9,290 research outputs found

    Study of psi' and chi_c decays as feed-down sources of J/psi hadro-production

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    The interpretation of the J/psi suppression patterns observed in nuclear collisions, at CERN and RHIC, as a signature of the formation of a deconfined phase of QCD matter, requires knowing which fractions of the measured J/psi yields, in pp collisions, are due to decays of heavier charmonium states. From a detailed analysis of the available mid-rapidity charmonium hadro-production cross sections, or their ratios, we determine that the J/psi feed-down contributions from psi' and chi_c decays are, respectively, (8.1 +/- 0.3) % and (25 +/- 5) %. These proton-proton values are derived from global averages of the proton-nucleus measurements, assuming that the charmonium states are exponentially absorbed with the length of matter they traverse in the nuclear targets.Comment: 12 pages, 4 figures, 3 table

    From ‘creative cities’ to ‘urban creativity’? Space, creativity and governance in the contemporary city

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    DINÂMIA, Dezembro de 2009This paper derives from a broader research program studying the forms of governance associated with creative dynamics in cities (the “Creatcity” project) and draws on the first empirical results generated by the study following analysis of a set of exploratory interviews involving actors central to thinking and acting on the contemporary city (political decision makers, official structures and civil society) in the three metropolitan areas selected for the project: Lisbon (Portugal), São Paulo (Brazil) and Barcelona (Spain). Analysis of the responses sought to identify the different perspectives on the concepts of urban creativity and creative city and the relationship between creativity, vitality and competitivity within urban contexts while seeking to understand interviewee perspectives on the structural conditions necessary for the development of creativity in the city in terms of spatial/geographic configurations and the associated cultural ambiances and economic activities. In parallel, we aim to debate the means of fostering and supporting creativity in urban environments and discuss just which strategic policies and governance processes best achieve this.FC

    Heavy-ion Physics at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC): Feasibility Studies for Quarkonium and Drell-Yan Production

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    We outline the case for heavy-ion-physics studies using the multi-TeV lead LHC beams in the fixed-target mode. After a brief contextual reminder, we detail the possible contributions of AFTER@LHC to heavy-ion physics with a specific emphasis on quarkonia. We then present performance simulations for a selection of observables. These show that Υ(nS)\Upsilon(nS), J/ψJ/\psi and ψ(2S)\psi(2S) production in heavy-ion collisions can be studied in new energy and rapidity domains with the LHCb and ALICE detectors. We also discuss the relevance to analyse the Drell-Yan pair production in asymmetric nucleus-nucleus collisions to study the factorisation of the nuclear modification of partonic densities and of further quarkonia to restore their status of golden probes of the quark-gluon plasma formation.Comment: 18 pages, 7 figure

    Cambio climatico y plagas forestales: el caso de la procesionaria del pino en el noreste de Portugal

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    The pine processionary moth, Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Thaumetopoeidae) is known as the most defoliating insect in Pinus and Cedrus in many countries. In the last three decades, climate change has led to a substantial expansion of its range and high attack rates in previously unaffected areas were observed. A 3-year analysis of the effect of several climatic elements on the T. pityocampa adult emergence was made and one climatic change scenario was tested in order to predict the insect’s behaviour in the future. Results showed that mean air temperature was the climatic element with the best single regression fit to adult emergence, whereas minimum air temperature and relative humidity provided the best multiple regression fits. Results also demonstrated that higher emergence of adults is often related to a maximum temperature above 30°C, a mean temperature above 23°C, a minimum temperature above 17°C, relative humidity lower than 60% and precipitation values lower than 10 mm. Using the same thresholds for future climatic conditions simulated by the COSMO-CLM model, the period for pine processionary moth emergence will be expanded, starting much sooner. Contrasting with the actual emergence period, the insect is projected to have favorable climatic conditions to start emerging in May. This might have serious implications in forest ecosystems, concerning not only ecological issues, but also forest management.La procesionaria del pino, Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Thaumetopoeidae), es conocido en muchos países como el insecto más defoliador de Pinus y Cedrus. En las últimas tres décadas el cambio climático ha originado una considerable expansión de su rango de distribución y aumentado la proporción de ataques en áreas previamente no atacadas. Durante tres años fue realizada una monitorización de los efectos de diversos elementos climáticos sobre la emergencia de los adultos de T. pityocampa y un escenario de cambio climático fue testado con el fin de predecir el comportamiento de los insectos en el futuro. Los resultados revelan que la temperatura media del aire es el elemento climático que más contribuye en la regresión simple para explicar la emergencia de adultos, seguidos de la temperatura mínima del aire y la humedad relativa. Nuestros resultados también demostraron que el aumento de emergencia de adultos estaba a menudo relacionado con temperaturas máximas superiores a 30°C, temperatura media por encima de los 23°C, temperatura mínima por encima de 17°C, humedad relativa inferior al 60% y valores de precipitación inferiores a los 10 mm. Atendiendo a los resultados para eses umbrales climáticos y el modelo de CLM, el periodo de emergencia de la procesionaria de pino se extenderá, comenzando mucho antes. En contraste con el actual periodo de emergencia, el insecto tendrá condiciones climáticas favorables para comenzar a emerger en Mayo. Esto tendrá consecuencias graves para los ecosistemas forestales no sólo al nivel de las cuestiones ecológicas, sino también para la gestión forestal

