States)

    Sibuet Watters, Christophe

    Cette these formalise le concept de la surface actuatrice (SA) et en presente l'implantation dans deux methodes de mecanique des fluides assistee par ordinateur (CFD) bidimensionnelle (2D) et tridimensionnelle (3D), la validation et l'application au probleme de modelisation du sillage tourbillonnaire d'une eolienne. En termes cinetiques, une SA est une nappe tourbillonnaire qui resulte en une discontinuite de vitesse tandis qu'en termes dynamiques, elle est associee a un systeme de forces dont la composante dans la direction normale a la SA resulte en une discontinuite de pression. Les methodes CFD utilisees sont des methodes aux volumes finis, adaptees pour prendre en compte l'action de la SA sur l'ecoulement. L'approche de la SA est validee pour des problemes 2D: aile infinie et disque actuateur, ainsi que pour le probleme 3D de l'aile en translation (aile effilee), avant d'etre appliquee a plusieurs eoliennes.

  3. PAR1 antagonists inhibit thrombin-induced platelet activation whilst leaving the PAR4-mediated response intact.

    Science.gov (United States)

    Judge, Heather M; Jennings, Lisa K; Moliterno, David J; Hord, Edward; Ecob, Rosemary; Tricoci, Pierluigi; Rorick, Tyrus; Kotha, Jayaprakash; Storey, Robert F

    2015-01-01

    Thrombin-induced platelet activation is initiated by PAR1 and PAR4 receptors. Vorapaxar, a PAR1 antagonist, has been assessed in patients with acute coronary syndromes (ACS) and stable atherosclerotic disease in addition to standard-of-care treatment. In clinical trials, vorapaxar has been observed to reduce the frequency of ischaemic events in some subgroups though in others has increased the frequency of bleeding events. Among patients undergoing CABG surgery, which is associated with excess thrombin generation, bleeding was not increased. The aim of these studies was to investigate the effects of selective PAR1 antagonism on thrombin-induced platelet activation in patients receiving vorapaxar or placebo in the TRACER trial and to explore the roles of PAR1 and PAR4 in thrombin-induced platelet activation in healthy volunteers. ACS patients receiving vorapaxar or placebo in the TRACER trial were studied at baseline and 4 hours, 1 and 4 months during drug administration. Thrombin-induced calcium mobilisation in platelet-rich plasma was assessed by flow cytometry. In vitro studies were performed in healthy volunteers using the PAR1 antagonist SCH79797 or PAR4 receptor desensitisation. Vorapaxar treatment significantly inhibited thrombin-induced calcium mobilisation, leaving a residual, delayed response. These findings were consistent with calcium mobilisation mediated via the PAR4 receptor and were reproduced in vitro using SCH79797. PAR4 receptor desensitization, in combination with SCH79797, completely inhibited thrombin-induced calcium mobilisation confirming that the residual calcium mobilisation was mediated via PAR4. In conclusion vorapaxar selectively antagonises the PAR1-mediated component of thrombin-induced platelet activation, leaving the PAR4-mediated response intact, which may explain why vorapaxar is well tolerated in patients undergoing CABG surgery since higher thrombin levels in this setting may override the effects of PAR1 antagonism through PAR4

  4. Bio-metric study of pig karyotype; Etude biometrique du caryotype du porc

    Energy Technology Data Exchange (ETDEWEB)

    Haag, J.; Lacourly, N.; Nizza, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    This study has a twofold purpose, the former is to determine the swine karyotype as accurately as possible, the latter is to try and develop a method of automatic classification and to show its possibilities and limits. (authors) [French] Cette etude a un double objet: d'une part, de definir de la facon aussi precise que possible le caryotype du porc et d'autre part, de tenter une methode de classification automatique et d'en montrer les possibilites ainsi que les limites. (auteurs)

  5. Study of the local stability of a feedback control having rectifiers with a controlled grid; Etude de la stabilite locale d'un asservissement comportant des redresseurs a grille controlee

    Energy Technology Data Exchange (ETDEWEB)

    Katz, A

    1962-07-01

    The equivalence of a rectifier with a controlled grid and a sampled device is established. Then, the sampled servomechanism theory is applied to the study of the response and of the local stability of a feedback control having a rectifiers system charged by an inductance-resistance assembly, in the case of the permanent conduction. The case of a feedback control of the first order and then of the second order are studied. The expressions of the test and sampled responses with a sinusoidal input is given. (O.M.) [French] On etablit l'equivalence d'un redresseur a grille controlee et d'un dispositif echantillonne. On applique ensuite la theorie des servomecanismes echantillonnes a l'etude de la reponse et de la stabilite locale d'un asservissement comportant un systeme de redresseurs charges par un ensemble inductance-resistance, dans le cas de la conduction permanente. On etudie le cas d'un asservissement du premier, puis du second ordre. On indique egalement les expressions des reponses miree et echantillonnee a une entree sinusoidale. (auteur)

  6. Study of filterable materials and protection instruments by the use of radioactive aerosols; Etude de materiaux filtrants et d'appareils de protection a l'aide des aerosols radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Billard; Chevalier; Pradel [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    Many filtration problems can be studied by means of radioactive aerosols. For the investigations described in this paper we have chosen the solid disintegration products of radon, the radioactive gas formed from radium, because of the facilities of generation and measurement it offers. Radon and its daughters are in fact always present in the atmosphere in sufficient concentration for certain tests. In order to improve the sensitivity of the measurements, radon from uranium ore can be used. The technique of measuring by counting {alpha} particles is rapid and easy to employ. We have thus been able to define a test for filterable substances, and to check filtering installation and individual protection instruments. (author) [French] Les aerosols radioactifs permettent d'etudier de nombreux problemes de filtration. Pour les etudes decrites dans ce document, nous avons choisi les produits solides de desintegration du radon, gaz radioactif forme a partir du radium en raison des facilites de generation et de mesure. Le radon et ses descendants sont, en effet, toujours presents dans l'atmosphere en concentration suffisante pour certains essais. Pour ameliorer la sensibilite des mesures, il suffit d'utiliser le radon provenant de minerai d'uranium. La technique de mesure par comptage des particules {alpha} est rapide et facile a mettre en oeuvre. Nous avons pu ainsi definir un test pour les substances filtrantes et controler les installations de filtration et des appareils de protection individuelle. (auteur)

  7. Fractional diffusion equations and anomalous diffusion

    CERN Document Server

    Evangelista, Luiz Roberto

    2018-01-01

    Anomalous diffusion has been detected in a wide variety of scenarios, from fractal media, systems with memory, transport processes in porous media, to fluctuations of financial markets, tumour growth, and complex fluids. Providing a contemporary treatment of this process, this book examines the recent literature on anomalous diffusion and covers a rich class of problems in which surface effects are important, offering detailed mathematical tools of usual and fractional calculus for a wide audience of scientists and graduate students in physics, mathematics, chemistry and engineering. Including the basic mathematical tools needed to understand the rules for operating with the fractional derivatives and fractional differential equations, this self-contained text presents the possibility of using fractional diffusion equations with anomalous diffusion phenomena to propose powerful mathematical models for a large variety of fundamental and practical problems in a fast-growing field of research.

  8. Etude des phenomenes dynamiques ultrarapides et des caracteristiques impulsionnelles d'emission terahertz du supraconducteur YBCO

    Science.gov (United States)

    Savard, Stephane

    Les premieres etudes d'antennes a base de supraconducteurs a haute temperature critique emettant une impulsion electromagnetique dont le contenu en frequence se situe dans le domaine terahertz remontent a 1996. Une antenne supraconductrice est formee d'un micro-pont d'une couche mince supraconductrice sur lequel un courant continu est applique. Un faisceau laser dans le visible est focalise sur le micro-pont et place le supraconducteur dans un etat hors-equilibre ou des paires sont brisees. Grace a la relaxation des quasiparticules en surplus et eventuellement de la reformation des paires supraconductrices, nous pouvons etudier la nature de la supraconductivite. L'analyse de la cinetique temporelle du champ electromagnetique emis par une telle antenne terahertz supraconductrice s'est averee utile pour decrire qualitativement les caracteristiques de celle-ci en fonction des parametres d'operation tels que le courant applique, la temperature et la puissance d'excitation. La comprehension de l'etat hors-equilibre est la cle pour comprendre le fonctionnement des antennes terahertz supraconductrices a haute temperature critique. Dans le but de comprendre ultimement cet etat hors-equilibre, nous avions besoin d'une methode et d'un modele pour extraire de facon plus systematique les proprietes intrinseques du materiau qui compose l'antenne terahertz a partir des caracteristiques d'emission de celle-ci. Nous avons developpe une procedure pour calibrer le spectrometre dans le domaine temporel en utilisant des antennes terahertz de GaAs bombarde aux protons H+ comme emetteur et detecteur. Une fois le montage calibre, nous y avons insere une antenne emettrice dipolaire de YBa 2Cu3O7-delta . Un modele avec des fonctions exponentielles de montee et de descente du signal est utilise pour lisser le spectre du champ electromagnetique de l'antenne de YBa 2Cu3O7-delta, ce qui nous permet d'extraire les proprietes intrinseques de ce dernier. Pour confirmer la validite du modele

  9. Regulatory cross-talk in the double par locus of plasmid pB171

    DEFF Research Database (Denmark)

    Ringgaard, Simon; Ebersbach, Gitte; Borch, Jonas

    2007-01-01

    -acting region of approximately 200 bp, called parC1, located between the two par loci. An additional cis-acting region, parC2, is located downstream of the parAB operon of par2. Here we show that ParR of par1 and ParB of par2 bind cooperatively to unrelated sets of direct repeats in parC1 to form the cognate...... partition and promoter repression complexes. Surprisingly, ParB repressed transcription of the noncognate par operon, indicating cross-talk and possibly epistasis between the two systems. The par promoters, P1 and P2, affected each other negatively. The DNA binding activities of ParR and ParB correlated...

  10. The effect of the substitution of D{sub 2}O for H{sub 2}O on the degradation of myosin {beta} in solution by heat and by {sup 60}Co {gamma} radiation (1962); Effet de la substitution de D{sub 2}O a H{sub 2}O sur l'alteration de la Myosine B en solution par la chaleur et par les rayons {gamma} du {sup 60}CO (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Pinset-Harstrom, I.; Fritsch, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    (1) Alterations of myosin B produced by heat or irradiation are shown to be qualitatively identical as demonstrated by analytical centrifugation. (2) A considerable isotope effect was demonstrated using 75 per cent D{sub 2}O in the solvent. The sensitivity of myosin B to heat and irradiation is discussed in the light of this isotope effect. (3) Polymers appearing upon heat treatment of myosin B seem to be of a very different nature than the polymers occurring alter a similar treatment upon myosin A. Polymers obtained from myosin B can be depolymerized by ATP and they appear in a much narrower temperature range than myosin A polymers. This fact indicates a considerable difference in the activation enthalpies in the two reactions. (authors) [French] (1) Cette etude montre que les alterations de la myosine B provoquees par la chaleur et par l'irradiation aux rayons {gamma} sont - telles qu'elles apparaissent a l'ultracentrifugation analytique - qualitativement semblables. (2) Nous avons observe un effet isotopique considerable de la presence de 75 pour cent de D{sub 2}O dans le solvant sur la sensibilite de la myosine B envers ces deux agents, et nous avons presente une tentative d'explication de ce fait. (3) Les polymeres qui apparaissent apres un traitement par la chaleur de la myosine semblent etre d'une nature tres differente des polymeres que l'on voit apparaitre apres un traitement identique de la myosine A. Ceux obtenus a partir de le myosine B sont depolymerisables par l'intermediaire de l'ATP et apparaissent dans une zone de temperature beaucoup plus etroite que celles de la myosine A. Ce dernier fait indique une difference considerable de l'enthalpie d'activation des deux reactions. (auteurs)

  11. The formation of scientists and technicians at the 'Centre d'Etudes Nucleaires' at Saclay

    International Nuclear Information System (INIS)

    Debiesse, J.

    1958-01-01

    The considerable needs in research workers and scientists which are asked by the nuclear energy obliged the Commissariat a l'Energie atomique to deal with a particular effort to increase the quantitative and qualitative formation of scientists. Most various ways have been used. 1- A National Institute of Nuclear Sciences and Nuclear Techniques was created, by a joint decree of the Prime Minister and the Minister for National Education (june 18, 1957). This Institute of Higher Teaching (250 students) indulges in the following matters: atomic engineering, quantum mechanics, theory and technic of particle accelerators, special metallurgy, radiobiology, thermic and mechanics of fluids. 2- An associated centre of the 'Conservatoire National des Arts et Metiers' was created (200 students) for technical assistants, drawers, etc. 3- In contribution with both electronic industry and Ministry of Work, the Centre d'Etudes Nucleaires contributes to an accelerated formation of technical assistants into Professional Centres. Conclusion: Training of scientists and research workers is one of the most important activities of the Centre d'Etudes Nucleaires de Saclay. Without losing its technical efficiency, it has supplied and varied means adapted to the various purposes that we shall reach. (author) [fr

  12. Hereditary Diffuse Infiltrating Retinoblastoma.

    Science.gov (United States)

    Schedler, Katharina J E; Traine, Peter G; Lohmann, Dietmar R; Haritoglou, Christos; Metz, Klaus A; Rodrigues, Eduardo B

    2016-01-01

    Retinoblastoma is one of the most common childhood cancers. The diffuse infiltrating retinoblastoma is a rare subtype of this neoplasm. The majority of cases of diffuse infiltrating retinoblastoma are unilateral and occur sporadically. Herein we report on a family with three children affected by retinoblastoma, among them one girl with diffuse infiltrating retinoblastoma. This girl was diagnosed at the age of 8 years with a unilateral diffuse infiltrating retinoblastoma. By contrast, the two brothers became clinically apparent in the first 2 years of life with bilateral retinoblastoma. The parents were clinically unremarkable. Genetic analysis of RB1 gene was performed. The girl with diffuse infiltrating RB was found to be heterozygous for an oncogenic mutation in the RB1 gene that was also carried by both brothers and the father of the family. These results show that diffuse infiltrating retinoblastoma can develop on the background of a hereditary predisposition to retinoblastoma.

  13. Metric diffusion along foliations

    CERN Document Server

    Walczak, Szymon M

    2017-01-01

    Up-to-date research in metric diffusion along compact foliations is presented in this book. Beginning with fundamentals from the optimal transportation theory and the theory of foliations; this book moves on to cover Wasserstein distance, Kantorovich Duality Theorem, and the metrization of the weak topology by the Wasserstein distance. Metric diffusion is defined, the topology of the metric space is studied and the limits of diffused metrics along compact foliations are discussed. Essentials on foliations, holonomy, heat diffusion, and compact foliations are detailed and vital technical lemmas are proved to aide understanding. Graduate students and researchers in geometry, topology and dynamics of foliations and laminations will find this supplement useful as it presents facts about the metric diffusion along non-compact foliation and provides a full description of the limit for metrics diffused along foliation with at least one compact leaf on the two dimensions.

  14. Radiobiological study of the radioprotective activity of a natural Iranian compound, ''Shir-Khecht''; Etude radiobiologique de l'activite radioprotectrice d'un compose naturel Iranien: le ''Shir-Khecht''

    Energy Technology Data Exchange (ETDEWEB)

    Rouhanizadeh, N. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-01-01

    After reviewing the primary mechanisms of the action of ionizing radiation, the possible mechanisms of the action of radioprotective substances, the various chemical structures having a protective effect and the methods for studying chemical radioprotection, the author presents the results he has obtained with natural Iranian product: ''Shir-Khecht''. Tests with this product at lethal and sublethal doses have been carried out on the rat using various means of introduction. The effect of radiation, both with and without protection, has been studied using histological and biochemical methods. The product examined has, in effect, a protective action; it is, furthermore, non-toxic and active when taken orally. (author) [French] Apres avoir rappele les mecanismes primaires de l'action des rayonnements ionisants, les mecanismes possibles de l'action des substances radioprotectrices, les diverses structures chimiques possedant un effet protecteur et les methodes d'etude de la radioprotection chimique, l'auteur presente les resultats qu'il a obtenus en utilisant un compose naturel iranien: le ''Shir-Khecht''. Des essais de ce produit, chez le rat, par diverses voies d'introduction, a dose letale et subletale ont ete effectues. L'effet des radiations, avec et sans protection, a ete etudie a l'aide de methodes histologiques et biochimiques. Le compose essaye possede un pouvoir protecteur; il est, de plus, non toxique et actif par voie orale. (auteur)

  15. Study of a case of essential hypoproteinaemia using the isotopes {sup 131}I and {sup 15}N; Etude a l'aide des isotopes {sup 131}I et {sup 15}N d'un cas d'hypoproteinemie essentielle

    Energy Technology Data Exchange (ETDEWEB)

    Dubert, A.; Coursaget, J.; Fallot, P.; Royer, P. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Hopital des Enfants Malades, 75 - Paris (France)

    1959-07-01

    Hypoproteinaemia both human and experimental has been studied with the help of nuclear labelling. A comparative study has been made of the fate of serum proteins labelled by an endogenous path after administration of nitrogen-15 glycine and also of serum albumin labelled by exogenous path using iodine-131. We have determined the biological period of the serum albumin and serum globulins and also the magnitude of the vascular and extravascular pools of serum albumin. In this way it has been possible to measure the speed of replacement of plasma proteins. A presentation of results taken from both clinical observation and experiment leads to a discussion on the pathogenic mechanism of hypoproteinaemia. (author) [French] Les hypoproteinemies humaine et experimentale ont ete explorees a l'aide d'indicateurs nucleaires. Une etude comparative du devenir des proteines seriques marquees par voie endogene, apres administration de glycocolle-{sup 15}N et de l'albumine serique marquee par voie exogene a l'iode-131 a ete realisee. On a determine la periode biologique de la serumalbumine et des globulines seriques ainsi que la grandeur des 'pools' vasculaire et extravasculaire de la serumalbumine. Il a ete ainsi possible d'evaluer la vitesse de renouvellement des proteines plasmatiques. La confrontation des resultats tires de l'observation clinique et de l'experimentation conduit a une discussion sur le mecanisme pathogenique de l'hypoproteinemie. (auteur)

  16. Gaseous diffusion system

    International Nuclear Information System (INIS)

    Garrett, G.A.; Shacter, J.

