4,325 research outputs found
Terminal suturing of Gondwana along the southern margin of South China Craton : evidence from detrital zircon U-Pb ages and Hf isotopes in Cambrian and Ordovician strata, Hainan Island
No full textThis work was supported by the National Natural Science Foundation of China (grants 41472086 and 41272120), “111” Project (B08030), the fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (CUG2012019240 and CUG2013019137). The first author also acknowledges China Scholarship Council (grant 201208420001) for supporting his research in the University of St. Andrews. Date of Acceptance: 20/11/2014Hainan Island, located near the southern end of mainland South China, consists of the Qiongzhong Block to the north and the Sanya Block to the south. In the Cambrian, these blocks were separated by an intervening ocean. U-Pb ages and Hf isotope compositions of detrital zircons from the Cambrian succession in the Sanya Block suggest that the unit contains detritus derived from late Paleoproterozoic and Mesoproterozoic units along the western margin of the West Australia Craton (e.g., Northampton Complex) or the Albany-Fraser-Wilkes orogen, which separates the West Australia and Mawson cratons. Thus, in the Cambrian the Sanya Block was not part of the South China Craton but rather part of the West Australian Craton and its environs. In contrast, overlying Late Ordovician strata display evidence for input of detritus from the Qiongzhong Block, which constituted part of the southeastern convergent plate margin of the South China Craton in the early Paleozoic. The evolving provenance record of the Cambrian and Ordovician strata suggests that the juxtaposition of South China and West Australian cratons occurred during the early to mid-Ordovician. The event was linked with the northern continuation of Kuungan Orogeny, with South China providing a record of final assembly of Gondwana.Peer reviewe
O processo de verticalização e seus problemas no bairro de Manaíra, João Pessoa-PB.
No full textThe work traces the verticalization process in District Manaíra in João Pessoa-PB. To fulfill its purpose broke the concept, causes, and consequences of this process mainly the problems caused by such a process. Reports related to the process of urban verticalization in order to understand the process and support research studies. "Was taken as a base study dissertation titled The study Manaíra neighborhood in João Pessoa, Paraíba," Nobrega (2011). Additionally, consultation to planning legislation relating to the theme. Research upgraded the empirical survey and mapping by the cited author. Thus, in addition to consulting government institutions such as the Water and Sewerage Company of Paraíba, the core of the research corresponds to the empirical survey of land use studied in the neighborhood that was recorded by consignment types of buildings. This survey maps of land use were developed. Finally, the article discusses the problems caused by the process of verticalization in District Manaíra located on the edge of João Pessoa-PB.O trabalho traça um panorama do processo de verticalização, no Bairro de Manaíra na cidade de João Pessoa-PB. Para cumprir seu propósito partiu-se do conceito, causas, consequências resultantes deste processo e principalmente, os problemas ocasionados por tal processo. Reporta-se a estudos relacionados ao processo de verticalização urbana, no intuito de compreender o processo e fundamentar a pesquisa. “Tomou-se como estudo base a dissertação de mestrado intitulada O estudo do bairro de Manaíra em João Pessoa, Paraíba”, de Nóbrega (2011). Além disso, consulta-se a legislação urbanística referente à temática. A pesquisa atualizou o levantamento empírico e o mapeamento realizado pela autora citada. Desta forma, além da consulta as instituições governamentais como a Companhia de Águas e Esgotos da Paraíba, IBGE, Corpo de Bombeiros e etc., o cerne da pesquisa corresponde ao levantamento empírico do uso do solo do bairro estudado em que se registrou lote por lote o tipo de edificação. Deste levantamento foram elaborados mapas do uso do solo. Por fim, foram identificados e abordados os problemas ocasionados pelo processo de verticalização no Bairro de Manaíra localizado na orla de João Pessoa-PB
Vector boson production in p+Pb and Pb+Pb collisions measured with ATLAS at the LHC
