82 research outputs found

    Geochemical and mineralogical characterization of the Loma de la Plata and Valle Esperanza deposits, Navidad district, Argentina

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    Los depósitos Loma de la Plata y Valle Esperanza del distrito Navidad, cuyos recursos argentíferos son de 5000 y 2000 t de Ag, respectivamente, contienen las principales anomalías de Ag y Cu en autobrechas de las andesitas de la Formación Cañadón Asfalto (Jurásico). El estudio de brechas, vetas y vetillas en tres secciones de estos depósitos indica dos estadios de relleno pre- y postmineralización estériles (calcita, laumontita, baritina, calcedonia) y un estadio mineralizante con tres pulsos principales: a) calcopirita-galena-esfalerita, b) tennantita-tetraedrita, bornita y c) polibasita, jalpaita, estromeyerita, mckinstryita y plata nativa. La alteración hidrotermal de las rocas volcánicas (clorita, titanita, adularia, calcita, laumontita, celadonita, calcedonia, illita-esmectita y esmectita) es débil a moderada y se restringe a las zonas de contacto con las brechas, vetas y vetillas. La mineralogía y paragénesis identificadas en ambos depósitos sugieren fluidos con pH neutro y un descenso progresivo de la fugacidad del S con la evolución del sistema hidrotermal. La precipitación de los metales pudo haber ocurrido por mezcla de fluidos y/o ebullición. Las características permiten clasificarlos como depósitos polimetálicos ricos en Ag. A diferencia de otros depósitos del distrito Navidad, la plata está contenida principalmente en los sulfuros de Cu y Ag y plata nativa.Geochemical and mineralogical characterization of the Loma de la Plata and Valle Esperanza deposits, Navidad district, Argentina. Loma de la Plata and Valle Esperanza deposits (with 5000 and 2000 t Ag, respectively) host the main Ag and Cu anomalies in the andesitic autobreccias of the Cañadón Asfalto Formation. The study of the hydrothermal breccias, veins and veinlets from three sections indicates two pre and post mineralization stages (calcite, laumontite, barite, chalcedony) and one mineralizing stage with three main pulses: a) chalcopyrite-galena-sphalerite, b) tennantite-tetrahedrite, bornite and c) polybasite, jalpaite, stromeyerite, mckinstryite and native silver. Weak to moderate hydrothermal alteration of the volcanic host rocks (chlorite, titanite, adularia, calcite, laumontite, celadonite, chalcedony, illite-smectite and smectite) occurs at the contact zones with the mineralization. In both deposits, mineral assemblages suggest that hydrothermal fluids were neutral to alkaline and a progressive decrease of the sulfur fugacity during the evolution of the hydrothermal system. Metal precipitation could have been triggered by fluid mixing and/or boiling. Based on the mineralogical textural and geochemical features, both are classified as Ag-rich polymetallic deposits. Unlike other deposits of the Navidad district, silver is mainly contained in Ag-Cu sulfides and in native silver.Fil: Mercado, Maximiliano Martín. Universidad Nacional de Río Negro; Argentina. Centro Patagónico de Estudios Metalogenéticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; ArgentinaFil: Peralta, Florencia Lucia. Universidad Nacional del Sur. Departamento de Geología; ArgentinaFil: Pons, María Josefina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Centro Patagónico de Estudios Metalogenéticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; ArgentinaFil: Franchini, Marta Beatriz. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Centro Patagónico de Estudios Metalogenéticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; ArgentinaFil: Impiccini, Agnes. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Geología y Petróleo; ArgentinaFil: Rainoldi, Ana Laura. Centro Patagónico de Estudios Metalogenéticos; Argentina. Universidad Nacional del Sur. Departamento de Geología; Argentin

    Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

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    Insights from an Integrated View of the Biology of Apple Snails (Caenogastropoda: Ampullariidae)