    1978-01-01

    A gaseous diffusion system is described comprising a plurality of diffusers connected in cascade to form a series of stages, each of the diffusers having a porous partition dividing it into a high pressure chamber and a low pressure chamber, and means for combining a portion of the enriched gas from a succeeding stage with a portion of the enriched gas from the low pressure chamber of each stage and feeding it into one extremity of the high pressure chamber thereof

  17. Study on the bound water of several high specific surface-area oxides (beryllia, alumina, silica-alumina); Etude de l'eau de constitution de plusieurs oxydes a grande surface specifique (glucine, alumine, silice-alumine)

    Energy Technology Data Exchange (ETDEWEB)

    Rouquerol, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-11-01

    This study is concerned with the bound water of several oxides (beryllia, alumina, silica-alumina) at different steps of their dehydration (heating temperatures between 150 and 1100 deg. C). The following techniques have been used simultaneously: Thermal analysis (a new method has been developed), nitrogen adsorption (study of the texture), Diborane hydrolysis (qualitative and quantitative analysis of surface water), Infra-red spectrography (in the absorption range of water), Nuclear magnetic resonance (in the resonance range of protons). Thanks to these different techniques, five kinds of bound water have been observed. Attention is called on the great influence of the thermal treatment conditions on the evolution of the products resulting from the decomposition of alumina {alpha}-trihydrate Al(OH){sub 3} and beryllium {alpha}-hydroxide, in the course of the dehydration. Moreover, the author emphasizes the peculiar properties of the two kinds of oxides (alumina and beryllia) prepared through a new method of treatment under low pressure and constant speed of decomposition. Such particular features concern mainly texture, bound water, and consequently, also catalytic activity. (author) [French] Ce travail porte sur l'eau de constitution de plusieurs oxydes (glucine, alumine, silice-alumine) aux differents degres de leur deshydratation (temperatures de traitement comprises entre 150 et 1100 deg. C). Cette etude met simultanement en oeuvre: l'analyse thermique (proposition d'une nouvelle methode), l'adsorption d'azote (etude de texture), l'hydrolyse du diborane (analyse qualitative et quantitative de l'eau de surface), la spectrographie infra-rouge (dans le domaine d'absorption de l'eau), la resonance magnetique nucleaire (dans le domaine de resonance des protons). A l'aide de ces differentes techniques, cinq formes d'eau de constitution ont ete observees. L'attention est attiree sur la tres grande influence

  18. Feasibility study for the installation of a small hydro electric power plant; Etude de faisabilite. Petite centrale hydro-electrique au lieu dit 'Sous les Roches' a Sonceboz

    Energy Technology Data Exchange (ETDEWEB)

    Tissot, N. [MHyLab, Mini-Hydraulics Laboratory, Montcherand (Switzerland); Hausmann, H. [Hans Hausmann, Bevilard (Switzerland)

    2003-07-01

    This report for the Swiss Federal Office of Energy presents a technical, economical and ecological analysis of the feasibility of a small hydroelectric power plant at Sonceboz, in the Swiss Jura mountains. The power of the planed plant would typically be 500 kW for a water head of about 10 m. The study shows that, compared to one single turbine, a pair of Kaplan type turbines would be operational over a larger range of the river's water flow rate. This solution would be a little bit more costly but offer more flexibility for maintenance. Two maximum water flow rates are considered, 4.5 and 6 m{sup 3}/s respectively. According to the economical study, done with current electric kWh prices, both configurations are viable while the largest flow rate leads to a larger profit. The report is rounded up by a sensitivity analysis considering variations in annual power generation, electro-mechanical and construction cost as well as turbine efficiency. It indicates that this last factor could be crucial for the overall profitability. [French] Ce rapport est le resultat detaille de l'analyse technico-economique et ecologique de faisabilite de la realisation d'une petite centrale hydroelectrique basse chute qui pourrait exploiter une denivellation d'environ 10 m pour une puissance de l'ordre de 500 kW pres de Sonceboz dans le Jura suisse. L'etude montre que le couplage de deux turbines Kaplan offrirait une possibilite de fonctionnement sur une plus grande plage de flux ainsi qu'une plus grande flexibilite de maintenance, ceci pour un cout legerement superieur a l'option a une seule turbine. Les debits de 4.5 et 6 m{sup 3}/s sont consideres. L'etude economique montre que le debit de 6 m{sup 3}/s est plus rentable au prix de vente actuel du kWh. L'article se termine par une analyse de sensibilite sur les incertitudes concernant la production annuelle, les prix de l'electromecanique et du genie civil et le rendement des

  19. A comparative study of the {sup 90}Sr/Ca ratio in human diet and bone tissue; Etude comparee chez l'homme du rapport {sup 90}Sr/Ca dans l'alimentation et le tissu osseux

    Energy Technology Data Exchange (ETDEWEB)

    Coulon, R.; Madelmont, C. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    A comparative study of both the evolution of strontium-90 content in the bones of individuals of different ages for the period 1962-1967 as related to calcium, and the corresponding diets allowed to establish the relationship between food contribution and the resulting bone burden. The study is mainly devoted to the group of adults for which a mathematical expression is proposed which allows for the exchangeable form of a skeletal calcium fraction turned over in less than a year from the dietary calcium, and the stabilized form constituting the larger part of bone tissue characterized by a slow turnover. Both the amount of the exchangeable fraction and the turnover rate of the stabilized fraction are determined for vertebrae and ribs. At birth, bone levels indicate that the calcium used for skeleton modelling during foetal life originates from both maternal diet and bone tissue and a value is given, to their relative significance. There appears a good relationship between bone levels in infants from 6 months to 1 year of age and their diets. The physiological parameters particular to this age are quantified. (authors. [French] L'etude comparee de l'evolution de la teneur en strontium 90 rapportee au calcium, mesuree dans les os d'individus a differents ages durant la periode 1962-1967 et celle du regime alimentaire correspondant, a permis d'etablir la relation qui existe entre l'apport du a l'alimentation et la charge osseuse qui en resulte. L'essentiel de l'etude est consacre au cas des adultes. Pour ce groupe la formulation mathematique proposee tient compte de la presence de la forme echangeable d'une fraction du calcium osseux, renouvelee en moins d'un an a partir du calcium alimentaire, et de la forme stabilisee, constituant la majeure partie du tissu osseux, caracterisee par un renouvellement lent. L'importance de la fraction echangeable, ainsi que le taux de renouvellement de la fraction stabilisee sont

  20. Aerodynamic study of the fluid flow in the channel of a reactor filled with internally and externally cooled fuel elements; Etude aerodynamique de l'ecoulement fluide dans un canal de reacteur charge en elements combustibles annulaires refroidis interieurement et exterieurement

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, J.C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    A study is made of the problem of the flow-rate and pressure distributions along the length of two volumes, internal and external, bounded by a series of non-continuous annular elements placed along the channel axis. It is observed that the phenomenon can easily be represented by equations. The theoretical expressions observed are particularly simple when the distances between the elements are above a certain minimum value. The experimental work has made it possible to show that the theoretical formulation derived is valid with a very great accuracy. The experimental study has also been carried out in the case of a very small spacing between the elements. It has been possible to show in this case that the hypothesis made for deriving the theoretical expressions was perfectly justified. In the last part finally, we consider the practical problem of evaluating the pressure-drops between the ends of a series of annular elements. (author) [French] On etudie le probleme de la repartition des debits et des pressions le long des deux espaces, interne et externe, delimites par une succession d'elements annulaires non jointifs, disposes suivant l'axe d'un canal. On constate que le phenomene peut etre mis aisement en equation. Les relations theoriques obtenues prennent en particulier une forme simple lorsque les intervalles entre elements sont superieurs a une valeur minimum. L'etude experimentale a permis de constater que cette formulation theorique etablie etait alors valable avec une precision excellente. L'etude experimentale a ete egalement effectuee dans le cas de tres faibles intervalles entre elements consecutifs. On a pu alors verifier que l'hypothese adoptee dans l'etablissement des relations theoriques etait parfaitement justifiee. Dans un dernier chapitre enfin, nous abordons le point de vue pratique de l'evaluation des pertes de charge aux bornes d'un train d'elements annulaires. (auteur)

  1. Inpainting using airy diffusion

    Science.gov (United States)

    Lorduy Hernandez, Sara

    2015-09-01

    One inpainting procedure based on Airy diffusion is proposed, implemented via Maple and applied to some digital images. Airy diffusion is a partial differential equation with spatial derivatives of third order in contrast with the usual diffusion with spatial derivatives of second order. Airy diffusion generates the Airy semigroup in terms of the Airy functions which can be rewritten in terms of Bessel functions. The Airy diffusion can be used to smooth an image with the corresponding noise elimination via convolution. Also the Airy diffusion can be used to erase objects from an image. We build an algorithm using the Maple package ImageTools and such algorithm is tested using some images. Our results using Airy diffusion are compared with the similar results using standard diffusion. We observe that Airy diffusion generates powerful filters for image processing which could be incorporated in the usual packages for image processing such as ImageJ and Photoshop. Also is interesting to consider the possibility to incorporate the Airy filters as applications for smartphones and smart-glasses.

  2. Etude des paramètres de la réverbération en champ diffus

    DEFF Research Database (Denmark)

    Polack, Jean-Dominique

    Three time-frequency distributions are used to extract parameters such as reverberation time and sound power of a source in a room. Results are compared to a simplified model for reverberation. Some new results are presented concerning the choice of the different distributions for different param...

  3. Accouchement par forceps: indications et pronostic materno-foetal ...

    African Journals Online (AJOL)

    L'accouchement par voie basse, peut être parfois compromis par des facteurs maternels, foetaux ou materno-foetaux nécessitant des moyens thérapeutiques comme le forceps pour achever l'accouchement par voie naturelle. Le forceps, une méthode qui n'est pas sans risque pour la mère et le nouveau-né. Nous avons ...

  4. Etude socio-économique et technologique de la production du ...

    African Journals Online (AJOL)

    L'étude a montré que cette activité assurée à 80% par des femmes, génère beaucoup d'emplois et de revenus, que le prix de vente fluctue entre 1000 et 3500 frs CFA.kg-1 et par conséquent qu'une grande productrice peut gagner en moyenne jusqu'à 400000 frs CFA par mois. Cependant, malgré son importance ...

  5. Diffusion d'informations dans les autobus par couplage de technologies wifi et satellitaires

    OpenAIRE

    GRANSART, C; AMBELLOUIS, S; RIOULT, J

    2004-01-01

    Dans cet article, nous présentons les résultats d'un projet de recherche visant à fournir de l'information en temps réel aux usagers des transports en commun de type autobus. Nous montrons que de nouveaux services innovants peuvent être développés à l'attention des objets mobiles avec une bonne qualité de service (avec une bande passante moyenne ou élevée), et un accès à l'information, au contenu multimédia et aux bases de données. Ce projet utilise un couplage de technologies innovantes pour...

  6. Inelastic x-ray scattering from polycrystalline materials; Diffusion inelastic par rayons x des materiaux polycristallins

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, I

    2008-09-15

    Inelastic X-ray scattering (IXS) is a tool to determine the phonon dispersion along high symmetry directions in single crystals. However, novel materials and crystals under extreme conditions are often only available in form of polycrystalline samples. Thus the investigation is limited to orientation-averaged properties. To overcome these limitations, a methodology to extract the single crystal phonon dispersion from polycrystalline materials was developed. The approach consists of recording IXS spectra over a large momentum transfer region and confront them with a Born - von Karman model calculation. A least-square refinement of the model IXS spectra then provides the single crystal dispersion scheme. In this work the method is developed on the test case Be. Further studies were performed on more and more complex systems, in order to explore the limitations. This novel application of IXS promises to be a valuable tool in cases where single crystalline materials are not available. (author)

  7. L'analyse par activation de neutrons de réacteur

    Science.gov (United States)

    Meyer, G.

    2003-02-01

    Quand les neutrons traversent la matière, certains sont transmis sans interaction, les autres interagissent avec le milieu traversé par diffusion et par absorption. Ce phénomène d'absorption est utilisé pour se protéger des neutrons, mais aussi pour les détecter; il peut également être utilisé pour identifier les noyaux “absorbants" et ainsi analyser le milieu traversé. En effet par différentes réactions nucléaires (n,γ), (n,p), (n,α), (n,fission), on obtient des noyaux résiduels qui sont souvent radioactifs; on dit que l'échantillon est “activé". Si l'on connaît le rendement d'activation et donc le pourcentage de noyaux ainsi “transmutés", les mesures de radioactivité induite vont permettre de déterminer la composition de l'échantillon irradié. Cette méthode dite d'analyse par activation neutronique est pratiquée depuis la découverte du neutron. Elle a permis grâce à sa sélectivité et à sa sensibilité d'avoir accès au domaine des traces et des ultra-traces dans des champs d'application très divers comme la métallurgie, l'archéologie, la biologie, la géochimie etc...

  8. An Evaluation of Semiempirical Models for Partitioning Photosynthetically Active Radiation Into Diffuse and Direct Beam Components

    Science.gov (United States)

    Oliphant, Andrew J.; Stoy, Paul C.

    2018-03-01

    Photosynthesis is more efficient under diffuse than direct beam photosynthetically active radiation (PAR) per unit PAR, but diffuse PAR is infrequently measured at research sites. We examine four commonly used semiempirical models (Erbs et al., 1982, https://doi.org/10.1016/0038-092X(82)90302-4; Gu et al., 1999, https://doi.org/10.1029/1999JD901068; Roderick, 1999, https://doi.org/10.1016/S0168-1923(99)00028-3; Weiss & Norman, 1985, https://doi.org/10.1016/0168-1923(85)90020-6) that partition PAR into diffuse and direct beam components based on the negative relationship between atmospheric transparency and scattering of PAR. Radiation observations at 58 sites (140 site years) from the La Thuille FLUXNET data set were used for model validation and coefficient testing. All four models did a reasonable job of predicting the diffuse fraction of PAR (ϕ) at the 30 min timescale, with site median r2 values ranging between 0.85 and 0.87, model efficiency coefficients (MECs) between 0.62 and 0.69, and regression slopes within 10% of unity. Model residuals were not strongly correlated with astronomical or standard meteorological variables. We conclude that the Roderick (1999, https://doi.org/10.1016/S0168-1923(99)00028-3) and Gu et al. (1999, https://doi.org/10.1029/1999JD901068) models performed better overall than the two older models. Using the basic form of these models, the data set was used to find both individual site and universal model coefficients that optimized predictive accuracy. A new universal form of the model is presented in section 5 that increased site median MEC to 0.73. Site-specific model coefficients increased median MEC further to 0.78, indicating usefulness of local/regional training of coefficients to capture the local distributions of aerosols and cloud types.

  9. Facteurs de risque de mortalité par tuberculose pulmonaire

    Science.gov (United States)

    Janah, Hicham; Souhi, Hicham; Kouismi, Hatim; Mark, Karima; Zahraoui, Rachida; Benamor, Jouda; Soualhi, Mona; Bourkadi, Jamal Eddine

    2014-01-01

    La tuberculose est une maladie infectieuse transmissible provoquée par myco-bacterium tuberculosis (bacille de Koch ou BK). Elle représente, selon les estimations del'Organisation Mondiale de la Santé (OMS), l'une des pathologies infectieuses causant le plus de décès au niveau mondial avec plus de 1 million de décès par an. Pour déterminer les facteurs de risque de mortalité au cours de la tuberculose pulmonaire à microscopie positive nous avons mené une étude rétrospective portant sur tous les cas de tuberculose pulmonaire à microscopie positive et qui étaient décédés au cours de leur hospitalisation. Cette étude a colligé 1803 cas de tuberculose sur une période de 2 ans et demi dont 46 sont décédés. La prévalence de décès est de 2,55%. La population se répartit en 32 hommes et 14 femmes. L’âge moyen était de 53ans ± 17 ans. Le tabagisme était retrouvé chez la moitié des cas. Une comorbidité était retrouvée dans 43%, avec 17% de diabète. Le délai de diagnostic avait une médiane de 60 jours avec percentile (30j; 105j). La symptomatologie clinique était dominée par la toux, la dyspnée et les expectorations soit respectivement: 97,8%, 69,6% et 67,4% des cas. Sur le plan radiologique les lésions étaient diffuses et bilatérales dans 76,1% des cas. Tous les patients étaient mis sous SRHZ. 11% avaient présenté une toxicité aux antibacillaires (de type hépatiques dans 3 cas et neurologiques dans 2 cas). Le délai médian de décès était de 8,5 jours (5j; 17j). Les causes de décès retrouvées étaient: Une hépatite fulminante (3 cas), une décompensation acido-cétosique (3 cas), un SDRA (2 cas), des hémoptysies foudroyantes (2 cas), et respectivement un cas secondaire à une décompensation de BPCO, une décompensation cardiaque, une hypoglycémie et un tableau d'anasarque. Cette étude suggère que le terrain, le retard diagnostique et les effets secondaires du traitement sont les principaux facteurs de risque de

  10. Déclenchement du travail à terme par le misoprostol: expérience d'une maternité tunisienne

    Science.gov (United States)

    Ouerdiane, Nadia; Tlili, Nihel; Othmani, Kaouther; Daaloul, Walid; Masmoudi, Abdelwaheb; Hamouda, Sonia Ben; Bouguerra, Badreddine

    2016-01-01

    Evaluer l'efficacité et l'innocuité de l'utilisation du misoprostol par voie vaginale pour le déclenchement du travail à terme. Etude prospective réalisée au service de gynécologie obstétrique B de l'hôpital Charles Nicolle de Tunis sur une durée de 4 mois. La population sélectionnée concernait les patientes à terme devant bénéficier d'une maturation cervicale. Le misoprostol à la dose de 50 µg par voie vaginale toutes les 12 h était utilisé. Les paramètres étudiés étaient les anomalies contractiles, les anomalies du RCF, le mode d'accouchement, le délai d'accouchement et l’état néonatal. 44 patientes ont bénéficié d'une maturation cervicale par misoprostol. Le terme moyen était de 40 SA. Le taux de nullipare était de 23/44 (52%). Le taux d'accouchement par voie basse était de 31/44 (70.4%). 84% des patientes ont reçu une seule dose de misoprostol. Les anomalies du RCF ont été notées dans 14/44 (32%). Le taux de liquides méconiaux était de 12/44 (27%). Un score d'Apgar à 5 mn inférieur à 7 était noté chez 7/44 (16%). Un cas de rupture utérine était survenue chez une primipare et ce après une seule prise de misoprostol. Nos résultats sont décevants en raison de la survenue d'une rupture utérine et d'une morbidité néonatale importante. D'autres études prospectives multicentriques restent utiles pour mieux s'assurer de l'efficacité mais surtout de l'innocuité du misoprostol à dose faible pour le déclenchement du travail à terme. PMID:27583092

  11. Oxygen Diffusion in Titanite

    Science.gov (United States)

    Zhang, X. Y.; Cherniak, D. J.; Watson, E. B.

    2004-05-01

    Oxygen diffusion in natural and synthetic single-crystal titanite was characterized under both dry and water-present conditions. For the dry experiments, pre-polished titanite samples were packed in 18O-enriched quartz powder inside Ag-Pd capsules, along with an FMQ buffer assemblage maintained physically separate by Ag-Pd strips. The sealed Ag-Pd capsules were themselves sealed inside evacuated silica glass tubes and run at 700-1050° C and atmospheric pressure for durations ranging from 1 hour to several weeks. The hydrothermal experiments were conducted by encapsulating polished titanite crystals with 18O enriched water and running them at 700-900° C and 10-160MPa in standard cold-seal pressure vessels for durations of 1 day to several weeks. Diffusive uptake profiles of 18O were measured in all cases by nuclear reaction analysis (NRA) using the 18O (p,α ) 15N reaction. For the experiments on natural crystals, under both dry and hydrothermal conditions, two mechanisms could be recognized responsible for oxygen diffusion. The diffusion profiles showed two segments: a steep one close to the initial surface attributed to self-diffusion in the titanite lattice; and a "tail" reaching deeper into the sample attributable to diffusion in a "fast path" such as sub-grain boundaries or dislocations. For the dry experiments, the following Arrhenius relation was obtained: D{dry lattice} = 2.6×10-8exp (-275 kJmol-1/RT) m2/s Under wet conditions at PH2O = 100MPa, Oxygen diffusion conforms to the following Arrehenius relation: D{wet lattice} = 9.7× 10-13exp (-174 kJmol-1/RT) m2/s Oxygen diffusivity shows only a slight dependence on water pressure at the following conditions we explored: temperatures 800° C, PH2O = 10-160MPa, and 880° C, PH2O =10-100MPa. For diffusive anisotropy, we explored it only at hydrothermal conditions, and no diffusive anisotropy was observed. Like many other silicates, titanite shows lower activation energy for oxygen diffusion in the presence of

  12. Investigation of the glide modes of single crystals of beryllium; Etude des modes de glissement de monocristaux de beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Regnier, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-05-01

    The flow characteristics of single crystals of beryllium specially oriented for slip along a single plane and a single direction have been thoroughly investigated. The elastic limit and the strain hardening in basal glide have been investigated in the temperature range (-195 deg. C, 400 deg. C) in tension as well as in compression. Observation of the slip lines and of the dislocation configurations have also been made in addition to the mechanical tests. The prismatic slip has been studied in greater detail: tensile tests have been performed on specimens carefully oriented at different temperatures, strain rates and with varying orientations of the basal and of the prism planes. Tests have also been made in the micro-strain range; the slip lines and the dislocation arrangements were observed in detail. The very unusual variation of the elastic limit with temperature is not due to impurities but to a cross slip mechanism. A model of dislocation locking is proposed to account for the experimental results. This mechanism assumes that the a-bar dislocations may also dissociate on the prism planes [101-bar 0]. Various possible dissociations are suggested, the most probable of which corresponds to the phase transformation: Hexagonal close packed to body centered cubic. This proposal can be extended to account for the relative ease of glide on the different systems in the hexagonal close packed metals. (author) [French] L' ecoulement de monocristaux de berylliurn deformes en glissement basal et en glissement prismatique a ete etudie sur des echantillons orientes de maniere a favoriser au maximum la deformation suivant une seule direction d'un seul systeme de glissement. L'influence de la temperature sur la limite elastique et la consolidation en glissement basal a ete etudie depuis -195 deg. C jusqu' 400 deg. C sur des echantillons deformes en tension et sur d'autres deformes en compression. Ces essais mecaniques ont ete completes par l

  13. Modelling of Innovation Diffusion

    Directory of Open Access Journals (Sweden)

    Arkadiusz Kijek

    2010-01-01

    Full Text Available Since the publication of the Bass model in 1969, research on the modelling of the diffusion of innovation resulted in a vast body of scientific literature consisting of articles, books, and studies of real-world applications of this model. The main objective of the diffusion model is to describe a pattern of spread of innovation among potential adopters in terms of a mathematical function of time. This paper assesses the state-of-the-art in mathematical models of innovation diffusion and procedures for estimating their parameters. Moreover, theoretical issues related to the models presented are supplemented with empirical research. The purpose of the research is to explore the extent to which the diffusion of broadband Internet users in 29 OECD countries can be adequately described by three diffusion models, i.e. the Bass model, logistic model and dynamic model. The results of this research are ambiguous and do not indicate which model best describes the diffusion pattern of broadband Internet users but in terms of the results presented, in most cases the dynamic model is inappropriate for describing the diffusion pattern. Issues related to the further development of innovation diffusion models are discussed and some recommendations are given. (original abstract

  14. Thermal diffusion (1963)

    International Nuclear Information System (INIS)

    Lemarechal, A.