    Factorial Moments in a Generalized Lattice Gas Model

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    We construct a simple multicomponent lattice gas model in one dimension in which each site can either be empty or occupied by at most one particle of any one of DD species. Particles interact with a nearest neighbor interaction which depends on the species involved. This model is capable of reproducing the relations between factorial moments observed in high--energy scattering experiments for moderate values of DD. The factorial moments of the negative binomial distribution can be obtained exactly in the limit as DD becomes large, and two suitable prescriptions involving randomly drawn nearest neighbor interactions are given. These results indicate the need for considerable care in any attempt to extract information regarding possible critical phenomena from empirical factorial moments.Comment: 15 pages + 1 figure (appended as postscript file), REVTEX 3.0, NORDITA preprint 93/4

    First record of the Hauxwell's Thrush, Turdus hauxwelli Lawrence, 1869 (Aves: Turdidae) from Mato Grosso do Sul, Brazil, and geographic range extension

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    We report the first record of the Hauxwell’s Thrush, Turdus hauxwelli Lawrence, 1869 (Aves: Turdidae) in the state of Mato Grosso do Sul, Brazil. During an ornithological inventory conducted in Serra de Maracajú, municipality of Corguinho, we mist-netted and collected an individual of the species. The specimen was prepared as study skin and is held in the ornithological collection of the Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro. This record is located 472 km south of the closest visual/song record and 616 km southeast of the closest museum specimen, being the southernmost occurrence of this thrush

    Uso e manejo de leguminosas em agroecossistemas na Amazônia Central.

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    Este estudo teve como objetivo gerar informações que poderão auxiliar os fruticultores da região na tomada de decisão quanto ao uso e manejo de leguminosas, como tefrósia, para inserção em sistemas de produção de fruteiras, visando à melhoria e manutenção da capacidade produtiva do solo, o controle de invasoras e o desenvolvimento e a produtividade das plantas

    Insights into the transcriptional regulation of poorly characterized alcohol acetyltransferase-encoding genes (HgAATs) shed light into the production of acetate esters in the wine yeast Hanseniaspora guilliermondii

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    Hanseniaspora guilliermondii is a well-recognized producer of acetate esters associated with fruity and floral aromas. The molecular mechanisms underneath this production or the environmental factors modulating it remain unknown. Herein, we found that, unlike Saccharomyces cerevisiae, H. guilliermondii over-produces acetate esters and higher alcohols at low carbon-to-assimilable nitrogen (C:N) ratios, with the highest titers being obtained in the amino acid-enriched medium YPD. The evidences gathered support a model in which the strict preference of H. guilliermondii for amino acids as nitrogen sources results in a channeling of keto-acids obtained after transamination to higher alcohols and acetate esters. This higher production was accompanied by higher expression of the four HgAATs, genes, recently proposed to encode alcohol acetyl transferases. In silico analyses of these HgAat's reveal that they harbor conserved AATs motifs, albeit radical substitutions were identified that might result in different kinetic properties. Close homologues of HgAat2, HgAat3, and HgAat4 were only found in members of Hanseniaspora genus and phylogenetic reconstruction shows that these constitute a distinct family of Aat's. These results advance the exploration of H. guilliermondii as a bio-flavoring agent providing important insights to guide future strategies for strain engineering and media manipulation that can enhance production of aromatic volatiles.info:eu-repo/semantics/publishedVersio
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