2,054 research outputs found

    La Formation du Grand Essert (Jura franco-suisse; Valanginien supérieur p.p. à Hauterivien supérieur basal)

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    Le terme de Formation du Grand Essert a Ă©tĂ© proposĂ© en 2016 pour remplacer ceux de « Marnes d’Hauterive » auct. et « Pierre jaune de NeuchĂątel » auct. attribuĂ©s Ă  l’« Hauterivien » auct. dans le Jura franco-suisse. L’objet de cette note est, dans un premier temps, de dĂ©crire et d’interprĂ©ter la lithologie de la coupe-type reprĂ©sentative de cette nouvelle formation, d’une Ă©paisseur de 112,5 m, relevĂ©e dans la localitĂ©-type du Grand Essert le long de la route D991, entre Confort et ChĂ©sery, sur la rive gauche de la vallĂ©e de la Valserine (Jura mĂ©ridional, Ain, France). La Formation du Grand Essert comprend, Ă  la base, le Membre d’Hauterive composĂ© de 52 m de marnes dans lesquelles apparaissent des bancs et des nodules calcaires contenant souvent des grains de quartz et de glauconie. Les faciĂšs indiquent un milieu calme en dessous de la limite de l’action des vagues de beau temps, avec l’apport pĂ©riodique de matĂ©riel bioclastique allochtone. Au-dessus, le Membre de NeuchĂątel d’une Ă©paisseur de 60,5 m se compose de calcaires bioclastiques localement quartzo-glauconieux. Au sein de ce membre s’intercale un horizon marneux d’origine marine, les Marnes des Uttins. Les bancs calcaires montrent des structures sĂ©dimentaires entrecroisĂ©es qui suggĂšrent la prĂ©sence de courants tidaux. Dans un deuxiĂšme temps, les auteurs proposent des corrĂ©lations basĂ©es sur la biostratigraphie (ammonites et dinokystes) et l’analyse sĂ©quentielle, entre la coupe-type et d’autres coupes et forages publiĂ©s dans le Jura franco-suisse. La corrĂ©lation avec une coupe du Bassin vocontien (Haut Vergons) permet de discuter jusqu’à quel point l’enregistrement sĂ©dimentaire de la Formation du Grand Essert Ă©tait contrĂŽlĂ© par des fluctuations du niveau marin. Finalement, les ammonites et dinokystes permettent de bien dater la Formation du Grand Essert qui s’étend du Valanginien supĂ©rieur pro parte jusqu’à la base de l’Hauterivien supĂ©rieur. Le Membre d’Hauterive commence dans la zone Ă  Peregrinus. L’intervalle Peregrinus-Furcillata est partout fortement condensĂ© (comme la partie sommitale de la Formation du Vuache sous-jacente dans le Jura neuchĂątelois) tandis que les sĂ©diments de la zone Ă  Radiatus sont bien reprĂ©sentĂ©s. La limite entre le Membre d’Hauterive et le Membre de NeuchĂątel se situe dans la zone Ă  Loryi. Le Membre de NeuchĂątel occupe la partie supĂ©rieure de la zone Ă  Loryi et toute la zone Ă  Nodosoplicatum. La limite Nodosoplicatum / Sayni se trouve au sein de la partie sommitale du Membre de NeuchĂątel. La base de la Formation des Gorges de l’Orbe sus-jacente est datĂ©e de la zone Ă  Sayni

    Local order around rare earth ions during the devitrification of oxyfluoride glasses.

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    International audienceErbium L(3)-edge extended x-ray absorption fine structure (EXAFS) measurements were performed on rare earth doped fluorosilicate and fluoroborate glasses and glass ceramics. The well known nucleating effects of erbium ions for the crystallization of cubic lead fluoride (based on x-ray diffraction measurements) and the fact that the rare earth ions are present in the crystalline phase (as indicated by Er(3+) emission spectra) seem in contradiction with the present EXAFS analysis, which indicates a lack of medium range structural ordering around the Er(3+) ions and suggests that the lead fluoride crystallization does not occur in the nearest neighbor distance of the rare earth ion. Molecular dynamics simulations of the devitrification process of a lead fluoride glass doped with Er(3+) ions were performed, and results indicate that Er(3+) ions lower the devitrification temperature of PbF(2), in good agreement with the experimental results. The genuine role of Er(3+) ions in the devitrification process of PbF(2) has been investigated. Although Er(3+) ions could indeed act as seeds for crystallization, as experiments suggest, molecular dynamics simulation results corroborate the experimental EXAFS observation that the devitrification does not occur at its nearest neighbor distance