    1963-01-01

    This report brings together the essential principles of thermal diffusion in the liquid and gaseous phases. The macroscopic and molecular aspects of the thermal diffusion constant are reviewed, as well as the various measurement method; the most important developments however concern the operation of the CLUSIUS and DICKEL thermo-gravitational column and its applications. (author) [fr

  15. Diffusion Based Photon Mapping

    DEFF Research Database (Denmark)

    Schjøth, Lars; Olsen, Ole Fogh; Sporring, Jon

    2006-01-01

    . To address this problem we introduce a novel photon mapping algorithm based on nonlinear anisotropic diffusion. Our algorithm adapts according to the structure of the photon map such that smoothing occurs along edges and structures and not across. In this way we preserve the important illumination features......, while eliminating noise. We call our method diffusion based photon mapping....

  16. Etude thermo-aeraulique d'une piscine interieure

    Science.gov (United States)

    Guerfala, Nasreddine

    Les grands espaces fermés (amphithéâtres, supermarchés, gymnases et piscines) jouent un rôle essentiel dans l'économie et la société canadienne mais n'assurent pas nécessairement le confort thermique et la bonne qualité de l'air intérieur. En outre, leur consommation énergétique demeure très élevée. Plus spécifiquement, les piscines intérieures présentent certaines particularités telles qu'une humidité relative élevée, une température contrôlée de l'eau et une condensation possible sur les parois ce qui rend la tâche d'assurer le confort des baigneurs encore plus difficile. Rares sont les études réalisées pour ce type de bâtiment malgré l'existence de pistes d'optimisation de la consommation énergétique et l'amélioration de la qualité d'air intérieur. Dans cette optique, ce mémoire présente une étude thermo-aéraulique réalisée sur la piscine intérieure de l'Université Bishop's (Sherbrooke, Canada). La simulation numérique a été effectuée en utilisant le logiciel TRNSYS. L'approche adoptée pour la modélisation est la méthode zonale qui découpe l'espace de travail étudié en plusieurs zones fictives tout en calculant les caractéristiques thermo-aérauliques (température, pression, nombre de changement d'air par heure). D'autre part, une validation expérimentale en situations réelles est mise en œuvre au sein de cette piscine moyennant un dispositif expérimental spécifique. Ce dernier a été conçu spécialement pour s'adapter aux caractéristiques du milieu (hauteur du bâtiment, présence de l'eau et forte humidité) afin de mesurer la température, la pression et la vitesse de l'air dans plusieurs endroits significatifs de la piscine. Cette étude développe un outil de calcul capable de prédire les températures de différentes zones thermiques et des surfaces de l'enveloppe du bâtiment d'une part et de calculer le débit massique de l'air entre les zones ainsi que le nombre de changement d'air par

  17. The urokinase receptor (uPAR) and the uPAR-associated protein (uPARAP/Endo180)

    DEFF Research Database (Denmark)

    Behrendt, Niels

    2004-01-01

    processes involve a highly organized interplay between proteases and their cellular binding sites as well as specific substrates and internalization receptors. This review article is focused on two components, the urokinase plasminogen activator receptor (uPAR) and the uPAR-associated protein (uPARAP, also...... designated Endo180), that are considered crucially engaged in matrix degradation. uPAR and uPARAP have highly diverse functions, but on certain cell types they interact with each other in a process that is still incompletely understood. uPAR is a glycosyl-phosphatidylinositol-anchored glycoprotein...

  18. Diffuse ceiling ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen

    Diffuse ceiling ventilation is an innovative ventilation concept where the suspended ceiling serves as air diffuser to supply fresh air into the room. Compared with conventional ventilation systems, diffuse ceiling ventilation can significantly reduce or even eliminate draught risk due to the low...... momentum supply. In addition, this ventilation system uses a ceiling plenum to deliver air and requires less energy consumption for air transport than full-ducted systems. There is a growing interest in applying diffuse ceiling ventilation in offices and other commercial buildings due to the benefits from...... both thermal comfort and energy efficient aspects. The present study aims to characterize the air distribution and thermal comfort in the rooms with diffuse ceiling ventilation. Both the stand-alone ventilation system and its integration with a radiant ceiling system are investigated. This study also...

  19. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  20. Diffusing Best Practices

    DEFF Research Database (Denmark)

    Pries-Heje, Jan; Baskerville, Richard

    2014-01-01

    resulting from the design were two-day training workshops conceptually anchored to TBP. The design theory was evaluated through execution of eight diffusion workshops involving three different groups in the same company. The findings indicate that the match between the practice and the context materialized...... in the successful techniques in one context. While the value for other contexts is unproven, knowledge of best practices circulates under an assumption that the practices will usefully self-diffuse through innovation and adoption in other contexts. We study diffusion of best practices using a design science...... approach. The study context is a design case in which an organization desires to diffuse its best practices across different groups. The design goal is embodied in organizational mechanisms to achieve this diffusion. The study used Theory of Planned Behavior (TPB) as a kernel theory. The artifacts...

  1. Degenerate nonlinear diffusion equations

    CERN Document Server

    Favini, Angelo

    2012-01-01

    The aim of these notes is to include in a uniform presentation style several topics related to the theory of degenerate nonlinear diffusion equations, treated in the mathematical framework of evolution equations with multivalued m-accretive operators in Hilbert spaces. The problems concern nonlinear parabolic equations involving two cases of degeneracy. More precisely, one case is due to the vanishing of the time derivative coefficient and the other is provided by the vanishing of the diffusion coefficient on subsets of positive measure of the domain. From the mathematical point of view the results presented in these notes can be considered as general results in the theory of degenerate nonlinear diffusion equations. However, this work does not seek to present an exhaustive study of degenerate diffusion equations, but rather to emphasize some rigorous and efficient techniques for approaching various problems involving degenerate nonlinear diffusion equations, such as well-posedness, periodic solutions, asympt...

  2. Taare Zameen Par and dyslexic savants

    Science.gov (United States)

    Chakravarty, Ambar

    2009-01-01

    The film Taare Zameen Par (Stars upon the Ground) portrays the tormented life at school and at home of a child with dyslexia and his eventual success after his artistic talents are discovered by his art teacher at the boarding school. The film hints at a curious neurocognitive phenomenon of creativity in the midst of language disability, as exemplified in the lives of people like Leonardo da Vinci and Albert Einstein, both of whom demonstrated extraordinary creativity even though they were probably affected with developmental learning disorders. It has been hypothesized that a developmental delay in the dominant hemisphere most likely ‘disinhibits’ the nondominant parietal lobe, unmasking talents—artistic or otherwise—in some such individuals. It has been suggested that, in remedial training, children with learning disorders be encouraged to develop such hidden talents to full capacity, rather than be subjected to the usual overemphasis on the correction of the disturbed coded symbol operations. PMID:20142854

  3. Taare Zameen Par and dyslexic savants

    Directory of Open Access Journals (Sweden)

    Chakravarty Ambar

    2009-01-01

    Full Text Available The film Taare Zameen Par (Stars upon the Ground portrays the tormented life at school and at home of a child with dyslexia and his eventual success after his artistic talents are discovered by his art teacher at the boarding school. The film hints at a curious neurocognitive phenomenon of creativity in the midst of language disability, as exemplified in the lives of people like Leonardo da Vinci and Albert Einstein, both of whom demonstrated extraordinary creativity even though they were probably affected with developmental learning disorders. It has been hypothesized that a developmental delay in the dominant hemisphere most likely ′disinhibits′ the nondominant parietal lobe, unmasking talents-artistic or otherwise-in some such individuals. It has been suggested that, in remedial training, children with learning disorders be encouraged to develop such hidden talents to full capacity, rather than be subjected to the usual overemphasis on the correction of the disturbed coded symbol operations.

  4. Investigation of APS PAR Vertical Beam Instability

    CERN Document Server

    Yao, Chihyuan; Sereno, Nicholas S; Yang Bing Xin

    2005-01-01

    The Advanced Photon Source (APS) particle accumulator ring (PAR) is a 325-MeV storage ring that collects and compresses linac pulse trains into a single bunch for booster injection. A vertical beam instability has been observed when only a single linac bunch is injected and the total beam charge is from 0.15 to 0.7 nC. The instability starts about 80 ms after the injection, lasts about 160 ms, and is highly reproducible. We performed spectral measurement and time-resolved imaging with both a gated-intensified camera and a streak camera in order to characterize this instability. Initial analysis of the data indicates that the instability is due to ion trapping. A stable lattice was established as result of the investigation. This report summarizes the experimental results and gives some preliminary analysis.

  5. PAR1 activation affects the neurotrophic properties of Schwann cells.

    Science.gov (United States)

    Pompili, Elena; Fabrizi, Cinzia; Somma, Francesca; Correani, Virginia; Maras, Bruno; Schininà, Maria Eugenia; Ciraci, Viviana; Artico, Marco; Fornai, Francesco; Fumagalli, Lorenzo

    2017-03-01

    Protease-activated receptor-1 (PAR1) is the prototypic member of a family of four G-protein-coupled receptors that signal in response to extracellular proteases. In the peripheral nervous system, the expression and/or the role of PARs are still poorly investigated. High PAR1 mRNA expression was found in the rat dorsal root ganglia and the signal intensity of PAR1 mRNA increased in response to sciatic nerve transection. In the sciatic nerve, functional PAR1 receptor was reported at the level of non-compacted Schwann cell myelin microvilli of the nodes of Ranvier. Schwann cells are the principal population of glial cells of the peripheral nervous system which myelinate axons playing an important role during axonal regeneration and remyelination. The present study was undertaken in order to determine if the activation of PAR1 affects the neurotrophic properties of Schwann cells. Our results suggest that the stimulation of PAR1 could potentiate the Schwann cell ability to favour nerve regeneration. In fact, the conditioned medium obtained from Schwann cell cultures challenged with a specific PAR1 activating peptide (PAR1 AP) displays increased neuroprotective and neurotrophic properties with respect to the culture medium from untreated Schwann cells. The proteomic analysis of secreted proteins in untreated and PAR1 AP-treated Schwann cells allowed the identification of factors differentially expressed in the two samples. Some of them (such as macrophage migration inhibitory factor, matrix metalloproteinase-2, decorin, syndecan 4, complement C1r subcomponent, angiogenic factor with G patch and FHA domains 1) appear to be transcriptionally regulated after PAR1 AP treatment as shown by RT-PCR. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Oxygen diffusion in monazite

    Science.gov (United States)

    Cherniak, D. J.; Zhang, X. Y.; Nakamura, M.; Watson, E. B.

    2004-09-01

    We report measurements of oxygen diffusion in natural monazites under both dry, 1-atm conditions and hydrothermal conditions. For dry experiments, 18O-enriched CePO4 powder and monazite crystals were sealed in Ag-Pd capsules with a solid buffer (to buffer at NNO) and annealed in 1-atm furnaces. Hydrothermal runs were conducted in cold-seal pressure vessels, where monazite grains were encapsulated with 18O-enriched water. Following the diffusion anneals, oxygen concentration profiles were measured with Nuclear Reaction Analysis (NRA) using the reaction 18O(p,α)15N. Over the temperature range 850-1100 °C, the Arrhenius relation determined for dry diffusion experiments on monazite is given by: Under wet conditions at 100 MPa water pressure, over the temperature range 700-880 °C, oxygen diffusion can be described by the Arrhenius relationship: Oxygen diffusion under hydrothermal conditions has a significantly lower activation energy for diffusion than under dry conditions, as has been found the case for many other minerals, both silicate and nonsilicate. Given these differences in activation energies, the differences between dry and wet diffusion rates increase with lower temperatures; for example, at 600 °C, dry diffusion will be more than 4 orders of magnitude slower than diffusion under hydrothermal conditions. These disparate diffusivities will result in pronounced differences in the degree of retentivity of oxygen isotope signatures. For instance, under dry conditions (presumably rare in the crust) and high lower-crustal temperatures (∼800 °C), monazite cores of 70-μm radii will preserve O isotope ratios for about 500,000 years; by comparison, they would be retained at this temperature under wet conditions for about 15,000 years.

  7. Study of stress relief cracking in titanium stabilized austenitic stainless steel; Etude de la fissuration differee par relaxation d'un acier inoxydable austenitique stabilise au titane

    Energy Technology Data Exchange (ETDEWEB)

    Chabaud-Reytier, M

    1999-07-01

    The heat affected zone (HAZ) of titanium stabilised austenitic stainless steel welds (AISI 321) may exhibit a serious form of intercrystalline cracking during service at high temperature. This type of cracking, called 'stress relief cracking', is known to be due to work hardening but also to ageing: a fine and abundant intragranular Ti(C,N) precipitation appears near the fusion line and modifies the mechanical behaviour of the HAZ. This study aims to better know the accused mechanism and to succeed in estimating the risk of such cracking in welded junctions of 321 stainless steel. To analyse this embrittlement mechanism, and to assess the lifetime of real components, different HAZ are simulated by heat treatments applied to the base material which is submitted to various cold rolling and ageing conditions in order to reproduce the HAZ microstructure. Then, we study the effects of work hardening and ageing on the titanium carbide precipitation, on the mechanical (tensile and creep) behaviour of the resulting material and on its stress relief cracking sensitivity. It is shown that work hardening is the main parameter of the mechanism and that ageing do not favour crack initiation although it leads to titanium carbide precipitation. The role of this precipitation is also discussed. Moreover, a creep damage model is identified by a local approach to fracture. Materials sensitive to stress relief cracking are selected. Then, creep tests are carried out on notched bars in order to quantify the intergranular damage of these different materials; afterwards, these measurements are combined with calculated mechanical fields. Finally, it is shown that the model gives good results to assess crack initiation for a compact tension (CT) specimen during relaxation tests, as well as for a notched tubular specimen tested at 600 deg. C under a steady torque. (author)

  8. Experimental study and modelling of iron ore reduction by hydrogen; Etude experimentale et modelisation de la reduction du minerai de fer par l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, D

    2008-01-15

    In an effort to find new ways to drastically reduce the CO{sub 2} emissions from the steel industry (ULCOS project), the reduction of iron ore by pure hydrogen in a shaft furnace was investigated. The work consisted of literature, experimental, and modelling studies. The chemical reaction and its kinetics were analysed on the basis of thermogravimetric experiments and physicochemical characterizations of partially reduced samples. A specific kinetic model was designed, which simulates the successive reactions, the different steps of mass transport, and possible iron sintering, at the particle scale. Finally, a 2-dimensional numerical model of a shaft furnace was developed. It depicts the variation of the solid and gas temperatures and compositions throughout the reactor. One original feature of the model is using the law of additive characteristic times for calculating the reaction rates. This allowed us to handle both the particle and the reactor scale, while keeping reasonable calculation time. From the simulation results, the influence of the process parameters was assessed. Optimal operating conditions were concluded, which reveal the efficiency of the hydrogen process. (author)

  9. Study of structural modifications induced by ion implantation in austenitic stainless steel; Etude des modifications structurales induites par implantation ionique dans les aciers austenitiques

    Energy Technology Data Exchange (ETDEWEB)

    Dudognon, J

    2006-12-15

    Ion implantation in steels, although largely used to improve the properties of use, involves structural modifications of the surface layer, which remain still prone to controversies. Within this context, various elements (N, Ar, Cr, Mo, Ag, Xe and Pb) were implanted (with energies varying from 28 to 280 keV) in a 316LVM austenitic stainless steel. The implanted layer has a thickness limited to 80 nm and a maximum implanted element concentration lower than 10 % at. The analysis of the implanted layer by grazing incidence X ray diffraction highlights deformations of austenite lines, appearance of ferrite and amorphization of the layer. Ferritic phase which appears at the grain boundaries, whatever the implanted element, is formed above a given 'threshold' of energy (produced of fluency by the energy of an ion). The formation of ferrite as well as the amorphization of the implanted layer depends only on energy. In order to understand the deformations of austenite diffraction lines, a simulation model of these lines was elaborated. The model correctly describes the observed deformations (broadening, shift, splitting) with the assumption that the expansion of the austenitic lattice is due to the presence of implanted element and is proportional to the element concentration through a coefficient k'. This coefficient only depends on the element and varies linearly with its radius. (author)

  10. NMR study of electrode materials for lithium ion-batteries; Etude par RMN de materiaux d'electrode pour batteries lithium-ion

    Energy Technology Data Exchange (ETDEWEB)

    Chazel, C.