No full textElectroweak boson production processes (W, Z and photon) provide access to the earliest moments of heavy ion collisions. Furthermore, because they do not undergo strong interactions, they are sensitive to the initial-state geometry of the collision and potentially the details of the nuclear parton distribution functions (PDF). ATLAS results on vector boson yields have demonstrated binary collision scaling in Pb+Pb collisions. In p+Pb collisions, the measurement of vector bosons provides possible constraints on the nuclear PDF and insights into the details of the initial collision geometry. We report on the latest results of vector boson production in p+Pb collisions at sqrt(sNN)=5.02 TeV and Pb+Pb collisions at sqrt(sNN)=2.76 TeV. In p+Pb collisions, production yields and lepton charge asymmetry of W bosons are presented as a function of pseudorapidity of the charged lepton and centrality. Photon and Z yields are presented differentially as a function of transverse momentum, rapidity and centrality. The vector boson yields are compared to calculations incorporating different PDF sets, as well as different centrality calculations
Gene expression of Ntann12 in Nicotiana tabacum to Pb treatment
No full textPlants are sessile organisms that are unable to move away from adverse environmental conditions. In order to survive or adapt their growth to environmental stresses, plants undergo physiological, biochemical and molecular changes. Lead (Pb), on the other hand, is a widespread heavy metal pollutant that is commonly found in the environment. It is highly persistent and causes toxicity to plants, animals, and human. To advance our understanding in Pb tolerance in plants and subsequently develop phytoremediation technology, there is a need to identify genes associated with Pb stress.
Nicotiana tabacum has the characteristics of a plant ideal for phytoremediation. It has deep and highly branched root system, is tolerant to Pb pollutant, and repulsive to herbivores. Recent studies have shown that annexins participate in abiotic stress responses. Ntann12 is an annexin in Nicotiana tabacum. It was found to be upregulated upon Rhodoccocus fascians infection, salt and abscisic acid treatments. It is likely that Ntann12 could be involved in the response of plants to Pb stress and play a role to defend plants against Pb-induced oxidative damage
Behavior and toxic effects of Pb in a waterfowl model with oral exposure to Pb shots : Investigating Pb exposure in wild birds
No full textAmong wild birds, lead (Pb) exposure caused by ingestion of ammunition is a worldwide problem. We aimed to reveal the behavior and toxic effect of Pb caused by ingesting Pb shots in waterfowl. Four male, eight-week old Muscovy ducks (Cairina moschata) were given three Pb shots (approximately 240 mg in total) orally and then fed for 29 days after exposure, simulating a low-dose Pb exposure in wild waterfowl. During the breeding period, blood samples were collected 10 times, and fecal samples every day. Additionally, 22 fresh tissue and 6 bone samples were obtained from each duck through the dissection. Although there were no gross abnormalities, the maximum blood Pb concentration of each duck ranged from 0.6 to 3.7 mg/L, reaching a threshold concentration indicative of clinical symptoms (>0.5 mg/L). delta-aminolevulinic acid dehydratase declined one day after exposure and remained low throughout the feeding period. Hematocrit also tended to decrease, indicating signs of anemia. The highest Pb accumulation was observed in the bones, followed by the kidneys, intestinal tracts, and liver. High Pb accumulation in the bones, which are known to have a long Pb half-life, suggested that Pb would remain in the body and possibly affect bird health beyond 28 days after exposure. Gene expression analysis showed a significant increase in the expression of the toll-like receptor-3 gene, which is involved in virus discrimination in the liver, suggesting a disruption of the immune system. Microbiota analyses showed a correlation between the blood Pb concentration and the abundances of Lachnospiraceae and Ruminococcaceae, suggesting that Pb affects lipid metabolism. These results provide fundamental data on Pb exposure in wild birds and a new perspective on the damage such exposure causes
Jet shapes in pp and Pb-Pb collisions at ALICE