    Le sanctuaire gallo-romain de Vieille-Cour Ă  Mauves-sur-Loire (Loire-Atlantique): bilan des connaissances

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    Le sanctuaire de l’agglomĂ©ration antique de Mauves-sur-Loire (Loire-Atlantique) a Ă©tĂ© fouillĂ© en 1885-1886, 1966 et 1976-1979, mais est restĂ© pratiquement inĂ©dit. La reprise de l’ensemble de la documentation de fouille permet d’en proposer une lecture renouvelĂ©e. AprĂšs une occupation latĂ©nienne d’interprĂ©tation malaisĂ©e, les phases principales datent du dĂ©but du iersiĂšcle, du dernier tiers de ce mĂȘme siĂšcle et du milieu du iie: elles signent le passage d’une aire cultuelle relativement modeste, oĂč aucun temple n’a pu ĂȘtre reconnu, Ă  un temple romano-celtique lui-mĂȘme transformĂ© ensuite en un Ă©difice pĂ©riptĂšre sur podium. Le sanctuaire est abandonnĂ© dans le courant de la seconde moitiĂ© du ivesiĂšcle de notre Ăšre. Les mobiliers associĂ©s font l’objet d’une Ă©tude plus ou moins complĂšte suivant les cas, Ă  vocation chronologique ou thĂ©matique.The sanctuary of the Gallo-Roman small town of Mauves-sur-Loire (Loire-Atlantique) was excavated in 1885-1886, 1966 and 1976-1979, but has so far remained practically unpublished. Going back over the whole documentation related to the excavation now provides an opportunity to cast a new light on these documents. After a La Tene occupation which is not easy to interpret, the three main phases date from the the early 1st century AD, the last third of the same century, and the middle 2nd one : they signal the passage from a relatively small worship area, where no temple could be recognized, to a Romano-Celtic temple, which itself was then transformed into a pillared bulding on podium. The sanctuary was abandoned during the second half of 4th century. Associated assemblages are the subject of a study which, depending on the topics, is more or less comprehensive, and which is conducted from a chronological or thematic standpoint

    The adoption of open access scholarly communication in Tanzanian public universities: some Influencing factors

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    Open access is a means for free availability of scholarly content via the internet. It is an emerging opportunity for wider and unlimited access to scholarly literature. Scholarly communication, through open access journals and self-arching, are the two main approaches of open access publishing. However, this mode of scholarly communication is not widely utilised in developing countries such as Tanzania. This article discusses the factors that influence the adoption of open access for scholarly communication in Tanzanian public universities, based on a study conducted in 2008 using a survey questionnaire. A sample of 544 researchers, selected through stratified random sampling from a population of 1 088 researchers and 69 policymakers at six public universities in Tanzania, provided their views. It was evident from the findings that researchers’ internet usage skills and self-efficacy, social influence, performance expectancy, effort expectancy, and the respondents’ general perceptions about open access were the positive factors likely to facilitate open access adoption. The current poor research conditions and researchers’ low internet self-efficacy (such as inadequate information search skills) were cited as the main hindrances for researchers to use open access outlets to access scholarly content. It is therefore recommended that university policies on scholarly communication should be revised to incorporate the use of open access publishing. Furthermore, universities should accelerate the establishment of institutional repositories, advocacy campaigns and training directed at researchers, policymakers, readers and information managers of scholarly content, and the improvement of internet speed through subscription to more bandwidth, so as to meet the demand from the scholarly communit

    Focus topics for the ECFA study on Higgs / Top / EW factories

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    In order to stimulate new engagement and trigger some concrete studies in areas where further work would be beneficial towards fully understanding the physics potential of an e+e−e^+e^- Higgs / Top / Electroweak factory, we propose to define a set of focus topics. The general reasoning and the proposed topics are described in this document.Comment: v3: fixed spelling of two author

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð„with constraintsð ð ð„ „ ðandðŽð„ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

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    The production of tt‟ , W+bb‟ and W+cc‟ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓΜ , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of tt‟t\overline{t}, W+bb‟W+b\overline{b} and W+cc‟W+c\overline{c} is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 ±\pm 0.02 \mbox{fb}^{-1}. The WW bosons are reconstructed in the decays W→ℓΜW\rightarrow\ell\nu, where ℓ\ell denotes muon or electron, while the bb and cc quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

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    A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

    Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

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    Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a ZZ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 <pT<100< p_{\textrm{T}} < 100 GeV and in the pseudorapidity range 2.5<η<42.5 < \eta < 4. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb−1^{-1}. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages
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