    2006-01-15

    This work is devoted to the study of LiMO{sub 2} et LiM{sub 2}O{sub 4} (M: transition metal) intercalation compounds used as electrode material for lithium-ion batteries. Solid state NMR allows one to characterise the local environment of the lithium ions present in these phases by the use of the hyperfine interactions due to the presence of some electron spin density coming from localised electrons (Fermi-contact shift) or itinerant electrons (Knight shift) on the lithium nucleus. By following the transformation of the LiNiO{sub 2} layered phase into the LiNi{sub 2}O{sub 4} spinel material using lithium NMR, we studied the nature of the asymmetric signal observed for LiNiO{sub 2}, and the influence of the departure from the ideal stoichiometry; we showed a coupled ion/electron hopping in Li{sub X}NiO{sub 2} phases linked to Li/vacancy and Ni{sup 3+}/Ni{sup 4+} ordering, and finally showed the existence of structural defects within the LiNi{sub 2}O{sub 4} spinel phase obtained by thermal treatment of Li{sub 0.5}NiO{sub 2}. Lithium NMR of the intercalated materials obtained from the LiTi{sub 2}O{sub 4} and Li{sub 4}Ti{sub 5}O{sub 12} spinels showed a metallic behaviour for Li{sub 2}Ti{sub 2}O{sub 4} with a Knight shift of the NMR signal similar to that of LiTi{sub 2}O{sub 4}, and signals intermediate in nature between Knight and Fermi-contact shifts for Li{sub 7}Ti{sub 5}O{sub 12}. (author)

  11. Large scale simulation numerical study of transition to turbulence in jets; Etude numerique par simulation des grandes echelles de la transition a la turbulence dans les jets

    Energy Technology Data Exchange (ETDEWEB)

    Urbin, Gerald [Institut National Polytechnique, 38 - Grenoble (France)

    1998-02-02

    This study highlights the potentialities of the numerical technique of large scale simulation in describing and understanding the turbulent flows in a complex geometry. Particularly, it is focussed on flows of free jet, confined jets and multiple jets of high solidity grid. Spatial simulations of the circular zone close to a free jet, of high Reynolds number were performed. In spite of an evident sensitivity to upstream conditions good agreement between our statistical predictions and different experimental measurements was obtained. The multiple coherent vortical structures implied in the transition to turbulence of the jet were found. At the same time, helical or annular axisymmetric vortices were observed. Also, an original vortical arrangement was evidenced, resulting from the alternating inclination and local pairing of these rings. It could been forced through an ad-hoc excitation which modifies subsequently drastically the jet development. When an axisymmetric excitation is imposed after formation of annular structures, pairs of counter-rotative longitudinal vortices occur and generate lateral jets. Their nature and presence in case of a helical excitation are discussed. An efficient method for controlling their number is developed. Then, one is studied the very low frequency periodic phenomenon of backward-facing transition to turbulence which develops in the confined jet and grid multiple jets (a phenomenon generic in numerous flows). It was found to depend not only on the characteristic of the re-circulation (pre-transition) zones but also on the upstream flow (zone of post-transition stagnation, pressure effect). Large scale transversal motions of the fluid have been found beginning from the grid. An interpretation of this phenomenon is suggested 193 refs., 109 figs.

  12. Study of the permeability up-scaling by direct filtering of geostatistical model; Etude du changement d'echelle des permeabilites par filtrage direct du modele geostatistique

    Energy Technology Data Exchange (ETDEWEB)

    Zargar, G.

    2005-10-15

    In this thesis, we present a new approach, which consists in directly up-scaling the geostatistical permeability distribution rather than the individual realizations. Practically, filtering techniques based on. the FFT (Fast Fourier Transform), allows us to generate geostatistical images, which sample the up-scaled distributions. In the log normal case, an equivalence hydraulic criterion is proposed, allowing to re-estimate the geometric mean of the permeabilities. In the anisotropic case, the effective geometric mean becomes a tensor which depends on the level of filtering used and it can be calculated by a method of renormalisation. Then, the method was generalized for the categorial model. Numerical tests of the method were set up for isotropic, anisotropic and categorial models, which shows good agreement with theory. (author)

  13. Contribution to the study of methane storage by adsorption; Contribution a l'etude du stockage du methane par adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, A.

    2004-09-01

    Natural gas, which methane is the main component, is an alternative fuel. It is abundant and has clean burning characteristics; however its storage is difficult due to its very low density. Two storage routes were investigated. Methane adsorption was studied in optimized microporous carbons. They were prepared by chemical activation of anthracite powders with sodium hydroxide, and were then compacted. Associating both high adsorptive capacities and high apparent densities finally allowed exceeding the target of 150 volumes of methane delivered per volume of storage vessel at 20 C and 3.5 MPa. Formation of methane hydrates was also observed in micro meso-porous carbons, at 2 C and at pressures higher than 4 MPa. (author)

  14. Study of the N=40 shell by using Coulomb excitation; Etude par excitation coulombienne de la fermeture de couche N=40

    Energy Technology Data Exchange (ETDEWEB)

    Leenhardt, St

    2000-01-01

    Two Coulomb excitation experiments on neutron rich exotic nuclei have been performed at GANIL. They allowed the measurement of the reduced transition probability B(E2) (from ground state to first excited state) of some nuclei around N = 40. This number, 40, is a half-magic number in the shell model. For nuclei with an important neutron excess, it is predicted that the shell closure is stronger at N = 40. The B(E2) is a good tool for testing this growing. We have measured, by using the LISE3 spectrometer and a {gamma} multidetector, B(E2) of {sup 68}Ni, {sup 66}Ni and {sup 72}Zn, unknown till now. We have used for the first time segmented germanium 'clovers' detector, for photon detection (v/c{approx}0.3). Results confirm the strong shell effect for {sup 68}Ni. Indeed {sup 68}Ni was shown to be the Nickel isotope with the lowest value of B(E2), and hence the most rigid isotope. Nevertheless it seems that the shell effect at N = 40 decreases rapidly, for other isotopes very close to {sup 68}Ni(Z = 28) and N = 40). (authors)

  15. Study of lanthanide tri-cations in aqueous solution by molecular dynamic; Etude des trications lanthanide en solution aqueuse par dynamique moleculaire

    Energy Technology Data Exchange (ETDEWEB)

    Duvail, M

    2007-11-15

    This is essentially a lanthanide tri-cation hydration study by means of classical molecular dynamics (CLMD) simulations using explicit polarization. Explicit polarization is calculated with a Car-Parrinello type of dynamics on induced dipoles, which decreases the CPU time as compared to the self-consistent resolution. Several pair interaction potentials are parametrized from ab initio calculations (MP2) and tested for the La{sup 3+}-OH{sub 2} interaction. The best results are obtained with an exponential-6 Buckingham potential. Next, the La{sup 3+}-OH{sub 2} interaction potential parameters are extrapolated to the other Ln{sup 3+}-OH{sub 2} interactions, only by using the ionic radii. The CLMD results reproduce the reliable experimental data (EXAFS distances), and the sigmoidal variation of the coordination number (with S shape), from 9 for La{sup 3+} to 8 for Lu{sup 3+}. This variation is explained by the linear variation of DrG0 (9,298) vs. atomic number. Insights are also given on the Co{sup 2+} hydration, CPMD simulations, reconstruction of EXAFS signal from MD simulations, and OH{sup -} complexation of La{sup 3+} in aqueous solution. (author)

  16. Etude d'une séquence allylmétallation-cycloaddition contrôlée par un groupe silyle

    OpenAIRE

    Distelmans, Anouk

    2004-01-01

    Notre thèse s'intéresse à l'étude de séquences réactionnelles permeettant la création de carbones quaternaires. Deux séquences de réactions sont envisagées : - La première s'inscrit dans le prolongement des travaux de J-M. Adam et combine une réaction d'allylmétallation asymétrique et une réaction de cycloaddition [2+2] intramoléculaire. Elle conduit à des cyclobutanones bicycliques portant un substituant méthyle en tête de pont. La réaction d'allylmétallation a tout d'abord été étud...

  17. Study of neutron deficient iridium isotopes by using laser spectroscopy; Etude des noyaux d'iridium deficients en neutrons par spectroscopie laser

    Energy Technology Data Exchange (ETDEWEB)

    Verney, D

    2000-12-19

    Resonance ionization spectroscopy was performed on neutron deficient iridium isotopes {sup 182-189}Ir, {sup 186}Ir{sup m} and stable isotopes {sup 191,193}Ir. Hyperfine spectra were recorded from the optical transition at 351,7 nm between the 5d{sup 7}6s{sup 2} {sup 4}F{sub 9/2} ground state and the 5d{sup 7}6s6p {sup 6}F{sub 11/2} excited state. Radioactive iridium isotopes were obtained from {beta}{sup +}/EC decay of radioactive mercury nuclei deposited on a graphite substrate. The radioactive mercury nuclei were produced at the ISOLDE facility at CERN through spallation reactions, by bombarding a molten lead target with the 1 GeV proton beam delivered by the PS-Booster. Magnetic dipole moments and spectroscopic quadrupole moments were extracted from the hyperfine spectra. The mean square charge radius variations, as deduced from the measured isotopic shift, show a sharp change between {sup 187}Ir and {sup 186}Ir{sup g}, accompanied by a sudden increase in deformation: from {beta}2 {approx} 0,16 to {beta}2 > 0, 2. These results were analysed in the framework of an axial rotor plus one or two quasiparticles. The wave functions of the osmium and platinum cores which are used in order to describe the iridium nuclei were calculated from the HF+BCS method with the Skyrme SIII effective interaction. The cores were constrained to take the deformation parameters extracted from the isotopic shift measurements. One shows then that this sudden deformation change corresponds also to a change in the proton state that describes the odd nuclei ground state or that participates in the coupling with the neutron in odd-odd nuclei. This state is identified with the {pi}3/2{sup +}[402] orbital for the smaller deformations nuclei and with the {pi}1/2{sup -}[541] orbital stemming from the h{sub 9/2} subshell for bigger deformations nuclei. (author)

  18. Study of the alkaline cations complexation by photo-isomerizable calixarenes; Etude de la complexation de cations alcalins par des calixarenes photoisomerisables

    Energy Technology Data Exchange (ETDEWEB)

    Reynier, N.

    1996-04-25

    The first step to reduce the volume and the toxicity of radioactive waste coming from the spent fuel reprocessing is to separate long life radioisotopes from others ones with a shorter period. The aim of this study is to show that the control of the two phenomenons, complexation of the cation by the calixarenes and its de-complexation, can be envisaged by the introduction on the molecule of a chromophore group, azo benzene, able to modify the complexing site structure of the calixarenes with an isomerization trans-cis induced by ultraviolet radiation, and isomerization cis-trans thermally induced by a visible radiation. (N.C.). 112 refs., 78 figs., 23 tabs.

  19. Temporal lobe dysfunction in childhood autism: a PET study; Dysfonctionnement bitemporal dans l'autisme infantile: etude en tomographie par emission de positons

    Energy Technology Data Exchange (ETDEWEB)

    Boddaert, N.; Poline, J.B.; Brunelle, F.; Zilbovicius, M. [Service Hospitalier Frederic Joliot, ER-M INSERM 0205, DSV, DRM CEA, 91 - Orsay (France); Brunelle, F. [Centre Hospitalier Universitaire Necker-Enfants-Malades, Service de Radiologie Pediatrique, 75 - Paris (France); Chabane, N. [Hopital Robert-Debre, Service de Pedopsychiatrie, 75 - Paris (France); Barthelemy, C.; Zilbovicius, M. [Centre Hospitalier Universitaire Bretonneau, INSERM Unite 316, 37 - Tours (France); Bourgeois, M. [Centre Hospitalier Universitaire Necker-Enfants-Malades, Dept. de Pediatrie, 75 - Paris (France); Samson, Y. [Centre Hospitalier Universitaire Pitie-Salpetriere, Service des Urgences Cerebraux Vasculaires, 75 - Paris (France)

    2002-12-01

    Childhood autism is a severe developmental disorder that impairs the acquisition of some of the most important skills in human life. Progress in understanding the neural basis of childhood autism requires clear and reliable data indicating specific neuro-anatomical or neuro-physiological abnormalities. The purpose of the present study was to research localized brain dysfunction in autistic children using functional brain imaging. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) in 21 primary autistic children and 10 age-matched non autistic children. A statistical parametric analysis of rCBF images revealed significant bilateral temporal hypoperfusion in the associative auditory cortex (superior temporal gyrus) and in the multimodal cortex (superior temporal sulcus) in the autistic group (p<0.001). In addition, temporal hypoperfusion was detected individually in 77% of autistic children. These findings provide robust evidence of well localized functional abnormalities in autistic children located in the superior temporal lobe. Such localized abnormalities were not detected with the low resolution PET camera (14-22). This study suggests that high resolution PET camera combined with statistical parametric mapping is useful to understand developmental disorders. (authors)

  20. Etude, par principes premiers, des effets de la correlation entre electrons sur les proprietes electroniques et magnetiques de polymeres pontes et de supraconducteurs a haute temperature critique

    Science.gov (United States)

    Pesant, Simon

    Description of complex systems by Density functional theory is treated in this thesis. First, the Density functional theory and a few functionals used to simulate cristals are presented. Specifically, the LDA and GGA functionnals are described and their limits are exposed. Furthermore, the Hubbard model as well as the LDA+U functionnal are addressed in this chapter. These methods enable the study of highly correlated materials. Then, results obtained on polymers are summarized in two articles. The first one treats the band gap variation of ladder-type polymers compared to non ladder type ones. The second article considers small band gap polymers. In this case, it will be shown that an hybrid functional, which contains exact exchange, is required to describe the electronic properties of the polymers under study. Finally, the last chapter address the study of cuprates superconductors. The LDA+U can account for the localization of electrons in copper orbitals. Consequently, a study of the impact of this functionnal on electronic properties of cuprates is conducted. The chapter is ended by an article treating magnetic orders in doped La 2CuO4. Supplementary materials of the second article and a description of the theory of superconductivity of Bardeen, Cooper and Schrieffer are put in annex. Keywords : Electronic correlation, DFT, LDA+U, cuprates, polymers, magnetic orders

  1. Progressive multifocal leuko-encephalopathy studied by magnetization transfer imaging; Leucoencephalopathie multifocale progressive. Etude de la demyelinisation par transfert de magnetisation

    Energy Technology Data Exchange (ETDEWEB)

    Armand, J.P.; Dousset, V.; Mieze, S.; Caille, J.M. [Hopital Pellegrin, 33 - Bordeaux (France); Franconi, J.M. [Siemens SA, 92 - Saint-Denis (France). Service Instrumentation Scientifique; Lacoste, D. [Gecsa, Groupe d`Epidemiologie Clinique du Sida en Aquitaine, CHU, 33 - Bordeaux (France); Letenneur, L. [Bordeaux-2 Univ., 33 (France)

    1997-09-01

    Purpose: magnetization transfer imaging (MT) has bees used to study the degree of demyelination in progressive multifocal leuko-encephalopathy (PML). Material and method: two groups were studied: a group of 10 HIV + patients with clinical, MR features, biological and/or biopsy proven PLM, and a group of 11 normal volunteers with matched age. MT ratio (MTR) were obtained from the center of the PLM lesions and 11 areas of normal appearing white matter (NAWM) in the control group. Results: the mean MTR of NAWM in the control group was 46.6% (SD = 2,3). PLM lesions demonstrated a strong and significant (p = 0) decreased of the MTR with mean MTR value of 22.4% (SD = 2,3). Conclusion: MT characterized the demyelinating process in PLM, and can be to used to improve diagnosis. Furthermore, MT allowed a quantification of the degree of the demyelination which can be helpful in other demyelinating process of CNS such multiple sclerosis. (authors). 11 refs.

  2. Etude de stratégies de gestion énergétique des bâtiments par l'application de la programmation dynamique

    OpenAIRE

    Favre , Bérenger

    2013-01-01

    The subject of this work is the control of building equipments with the use of a dynamic programming optimization. This algorithm allows to develop a predictive controller in order to reduce the energy counsumption of the building or to increase the comfort of the occupants.A first case study is developed with the control of the heating system in order to shift the load from peak hours to off-peak hours according to utility rate incentives or carbon emissions.A second case study is about the ...

  3. Etude des propriétés physiques des astéroïdes par imagerie à haute ré́solution angulaire

    OpenAIRE

    Carry , Benoît

    2009-01-01

    Our understanding of the origin and evolution of the Solar System and its implication towards the formation of the early planetesimal has become a primary goal in planetary sciences over the recent years. In this respect, a considerable amount of information regarding the primordial planetary processes that occurred during and immediately after the accretion of the early planetesimals is still present among the population of Small Solar System Bodies. Consequently, studying asteroids is of pr...

  4. Etude comparative des coagulations du lait par actions de l'extrait des écorces de l'Ongokea gore et des enzymes coagulants bien connus

    Directory of Open Access Journals (Sweden)

    Libouga, DG.

    2008-01-01

    Full Text Available Milk Clotting Using Ongokea gore Bark Extract Compared to those Obtained to Well Known Milk Clotting Extracts. The evolution of firmness in curd obtained using plant extract (Ongokea gore barks and that using renounce coagulating enzymes (bovine pepsin, Endothia parasitica, porcine pepsin, Mucor pusillis, rennet were compared. The study was carried out using reconstituted milk (Berrigde substrate and a formagraph was used for the analysis of curd firmness. Variations in amplitude of the formagrammes were measured with time. It was noticed that at the same coagulation time, the curd firming rate of Ongokea gore extracts was higher than that of porcine pepsin but lower than those of Endothia parasitica, Mucor pusillis, bovine pepsin and rennet. The evolution of curd firmness with pH on one hand and the quantity of dissolved powder milk on the other hand showed some similarities in rennet and Ongokea gore extract curds: the effect of the pH of the milk substrate is less remarkable on the rate of curd firmness while this rate increases with the quantity of dissolved powder milk.

  5. Study of the extraction mechanisms by TBP saturated by uranyl nitrate; Etude des mecanismes d'extraction du TBP sature par le nitrate d'uranyle

    Energy Technology Data Exchange (ETDEWEB)

    Meze, F

    2004-02-15

    This work deals with a particular phenomenon likely to occur in the nuclear waste reprocessing process PUREX. It was shown earlier by Russian works that the extractant molecule, tributyl phosphate (TBP), saturated by uranyl nitrate keeps its extraction capacities for nitric acid and tetravalent actinides. This study is composed of three parts. Firstly, some liquid-liquid extraction experiments were conducted to verify the ability of TBP saturated by uranyl nitrate to conserve its extraction capacities for nitric acid. Then, during these experiments, the UV and infrared spectra of both phases were recorded to obtain the organic phase speciation. At last, the informations gathered during the experimental part were used to build a general species distribution model of the H{sub 2}O/HNO{sub 3}/UO{sub 2}(NO{sub 3}){sub 2}/TBP system. (author)

  6. Study of the reactivity of an aggregative explosive sensitized by dynamical damage; Etude de la reactivite d`un explosif agregataire sensibilise par endommagement dynamique

    Energy Technology Data Exchange (ETDEWEB)

    Pertuis, Ch.

    1997-11-13

    The thermal decomposition of a TATB-based explosive that have been exposed to a projectile impact, is studied in order to determine its sensitivity based on the morphological state of the damaged material. Two self-maintained thermal decomposition modes have been identified, one is a slow mode, the other is a rapid mode; four media have been differentiated in the damaged explosive: sound, porous, micro-cracked and fractured media, and thermal decomposition is studied for each media, using two experimental techniques, manometric bomb and a specifically designed strand burner. Laws giving the regression speed of each media has been established considering confinement pressure and initial temperature of the explosive. Analytical calculations yield the regression speed evolution as a function of certain parameters

  7. Identification d'indicateurs de risque des populations victimes de conflits par imagerie satellitaire. Etude de cas: Le nord de l'Irak

    Science.gov (United States)

    Mubareka, Sarah Betoul

    Remote sensing and security, terms which are not usually associated, have found a common platform this decade with the conjuring of the GMOSS network (Global Monitoring for Security and Stability), whose mandate is to discover new applications for satellite-derived imagery to security issues. This study focuses on human security, concentrating on the characterisation of vulnerable areas to conflict. A time-series of satellite imagery taken from Landsat sensors from 1987 to 2001 and the SRTM mission imagery are used for this purpose over a site in northern Iraq. Human security issues include the exposure to any type of hazard. The region of study is first characterised in order to understand which hazards are and were present in the past for the region of study. The principal hazard for the region of study is armed conflict and the relative field data was analysed to determine the links between geographical indicators and vulnerable areas. This is done through historical research and the study of open-sourced information about disease outbreaks; the movements of refugees and the internally displaced; and humanitarian aid and security issues. These open sources offer information which are not always consistent, objective, or normalized and are therefore difficult to quantify. A method for the rapid mapping and graphing and subsequent analysis of the situation in a region where limited information is available is developed. This information is coupled with population numbers to create a "risk map": A disaggregated matrix of areas most at risk during conflict situations. The results show that describing the risk factor for a population to the hazard conflict depends on three complex indicators: Population density, remoteness and economic diversity. Each of these complex indicators is then derived from Landsat and SRTM imagery and a satellite-driven model is formulated. This model based on satellite imagery is applied to the study site for a temporal study. The output are three 90 m x 90 m resolution grids which describe, at a pixel level, the risk level within the region for each of the dates studies, and the changes which occur in northern Iraq as the result of the Anfal Campaigns. Results show that satellite imagery, with a minimum of processing, can yield indicators for characterising risk in a region. Although by no means a replacement for field data, this technological source, in the absence of local knowledge, can provide users with a starting point in understanding which areas are most at risk within a region. If this data is coupled with open sourced information such as political and cultural discrimination, economy and agricultural practices, a fairly accurate risk map can be generated in the absence of field data. Keywords. SRTM, Landsat, risk indicators, Iraq, conflict, population vulnerability, segmentation, land-use, fuzzy-classification, atmospheric corrections.