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    Submitted by sandra infurna ([email protected]) on 2016-02-16T12:59:35Z No. of bitstreams: 1 silvana_thiengo_etal_IOC_2015.pdf: 1030588 bytes, checksum: 1feaf6021ccd94c9bf314dbc7b49ccc8 (MD5)Approved for entry into archive by sandra infurna ([email protected]) on 2016-02-16T13:49:31Z (GMT) No. of bitstreams: 1 silvana_thiengo_etal_IOC_2015.pdf: 1030588 bytes, checksum: 1feaf6021ccd94c9bf314dbc7b49ccc8 (MD5)Made available in DSpace on 2016-02-16T13:49:31Z (GMT). No. of bitstreams: 1 silvana_thiengo_etal_IOC_2015.pdf: 1030588 bytes, checksum: 1feaf6021ccd94c9bf314dbc7b49ccc8 (MD5) Previous issue date: 2015Howard University. Department of Biology. Washington, DC, USA / University of Hawaii. Pacific Biosciences Research Center. Honolulu, Hawaii, USA /Smithsonian Institution. National Museum of Natural History. Washington, DC, USA.Southwestern University. Department of Biology. Georgetown, Texas, USA.Instituto de Fisiología (FCM-UNCuyo). Laboratorio de Fisiología (IHEM-CONICET). Mendoza, Argentina.University of West Florida. Department of Biology. Pensacola, Florida, USA.Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP, CONICET). La Plata, Argentina.Universidad Nacional del Sur-CONICET. Laboratorio de Ecología, INBIOSUR. Bahia Blanca, Argentina.Hong Kong Baptist University. Department of Biology. Kowloon, Hong Kong.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Malacologia. Rio de Janeiro, RJ, Brasil.Instituto de Fisiología (FCM-UNCuyo). Laboratorio de Fisiología (IHEM-CONICET). Mendoza, Argentina / Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Área de Biologia. Mendoza, Argentina.NARO Kyushu Okinawa Agricultural Research Center. Kumamoto, Japan.Nara Women’s University. Faculty of Science. Kitauoya-nishi, Nara, Japan.Universidad Nacional del Sur-CONICET. Laboratorio de Ecología, INBIOSUR. Bahia Blanca, Argentina.Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP, CONICET). La Plata, Argentina.Instituto de Fisiología (FCM-UNCuyo). Laboratorio de Fisiología (IHEM-CONICET). Mendoza, Argentina / Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Área de Biologia. Mendoza, Argentina.Instituto de Fisiología (FCM-UNCuyo). Laboratorio de Fisiología (IHEM-CONICET). Mendoza, Argentina / Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Área de Biologia. Mendoza, Argentina.Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP, CONICET). La Plata, Argentina / Comisión de Investigaciones Científicas (CIC). La Plata, Argentina.Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP, CONICET). La Plata, Argentina.Instituto de Fisiología (FCM-UNCuyo). Laboratorio de Fisiología (IHEM-CONICET). Mendoza, Argentina / Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Área de Biologia. Mendoza, Argentina.Instituto de Fisiología (FCM-UNCuyo). Laboratorio de Fisiología (IHEM-CONICET). Mendoza, Argentina / Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Área de Biologia. Mendoza, Argentina.Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP, CONICET). La Plata, Argentina.Instituto de Fisiología (FCM-UNCuyo). Laboratorio de Fisiología (IHEM-CONICET). Mendoza, Argentina / Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Área de Biologia. Mendoza, Argentina.University of Hawaii. Pacific Biosciences Research Center. Honolulu, Hawaii, USA / NARO Kyushu Okinawa Agricultural Research Center. Koshi, Kumamoto, Japan.Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP, CONICET). La Plata, Argentina.Instituto de Fisiología (FCM-UNCuyo). Laboratorio de Fisiología (IHEM-CONICET). Mendoza, Argentina.Universidad Nacional del Sur-CONICET. Laboratorio de Ecología, INBIOSUR. Bahia Blanca, Argentina.Universidad Nacional del Sur-CONICET. Laboratorio de Ecología, INBIOSUR. Bahia Blanca, Argentina.Smithsonian Institution. National Museum of Natural History. Washington, DC, USA..Hong Kong Baptist University. Department of Biology. Kowloon, Hong Kong.Universidad Nacional del Sur-CONICET. Laboratorio de Ecología, INBIOSUR. Bahia Blanca, Argentina.Universidad Nacional del Sur-CONICET. Laboratorio de Ecología, INBIOSUR. Bahia Blanca, Argentina.Florida Institute of Technology. Biological Sciences Department. Melbourne, Florida, USA.The Pomacea Project, Inc., Pensacola, Florida, USA.University of Hawaii. Pacific Biosciences Research Center. Honolulu, Hawaii, USA.Apple snails (Ampullariidae) are among the largest and most ecologically important freshwater snails. The introduction of multiple species has reinvigorated the field and spurred a burgeoning body of research since the early 1990s, particularly regarding two species introduced to Asian wetlands and elsewhere, where they have become serious agricultural pests. This review places these recent advances in the context of previous work, across diverse fields ranging from phylogenetics and biogeography through ecology and developmental biology, and the more applied areas of environmental health and human disease. The review does not deal with the role of ampullariids as pests, nor their control and management, as this has been substantially reviewed elsewhere. Despite this large and diverse body of research, significant gaps in knowledge of these important snails remain, particularly in a comparative framework. The great majority of the work to date concerns a single species, Pomacea canaliculata, which we see as having the potential to become a model organism in a wide range of fields. However, additional comparative data are essential for understanding this diverse and potentially informative group. With the rapid advances in genomic technologies, many questions, seemingly intractable two decades ago, can be addressed, and ampullariids will provide valuable insights to our understanding across diverse fields in integrative biology

    Insights from an Integrated View of the Biology of Apple Snails (Caenogastropoda: Ampullariidae)

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    Coherent ψ(2S) photo-production in ultra-peripheral PbPb collisions at √sNN=2.76 TeV

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    We have performed the first measurement of the coherent ψ(2S) photo-production cross section in ultra-peripheral PbPb collisions at the LHC. This charmonium excited state is reconstructed via the ψ(2S)→l+l− and ψ(2S)→J/ψπ+π− decays, where the J/ψ decays into two leptons. The analysis is based on an event sample corresponding to an integrated luminosity of about 22 μb−1. The cross section for coherent ψ(2S) production in the rapidity interval −0.9<y<0.9 is dσψ(2S)coh/dy=0.83±0.19(stat+syst) mb. The ψ(2S) to J/ψ coherent cross section ratio is 0.34−0.07+0.08(stat+syst). The obtained results are compared to predictions from theoretical models

