Taphonomic analysis of fossil concentrations from La Manga Formation (Oxfordian), Neuquén Basin, Mendoza Province, Argentina

Griphaeid-dominated fossil concentrations of La Manga Formation are characterized on the basis of taphonomic, sedimentologic, stratigraphic and palaeoecologic criteria. These concentrations are present in the basal deposits (Unit 1) of three outcrops in the locality of Bardas Blancas. Their attributes allow distinguishing seven different fossil accumulations: A) Channelized fossil concentrations of Gryphaea sp.; B) Shell beds of Gryphaea sp. highly reworked; C) Shell beds of Gryphaea sp. moderately reworked; D) Accumulations of Gryphaea sp. with biomicrite to biopelmicrite matrix; E) Shell detritus; F) Accumulations produced by bottom currents; and G) Accumulations found in clumps. Accumulations A-C were deposited by high energy processes (storm waves and currents) in the upper middle ramp. Accumulations D and E were produced by high energy processes (storm waves and currents) but the final depositions were produced out of suspension in low energy environments, in lower middle ramp settings. Accumulations F were generated by weak bottom currents, meanwhile accumulations G correspond to gryphaeids associations reworked by bioturbators or by hydraulic processes after variable periods of permanence in sediment/water interface. Both are interpreted as lower middle or outer ramp. This interpretation suggests that these deposits that in previous works were interpreted as outer ramp settings, characterize middle and outer ramp settings. The vertical distribution of fossil concentrations from upper middle ramp to lower middle and outer ramp settings evidences a continuously growing accommodation space and allows to interpret the Unit 1 as part of a transgressive systems tract.Las concentraciones bioclásticas dominadas por grifeidos de la Formación La Manga (Oxfordiense) de la Cuenca Neuquina fueron caracterizadas sobre la base de criterios tafonómicos, sedimentológicos, estratigráficos y paleoecológicos. Estas concentraciones están presentes en los depósitos basales (Unidad 1) de tres afloramientos en la localidad de Bardas Blancas. Sus atributos permitieron distinguir siete tipos diferentes de concentraciones bioclásticas: A) concentraciones bioclásticas canalizadas de Gryphaea sp.; B) Estratos de conchillas de Gryphaea sp. fuertemente retrabajadas; C) Estratos de conchillas de Gryphaea sp. moderadamente retrabajadas; D) Acumulaciones de Gryphaea sp. con matriz biomicrítica y biopelmicrítica; E) Detrito de conchillas; F) Concentraciones generadas por corrientes de fondo; y G) Agrupaciones de conchillas (clumps). Las acumulaciones A-C fueron depositadas por procesos de alta energía (olas y corrientes de tormenta) en sectores de rampa media superior. Las acumulaciones D y E fueron generadas por procesos de alta energía (olas y corrientes de tormenta) pero la depositación final ocurrió por decantación en ambientes de baja energía, en la rampa media inferior. Las acumulaciones F fueron generadas por débiles corrientes de fondo, mientras que las acumulaciones G corresponden a asociaciones de grifeidos retrabajadas por organismos bioturbadores o por procesos hidráulicos después de períodos variables de permanencia en la interfase agua/sedimento. Ambas acumulaciones fueron interpretadas como depósitos de rampa media inferior o rampa externa. La distribución vertical de concentraciones bioclásticas desde ambientes de rampa media superior hasta ambientes de rampa media inferior y rampa externa, evidencia un aumento en el espacio de acomodación y permite interpretar a la Unidad 1 como parte de un cortejo transgresivo

Comparison of observed data and high-resolution regional climate simulations on process based modelling

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Oxfordian microbial laminites from La Manga Formation, Neuquén Basin, Argentina: Remarkable nanobacteria preservation