  8. Study of an ultrasonic generation by the electromagnetic waves; Etude de la generation d'ultrasons par des ondes electromagnetiques

    Energy Technology Data Exchange (ETDEWEB)

    Juillard, J

    2000-07-01

    The main subject of this work is the development of a bulk-wave EMAT (Electro-Magnetic Acoustic Transducer) semi-analytical model. At first, we consider the general theory behind this type of transduction, especially in the case of P-Waves; this is followed by an experimental study which points out the need of modelling for the design of EMAT probes. Under certain hypotheses, this modelling can be reduced to three separate models: one model giving the eddy currents, another one the permanent magnetic field and one for the acoustic field generated by a surface density of forces. For each of these phenomena, 3-D semi-analytical models are built: they are based on a decomposition of the source terms into elementary sources. The final solutions are obtained through a convolution of the elementary solutions and of the sources. The implementation of these models is then given, as well as some applications to the field of EC and of EMAT. (author)

  9. Etude experimentale et optimisation d'un systeme hybride hydraulique pour camions a ordures et amelioration des performances par raffinement de sa logique de controle

    Science.gov (United States)

    Lacroix, Benoit

    The aim of this thesis is to demonstrate experimentally the operation of a hydraulic hybrid system specifically dedicated to the application of refuse trucks in addition to proposing solutions to improve its control strategy. The developed hybrid system recovers the vehicle's kinetic energy during braking. A variable displacement hydraulic motor then uses the energy stored in a hydraulic accumulator to assist the internal combustion engine (ICE) at suitable times. The particular aspect of this system is that assistance to the ICE can occur when it operates at idle and drives the auxiliary hydraulic equipment of the refuse truck. Essentially, the control strategy initially developed maximizes the recovery of braking energy and uses that energy to minimize the solicitation of the ICE at idle. The experimental results obtained with two prototypes tested in real operating conditions show that the hybrid system can recover a significant portion of braking energy. In addition, the results show that it is possible to reduce the load on the ICE during idle with the application of an assisting torque. However, the advantage of assisting the ICE in specific areas of the operating range is slim since the ICE's gross efficiency varies only slightly depending on conditions of operation. This is confirmed by the optimization of the control logic using deterministic dynamic programming. Indeed, by managing the pressure in the accumulator to maximize the amount of energy recovered during braking and by dosing the assistance to the ICE in an ideal fashion, the optimal control only managed to improve fuel savings by 6% in comparison to the original control. Therefore, since the efforts that would be required to emulate the ideal behavior in real time are significant for a relatively small and uncertain gain, the initial control logic is considered near optimal. Finally, this thesis proposes an improved version of the torque assisting hybrid system that could shut down the ICE when the vehicle is stopped while maintaining functional the auxiliary hydraulic equipment. An optimization of the control logic indicates that proper management of the pressure in the accumulator would allow turning off the ICE most of the time at stop and thus, would increase the fuel savings by over 40% compared to the original system. The simulation of a basic control strategy shows that such pressure management may be feasible in real time and that the potential gain in fuel savings is achievable. Keywords: hybrid system, hydraulic, control, refuse truck.

  10. Atomic spectroscopy study of nuclear properties of francium and cesium isotopes; Etude par spectroscopie atomique de proprietes nucleaires d'isotopes de francium et de cesium

    Energy Technology Data Exchange (ETDEWEB)

    Coc, A

    1986-04-15

    This work is based on the study of cesium ({sup 118,146}Cs) and francium ({sup 207-213}Fr,{sup 220-228}Fr) isotopes by hyperfine atomic spectroscopy and on the interpretation of these results from the nuclear physics point of view. The measured nuclear quantities are: the spin, the magnetic moment, the electric quadrupole moment and the mean square charge radius. The experimental method which is based on hyperfine optical pumping with a tunable laser, followed by magnetic analysis of the atoms is described in the first part. Results related to atomic physics are also presented. In the second part, these data are interpreted in the framework of nuclear models. The deformation of light cesium isomers are compared to values obtained from a theoretical self-consistent calculation. Heavy francium isotopes are situated in an area where the existence of static octupole deformations have been predicted. The odd-even staggering measured on the mean square radius is abnormal in this region. However, on the basis of experimental data, no definitive conclusion can be drawn regarding the nature of these deformations. (author)

  11. PROPOS SUR LE SAVOIR-FAIRE DES ETUDIANTS NON-PHILOLOGUES ACQUIS PAR DES APPROCHES PLURIELLES. ETUDE DE CAS : LE METALANGAGE

    Directory of Open Access Journals (Sweden)

    Constantin Felicia

    2012-07-01

    Full Text Available The Framework of reference for pluralistic approaches to languages and cultures (CARAP, developed in 2007 under Michel Candelier’s coordination is an imperative instrument for all the teachers and decision makers preoccupied with the didactic stances of plurilinguism. Much less known than the Common European Framework of Reference for Languages, CARAP provides an inventory of knowledge, attitudes and skills the students will get to master within certain plural didactic approaches, oriented towards the development of plurilinguism. These didactic approaches are profoundly original compared with a traditional training path. We will consider as a reference point for our reflection one of the most promising and dynamic plural approaches: intercomprehension, more exactly the model developed by the InterCompréhension Européenne (ICE team of the University of Reims, France. The census of knowledge, attitudes and skills allows a systematic look on linguistic and cultural realities that the future plurilinguistic individual is meant to assimilate. Our attention will be focused on skills. Attending the ICE meetings made us familiar with a running manner excluding the preoccupation for the acquiring of a complete foreign language grammar, circumscribed to assuming its partial knowledge, in one or two of the competences defining it (written and oral understanding. The results of the experiments allow us to state that a minimum of grammar is enough to get the access to the global understanding of texts written in a foreign language: « intercomprehenders » getting involved in the global understanding of foreign languages previously unknown, related to their mother tongue, using a very reduced metalanguage, complementary with a wide range of relieve strategies. This observation has led to our professional activity, marked by the recurrent confrontation with the reality of teaching classes – economic students’ inability to remember, understand, and naturally use a significant part of the grammar metalanguage acquired in their mother tongue. To emphasize this, we applied an empirical survey related to the fundamental grammar terminology in their mother tongue and interpreted the answers of a significant number of first and second year students of the Faculty of Economics. The results prove a disquieting inability to manage the already acquired morphological and syntactical categories within grammar analysis of mother tongue and subsequently transferred to the process of teaching-acquiring foreign languages. We have established a contiguity between the natural path in a training session in ICE type intercomprehension and the didactic path in institutional education, concluding that (1 a simplification of the grammar taught within traditional education is beneficial for students and teacher and that (2 the use of certain intercomprehensive techniques, such as the parangon, is extremely profitable when approaching certain aspects connected to foreign language grammar.

  12. Etude numérique des ouvrages de soutènement à parement en blocs modulaires renforcés par géogrille

    OpenAIRE

    RAHMOUNI, Ouassim; MABROUKI, Abdelhak; MELLAS, Mekki; BENMEDDOUR, Djamel

    2015-01-01

    International audience; De nombreuses études expérimentales ont permis d'expliquer le mécanisme de fonctionnement interne, des ouvrages de soutènement en sol renforcé, en précisant la répartition des efforts de traction le long des renforcements. Toutefois, des études très limitées ont été menées concernant l'influence de l'interface sol-parement et l'inclinaison du remblai. La présente étude s'intéresse à l'étude numérique en utilisant le code FLAC3D (Fast Lagrangian Analysis of Continua in ...

  13. Study of the two-dimensional Hubbard model at half-filling through constructive methods; Etude du modele de Hubbard bidimensionnel a demi remplissage par des methodes constructives

    Energy Technology Data Exchange (ETDEWEB)

    Afchain, St

    2005-02-15

    The Hubbard model is the simplest model to describe the behaviour of fermions on a network, it takes into account only fermion scattering and only interactions with other fermions located on the same site. Half-filling means that the total number of fermions is equal to half the number of sites. In the first chapter we show how we can pass trough successive approximations from a very general Hamiltonian to the Hubbard Hamiltonian. The second chapter is dedicated to the passage from the Hamiltonian formalism to the Grassmanian functional formalism. The main idea is to show that the correlation functions of the Hamiltonian approach can be described through fermionic functional integrals which implies the possibility of speaking of the model in terms of field theory. The chapter 3 deals with the main constructive techniques that allow the strict and consistent construction of models inside the frame of field theory. We show by proving the violation of a condition concerning self-energy, that the two-dimensional Hubbard model at half-filling has not the behaviour of a Fermi liquid in the Landau's interpretation. (A.C.)

  14. Etude de la dynamique de la matière organique (M.O. dans les sols affectés par la salinité

    Directory of Open Access Journals (Sweden)

    Mallouhi, N.

    1989-01-01

    Full Text Available Study of the dynamic of organic matter (O.M. in saline soil. Using "in vitro" experiments, we studied the influence of salinity on the evolution and the transferts of humified compounds obtained from glucose and straw labelled with 14C. The intensity of these mechanisms were examined in different clayed horizons with increasing salinity contents. During incubation experiments parformed under controlled conditions, we found a negative correlation between salinity infered from electrical conductivity measurements and the degree of humification determined by the ratio FA/HA. The inhibition of the biological activity was associated with the presence of high amounts of very mobile soluble or pseudosoluble compounds in the soil to the detriment of more condensed compounds. A high FA/HA ratio, and a low residual humin characterized the evolution of the organic matter in sodic soils. The extent of the movement of the radioactive humified compounds (soluble and pseudosoluble was shown to increase as the soil salinity increases. The humification mechanisms in saline were then compared to those taking place in an eutrophic mull.

  15. Coldness distribution by stabilized ice slurries. Study of the behaviour under thermal cycling; Distribution du froid par coulis de glace stabilisee. Etude du comportement sous cyclage thermique

    Energy Technology Data Exchange (ETDEWEB)

    Jacquier, D.

    2004-10-01

    The purpose of this work is to study a two-phase secondary refrigerant composed of phase-change particles suspended in a carrying liquid. This mixture has been hydraulically and thermally characterised. Moreover, some visualizations of flow patterns have been performed. Measurements of pressure losses have been realised in the case of solid state of the particles and in the case of liquid state. Heat transfer balances allowed us to show an improvement of a 1,9 factor before phase-change, in comparison with the case of a pure carrying liquid (without any particles). Flow patterns, which were theoretically specified, in function of fluid speed, have been observed experimentally. (author)

  16. Etude, conception et optimisation d'une plate-forme de mesure de micro et nano force par flottaison magnétique.

    OpenAIRE

    Cherry, Ali

    2009-01-01

    In microrobotics, the micro and nano force measurement is among the necessary information needed to characterize mechanical interactions present at the micrometer scale. Accordingly, we developed a micro and nano force sensor based on a floating-magnetic principle. The sensor sensign part is a macroscopic rectangular platform on which is applied the forces and the torques to be measured. The sustentation of the platform is done thanks to magnetic forces and upthrust buoyancy applied on four f...

  17. Study of the number of neutrons produced by fission of {sup 239}Pu; Etude du nombre de neutrons produits par la fission de {sup 239}Pu

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    Study of the number of neutrons produced by fission of {sup 239}Pu. The counting by coincidence of fissions and neutrons produced by these fissions allows the study of the variation of the mean number of neutrons emitted by {nu} fission. In the first chapter, it studied the variation of the mean number of neutrons emitted by {sup 239}Pu fission with the energy of the incident neutron. A description of the experiment is given: a spectrometer with a crystal of sodium chloride or beryllium (mounted on a goniometer) is used, a fission chamber containing 10 mg of {sup 239}Pu and the neutron detection system constituted of BF{sub 3} counters which are enriched in {sup 10}B. In the second part, the counting by coincidence of fissions and neutrons produced by the same fission and received by two different groups of counters allow the determination of a relationship between the root mean square and the average of neutron number produced by fission. The variation of the mean number of neutrons emitted by fission of {sup 239}Pu is studied when we change from a thermal spectra of neutrons to a fission spectra of incident neutrons. Finally, when separating in two different part the fission chamber, it is possible to measure the mean number of neutrons emitted from fission of two different sources. It compared the mean number of neutrons emitted by fission of {sup 239}Pu and {sup 233}U. (M.P.)

  18. New structural studies of liquid crystal by reflectivity and resonant X-ray diffraction; Nouvelles etudes structurales de cristaux liquides par reflectivite et diffraction resonante des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, P

    2007-04-15

    This memory presents three structural studies of smectic Liquid Crystals by reflectivity and resonant diffraction of X-rays. It is divided in five chapters. In the first a short introduction to Liquid Crystals is given. In particular, the smectic phases that are the object of this study are presented. The second chapter is consecrated to the X-ray experimental techniques that were used in this work. The three last chapters present the works on which this thesis can be divided. Chapter three demonstrates on free-standing films of MHPOBC (historic liquid crystal that possesses the antiferroelectric sub-phases) the possibility to extend the technique of resonant X-ray diffraction to liquid crystals without resonant element. In the fourth chapter the structure of the B{sub 2} liquid crystal phase of bent-core molecules (or banana molecules) is elucidated by using resonant X-ray diffraction combined with polarization analysis of the diffracted beam. A model of the polarization of the resonant beam diffracted by four different structures proposed for the B{sub 2} phase is developed in this chapter. In the fifth chapter a smectic binary mixture presenting a very original critical point of phase separation is studied by X-ray reflectivity and optical microscopy. A concentration gradient in the direction perpendicular to the plane of the film seems to be induced by the free-standing film geometry. The results of a simplified model of the system are compatible with this interpretation.

  19. A study on hydrogen storage through adsorption in nano-structured carbons; Etude du stockage d'hydrogene par adsorption dans des carbones nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Langohr, D

    2004-10-15

    The aim of this work is to build and calibrate an experimental set-up for the testing of the materials, to produce some carbon materials in large amounts and characterise them, and finally, to test these materials in their ability to store hydrogen. This will help in establishing a link between the hydrogen storage capacities of the carbons and their nano-structure. The script is divided into four chapters. The first chapter will deal with the literature review on the thematic of hydrogen storage through adsorption in the carbon materials, while the second chapter will present the experimental set-up elaborated in the laboratory. The third chapter explains the processes used to produce the two families of carbon materials and finally, the last chapter presents the structural characterisation of the samples as well as the experimental results of hydrogen storage on the materials elaborated. (author)

  20. Study of the mechanisms induced by a ionizing particle on simple structures; Etude des mecanismes de base induits par une particule ionisante sur des structures simples

    Energy Technology Data Exchange (ETDEWEB)

    Hubert, G.; Palau, J.M.; Roche, Ph.; Sagnes, B.; Gasiot, J. [Montpellier-2 Univ., CEM2, 34 (France); Calvet, M.C. [Aerospatiale Espace et Defense, 78 - Les Muraux (France)

    1999-07-01

    Ion induced currents in a diode and a semiconductor bar are compared. A short track, located inside the structure, and a long track passing through it are considered. The involved mechanisms are analysed in order to explain why the observed effects are very similar. (authors)

  1. Swift heavy ion irradiation effects in {alpha} poly(vinylidene fluoride); Etude des effets induits par les ions lourds energetiques dans le poly(fluorure de vinylidene)

    Energy Technology Data Exchange (ETDEWEB)

    Le Bouedec, A

    1999-11-29

    The goal of this study is to characteristic and to localised defects created in {alpha} Poly (vinylidene fluoride) after swift heavy ion irradiations. PVDF films are irradiated with several Swift Heavy Ions (SHI), in the electronic stopping power (dE/dx){sub e}, in order to study the influence of irradiation parameters (absorbed dose, ion). These irradiated films are studied by different analysis techniques such as FTIR, ESR (X and Q band) spectroscopies and DSC. The crystalline level of PVDF is about 50% and we follow it destruction and amorphization as the absorbed dose increase by DSC and FTIR studies. The variation of the various FTIR bands allow us to observe the unsaturations induced by SHI radiations. Two sets of defects are observed: those which yield is sensitive to an increase of (dE/dx){sub e} and those that are not. A spatial distribution of the various defects within the talent track is provided and defects that are difficult to create are the closest of the ion path. The different kind of radicals created after irradiations are studied by ESR spectroscopy. Alkyl, peroxy and polyenyl radicals are detected after SHI radiations like after electron or {gamma} irradiations. Their yield of creation is independent of (dE/dx){sub e} and their localised in the crystalline zone or/and at the interfacial zone between crystalline and amorphous one. An other kind of radicals is created only after SHI radiations that are specific of the SHI-polymer interaction. We observe that these radicals are localised on a carbon cluster, in the core of the latent track for low doses and highly sensitive at the (dE/dx){sub e} of the ion. (author)

  2. Study of an intense proton beam profiler based on laser absorption; Etude d'un profileur optique de faisceaux intenses de protons par absorption laser

    Energy Technology Data Exchange (ETDEWEB)

    Pottin, B

    2001-10-01

    Among the challenges of high current proton accelerators, the development of new beam diagnostics is of major importance. The main difficulty for these instruments, is the beam power which deteriorates any instruments used to catch it. The chosen detectors are therefore 'non-interceptive systems. After an introduction concerning characteristics of the used accelerator (chapter I), parameters defining a beam of particles are presented (chapter II). Among these ones, the profile is an important beam characteristic for its transport. After the description of the different types of beam profilers, their problematic application to intense beams is discussed. New physical phenomena have to be used for profilers. Thus, we have prospected optical luminescence phenomena. The light produced during the interaction of protons with the residual gas and/or locally injected is a source of informations on beam characteristics. In chapters III and IV, there is an experimental and theoretical analysis of the luminescence. Chapter V is a direct application of spectroscopic measurements to estimate the output of protons with a non-interceptive technique. With the spectral analysis, the idea of a profiler based on laser absorption is developed. This presentation is both theoretical and experimental (chapters 6 and 7). The laser absorption needs the use of metastable states we define in the chapter 6. The evolution of the metastable states, with time and space, has been rigorously studied to discuss the concept of an optical profiler. Chapter VII presents all the necessary instrumentation for the use of a laser and the first measurements with the beam. At the thesis end, the first recorded profile is presented. An experimental critic is presented with a description of the different sources of errors and the proposed cures. (author)

  3. Creep of uranium dioxide: bending test and mechanical behaviour; Etude du fluage du dioxyde d'uranium: caracterisation par essais de flexion et modelisation mecanique

    Energy Technology Data Exchange (ETDEWEB)