No full textThe aim of this work is to explore possible medium modifications to the substructure of inclusive charged jets in Pb-Pb relative to proton-proton collisions by measuring a set of jet shapes. The set of shapes includes the radial moment, , and the momentum dispersion D. They provide complementary information on the fragmentation and can help to discriminate between two different scenarios: intra-jet broadening or collimation as a result of jet quenching. \noindent The shapes are measured in Pb--Pb collisions at = 2.76 TeV with a constituent cutoff of 0.15 GeV/c and jet resolution 0.2. New techniques for background subtraction are applied and a two-dimensional unfolding is performed to correct the shapes to particle level. The corrected jet shapes for jet GeV/c are presented and discussed. The observed jet shape modifications suggest that the in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by a PYTHIA calculation. The PYTHIA calculation is validated with proton-proton data at 7 TeV.The aim of this work is to explore possible medium modifications to the substructure of inclusive charged jets in Pb-Pb relative to proton-proton collisions by measuring a set of jet shapes. The set of shapes includes the radial moment, g , and the momentum dispersion p T D . They provide complementary information on the fragmentation and can help to discriminate between two different scenarios: intra-jet broadening or collimation as a result of jet quenching. The shapes are measured in Pb–Pb collisions at sNN=2.76 TeV with a constituent cutoff of 0.15 GeV/ c and jet resolution R=0.2 . New techniques for background subtraction are applied and a two-dimensional unfolding is performed to correct the shapes to particle level. The corrected jet shapes for jet pT 40≤pT,jet≤60 GeV/c are presented and discussed. The observed jet shape modifications suggest that the in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by a PYTHIA calculation. The PYTHIA calculation is validated with proton-proton data at 7 TeV.The aim of this work is to explore possible medium modifications to the substructure of inclusive charged jets in Pb-Pb relative to proton-proton collisions by measuring a set of jet shapes. The set of shapes includes the radial moment, , and the momentum dispersion D. They provide complementary information on the fragmentation and can help to discriminate between two different scenarios: intra-jet broadening or collimation as a result of jet quenching. \noindent The shapes are measured in Pb--Pb collisions at = 2.76 TeV with a constituent cutoff of 0.15 GeV/c and jet resolution 0.2. New techniques for background subtraction are applied and a two-dimensional unfolding is performed to correct the shapes to particle level. The corrected jet shapes for jet GeV/c are presented and discussed. The observed jet shape modifications suggest that the in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by a PYTHIA calculation. The PYTHIA calculation is validated with proton-proton data at 7 TeV
Collective flow in 2.76 and 5.02 A TeV Pb + Pb collisions
No full textIn this paper, we study and predict flow observables in 2.76 and 5.02 A TeV Pb + Pb collisions, using the iEBE-VISHNU hybrid model with TRENTo and AMPT initial conditions and with different forms of the QGP transport coefficients. With properly chosen and tuned parameter sets, our model calculations can nicely describe various flow observables in 2.76 A TeV Pb + Pb collisions, as well as the measured flow harmonics of all charged hadrons in 5.02 A TeV Pb + Pb collisions. We also predict other flow observables, including v(n)(pT) of identified particles, eventby-event vn distributions, event-plane correlations, (normalized) symmetric cumulants, non-linear response coefficients and pT -dependent factorization ratios, in 5.02ATeV Pb + Pb collisions. We find many of these observables to remain approximately the same values as the ones in 2.76 A TeV Pb + Pb collisions. Our theoretical studies and predictions could shed light to the experimental investigations in the near future.NSFC; MOST [11435001, 11675004, 2015CB856900]; China Postdoctoral Science Foundation [2015M580908]SCI(E)ARTICLE97
Reología de los Residuos Post-Flotación de Pb-Zn en la Sierra de Cartagena: La Unión (SE España)
No full text[SPA] El objetivo de esta tesis es contribuir a la interpretación de los factores geogénicos y