Exceptionally preserved stromatolites have been found in the shallow marine carbonate facies of the Callovian-Oxfordian La Manga Formation, in the Neuquén Basin (Argentina). The stromatolites exhibit planar and crinkle lamination, often disrupted by sheet-cracks, mudcracks, and fenestral structures, which indicate periodic subaerial exposure. These and other evidences suggest that these stromatolites grew in low energy upper intertidal to lower supratidal environments. They consist of fine micrite/microsparite crystal fabrics (with a remarkable lack of allochems) that define submillimiter alternations of dense laminae. Extensive SEM examinations of polished samples of the stromatolites reveal exceptional preservation of rod-shaped bacteria, coccoid like microorganisms, and abundant aggregates of framboidal pyrite. The rod-like bacteria consists of a network of irregular distributed filaments, which range from 150 nm to an uncommon 640 nm in length; diameters range from 54 nm to 90 nm. Subspherical bodies range in size between 70 and 89 nm. The presence of abundant framboidal pyrites is interpreted as the result of the metabolic activity of sulfate–reducing bacteria and decay of organic matter.Se describen estromatolitos excepcionalmente preservados en facies carbonáticas marinas someras en la Formación La Manga, de edad Calloviense-Oxfordiense, en la Cuenca de Neuquén (Argentina). Los estromatolitos muestran una laminación tanto planar como ondulada, frecuentemente alterada por estructuras de tipo fenestral, y sheet y mud-crack, que indican etapas de exposición subaérea. Estas y otras características sugieren que estos estromatolitos crecieron en ambientes de baja energía, intermareales altos y supramareales. Están constituidos por una fábrica de micrita-microesparita (con una destacada ausencia de aloquímicos) que constituyen alternancias submilimétricas de laminación densa. Estudios detallados con SEM sobre muestras pulidas revelan una preservación excepcional con morfología alargada, microorganismos tipo cocoide, y abundantes agregados de pirita framboidal. Las bacterias con morfologías alargadas están constituyendo una red irregularmente distribuida de filamentos que oscilan en tamaño desde 150 nm hasta, excepcionalmente, 640 nm en longitud; el diámetro oscila entre 50 nm y 90 nm. Las morfologías subesféricas oscilan entre 70 nm y 89 nm. La presencia de abundantes piritas framboidales es interpretada como resultado de una actividad metabólica de bacterias sulfato-reductoras y la descomposición de materia orgánica

Evaluation of tests to assess the quality of mine-contaminated soils

An acid metal-contaminated soil from the Aljustrel mining area (a pyrite mine located in SW Portugal in the Iberian Pyrite Belt) was subjected to chemical characterisation and total metal quantiWcation (Cd, Cr, Cu, Ni, Pb and Zn). Water-soluble metals were determined and a sequential extraction procedure was used to investigate metal speciation. Two bioavailable metal fractions were determined: a mobile fraction and a mobilisable fraction. Soil ecotoxicity was studied using a battery of bioassays: plant growth test and seed germination with cress (Lepidium sativum L.), earthworm (Eisenia fetida) mortality, E. fetida avoidance behaviour, luminescent inhibition of Vibrio Wscheri and Daphnia magna immobilisation. Although the total content of Cu, Zn and Pb in the soil was large (362, 245 and 1,250 mg/ kg dry matter, respectively), these metals were mostly structurally bound (87% for Cu, 81% for Zn and 89% for Pb) and, therefore, scarcely bioavailable. Nonetheless, the D. magna immobilization test using soil leachate showed an EC50 (48 h) of 36.3% (v/v), and the luminescent inhibition of V. Wscheri presented an EC20 (15 min) of 45.2% and an EC20 (30 min) of 10.7% (v/v), suggesting a considerable toxic eVect. In the direct exposure bioassays, E. fetida avoided the mine soil at the highest concentrations (50%, 75% and 100% v/v). At the same soil concentrations, cress showed negligible growth. The results suggest the need to use a battery of toxicity tests, in conjunction with chemical methods, in order to assess the quality of mine-contaminated soils correctly

Measurement of Two-Qubit States by a Two-Island Single Electron Transistor

We solve the master equations of two charged qubits measured by a single-electron transistor (SET) consisted of two islands. We show that in the sequential tunneling regime the SET current can be used for reading out results of quantum calculations and providing evidences of two-qubit entanglement, especially when the interaction between the two qubits is weak

Farmers' reasoning behind the uptake of agroforestry practices: evidence from multiple case-studies across Europe

Potential benefits and costs of agroforestry practices have been analysed by experts, but few studies have captured farmers’ perspectives on why agroforestry might be adopted on a European scale. This study provides answers to this question, through an analysis of 183 farmer interviews in 14 case study systems in eight European countries. The study systems included high natural and cultural value agroforestry systems, silvoarable systems, high value tree systems, and silvopasture systems, as well as systems where no agroforestry practices were occurring. A mixed method approach combining quantitative and qualitative approaches was taken throughout the interviews. Narrative thematic data analysis was performed. Data collection proceeded until no new themes emerged. Within a given case study, i.e. the different systems in different European regions, this sampling was performed both for farmers who practice agroforestry and farmers who did not. Results point to a great diversity of agroforestry practices, although many of the farmers are not aware of the term or concept of agroforestry, despite implementing the practice in their own farms. While only a few farmers mentioned eligibility for direct payments in the CAP as the main reason to remove trees from their land, to avoid the reduction of the funded area, the tradition in the family or the region, learning from others, and increasing the diversification of products play the most important role in adopting or not agroforestry systems

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up

Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02