    Colin, Ch

    2003-09-01

    These PhD work in the frame of Pellet-Cladding Interactions studies, in the fuel assemblies of nuclear plants. Electricite de France (EDF) must well demonstrate and insure the integrity of the cladding. For that purpose, the viscoplastic behaviour of the nuclear fuel has to be known and, if possible, controlled. This PhD work aimed to characterize the creep of uranium dioxide, in conditions of transient power regime. First, a literature survey on mechanical behaviour of UO{sub 2} revealed that the ceramic was essentially studied with compressive tests, and that its creep behaviour is characterized by two domains, depending on the stress level. To estimate the loadings in a fuel pellet, EDF and CEA developed specific global codes. A simulation during a power ramp allowed the order of magnitude of the loadings in the pellet to be determined (temperature, thermal gradients, strains, strain rate...). The stress calculation using a finite element simulation requires the identification of behaviour laws, able to describe the behaviour under small strains, low strain rates, and under tensile stresses. Starting from this observation, three point bending method has been chosen to test the uranium dioxide. As, for representativeness reasons, testing specimens cut in actual fuel pads was required in our study; a ten millimeters span has been used. For this study, a specific three-point testing device has been developed, that can tests specimens up to 2 000 C in a controlled atmosphere (Ar + 5% H{sub 2}). A special care has been taken for the measurement of the deflexion of the sample, which is measured using a laser beam, that allow an accuracy of {+-}2{mu}m to be reached at high temperature. Specimens with 0,5 to 1 mm thickness have been tested using this jig. A Norton's law describe, with respective stress exponent and activation energy values of 1.73 and 540 kJ.mole-1, provided a good description of the stationary creep rate. Then, the mechanical behaviour of the fuel has been modeled. The introduction of internal variables in a law describing a kinematic hardening of the material allowed the first two stages of creep and the recovery phenomena observed during partial un-loadings to be described. The identification was realized by inverse method, coupling an optimization of the parameters with a finite element calculation of the deformation of the bending specimen. The application of this model to simulate a transient power ramp demonstrated that the expected stress relaxation in the fuel does not prevent a radial break of pellet at the end of the power increase. During a maintain at high power, the high temperature in the core of the pellet allows a stress relaxation, especially close from the hollows. That results in a flow of the ceramic, mainly axial, that is clearly confirmed by the observation of used pellets. A final application of our experimental device consisted in testing ion-irradiated specimens, with a 50 {mu}m penetration depth. The small thickness of our samples allows the effect of an irradiation on the creep of UO{sub 2} to be revealed. (author)

  4. Quantitative study of a gaseous atmosphere by Fourier transformation infrared spectroscopy (FTIR); Etude quantitative d atmosphere gazeuse par spectroscopie infrarouge a transformee de Fourier

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, G.; Faivret, O.; Doncourt, A.; Dubard, V. [CEA, Is sur Tille, (France)

    2006-07-01

    The aim of this work is to implement an in situ quantitative analysis of gases present in a gaseous atmosphere by Fourier transformation infrared spectroscopy in order to determine the processes occurring during the uranium corrosion reactions. Indeed, during these reactions, the gaseous atmosphere initially present evolves during the reaction and leads to the formation of new gaseous species. The aim is then to in situ quantify the proportion of species present during all the reactional process. A preliminary study on pure gases has been carried out. The studied gases are: CH{sub 4}, CO{sub 2}, H{sub 2} and CO. The aim is to identify their spectral symbol in the infrared and to determine their behaviour (absorbance) in terms of their concentration. The study of different binary gases mixtures, as for instance CO{sub 2}/H{sub 2}, CH{sub 4}/H{sub 2}, CO/H{sub 2} or CH{sub 4}/CO{sub 2} has been carried out too. This study presents the results concerning the CO{sub 2}/H{sub 2} mixture and more particularly the evolution of the spectral sign of gases in terms of the partial concentrations of H{sub 2} and CO{sub 2}. The study of the spectra of this mixtures show that the presence of a gaseous specie has an influence on the characteristics of the peaks (intensity and area) of the spectra relative to other gaseous species present in the mixture according to a transfer function which has then been determined. The feasibility of the implementation of an in situ quantitative gaseous analysis by Fourier transformation infrared spectroscopy is then discussed from FTIR tables (intensity and area of peaks) obtained on gaseous mixtures. (O.M.)

  5. Workshop day on ``films and droplets heat transport``; Journee d`etude sur ``le transport de chaleur par films ou gouttelettes``

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    This workshop day was organized by the French society of thermal engineers (SFT). This compilation of proceedings comprises 9 papers dealing with: the effect of droplets evaporation on a poly-dispersed jet under pressure (application to combustion chambers of diesel engines); effect of two-phase heat exchanges on the performances of a piston engine; heat and mass transfers in the entering region of a laminar liquid film; mass transfer at the interface of a free or sheared turbulent film; measurement of gasoline films thickness using laser induced fluorescence - evaluation of the evaporation quickness using several tracers (application to the intake manifold of port-injected and of indirect injection spark ignition engines); heat transfers and condensation inside ducts for the evacuation of combustion products; evaporation of a climbing film on a wall with discontinuous fins (application to the ebullition in heat exchangers); temperature measurement of droplets in a mono-dispersed jet using IR technique and refractometry; influence of homogeneous and isotropic turbulence on the vaporization of fuel droplets. (J.S.)

  6. Special Course on Unstructured Grid Methods for Advection Dominated Flows (Les Methodes Utilisant un Maillage non Structure Pour l’Etude des Ecoulements Caracterises par l’Advection)

    Science.gov (United States)

    1992-05-01

    Comput. Methods element method, Matematica Appl. Mechi. Engrg. 45 (1984) Aplicada e Computacional , 10 285-312. (1992), Proc. from Conf. on Innovative...possibility of computing geometrically corn- purud. Forg th e ro a son of weplexdesgnsbecoe areaity.It as t ths pint pursue CFD. Forget the romantic vision of...traverse the days seconds months data at hand, but also to ways of seeing this da- EU Sp, AC ta (plane-cuts, iso-surfaces, X-rays, stereo- vision , DO TT BM

  7. Etude de la caractérisation et la composition qualitative des huiles essentielles de six plantes médicinales par spectroscopie IR

    OpenAIRE

    N. BELBOUKHARI; Z. MERZOUG; A. CHERITI; K. SEKKOUM; M. YAAKOUBI

    2013-01-01

    La séparation et l’identification des constituants des huiles essentielles des plantes ou d’autres sources naturels basée largement sur la chromatographie en phase gazeuse. Dans ce travail on nous développons des techniques de comparaison qui évitent en premier temps la séparation chromatographique, on se basant sur la comparaison des spectres infra rouge (IR) des huiles essentielles avec celle des terpènes et sesquiterpènes purs qui constituent en majorité les huiles essentiel...

  8. Etude de la caractérisation et la composition qualitative des huiles essentielles de six plantes médicinales par spectroscopie IR

    Directory of Open Access Journals (Sweden)

    N. BELBOUKHARI

    2013-03-01

    Full Text Available La séparation et l’identification des constituants des huiles essentielles des plantes ou d’autres sources naturels basée largement sur la chromatographie en phase gazeuse. Dans ce travail on nous développons des techniques de comparaison qui évitent en premier temps la séparation chromatographique, on se basant sur la comparaison des spectres infra rouge (IR des huiles essentielles avec celle des terpènes et sesquiterpènes purs qui constituent en majorité les huiles essentielles.

  9. TMS suppression of right pars triangularis, but not pars opercularis, improves naming in aphasia

    Science.gov (United States)

    Naeser, Margaret A.; Martin, Paula I.; Theoret, Hugo; Kobayashi, Masahito; Fregni, Felipe; Nicholas, Marjorie; Tormos, Jose M.; Steven, Megan S.; Baker, Errol H.; Pascual-Leone, Alvaro

    2011-01-01

    This study sought to discover if an optimum 1 cm2 area in the non-damaged right hemisphere (RH) was present, which could temporarily improve naming in chronic, nonfluent aphasia patients when suppressed with repetitive transcranial magnetic stimulation (rTMS). Ten minutes of slow, 1 Hz rTMS was applied to suppress different RH ROIs in eight aphasia cases. Picture naming and response time (RT) were examined before, and immediately after rTMS. In aphasia patients, suppression of right pars triangularis (PTr) led to significant increase in pictures named, and significant decrease in RT. Suppression of right pars opercularis (POp), however, led to significant increase in RT, but no change in number of pictures named. Eight normals named all pictures correctly; similar to aphasia patients, RT significantly decreased following rTMS to suppress right PTr, versus right POp. Differential effects following suppression of right PTr versus right POp suggest different functional roles for these regions. PMID:21864891

  10. 27 Etude comparative de la compacité expérimentale et ...

    African Journals Online (AJOL)

    Moussa

    objectif de notre recherche ... Par définition la compacité virtuelle est inaccessible à l'expérience et à partir de la formule (1) on remarque .... l'optimisation granulaire par des modèles théoriques constitue un bon outil d'étude des empilements.

  11. Etude expérimentale de la performance thermique d'un caloduc ...

    African Journals Online (AJOL)

    par les cellules thermo-convectives (convection naturelle) formées par l'air contenu dans le tube thermosiphon. L'influence de ..... investigation on the gravity assisted solar heat pipe under the climatic conditions of Tunisia, Energy Conversation and Management 64, 594-605. [8] A. Kamyar, 2013. Effects of nanofluids on ...

  12. Etude sur les Aphanocephalus et descriptions d’espèces nouvelles

    NARCIS (Netherlands)

    Grouvelle, A.

    1912-01-01

    Le genre Aphanocephalus Woll. (Ent. Monthl. Mag. IX, 1873, p. 278) a été redécrit, avec le plus grand soin, par Matthews, dans sa Monographie des Corylophidae, 1899, p. 197, tab. 7, fig. c. Nous ne reviendrons donc pas sur les caractères de ce genre; nous nous bornerons à les compléter par

  13. 107 Etude des facteurs de variation des prix d'intérêt des matières ...

    African Journals Online (AJOL)

    DELL

    Imen BELHADJ SLIMEN et Taha NAJAR. Etude des facteurs de variation des prix d'intérêt des matières premières de substitution utilisées dans les aliments concentrés des animaux d'élevage. Imen BELHADJ SLIMEN1,2* et Taha NAJAR1,2. 1Institut National Agronomique de Tunisie, Département Ressources Animales, ...

  14. Etude cinétique de la dégradation de l'Endosufane en solution ...

    African Journals Online (AJOL)

    Etude cinétique de la dégradation de l'Endosufane en solution. S Traore, K Mamadou, A Dembele, V Yao, Y Bekro, P Mazellier, B Legube, P Houenou. Abstract. Les pesticides sont fréquemment utilisés en Côte d'Ivoire. Leur détection dans les eaux de forage témoigne de leur mauvais usage et d'un grave problème ...

  15. Etude in vitro de l'activité antibactérienne et antifongique de l'extrait ...

    African Journals Online (AJOL)

    user

    UNR –Journal Etudes Rwandaises– Series C:Life Science & Natural Sciences– August 2009. 12. Tableau 4 : Test de l'activité de l'extrait et fractions à différents degrés de pH. Extrait hydroéthanolique. F2. F3. Souches microbiennes. A B C D E. A B C D E A B C D E. pH : 5. - - - - -. - - - - - - - - - -. pH : 7. - - - - - - - - - - - - - - -.

  16. Bacterial mitosis: partitioning protein ParA oscillates in spiral-shaped structures and positions plasmids at mid-cell

    DEFF Research Database (Denmark)

    Ebersbach, Gitte; Gerdes, Kenn; Charbon, Gitte Ebersbach

    2004-01-01

    The par2 locus of Escherichia coli plasmid pB171 encodes oscillating ATPase ParA, DNA binding protein ParB and two cis-acting DNA regions to which ParB binds (parC1 and parC2). Three independent techniques were used to investigate the subcellular localization of plasmids carrying par2. In cells w...

  17. ParABS system in chromosome partitioning in the bacterium Myxococcus xanthus.

    Directory of Open Access Journals (Sweden)

    Antonio A Iniesta

    Full Text Available Chromosome segregation is an essential cellular function in eukaryotic and prokaryotic cells. The ParABS system is a fundamental player for a mitosis-like process in chromosome partitioning in many bacterial species. This work shows that the social bacterium Myxococcus xanthus also uses the ParABS system for chromosome segregation. Its large prokaryotic genome of 9.1 Mb contains 22 parS sequences near the origin of replication, and it is shown here that M. xanthus ParB binds preferentially to a consensus parS sequence in vitro. ParB and ParA are essential for cell viability in M. xanthus as in Caulobacter crescentus, but unlike in many other bacteria. Absence of ParB results in anucleate cells, chromosome segregation defects and loss of viability. Analysis of ParA subcellular localization shows that it clusters at the poles in all cells, and in some, in the DNA-free cell division plane between two chromosomal DNA masses. This ParA localization pattern depends on ParB but not on FtsZ. ParB inhibits the nonspecific interaction of ParA with DNA, and ParA colocalizes with chromosomal DNA only when ParB is depleted. The subcellular localization of ParB suggests a single ParB-parS complex localized at the edge of the nucleoid, next to a polar ParA cluster, with a second ParB-parS complex migrating after the replication of parS takes place to the opposite nucleoid edge, next to the other polar ParA cluster.

  18. The protein kinase SIK downregulates the polarity protein Par3

    DEFF Research Database (Denmark)

    Vanlandewijck, Michael; Dadras, Mahsa Shahidi; Lomnytska, Marta

    2018-01-01

    that SIK can potentially phosphorylate the polarity complex protein Par3, an established regulator of tight junction assembly. SIK associates with Par3, and induces degradation of Par3 that can be prevented by proteasomal and lysosomal inhibition or by mutation of Ser885, a putative phosphorylation site...... protein. HighSIKmRNA expression also correlates with lower chance for survival in various carcinomas. In specific human breast cancer samples, aneuploidy of tumor cells best correlated with cytoplasmic SIK distribution, and SIK expression correlated with TGFβ/Smad signaling activity and low...... or undetectable expression of Par3. Our model suggests that SIK can act directly on the polarity protein Par3 to regulate tight junction assembly....

  19. Diffuse interstellar clouds

    International Nuclear Information System (INIS)

    Black, J.H.

    1987-01-01

    The author defines and discusses the nature of diffuse interstellar clouds. He discusses how they contribute to the general extinction of starlight. The atomic and molecular species that have been identified in the ultraviolet, visible, and near infrared regions of the spectrum of a diffuse cloud are presented. The author illustrates some of the practical considerations that affect absorption line observations of interstellar atoms and molecules. Various aspects of the theoretical description of diffuse clouds required for a full interpretation of the observations are discussed

  20. Self diffusion in tungsten

    International Nuclear Information System (INIS)

    Mundy, J.N.; Rothman, S.J.; Lam, N.Q.; Nowicki, L.J.; Hoff, H.A.

    1978-01-01

    The lack of understanding of self-diffusion in Group VI metals together with the wide scatter in the measured values of tungsten self-diffusion has prompted the present measurements to be made over a wide temperature range (1/2Tsub(m) to Tsub(m)). The diffusion coefficients have been measured in the temperature range 1430-2630 0 C. The present measurements show non-linear Arrhenius behavior but a reliable two-exponential fit of the data should await further measurements. (Auth.)

  1. Diffuse Ceiling Ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

    -cooling period and night cooling potential. The investment cost of this ventilation system is about 5-10% lower than the conventional ones, because the acoustic ceiling could be directly applied as air diffuser and the use of plenum to distribute air reduces the cost of ductwork. There is a growing interest...... in applying diffuse ceiling ventilation in offices and other commercial buildings because of the benefits from both thermal comfort and energy efficiency aspects. The design guide introduces the principle and key characteristics of room air distribution with diffuse ceiling ventilation and the design...

  2. Diffuse Ceiling Ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

    -cooling period and night cooling potential. The investment cost of this ventilation system is about 5-10% lower than the conventional ones, because the acoustic ceiling could be directly applied as air diffuser and the use of plenum to distribute air reduces the cost of ductwork. There is a growing interest...... and manufacturers and the users of diffuse ceiling technology. The design guide introduces the principle and key characteristics of room air distribution with diffuse ceiling ventilation. It provides an overview of potential benefit and limitations of this technology. The benefits include high thermal comfort, high...

  3. Spatial Distribution of Diffuse Attenuation of Photosynthetic Active Radiation and Its Main Regulating Factors in Inland Waters of Northeast China

    Directory of Open Access Journals (Sweden)

    Jianhang Ma

    2016-11-01

    Full Text Available Light availability in lakes or reservoirs is affected by optically active components (OACs in the water. Light plays a key role in the distribution of phytoplankton and hydrophytes, thus, is a good indicator of the trophic state of an aquatic system. Diffuse attenuation of photosynthetic active radiation (PAR (Kd(PAR is commonly used to quantitatively assess the light availability. The PAR and the concentration of OACs were measured at 206 sites, which covered 26 lakes and reservoirs in Northeast China. The spatial distribution of Kd(PAR was depicted and its association with the OACs was assessed by grey incidences(GIs and linear regression analysis. Kd(PAR varied from 0.45 to 15.04 m−1. This investigation revealed that reservoirs in the east part of Northeast China were clear with small Kd(PAR values, while lakes located in plain areas, where the source of total suspended matter (TSM varied, displayed high Kd(PAR values. The GIs and linear regression analysis indicated that the TSM was the dominant factor in determining Kd(PAR values and best correlated with Kd(PAR (R2 = 0.906, RMSE = 0.709. Most importantly, we have demonstrated that the TSM concentration is a reliable measurement for the estimation of the Kd(PAR as 74% of the data produced a relative error (RE of less than 0.4 in a leave-one-out cross validation (LOO-CV analysis. Spatial transferability assessment of the model also revealed that TSM performed well as a determining factor of the Kd(PAR for the majority of the lakes. However, a few exceptions were identified where the optically regulating dominant factors were chlorophyll-a (Chl-a and/or the chromophroic dissolved organic matter (CDOM. These extreme cases represent lakes with exceptionally clear waters.

  4. Recombination in the human Pseudoautosomal region PAR1.

    Directory of Open Access Journals (Sweden)

    Anjali G Hinch

    2014-07-01

    Full Text Available The pseudoautosomal region (PAR is a short region of homology between the mammalian X and Y chromosomes, which has undergone rapid evolution. A crossover in the PAR is essential for the proper disjunction of X and Y chromosomes in male meiosis, and PAR deletion results in male sterility. This leads the human PAR with the obligatory crossover, PAR1, to having an exceptionally high male crossover rate, which is 17-fold higher than the genome-wide average. However, the mechanism by which this obligatory crossover occurs remains unknown, as does the fine-scale positioning of crossovers across this region. Recent research in mice has suggested that crossovers in PAR may be mediated independently of the protein PRDM9, which localises virtually all crossovers in the autosomes. To investigate recombination in this region, we construct the most fine-scale genetic map containing directly observed crossovers to date using African-American pedigrees. We leverage recombination rates inferred from the breakdown of linkage disequilibrium in human populations and investigate the signatures of DNA evolution due to recombination. Further, we identify direct PRDM9 binding sites using ChIP-seq in human cells. Using these independent lines of evidence, we show that, in contrast with mouse, PRDM9 does localise peaks of recombination in the human PAR1. We find that recombination is a far more rapid and intense driver of sequence evolution in PAR1 than it is on the autosomes. We also show that PAR1 hotspot activities differ significantly among human populations. Finally, we find evidence that PAR1 hotspot positions have changed between human and chimpanzee, with no evidence of sharing among the hottest hotspots. We anticipate that the genetic maps built and validated in this work will aid research on this vital and fascinating region of the genome.

  5. Theories on diffusion of technology

    DEFF Research Database (Denmark)

    Munch, Birgitte

    Tracing the body of the diffusion proces by analysing the diffusion process from historical, sociological, economic and technical approaches. Discussing central characteristics of the proces of diffusion og CAD/CAM in Denmark....

  6. Study of the new properties of magnetite and hematite after transformation by irradiation and by grinding; Etude des nouvelles proprietes de la magnetite et de l`hematite apres transformation par irradiation et par mecanosynthese

    Energy Technology Data Exchange (ETDEWEB)

    Meillon, S.