antropogénicos, a escalas local (cuenca hidrográfica) y regional, que controlan la geodisponibilidad (solubilidad y movilidad) de Ni, Cu, Zn, As, Cd, and Pb en la Sierra Minera de Cartagena – La Unión, así como evaluar la influencia del paisaje minero abandonado sobre el Campo de Cartagena y el Mar Menor. El período de estudio se extendió desde 2003 hasta 2012. Se recogieron 920 muestras de agua de lluvia en las 15 estaciones pluviométricas repartidas
por la gran llanura de 1600 km2 que constituye el Campo de Cartagena. Además, el estudio de
campo se complementó con 179 muestras de agua superficial recogidas en 13 ramblas, 127
muestras de agua subterránea recogidas en 5 manantiales, 16 muestras de agua de mar recogidas
en 8 desembocaduras de ramblas, 15 especímenes de eflorescencias de sulfatos, 7 tipos de
residuos mineros y 23 tipos de rocas. La evaluación de tal variedad de muestras ayudó a comprender los mecanismos que hacen geodisponibles estos metales en la Sierra Minera de Cartagena – La Unión. Dichos elementos traza se estudiaron en su contexto geológico, teniendo en cuenta sus ciclos geoquímicos, los diferentes tipos de residuos minero-metalúrgicos presentes en esta zona minera abandonada y la esfera de influencia hacia las áreas circundantes. La geodisponibilidad de los elementos traza depende de la especiación de sus fases
solubles, la cual se ve afectada por parámetros geoquímicos, hidrogeológicos, biológicos y
antropogénicos (actividades minera, agrícola e industrial). El conocimiento de la
geodisponibilidad de los metales en el suelo, su mecanismo de transferencia a la biota y el
riesgo para la salud pública, continúan siendo cuestiones clave a abordar. La presente tesis
doctoral trata de evaluar estos problemas con ayuda de las técnicas instrumentales más
avanzadas. Las muestras líquidas se evaluaron mediante la determinación del pH,
Conductividad Eléctrica (CE), iones mayoritarios por Cromatografía Iónica (CI) y los metales
de interés por Espectrometría de Masas de Plasma Acoplado Inductivamente (EM–PAI). La
caracterización fisicoquímica de las muestras sólidas se llevó a cabo mediante observación
estereomicroscópica, determinación de su estructura mediante Difracción de Rayos X (DRX),
análisis composicional por espectrometría de Fluorescencia de Rayos X por Dispersión de
Longitud de onda (FRXDL), análisis CHN y Análisis TermoGravimétrico acoplado a
Espectrometría de Masas (ATG–EM). Además, sobre las muestras sólidas se realizó el test de
lixiviado DIN 38414-S4, con el fin de valorar el riesgo y movilidad potencial de los diferentes
analitos. En las muestras de lixiviado se midió el pH, CE, los iones mayoritarios y los metales
Ni, Cu, Zn, As, Cd, Sb y Pb.
Los resultados han confirmado que la geodisponibilidad de los metales traza en la Sierra
Minera está regulada por la meteorización fisicoquímica de los residuos minero-metalúrgicos,
así como por la oxidación de los sulfuros metálicos asociados a los yacimientos de Pb-Zn.
Respecto a los mecanismo de transporte, dispersión y deposición de Ni, Cu, Zn, As, Cd y Pb, el
balance de masas de metales traza geodisponibles en el Mar Menor reveló que la erosión eólica
transfirió el 81 % de la entrada total de metales provenientes de la Sierra Minera, las aguas
subterráneas contribuyeron en un 16 % y la escorrentía superficial en un 3 %. Todo ello
demostró que la dispersión de estos contaminantes NO está controlada por las aguas
continentales (escorrentía superficial y agua subterránea). [ENG] The aim of this thesis was to contribute to the interpretation of the geogenic and anthropogenic factors, at local (hydrographic basin) and regional levels, that control the geoavailability (solubility and mobility) of Ni, Cu, Zn, As, Cd, and Pb in the Sierra Minera de Cartagena – La Unión, as well as to evaluate the influence of the abandoned mining landscape on the Campo de Cartagena and Mar Menor lagoon. The study period extended from 2003 to 2012. Across the large plain of 1600 km2 that forms the Campo de Cartagena, 15 weather stations were monitored to collect 920 rainwater samples. In addition, 179 surface runoff water samples were gathered in 13 ephemeral watercourses, 127 springwater samples in 5 springs, 16 seawater samples in 8 wadi outlets, 15 efflorescent sulfate salts, 7 types of mine wastes, and 23 types of parent