    Production of inclusive ϒ(1S) and ϒ(2S) in p–Pb collisions at √sNN = 5.02 TeV

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    We report on the production of inclusive Υ(1S) and Υ(2S) in p-Pb collisions at sNN−−−√=5.02 TeV at the LHC. The measurement is performed with the ALICE detector at backward (−4.46<ycms<−2.96) and forward (2.03<ycms<3.53) rapidity down to zero transverse momentum. The production cross sections of the Υ(1S) and Υ(2S) are presented, as well as the nuclear modification factor and the ratio of the forward to backward yields of Υ(1S). A suppression of the inclusive Υ(1S) yield in p-Pb collisions with respect to the yield from pp collisions scaled by the number of binary nucleon-nucleon collisions is observed at forward rapidity but not at backward rapidity. The results are compared to theoretical model calculations including nuclear shadowing or partonic energy loss effects

    Neutral pion and η meson production at mid-rapidity in Pb–Pb collisions at √sNN = 2.76 TeV

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    Neutral pion and η meson production in the transverse momentum range 1 < pT < 20 GeV/c have been measured at mid-rapidity by the ALICE experiment at the Large Hadron Collider (LHC) in central and semi-central Pb-Pb collisions at sNN−−−−√ = 2.76 TeV. These results were obtained using the photon conversion method as well as the PHOS and EMCal detectors. The results extend the upper pT reach of the previous ALICE π0 measurements from 12 GeV/c to 20 GeV/c and present the first measurement of η meson production in heavy-ion collisions at the LHC. The η/π0 ratio is similar for the two centralities and reaches at high pT a plateau value of 0.457 ± 0.013stat ± 0.018syst. A suppression of similar magnitude for π0 and η meson production is observed in Pb-Pb collisions with respect to their production in pp collisions scaled by the number of binary nucleon-nucleon collisions. We discuss the results in terms of NLO pQCD predictions and hydrodynamic models. The measurements show a stronger suppression with respect to what was observed at lower center-of-mass energies in the pT range 6 < pT < 10 GeV/c. At pT < 3 GeV/c, hadronization models describe the π0 results while for the η some tension is observed

    Measurement of electrons from beauty-hadron decays in p–Pb collisions at √sNN = 5.02 TeV and Pb–Pb collisions at √sNN = 2.76 TeV

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    The production of beauty hadrons was measured via semi-leptonic decays at mid-rapidity with the ALICE detector at the LHC in the transverse momentum interval 1<pT<8 GeV/c in minimum-bias p-Pb collisions at sNN−−−√=5.02 TeV and in 1.3<pT<8 GeV/c in the 20% most central Pb-Pb collisions at sNN−−−√=2.76 TeV. The pp reference spectra at s√=5.02 TeV and s√=2.76 TeV, needed for the calculation of the nuclear modification factors RpPb and RPbPb, were obtained by a pQCD-driven scaling of the cross section of electrons from beauty-hadron decays measured at s√=7 TeV. In the pT interval 3<pT<8 GeV/c a suppression of the yield of electrons from beauty-hadron decays is observed in Pb-Pb compared to pp collisions. Towards lower pT, the RPbPb values increase with large systematic uncertainties. The RpPb is consistent with unity within systematic uncertainties and is well described by theoretical calculations that include cold nuclear matter effects in p-Pb collisions. The measured RpPb and these calculations indicate that cold nuclear matter effects are small at high transverse momentum also in Pb-Pb collisions. Therefore, the observed reduction of RPbPb below unity at high pT may be ascribed to an effect of the hot and dense medium formed in Pb-Pb collisions

    Anomalous evolution of the near-side jet peak shape in Pb–Pb collisions at √sNN = 2.76 TeV

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    The measurement of two-particle angular correlations is a powerful tool to study jet quenching in a pT region inaccessible by direct jet identification. In these measurements pseudorapidity (Δη) and azimuthal (Δφ) differences are used to extract the shape of the near-side peak formed by particles associated to a higher pT trigger particle (1<pT,trig< 8 GeV/c). A combined fit of the near-side peak and long-range correlations is applied to the data allowing the extraction of the centrality evolution of the peak shape in Pb-Pb collisions at sNN−−−√ = 2.76 TeV. A significant broadening of the peak in the Δη direction at low pT is found from peripheral to central collisions, which vanishes above 4 GeV/c, while in the Δφ direction the peak is almost independent of centrality. For the 10% most central collisions and 1<pT,assoc< 2 GeV/c, 1<pT,trig< 3 GeV/c a novel feature is observed: a depletion develops around the centre of the peak. The results are compared to pp collisions at the same centre of mass energy and to AMPT model simulations. The comparison to the investigated models suggests that the broadening and the development of the depletion is connected to the strength of radial and longitudinal flow
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