    1996-01-26

    We have investigated the evolution of magnetite (Fe{sub 3}O{sub 4}) and hematite ({alpha}Fe{sub 2}0{sub 3}) when faced with high energy heavy ions (5.9 6 GeV Pb) irradiation, fast neutron irradiation, and grinding. Magnetite is formed by a ceramic treatment. Heating hematite particles to about 1300 deg (under inert atmosphere) results in a conversion to magnetite. The damage induced in magnetite by high energy ion irradiation (electronic excitation) has the form of extended spherical defects (discontinuous latent tracks) in the ion wakes. High resolution electron microscopy observations have indicated only slight atomic displacements without profound modification of the structure (absence of an amorphous phase), even after high fluences (3*10{sup 12} Pb.cm{sup -2}). The results obtained by Moessbauer spectroscopy, by magnetization measurements and by low field hysteresis loops determination are coherently interpreted using a model based on magnetoelastic concepts. This model explains the restoration of the magnetic properties of magnetite after irradiation. The damage induced in magnetite and hematite following fast neutron irradiation was studied by thermal neutron diffraction. A very small variation of the lattice parameter has been observed for magnetite. The distribution of the magnetic moments of the iron ions in the tetrahedral and octahedral sites is not modified. For hematite, we have observed an expansion along the c-axis of hexagonal unit cell. This result is coherent with the results obtained by grinding. Finally, the observation of original direct phase transformation by the mechanical action of grinding is reported: hematite transforms into maghemite. As previously observed after fast neutron irradiation, here again the transition from an hexagonal (hematite) to a f.c.c lattice (maghemite) is accompanied by an expansion along the c-axis direction of the lattice. The transformation occurs through a shear sequence of oxygen planes. (Abstract Truncated)

  7. Study of hydrogenases activity inhibition by O{sub 2} and direct electrochemistry; Etude de l'inhibition par O{sub 2} de l'activite d'hydrogenases par electrochimie directe

    Energy Technology Data Exchange (ETDEWEB)

    Baffert, C.; Leger, Ch.; Leroux, F.; Bertrand, P.; Guigliarelli, B. [Laboratoire de Bioenergetique et d' Ingenierie des proteines, BIP-CNRS, 13 - Marseille (France)

    2007-07-01

    At the present time, a great effort of research is made on the identification and the design of enzymes insensitive or low sensitive to O{sub 2}. In parallel, it seems important to understand the inhibition mechanisms in order to propose mutations able to limit this inhibition. The Protein Film Voltametry allows to obtain data which can not be observed or quantitatively obtained by other techniques. The enzyme is immobilized directly on the electrode and the electronic transfer is direct. The redox state of the enzyme depends on the potential of the electrode and the catalytic current is proportional to the enzyme activity. The data obtained for the Ni-Fe hydrogenase (Desulfovibrio fructosovorans) and for the Fe hydrogenase (Clostridium Acetobutylicum) will be compared to the data obtained for hydrogenases of other organisms, by Protein Film Voltametry as well as by other techniques. (O.M.)

  8. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons; Etude de la production de faisceaux riches en neutrons par fission induite par neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Ch

    2000-09-15

    This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons.

  9. ETUDE QUANTITATIVE PAR RADIOAUTOGRAPHIE AU MICROSCOPE ELECTRONIQUE DE L'UTILISATION DE LA DL-LEUCINE-3H PAR LES CELLULES DE L'HYPOPHYSE DU CANARD EN CULTURE ORGANOTYPIQE

    Science.gov (United States)

    Tixier-Vidal, A.; Picart, R.

    1967-01-01

    The synthesis, intracellular transport, storing, and excretion of proteins by duck hypophyseal cells in organ culture were studied with tritiated DL-leucine and high resolution radioautography (pulse-labeling experiments). Quantitative study of the radioautographs allowed a determination of the relative proportions of cytoplasmic radioactivity located in each cellular compartment (ergastoplasm, Golgi apparatus, and protein granules) as well as the variations in these proportions as a function of time. The number of labeled protein granules as opposed to the total number of granules in the cell was also determined (RSg). These data were separately analyzed for the two types of cells present in the explants: prolactin cells and "MSH" cells. The synthetic process follows a course common to both cell types, each of which is distinguished by its particular modalities. The labeled proteins, synthesized within several minutes in the ergastoplasm, are concentrated in the Golgi zone within 30 min. They then migrate out of this area, the emptying of which is accomplished in about 4 hr. These proteins become equally distributed between the protein granules, on the one hand, and the cytoplasm ("sedentary" proteins), on the other. The RSg reaches its maximum when the Golgi zone is emptied, but this figure remains very low (3%). The RSg then decreases slowly (1% in 40 hr). It is concluded that hypophyseal cells are able to store protein in their granules and that their processes of synthesis and excretion are not continuous. The prolactin cells differ from the "MSH" cells in that they have a slower migration of newly synthesized proteins, and these proteins pass via the dilated ergastoplasmic cisterns in which they may possibly be stored. PMID:6064363

  10. Effects of thrombin, PAR-1 activating peptide and a PAR-1 antagonist on umbilical artery resistance in vitro

    Directory of Open Access Journals (Sweden)

    Elliott John T

    2005-02-01

    Full Text Available Abstract Background The non-thrombotic effects of thrombin in cardiovascular tissues, as mediated via the protease activated receptors (PARs, and particularly PAR-1, have been the focus of much recent research. The aims of this study were to evaluate the effects of thrombin, a specific PAR-1 activating peptide (PAR1-AP, and a PAR-1 antagonist on human umbilical artery tone in vitro. Methods Human umbilical artery samples were obtained from 17 women at term. Arterial rings were suspended under physiologic conditions for isometric recording. The in vitro effects of thrombin (0.5 units/mL to 3 units/mL, PAR1-AP TFLLR-NH2 [10(-9 to 10(-6 M], and PAR-1 antagonist (N-trans cinnamoyl- p-fluoroPhe-p-guanidinoPhe-Leu-Arg-Orn-NH2 [10(-9 M to 10(-5 M] on umbilical artery tone were measured. Results Both thrombin and TFLLR-NH2 exerted a potent cumulative vasodilatory effect on human umbilical artery resistance (P 0.05. Conclusion These findings highlight a potential role for thrombin and PAR-1 receptors in vascular regulation of feto-placental blood flow in normal pregnancy, and in association with the vascular lesions associated with IUGR and pre-eclampsia.

  11. Preliminary studies leading to a conceptual design of a 1000 MWe fast neutron reactor; Etudes preliminaires conduisant a un concept de reacteur a neutrons rapides de 1000 MWe

    Energy Technology Data Exchange (ETDEWEB)

    Vendryes, G.; Zaleski, C.P. [Association Euratom-CEA Cadarache (France). Centre d' Etudes Nucleaires

    1964-07-01

    This report presents the results of studies which seemed important to undertake in connexion with the development of fast neutron reactors. - It points out the advantage of high internal breeding ratios ({approx}1, 1) which are necessary in order to get a small change in time both in power distribution and reactivity (less: than 0.005 {delta}k/k in 18 months). - It shows how to achieve this goal, when simultaneously power distribution flattening is obtained. These results in a higher mean specific power (which is an economic gain) and therefore in a smaller doubling time (about 10 years). - It attempts to find criteria concerning the specific power that should be used in future reactor designs -It presents a conceptional design of a 1000 MWe fast neutron reactor, for the realisation of which no technological impossibility appears. - It shows that the dynamic behaviour seems satisfactory despite a positive total isothermal sodium coefficient. - It tries to predict the development of fast reactors within the future total nuclear program. It does not appear that fissile materials supply problems should in France slow down the development of fast neutron reactors, which will be essentially tied up to its economical ability to produce cheap electric power. (authors) [French] Ce rapport presente les etudes qu'il nous a paru important d'aborder dans le cadre du developpement des reacteurs a neutrons rapides. - Il met en evidence l'interet des taux de regeneration internes eleves ({approx}1, 1) pour obtenir une bonne evolution dans le temps de la distribution de puissance et de la reactivite (moins de 0,005 {delta}k/k pour 18 mois). - Il montre la possibilite d'y parvenir tout en applatissant la distribution des fissions, ce qui se traduit par une puissance specifique moyenne plus elevee (gain economique), et donc un temps de doublement plus faible de l'ordte de 10 ans - Il tente de definir un optimum de la puissance specifique valable pour les

  12. Diffusion of Wilson loops

    International Nuclear Information System (INIS)

    Brzoska, A.M.; Lenz, F.; Thies, M.; Negele, J.W.

    2005-01-01

    A phenomenological analysis of the distribution of Wilson loops in SU(2) Yang-Mills theory is presented in which Wilson loop distributions are described as the result of a diffusion process on the group manifold. It is shown that, in the absence of forces, diffusion implies Casimir scaling and, conversely, exact Casimir scaling implies free diffusion. Screening processes occur if diffusion takes place in a potential. The crucial distinction between screening of fundamental and adjoint loops is formulated as a symmetry property related to the center symmetry of the underlying gauge theory. The results are expressed in terms of an effective Wilson loop action and compared with various limits of SU(2) Yang-Mills theory

  13. On Diffusion and Permeation

    KAUST Repository

    Peppin, Stephen S. L.

    2009-01-01

    Diffusion and permeation are discussed within the context of irreversible thermodynamics. A new expression for the generalized Stokes-Einstein equation is obtained which links the permeability to the diffusivity of a two-component solution and contains the poroelastic Biot-Willis coefficient. The theory is illustrated by predicting the concentration and pressure profiles during the filtration of a protein solution. At low concentrations the proteins diffuse independently while at higher concentrations they form a nearly rigid porous glass through which the fluid permeates. The theoretically determined pressure drop is nonlinear in the diffusion regime and linear in the permeation regime, in quantitative agreement with experimental measurements. © 2009 Walter de Gruyter, Berlin, New York.

  14. Computational Diffusion MRI

    CERN Document Server

    Grussu, Francesco; Ning, Lipeng; Tax, Chantal; Veraart, Jelle

    2018-01-01

    This volume presents the latest developments in the highly active and rapidly growing field of diffusion MRI. The reader will find numerous contributions covering a broad range of topics, from the mathematical foundations of the diffusion process and signal generation, to new computational methods and estimation techniques for the in-vivo recovery of microstructural and connectivity features, as well as frontline applications in neuroscience research and clinical practice. These proceedings contain the papers presented at the 2017 MICCAI Workshop on Computational Diffusion MRI (CDMRI’17) held in Québec, Canada on September 10, 2017, sharing new perspectives on the most recent research challenges for those currently working in the field, but also offering a valuable starting point for anyone interested in learning computational techniques in diffusion MRI. This book includes rigorous mathematical derivations, a large number of rich, full-colour visualisations and clinically relevant results. As such, it wil...

  15. Isomorphism, Diffusion and Decoupling

    DEFF Research Database (Denmark)

    Boxenbaum, Eva; Jonsson, Stefan

    2017-01-01

    This chapter traces the evolution of the core theoretical constructs of isomorphism, decoupling and diffusion in organizational institutionalism. We first review the original theoretical formulations of these constructs and then examine their evolution in empirical research conducted over the past...

  16. Resilient Diffusive Clouds

    Science.gov (United States)

    2017-02-01

    RESILIENT DIFFUSIVE CLOUDS TRUSTEES OF DARTMOUTH COLLEGE FEBRUARY 2017 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC...To) SEP 2011 – SEP 2016 4. TITLE AND SUBTITLE RESILIENT DIFFUSIVE CLOUDS 5a. CONTRACT NUMBER FA8750-11-2-0257 5b. GRANT NUMBER N/A 5c. PROGRAM...diversified virtual machines. The concepts lead to a view of cloud computing in which vulnerabilities are different at every host, attackers cannot

  17. Advanced manufacturing: Technology diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Tesar, A.

    1995-12-01

    In this paper we examine how manufacturing technology diffuses rom the developers of technology across national borders to those who do not have the capability or resources to develop advanced technology on their own. None of the wide variety of technology diffusion mechanisms discussed in this paper are new, yet the opportunities to apply these mechanisms are growing. A dramatic increase in technology diffusion occurred over the last decade. The two major trends which probably drive this increase are a worldwide inclination towards ``freer`` markets and diminishing isolation. Technology is most rapidly diffusing from the US In fact, the US is supplying technology for the rest of the world. The value of the technology supplied by the US more than doubled from 1985 to 1992 (see the Introduction for details). History shows us that technology diffusion is inevitable. It is the rates at which technologies diffuse to other countries which can vary considerably. Manufacturers in these countries are increasingly able to absorb technology. Their manufacturing efficiency is expected to progress as technology becomes increasingly available and utilized.

  18. Low-Profile Diffuser

    Science.gov (United States)

    Martin, Michael A.; Nettles, Mindy

    2015-01-01

    The propellant tanks used in liquid rockets require pressurization gases in order to maintain tank pressure while the tanks are being drained during engine operation. The pressurization gas, which is typically much warmer than the relatively cold propellants in the tank, must be introduced into the empty ullage space at the top of the tank. The purpose of the diffuser is to control the flow of the gas into the tank in order to prevent direct impingement of the gas on the liquid surface and/or the tank walls. If the diffuser did not perform those tasks, the warm gas can create excess heat transfer causing an increase in the amount of pressurization mass required. Typical diffusers are long vertical cylinders that create a large exit area in order to minimize gas velocities. However, long vertical cylinders limit the amount of liquid that can be loaded into the tank in order not to have the liquid surface near the diffuser. A design goal for a pressurization diffuser is to create uniform flow in order to prevent jets that can impact the liquid surface and/or tank walls. The purpose of the task was to create a diffuser design that had a lower vertical profile (in order to be able to raise the liquid surface) while still maintaining uniform flow.

  19. Etudes physiques des mélanges eau-cryoprotecteurs

    Science.gov (United States)

    Vassoille, R.; Perez, J.

    refroidissement est souvent invoquée. Ainsi, il est possible d'éviter les dommages liés à la cristallisation : contrainte mécanique due à l'augmentation de volume, effets de sel dus à l'existence d'un gradient de pression osmotique de part et d'autre de la membrane cellulaire. Les conditions d'obtention et de maintien de cet état vitreux lors des opérations de congélation peuvent être définies par des études physiques dont nous proposons une revue.

  20. The atomic energy course of the 'Institut National des Sciences et Techniques nucleaires' at the centre d'Etudes Nucleaires at Saclay; L'enseignement de genie atomique de l'Institut national des Sciences et Techniques nucleaires au Centre d'Etudes nucleaires de Saclay

    Energy Technology Data Exchange (ETDEWEB)

    Baissas, H. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    foreign students. 8- Annexe: list of courses, practical work, pile projects drawn up by the 1957 students. (author)Fren. [French] 1- Les raisons de sa creation. L'electricite de France et l'industrie interessee par le developpement de l'Energie atomique ont demande au Commissariat a l'Energie atomique de former des ingenieurs capables d'etudier des projets de piles et de diriger leur construction. 2- Recrutement et Droits d'inscription. Les demandes d'inscription ont toujours depasse les possibilites. Cette annee, les cours sont suivis par 74 eleves permanents, dont 20 etrangers, et une centaine d'auditeurs libres. Tous les elevont deja ingenieurs ou nantis de grades universitaires eleves. Droit d'inscription: 250 000 F pour les eleves, 125 000 F pour les auditeurs. 3- Organisation de l'Enseignement. II comprend deux options: physique et chimie et dans chaque option: une centaine de conferences, une trentaine de travaux pratiques, des stages dans les services, l'etude d'un projet de reacteur par un groupe de 4 ou 5 eleves. L'ensemble occupe l'annee universitaire du 1 novembre au 14 juillet. 4- Sanction. Un examen final combinant les notes de deux epreuves theoriques, des travaux pratiques, du stage, et du projet conduit a un diplome d'ingenieur en genie atomique. Il n'est pas cree en realite de nouveaux ingenieurs; une mention nouvelle est seulement ajoutee a un diplome deja acquis. Les resultats ont toujours ete excellents. Le pourcentage des echecs est tres faible. 5- Placement des Diplomes. Ils reviennent tous dans leurs industries d'origine qui ont paye leurs salaires et les droits d'inscription en se privant de leurs services pendant les neuf mois de duree des cours. 6- Creations analogues. Un cours analogue a ete cree au Centre d'Etudes Nucleaires de Grenoble. Tandis que celui de SACLAY s'adresse plus specialement aux ingenieurs deja en fonctions, celui de Grenoble

  1. Movement and equipositioning of plasmids by ParA filament disassembly

    DEFF Research Database (Denmark)

    Ringgaard, Simon; van Zon, Jeroen; Howard, Martin

    2009-01-01

    Bacterial plasmids encode partitioning (par) loci that confer stable plasmid inheritance. We showed previously that, in the presence of ParB and parC encoded by the par2 locus of plasmid pB171, ParA formed cytoskeletal-like structures that dynamically relocated over the nucleoid. Simultaneously......, the par2 locus distributed plasmids regularly over the nucleoid. We show here that the dynamic ParA patterns are not simple oscillations. Rather, ParA nucleates and polymerizes in between plasmids. When a ParA assembly reaches a plasmid, the assembly reaction reverses into disassembly. Strikingly......, plasmids consistently migrate behind disassembling ParA cytoskeletal structures, suggesting that ParA filaments pull plasmids by depolymerization. The perpetual cycles of ParA assembly and disassembly result in continuous relocation of plasmids, which, on time averaging, results in equidistribution...

  2. Stabilization of spectra provided by a gamma-ray spectrometer. Application to the construction of a stabilizer; Stabilisation des spectres fournis par un spectrometre a rayons gamma. Application a la realisation d'un stabilisateur

    Energy Technology Data Exchange (ETDEWEB)

    Detourne, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-06-15

    This research is concerned with the stabilization of spectra provided by a gamma-ray spectrometer. It is required to hold the calibration straight line of the spectrometer in a position which is fixed initially to better than 5x10{sup -5} channel. A prototype numerical stabilizer has been constructed : the SPECTROSTAB; it is made up of two independent control loops; one of these makes the spectrometer gain depend on the derivatives of a reference peak at high energies; the other makes the origin of the energy scale depend on the derivatives of a second reference peak at low energies A theoretical study of the behaviour of a control loop shows that a direct action stabilizer gives the most accurate stabilization; the loss in resolving power on the theoretical peaks of the spectra attains about 1 % with a scintillation detector, and 10 % with a semi-conductor detector. Various tests show that the expected results are obtained and that the displacement of the spectral peaks produced by the derivatives are hidden by errors in the calculation of the peak abscissae. (author) [French] Cette etude a pour objet la stabilisation des spectres fournis par un spectrometre a rayons gamma. On veut maintenir la droite d'etalonnage du spectrometre dans une position fixee initialement a mieux de 6.10{sup -5} canal pres. On realise un prototype de stabilisateur numerique, le SPECTROSTAB; il comprend deux boucles d'asservissement independantes; l'une d'elles asservit le gain du spectrometre aux derives d'un pic de reference aux hautes energies; l'autre asservit l'origine de l'echelle des energies aux derives d'un second pic de reference aux basses energies. Une etude theorique du comportement d'une boucle d'asservissement montre qu'un stabilisateur a action directe permet la stabilisation la plus precise; la perte en resolution sur les pics theoriques des spectres atteint environ 1 % avec un detecteur a scintillateur et 10

  3. Transient Enhanced Diffusion

    Science.gov (United States)

    Gossmann, Hans-Joachim L.

