11,671 research outputs found

    Λb\Lambda_b Decays into Λ\Lambda-Vector

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    A complete study of the angular distributions of the processes, Λb→ΛV(1−)\Lambda_b \to {\Lambda} V(1^-), with Λ→pπ−\Lambda \to p {\pi}^- and V(J/Κ)→ℓ+ℓ−V (J/{\Psi}) \to {\ell}^+ {\ell}^- or V(ρ0,ω)→π+π−,V ({\rho}^0,\omega) \to {\pi}^+ {\pi}^-, is performed. Emphasis is put on the initial Λb\Lambda_b polarization produced in the proton-proton collisions. The polarization density-matrices as well as angular distributions are derived and help to construct T-odd observables which allow us to perform tests of both Time-Reversal and CP violation.Comment: 10 pages, 2 figure

    Les petites activitĂ©s de pĂȘche dans le Pacifique Sud

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    Les cinq archipels qui composent l'actuelle PolynĂ©sie française comptent 120 Ăźles dont des Ăźles volcaniques et des atolls, essentiellement aux Tuamotu. Comme pour la plupart des Ăźles du Pacifique, les recherches archĂ©ologiques dans cette rĂ©gion en sont encore Ă  leurs balbutiements - les premiĂšres fouilles ne datent que des annĂ©es cinquante - et les connaissances sur la prĂ©histoire sont trĂšs fragmentaires, le plus souvent conjecturelles. On pense que les archipels centraux de la PolynĂ©sie orientale - au nombre desquelles se trouvent ceux de la PolynĂ©sie française - ont Ă©tĂ© colonisĂ©s juste avant notre Ăšre, encore que les dates aussi anciennes soient rares, discutĂ©es, et ne se rencontrent qu'aux Cook du Nord et aux Marquises. Ce peuplement s'effectua depuis la PolynĂ©sie occidentale (Tonga et/ou Samoa) oĂč des groupes porteurs de la fameuse poterie #lapita$ s'Ă©taient installĂ©s plusieurs siĂšcles auparavant au terme d'une rapide expansion depuis l'Asie du Sud-Est et la MĂ©lanĂ©sie occidentale et avaient Ă©voluĂ© culturellement jusqu'Ă  constituer vers 500 BC "la sociĂ©tĂ© polynĂ©sienne ancestrale" (GREEN, 1979 ; KIRCH, 1984 ; CONTE, 1992). Les premiers occupants de la PolynĂ©sie française, issus de ces populations qui colonisĂšrent les Ăźles du Pacifique, avaient donc une frĂ©quentation millĂ©naire de la mer et de l'exploitation de ses ressources. (D'aprĂšs rĂ©sumĂ© d'auteur

    Modeling population dynamics and economic growth as competing species: An application to CO2 global emissions

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    Since the beginning of the last century the world is experiencing an important demographic transition, which will probably impact on economic growth. Many demographers and social scientists are trying to understand the key drivers of such transition as well as its profound implications. A correct understanding will help to predict other important trends of the world primary energy demand and the carbon emission to the atmosphere, which may be leading to an important climate change. This paper proposes a set of coupled differential equations to describe the changes of population, gross domestic product, primary energy consumption and carbon emissions, modeled as competing-species as in Lokta-Volterra prey-predator relations. The predator–prey model is well known in the biological, ecological and environmental literature and has also been applied successfully in other fields. This model proposes a new and simple conceptual explanation of the interactions and feedbacks among the principal driving forces leading to the present transition. The estimated results for the temporal evolution of world population, gross domestic product, primary energy consumption and carbon emissions are calculated from year 1850 to year 2150. The calculated scenarios are in good agreement with common world data and projections for the next 100 years.Population dynamics, economic growth, primary energy consumption, carbon emission model, Lokta-Volterra Equations, Prey-predator model.