materials. The assessment of such variety of specimens helped to understand the mechanisms that make Ni, Cu, Zn, As, Cd, and Pb geoavailable in the Sierra Minera of Cartagena – La Unión. For this purpose, these trace elements were studied in the geological context, taking into account their geochemical cycles, the different types of mining and metallurgical wastes present in the derelict mining site, and the sphere of influence to the bordering areas. Geoavailability of trace elements depends on the speciation of its soluble phases, which is affected by geochemical, hydrogeological, biological, and anthropogenic (mining, agricultural, and industrial activities) parameters. Knowledge of the geoavailability of metals in soils, its transfer mechanism to plants and other organisms, as well as the risk to public health remain key issues. This doctoral thesis wishes to tackle these problems with the most advanced instrumental techniques. Liquid samples were evaluated through the determination of pH, Electrical Conductivity (EC), major ions by Ion Chromatography (IC), and the metals of interest by Inductively Coupled Plasma – Mass Spectrometry (ICP–MS). The physico-chemical characterization of the solid samples involved its stereo microscopic observation, the determination of the structure by X-Ray powder Diffraction (XRD), the compositional analysis by Wavelength Dispersive X-Ray Fluorescence spectrometry (WDXRF), CHN analysis, and ThermoGravimetric analysis coupled to Mass Spectrometry (TG–MS). Furthermore, the leaching test DIN 38414-S4 was performed over the solid specimens to appreciate the hazard and potential mobility of the different analytes. pH, EC, major ions and several metals (Ni, Cu, Zn, As, Cd, Sb, and Pb), were measured in the leachate samples. The results have confirmed that geoavailability of trace metals in the Sierra Minera is governed by physico-chemical weathering of mining and metallurgical wastes, as well as by the oxidation of metallic sulfides associated to the Pb-Zn ores. Regarding the transport, dispersion, and deposition mechanisms of Ni, Cu, Zn, As, Cd, and Pb, the geoavailable trace-metal mass balance for Mar Menor lagoon disclosed that Aeolian erosion transfered 81% of the overall input of metal pollutants coming from the Sierra Minera, groundwater input contributed 16%, and watershed stream input only represented 3%. This proved that scattering of those trace elements is NOT controlled by continental water bodies (surface runoff and groundwater).[ENG] The aim of this thesis was to contribute to the interpretation of the geogenic and anthropogenic factors, at local (hydrographic basin) and regional levels, that control the geoavailability (solubility and mobility) of Ni, Cu, Zn, As, Cd, and Pb in the Sierra Minera de Cartagena – La Unión, as well as to evaluate the influence of the abandoned mining landscape on the Campo de Cartagena and Mar Menor lagoon. The study period extended from 2003 to 2012. Across the large plain of 1600 km2 that forms the Campo de Cartagena, 15 weather stations were monitored to collect 920 rainwater samples. In addition, 179 surface runoff water samples were gathered in 13 ephemeral watercourses, 127 springwater samples in 5 springs, 16 seawater samples in 8 wadi outlets, 15 efflorescent sulfate salts, 7 types of mine wastes, and 23 types of parent materials. The assessment of such variety of specimens helped to understand the mechanisms that make Ni, Cu, Zn, As, Cd, and Pb geoavailable in the Sierra Minera of Cartagena – La Unión. For this purpose, these trace elements were studied in the geological context, taking into account their geochemical cycles, the different types of mining and metallurgical wastes present in the derelict mining site, and the sphere of influence to the bordering areas. Geoavailability of trace elements depends on the speciation of its soluble phases, which is affected by geochemical, hydrogeological, biological, and anthropogenic (mining, agricultural, and industrial activities) parameters. Knowledge of the geoavailability of metals in soils, its transfer mechanism to plants and other organisms, as well as the risk to public health remain key issues. This doctoral thesis wishes to tackle these problems with the most advanced instrumental techniques. Liquid samples were evaluated through the determination of pH, Electrical