    1996-03-01

    Ion implantation is the standard method for dopant introduction during integrated circuit manufacturing, determining crucial device characteristics. Implantation creates point-defects, such as Si self-interstitials and vacancies, far in excess of equilibrium concentrations. Since the diffusion of common dopants involves Si point defects, the interaction of damage and dopants during subsequent annealing steps leads to the phenomenon known as "transient enhanced diffusion" (TED): The dopant diffusivities are enhanced, possibly by many orders of magnitude. The enhancement is transient since the intrinsic defects eventually diffuse into the bulk or annihilate at the surface. The desired specific dopant profile of the device is thus the result of a complex reaction, involving the creation of damage and its spatial distribution, diffusion, and interaction of the point defects among themselves and with interfaces and other defects. As device dimensions shrink and experiments become more and more expensive, the capability to predict these kinds of non-equilibrium phenomena accurately becomes crucial to Si technology development. In our experiments to extract physical mechanisms and parameters of TED we use the method of sharp B- and Sb doping spikes to track interstitial and vacancy concentrations as a function of depth during processing. Thus we gain sensitivity to small diffusion distances (low temperatures) and separate the damaged region from the region of the interaction with dopants. In addition, our method yields directly the actual point defect diffusivity. Although an ion implant initially produces Frenkel pairs, Monte-carlo simulations show that the vacancies annihilate quickly. The excess interstitials, roughly one for each implanted ion coalesce into 311defects. The subsequent evaporation of interstitials from 311ś drives TED. Si interstitial diffusion is influenced by carbon-related traps and we will demonstrate that this finding reconciles quantitatively a

  4. Injection and temporary capture of a charged particle beam in an open magnetic configuration. Optimization of the configuration. Case of cylindrical symmetry: A mirror machine; Etude de l'injection et de la capture temporaire d'un faisceau de particules chargees dans une configuration magnetique ouverte. Optimisation de la configuration. Cas de la symetrie de revolution: Machine a miroirs

    Energy Technology Data Exchange (ETDEWEB)

    Capdequi-Peyranere, P. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-12-01

    A study has been made of a new method of transverse injection of charged particles into a magnetic mirror configuration. This injection scheme permits the penetration and temporary capture by non-adiabatic effect of a particle beam of approximately 1 cm{sup 2} cross-section. A theoretical study of the injection and capture is made in the approximation that space charge is negligible. The original programs for IBM 7094 computer calculations are described; these programs were used to obtain an optimization of the configuration. The results of a statistical numerical study of the optimum configuration are then given. This study indicates that, if the energy of the particles of the beam is about 1 per cent greater than a minimum penetration energy, the entire beam can be captured with an average capture length of 100 meters (50 reflections between the two mirrors). If the energy is about 4 per cent greater than the minimum penetration energy, the capture length is reduced to 40 meters. We have studied the distribution of energy transverse and longitudinal with the magnetic field for the population of captured particles. For the cases of injected molecular hydrogen ions or heavy CH{sub 4}{sup +} ions, a study is made of the capture time of protons resulting from the dissociation of the ions by collisions with the neutral gas. Finally, we describe a model experiment using electrons designed to provide an experimental verification of the capture of the primary beam. (author) [French] On etudie un nouveau schema d'injection transversale de particules chargees dans une configuration magnetique a miroirs. Ce mode d'injection permet la penetration et la capture temporaire par effet non adiabatique d'un faisceau de particules presentant une section de l'ordre de 1 cm{sup 2}. Une etude theorique du probleme de l'injection et de la capture est faite en supposant la charge d'espace negligeable. On decrit des programmes originaux de calcul sur

  5. Limnological database for Par Pond: 1959 to 1980

    Energy Technology Data Exchange (ETDEWEB)

    Tilly, L.J.

    1981-03-01

    A limnological database for Par Pond, a cooling reservoir for hot reactor effluent water at the Savannah River Plant, is described. The data are derived from a combination of research and monitoring efforts on Par Pond since 1959. The approximately 24,000-byte database provides water quality, primary productivity, and flow data from a number of different stations, depths, and times during the 22-year history of the Par Pond impoundment. The data have been organized to permit an interpretation of the effects of twenty years of cooling system operations on the structure and function of an aquatic ecosystem.

  6. Limnological database for Par Pond: 1959 to 1980

    International Nuclear Information System (INIS)

    Tilly, L.J.

    1981-03-01

    A limnological database for Par Pond, a cooling reservoir for hot reactor effluent water at the Savannah River Plant, is described. The data are derived from a combination of research and monitoring efforts on Par Pond since 1959. The approximately 24,000-byte database provides water quality, primary productivity, and flow data from a number of different stations, depths, and times during the 22-year history of the Par Pond impoundment. The data have been organized to permit an interpretation of the effects of twenty years of cooling system operations on the structure and function of an aquatic ecosystem

  7. PSD-Constrained PAR Reduction for DMT/OFDM

    Science.gov (United States)

    Andgart, Niklas; Krongold, Brian S.; Ödling, Per; Johansson, Albin; Börjesson, Per Ola

    2004-12-01

    Common to all DMT/OFDM systems is a large peak-to-average ratio (PAR), which can lead to low power efficiency and nonlinear distortion. Tone reservation uses unused or reserved tones to design a peak-canceling signal to lower the PAR of a transmit block. In DMT ADSL systems, the power allocated to these tones may be limited due to crosstalk issues with many users in one twisted pair bundle. This PSD limitation not only limits PAR reduction ability, but also makes the optimization problem more challenging to solve. Extending the recently proposed active set tone reservation method, we develop an efficient algorithm with performance close to the optimal solution.

  8. Lead diffusion in monazite

    International Nuclear Information System (INIS)

    Gardes, E.

    2006-06-01

    Proper knowledge of the diffusion rates of lead in monazite is necessary to understand the U-Th-Pb age anomalies of this mineral, which is one of the most used in geochronology after zircon. Diffusion experiments were performed in NdPO 4 monocrystals and in Nd 0.66 Ca 0.17 Th 0.17 PO 4 polycrystals from Nd 0.66 Pb 0.17 Th 0.17 PO 4 thin films to investigate Pb 2+ + Th 4+ ↔ 2 Nd 3+ and Pb 2+ ↔ Ca 2+ exchanges. Diffusion annealings were run between 1200 and 1500 Celsius degrees, at room pressure, for durations ranging from one hour to one month. The diffusion profiles were analysed using TEM (transmission electronic microscopy) and RBS (Rutherford backscattering spectroscopy). The diffusivities extracted for Pb 2+ + Th 4+ ↔ 2 Nd 3+ exchange follow an Arrhenius law with parameters E equals 509 ± 24 kJ mol -1 and log(D 0 (m 2 s -1 )) equals -3.41 ± 0.77. Preliminary data for Pb 2+ ↔ Ca 2+ exchange are in agreement with this result. The extrapolation of our data to crustal temperatures yields very slow diffusivities. For instance, the time necessary for a 50 μm grain to lose all of its lead at 800 Celsius degrees is greater than the age of the Earth. From these results and other evidence from the literature, we conclude that most of the perturbations in U-Th-Pb ages of monazite cannot be attributed to lead diffusion, but rather to interactions with fluids. (author)

  9. Diffusion tensor imaging of the nigrostriatal fibers in Parkinson's disease.

    Science.gov (United States)

    Zhang, Yu; Wu, I-Wei; Buckley, Shannon; Coffey, Christopher S; Foster, Eric; Mendick, Susan; Seibyl, John; Schuff, Norbert

    2015-08-01

    Parkinson's disease (PD) is histopathologically characterized by the loss of dopamine neurons in the substantia nigra pars compacta. The depletion of these neurons is thought to reduce the dopaminergic function of the nigrostriatal pathway, as well as the neural fibers that link the substantia nigra to the striatum (putamen and caudate), causing a dysregulation in striatal activity that ultimately leads to lack of movement control. Based on diffusion tensor imaging, visualizing this pathway and measuring alterations of the fiber integrity remain challenging. The objectives were to 1) develop a diffusion tensor tractography protocol for reliably tracking the nigrostriatal fibers on multicenter data; 2) test whether the integrities measured by diffusion tensor imaging of the nigrostriatal fibers are abnormal in PD; and 3) test whether abnormal integrities of the nigrostriatal fibers in PD patients are associated with the severity of motor disability and putaminal dopamine binding ratios. Diffusion tensor tractography was performed on 50 drug-naïve PD patients and 27 healthy control subjects from the international multicenter Parkinson's Progression Marker Initiative. Tractography consistently detected the nigrostriatal fibers, yielding reliable diffusion measures. Fractional anisotropy, along with radial and axial diffusivity of the nigrostriatal tract, showed systematic abnormalities in patients. In addition, variations in fractional anisotropy and radial diffusivity of the nigrostriatal tract were associated with the degree of motor deficits in PD patients. Taken together, the findings imply that the diffusion tensor imaging characteristic of the nigrostriatal tract is potentially an index for detecting and staging of early PD. © 2015 International Parkinson and Movement Disorder Society.

  10. ETUDES EXPERIMENTALES EN ACOUSTIQUE : DE L'ELASTOGRAPHIE AUX CAVITES REVERBERANTES

    OpenAIRE

    Catheline, Stefan

    2006-01-01

    Le premier chapitre de ce mémoire porte sur l'élastographie transitoire, une nouvelle technique ultrasonore capable de cartographier l'élasticité de cisaillement du corps humain. Cette information est utilisée depuis longtemps par les médecins lorsqu'ils procèdent à un examen par palpation. Un outil de palpation ultrasonore pourrait être extrêmement efficace pour dépister ou diagnostiquer certains cancers comme celui du sein par exemple. C'est le sujet de la première partie. La thèse de Laure...

  11. Protease-activated receptor (PAR2, but not PAR1, is involved in collateral formation and anti-inflammatory monocyte polarization in a mouse hind limb ischemia model.

    Directory of Open Access Journals (Sweden)

    Lisa G van den Hengel

    Full Text Available AIMS: In collateral development (i.e. arteriogenesis, mononuclear cells are important and exist as a heterogeneous population consisting of pro-inflammatory and anti-inflammatory/repair-associated cells. Protease-activated receptor (PAR1 and PAR2 are G-protein-coupled receptors that are both expressed by mononuclear cells and are involved in pro-inflammatory reactions, while PAR2 also plays a role in repair-associated responses. Here, we investigated the physiological role of PAR1 and PAR2 in arteriogenesis in a murine hind limb ischemia model. METHODS AND RESULTS: PAR1-deficient (PAR1-/-, PAR2-deficient (PAR2-/- and wild-type (WT mice underwent femoral artery ligation. Laser Doppler measurements revealed reduced post-ischemic blood flow recovery in PAR2-/- hind limbs when compared to WT, while PAR1-/- mice were not affected. Upon ischemia, reduced numbers of smooth muscle actin (SMA-positive collaterals and CD31-positive capillaries were found in PAR2-/- mice when compared to WT mice, whereas these parameters in PAR1-/- mice did not differ from WT mice. The pool of circulating repair-associated (Ly6C-low monocytes and the number of repair-associated (CD206-positive macrophages surrounding collaterals in the hind limbs were increased in WT and PAR1-/- mice, but unaffected in PAR2-/- mice. The number of repair-associated macrophages in PAR2-/- hind limbs correlated with CD11b- and CD115-expression on the circulating monocytes in these animals, suggesting that monocyte extravasation and M-CSF-dependent differentiation into repair-associated cells are hampered. CONCLUSION: PAR2, but not PAR1, is involved in arteriogenesis and promotes the repair-associated response in ischemic tissues. Therefore, PAR2 potentially forms a new pro-arteriogenic target in coronary artery disease (CAD patients.

  12. Anomalous Diffusion Near Resonances

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Tanaji; /Fermilab

    2010-05-01

    Synchro-betatron resonances can lead to emittance growth and the loss of luminosity. We consider the detailed dynamics of a bunch near such a low order resonance driven by crossing angles at the collision points. We characterize the nature of diffusion and find that it is anomalous and sub-diffusive. This affects both the shape of the beam distribution and the time scales for growth. Predictions of a simplified anomalous diffusion model are compared with direct simulations. Transport of particles near resonances is still not a well understood phenomenon. Often, without justification, phase space motion is assumed to be a normal diffusion process although at least one case of anomalous diffusion in beam dynamics has been reported [1]. Here we will focus on the motion near synchro-betatron resonances which can be excited by several means, including beams crossing at an angle at the collision points as in the LHC. We will consider low order resonances which couple the horizontal and longitudinal planes, both for simplicity and to observe large effects over short time scales. While the tunes we consider are not practical for a collider, nonetheless the transport mechanisms we uncover are also likely to operate at higher order resonances.

  13. Positron Accumulator Ring (PAR) power supply

    International Nuclear Information System (INIS)

    Fathizadeh, M.

    1995-01-01

    The Positron Accumulator Ring (PAR) consists of 8 dipole magnets connected in series. These magnets are energized via one 12-pulse dc power supply. The power supply consists of four phase controlled half-wave wye group converters. Each of the two half-wave converters are connected through an interphase transformer to obtain a full-wave converter with 120 degrees conduction. The input voltage for these two half-wave converters are 180 degrees apart. The two full-wave converters are connected in parallel through a third interphase transformer. This type of connection of the converters not only provides the required output current, it also improves the input power factor of the power supply. The output of the wye group converters is filtered through a passive L-R-C filter to reduce the ripple content of the output current. At low current values of the power supply the current ripple is high, thus a large filter is needed, which adds to the cost of the power supply, however at high output current levels, the current ripple is less severe. The large size of the filter can be reduced by adding an anti-parallel rectifier diode(D1) to the output of the power supply. A freewheeling diode(D2) is connected before the choke to circulate the current once the power supply is turned off. In order to measure the current in the magnet a high precision, low drift, zero flux current transductor is used. This transductor senses the magnet current which provides a feedback signal to control the gating of the converter's thyristors. A true 14 bit Digital to Analog Converter (DAC) is programmed by the control computer for the required current value, providing a reference for the current regulator. Fast correction of the line transients is provided by a relatively fast voltage loop controlled by a high gain slow response current loop

  14. Parálisis cerebral Cerebral palsy

    Directory of Open Access Journals (Sweden)

    Jorge Malagon Valdez

    2007-01-01

    Full Text Available El término parálisis cerebral (PC engloba a un gran número de síndromes neurológicos clínicos, de etiología diversa. Estos síndromes se caracterizan por tener una sintomatología común: los trastornos motores. Algunos autores prefieren manejar términos como "encefalopatía fija", "encefalopatías no evolutivas". Se mencionan la utilidad de programas de intervención temprana y métodos especiales de rehabilitación, así como el manejo de las deficiencias asociadas como la epilepsia, deficiencia mental, trastornos del lenguaje, audición, visión, déficit de la atención que mejoran el pronóstico de manera significativa. El pronóstico también depende de la gravedad del padecimiento y de las manifestaciones asociadas.The term cerebral palsy (CP, is used for a great number of clinical neurological syndromes. The syndromes are characterized by having a common cause, motor defects. It is important, because they can cause a brain damage by presenting motor defects and some associated deficiencies, such as mental deficiency, epilepsy, language and visual defects and pseudobulbar paralysis, with the nonevolving fact. Some authors prefer using terms such as "non-evolving encephalopathies". In the treatment the utility of prevention programs of early stimulation and special rehabilitation methods, and treatment of associated deficiencies such as epilepsy, mental deficiency, language, audition and visual problems, and the attention deficit improve the prognosis in an important way. The prognosis depends on the severity of the disease and the associated manifestations.

  15. Préparation et carectérisation du vanadium supporté sur la bentonite activée par acide. Application à l'oxydation du cyclohexane et à l'épxydation de cyclohexene.

    OpenAIRE

    AMIRI, ABDELALI

    2014-01-01

    Pa ge 26 Notre étude avait pour but la préparation des catalyseurs à base de vanadium supporté sur Montmorillonite activé par acide. Ces matériaux sont caractérisés par UV-vis et IR, ils sont testés ensuite dans l’oxydation du cyclohexane et désoxydation du cyclo hexene.L’analyse par UV- vis à réflexion diffuse du catalyseur V/H-Mont montre un pic autour 320 nm attribué à l’espèce du vanadium tétraédrique.La caractérisation par IR montre la présence des ponts entre le support et le vana...

  16. Spectroscopie résolue en temps par continuum femtoseconde Applications en neurobiologie

    Science.gov (United States)

    Ramstein, S.; Mottin, S.

    2003-06-01

    La spectroscopie résolue en temps utilisant un laser blanc femtoseconde est appliquée à la mesure in vivo des principaux absorbeurs du cerveau. Après génération adéquate du continuum de lumière blanche femtoseconde (50mW/[580-756nm] à 1Hz), cette source se propage dans la calvaria, les méninges et le cortex chez le rat anesthésié. La transmission est étudiée sur 7mm de distance entre l'impact laser et la fibre optique de collection. Le signal transmis est analysé dans la fenêtre 580-760nm, par un spectromètre couplé à une caméra à balayage de fente permettant la décorrélation de l'absorption et de la diffusion.

  17. First-in-human uPAR PET

    DEFF Research Database (Denmark)

    Persson, Morten; Skovgaard, Dorthe; Brandt-Larsen, Malene

    2015-01-01

    A first-in-human clinical trial with Positron Emission Tomography (PET) imaging of the urokinase-type plasminogen activator receptor (uPAR) in patients with breast, prostate and bladder cancer, is described. uPAR is expressed in many types of human cancers and the expression is predictive...... of invasion, metastasis and indicates poor prognosis. uPAR PET imaging therefore holds promise to be a new and innovative method for improved cancer diagnosis, staging and individual risk stratification. The uPAR specific peptide AE105 was conjugated to the macrocyclic chelator DOTA and labeled with (64)Cu...... for targeted molecular imaging with PET. The safety, pharmacokinetic, biodistribution profile and radiation dosimetry after a single intravenous dose of (64)Cu-DOTA-AE105 were assessed by serial PET and computed tomography (CT) in 4 prostate, 3 breast and 3 bladder cancer patients. Safety assessment...

  18. La preuve apportée par les sciences

    Directory of Open Access Journals (Sweden)

    1997-04-01

    Full Text Available A propos d´une enquête menée par deux immunologistes de l´Université de Göteborg, rapportée par la très sérieuse revue Nature, le journal Le Monde n´hésitait pas à titrer : " La preuve du sexisme apportée par les sciences ". Les auteurs avaient en effet pu démontrer, irréfutables tests statistiques à l´appui, que, pour obtenir une bourse de post-doctorat offerte par le Swedisch Medical Research Council, les femmes devaient être deux fois et demie plus productives que les hommes ! Nous voulons...

  19. Distributed Control Diffusion

    DEFF Research Database (Denmark)

    Schultz, Ulrik Pagh

    2007-01-01

    . Programming a modular, self-reconfigurable robot is however a complicated task: the robot is essentially a real-time, distributed embedded system, where control and communication paths often are tightly coupled to the current physical configuration of the robot. To facilitate the task of programming modular....... This approach allows the programmer to dynamically distribute behaviors throughout a robot and moreover provides a partial abstraction over the concrete physical shape of the robot. We have implemented a prototype of a distributed control diffusion system for the ATRON modular, self-reconfigurable robot......, self-reconfigurable robots, we present the concept of distributed control diffusion: distributed queries are used to identify modules that play a specific role in the robot, and behaviors that implement specific control strategies are diffused throughout the robot based on these role assignments...

  20. Cesium diffusion in graphite

    International Nuclear Information System (INIS)

    Evans, R.B. III; Davis, W. Jr.; Sutton, A.L. Jr.

    1980-05-01

    Experiments on diffusion of 137 Cs in five types of graphite were performed. The document provides a completion of the report that was started and includes a presentation of all of the diffusion data, previously unpublished. Except for data on mass transfer of 137 Cs in the Hawker-Siddeley graphite, analyses of experimental results were initiated but not completed. The mass transfer process of cesium in HS-1-1 graphite at 600 to 1000 0 C in a helium atmosphere is essentially pure diffusion wherein values of (E/epsilon) and ΔE of the equation D/epsilon = (D/epsilon) 0 exp [-ΔE/RT] are about 4 x 10 -2 cm 2 /s and 30 kcal/mole, respectively