    Screening of Rayleigh Waves by Open Trenches

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    This paper presents results of a numerical study on the effectiveness of open trenches in reducing the ground vibration caused by propagating Rayleigh waves. The analysis is performed in the frequency domain and under conditions of plane strain using the Boundary Element Method. The soil is modelled as a homogeneous isotropic linear elastic half space. In order to represent the screening effect due to the installation of the barrier, the index ER is introduced. ER is defined as the ratio of the rate of energy transmission over the area to be protected in the presence of the trench and that without the trench. By means of ER, the influence of several parameters on the screening efficiency of the trench is investigated in some detail

    Angular Analysis of Lambda_b Decays into Lambda v(1-) Applications to Time-Odd Observables and CP violation in Lambda_b Decays (I)

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    A complete study of teh angualr distributions of the process Lambda_b to Lambda V(1-) with lambda to p pi- and V(J/Psi) to l+l- or V(rho0,omega, phi) to pi+ pi-, K+K- is performed. Emphasis is put on the initial Lambda-b polarization produced in the proton-proton collisions and, without any dynamical assumption, polarized density-matrices of the vector-mesons V are derived and help to construct T-odd observables which allow us to perform tests of both Time-Reversal and CP violation.Comment: 12 pages, 2 figure

    Summer air temperature anomalies in Europe during the century 1811-1910

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    Solar cycle, volcanic eruptions, sea surface temperature anomalies (ENSO) and increase of the concentration of the greenhouse gases are the main forcing factors in the evolution of the Earth climate. Therefore, a sizeable amount of research is devoted to assess the impact of these factors on the climate parameters, as the mean air temperature. In the present work a study concerning the behaviour of the summer temperatures over Europe during the century 1811-1910 is carried out. The possible influence of the volcanic eruptions and ENSO has been also analysed. The results show the presence of a volcanic signal in the summer temperature during the year following an eruption, even if the anomalous coldest summers do not seem to be driven by the volcanic activity. The connection between thermal anomalies and ENSO events is more uncertain because of the paucity of data. Finally, the anomalous summers—both very cold and very warm—can be explained in terms of the atmospheric circulation, since cold events seem to be associated to persistent blocking systems and warm events are associated to persistent high-pressure patterns

    Rainfall over the Central-Western Mediterranean basin in the period 1951-1995. Part I: precipitation trends

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    Climatic changes due to the anthropic enhancement of the greenhouse effect could modify the hydrological cycle, resulting in a reduction of the precipitation over the Mediterranean basin. In particular, a negative trend over the Italian peninsula could occur with prolonged periods of dryness as that recorded in the biennium 1988-1990. In order to verify if a climatic variability is already detectable, the pluviometric regime over the Central-Western Mediterranean is here analysed for the period 1951-1995. The analysis indicates that a reduction of about 20% in the total precipitation has occurred, which is statistically significant and can have serious impact on the availability of the water supplies

    Settlement patterns of two spirorbidae (annelida, polychaeta) species in the harbour of Ischia (Gulf of Naples, Mediterranean Sea)

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    Studies on settlement rate of Neodexiospira pseudocorrugata and Simplaria pseudomilitaris (Polychaeta, Spirorbidae) in the Port of Ischia (Naples) are reported. Observations were carried out monthly, during a one-year cycle (April 1995-April 1996) at two different depths (0.5 and 1.5 m) using unglazed ceramic tiles as substrate. Both species reproduced throughout the year with maximum settlement in June and July at 1.5 m depth. On tiles exposed during June, 40% of individuals of N. pseudocorrugata, ranging between 0.8 and 1.6 mm coil diameter, were brooding, with broods smaller (6–14 eggs, egg diameter 75 um) than in most spirorbid species. Simplaria pseudomilitaris did not reach brooding size within any of the monthly exposure periods. In and after August, an algal bloom of attached brown filaments (Ectocarpa-ceae) covered the tiles and was accompanied by decreased settlement and heavy mortality of spirorbids. © 2000 Taylor & Francis Group, LLC

    Towards a public analysis database for LHC new physics searches using MadAnalysis 5

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    We present the implementation, in the MadAnalysis 5 framework, of several ATLAS and CMS searches for supersymmetry in data recorded during the first run of the LHC. We provide extensive details on the validation of our implementations and propose to create a public analysis database within this framework.Comment: 20 pages, 15 figures, 5 recast codes; version accepted by EPJC (Dec 22, 2014) including a new section with guidelines for the experimental collaborations as well as for potential contributors to the PAD; complementary information can be found at http://madanalysis.irmp.ucl.ac.be/wiki/PhysicsAnalysisDatabas
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