Conductivity (EC), major ions by Ion Chromatography (IC), and the metals of interest by Inductively Coupled Plasma – Mass Spectrometry (ICP–MS). The physico-chemical characterization of the solid samples involved its stereo microscopic observation, the determination of the structure by X-Ray powder Diffraction (XRD), the compositional analysis by Wavelength Dispersive X-Ray Fluorescence spectrometry (WDXRF), CHN analysis, and ThermoGravimetric analysis coupled to Mass Spectrometry (TG–MS). Furthermore, the leaching test DIN 38414-S4 was performed over the solid specimens to appreciate the hazard and potential mobility of the different analytes. pH, EC, major ions and several metals (Ni, Cu, Zn, As, Cd, Sb, and Pb), were measured in the leachate samples. The results have confirmed that geoavailability of trace metals in the Sierra Minera is governed by physico-chemical weathering of mining and metallurgical wastes, as well as by the oxidation of metallic sulfides associated to the Pb-Zn ores. Regarding the transport, dispersion, and deposition mechanisms of Ni, Cu, Zn, As, Cd, and Pb, the geoavailable trace-metal mass balance for Mar Menor lagoon disclosed that Aeolian erosion transfered 81% of the overall input of metal pollutants coming from the Sierra Minera, groundwater input contributed 16%, and watershed stream input only represented 3%. This proved that scattering of those trace elements is NOT controlled by continental water bodies (surface runoff and groundwater).The development of this thesis has been possible with the Research Funding source of Seneca Foundation of Murcia, Spain, Project PB/44/FS/2002. The author gratefully acknowledges the infrastructural support of the Assistance
Service for Technological Research (Servicio de Apoyo a la Investigación Tecnológica, SAIT) of the Universidad Politécnica de Cartagena (Spain), where all the experimental analyses were performed.Universidad Politécnica de Cartagen
Searches for transverse momentum dependent flow vector fluctuations in Pb-Pb and p-Pb collisions at the LHC
No full textThe measurement of azimuthal correlations of charged particles is presented for Pb-Pb collisions at sNN=2.76 TeV and p-Pb collisions at sNN=5.02 TeV with the ALICE detector at the CERN Large Hadron Collider. These correlations are measured for the second, third and fourth order flow vector in the pseudorapidity region |η| < 0.8 as a function of centrality and transverse momentum pT using two observables, to search for evidence of pT-dependent flow vector fluctuations. For Pb-Pb collisions at 2.76 TeV, the measurements indicate that pT-dependent fluctuations are only present for the second order flow vector. Similar results have been found for p-Pb collisions at 5.02 TeV. These measurements are compared to hydrodynamic model calculations with event-by-event geometry fluctuations in the initial state to constrain the initial conditions and transport properties of the matter created in Pb–Pb and p–Pb collisions.[Figure not available: see fulltext.]. © 2017, The Author(s)
First measurement of jet mass in Pb-Pb and p-Pb collisions at the LHC
No full textThis letter presents the first measurement of jet mass in Pb-Pb and Pb-Pb collisions at root s(NN) = 2.76 TeV and root s(NN) = 5.02 TeV, respectively. Both the jet energy and the jet mass are expected to be sensitive to jet quenching in the hot Quantum Chromodynamics (QCD) matter created in nuclear collisions at collider energies. Jets are reconstructed from charged particles using the anti-k(T) jet algorithm and resolution parameter R = 0.4. The jets are measured in the pseudorapidity range |eta(jet)| <0.5 and in three intervals of transverse momentum between 60 GeV/c and 120 GeV/c. The measurement of the jet mass in central Pb-Pb collisions is compared to the jet mass as measured in p-Pb reference collisions, to vacuum event generators, and to models including jet quenching. It is observed that the jet mass in central Pb-Pb collisions is consistent within uncertainties with p-Pb reference measurements. Furthermore, the measured jet mass in Pb-Pb collisions is not reproduced by the quenching models considered in this letter and is found to be consistent with PYTHIA expectations within systematic uncertainties. (C) 2017 The Author. Published by Elsevier B.V.Peer reviewe
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