726 research outputs found

    First Report of Cladode Brown Spot in Cactus Prickly Pear Caused by Neofusicoccum batangarum in Brazil

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    Cactus prickly pear (Nopalea cochenilifera) cladodes showing brown spot symptoms were collected of 18 fields of the State of Pernambuco, northeastern Brazil, from March to June 2014. The symptoms were prevalent in 100% of fields surveyed. Small pieces (4 to 5 mm) of necrotic tissues were surface sterilized for 1 min in 1.5% NaOCl, washed twice with sterile distilled water, and plated onto potato dextrose agar (PDA) amended with 0.5 g /liter streptomycin sulfate. Colonies morphologically similar to species of Botryosphaeriaceae were transferred to malt extract agar (MEA); five isolates (CMM 1424, CMM 1425, CMM 1426, CMM 1427, and CMM 1428) presented colonies forming concentric rings, and white mycelium becoming gray to gray-olivaceous after 5 days. Conidial characters were observed after growth on 2% water agar bearing sterilized pine needles for 3 weeks at 25°C under near-UV light. Conidiogenous cells holoblastic, hyaline, smooth, and cylindrical. Conidia were nonseptate, hyaline, smooth, fusoid to ovoid, thin-walled, 15.3 ± 1.4 × 5.4 ± 0.6 µm (n = 50), L/W ratio= 2.8, which are morphological and cultural characteristics typical of Neofusicoccum spp. (Phillips et al. 2013). DNA sequencing of part of the elongation factor 1-alpha (EF1-α) gene and the internal transcribed spacer (ITS1-5.8S-ITS2 rDNA) region were conducted to identify the species as described by (Marques et al. 2013). Sequences of the isolates were 99% similar to those of N. batangarum for EF1-α (GenBank Accession Nos. FJ900653 and FJ900654) and ITS (FJ900607 and FJ900608).Instituto de Patología VegetalFil: Conforto, Erica Cinthia. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Bernardi Lima, Nelson. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Fitopatología y Modelización Agrícola (UFyMA); ArgentinaFil: Bernardi Lima, Nelson. Universidade Federal Rural de Pernambuco. Departamento de Agronomia; BrasilFil: Garcete-Gómez, José María. Universidade Federal Rural de Pernambuco. Departamento de Agronomia; BrasilFil: Câmara, M. P. S. Universidade Federal Rural de Pernambuco. Departamento de Agronomia; BrasilFil: Michereff, S. J. Universidade Federal Rural de Pernambuco. Departamento de Agronomia; Brasi

    Influencia de la fertilización inorgánica sobre la actividad microbiana del suelo

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    Las mediciones se llevaron a cabo en la campaña 2010/11 en un ensayo en el establecimiento Balducchi, ubicado en la localidad de Teodelina (Santa Fe), que forma parte de la Red de Nutrición CREA Sur de Santa Fe (CREA-IPNI-ASP). En ese ensayo, bajo rotación maíz-trigo/soja, se evalúan, anualmente desde la campaña 2000/01, fertilizaciones con N, P, S y micronutrientes en las siguientes combinaciones: PS, NS, NP, NPS, NPS+Micronutrientes, y Testigo (sin adición de fertilizante) en 3 repeticiones siguiendo un diseño en bloques completos al azar.Según la información obtenida, la actividad microbiana del suelo, medida por la cuantificación del consumo de diversas fuentes de C, fue influenciada por la fertilización inorgánica. De acuerdo al ACP, el tratamiento con nutrición más balanceada (NPS+Micros) registró mayor consumo de sustratos carbonados, que los restantes tratamientos. Según algunos autores, los fertilizantes inorgánicos afectan los parámetros biológicos debido al incremento del contenido de C orgánico del suelo, que determina el crecimiento de los microorganismos, siendo el P un factor clave en el aumento de la diversidad microbiana y fertilidad del suelo. Finalmente, el rendimiento del cultivo también se incrementó en respuesta a la fertilización, en comparación con el Testigo. Existe una compleja interacción entre el nivel óptimo de fertilización, la disponibilidad de nutrientes para el crecimiento de los microorganismos y el buen desarrollo de las plantas. Esto demuestra que son necesarios más estudios para profundizar el conocimiento acerca del efecto de la fertilización inorgánica sobre las funciones metabólicas de la microbiota del suelo.Fil: Conforto, C.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Correa, Olga Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; ArgentinaFil: Rovea, A.. Grupo Crea Santa Fe; ArgentinaFil: Boxler, M.. Grupo Crea Santa Fe; ArgentinaFil: Rodríguez Grastorf, S.. Grupo Crea Santa Fe; ArgentinaFil: Minteguiaga, J.. Grupo Crea Santa Fe; ArgentinaFil: Meriles, Jose Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Vargas Gil, Silvina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Effects for atmospheric neutrino experiments from electron neutrino oscillations

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    The minimal interpretation of the atmospheric neutrino data suggests that the muon neutrino oscillates into another species with a mixing angle close to the maximal π/4\pi/4. In the Exact Parity Symmetric Model, both the muon and electron neutrinos are expected to be maximally mixed with essentially sterile partners (νμ\nu'_{\mu} and νe\nu'_e respectively). We examine the impact of maximal νeνe\nu_e - \nu'_e oscillations on the atmospheric neutrino experiments. We estimate that maximal νeνe\nu_e - \nu'_e oscillations will have effects on atmospheric neutrino data for δm2(νeνe)>7×105eV2|\delta m^2 (\nu_e - \nu_e')| > 7 \times 10^{-5} eV^2. For δm2\delta m^2 in this range, a slight but distinctive rise in the ratio of muon-like to electron-like events is predicted for the low-energy sample. Furthermore, the ratio of low-energy electron-like events with zenith angles less than 90deg90\deg to those with zenith angles greater than 90deg90\deg should be greater than 1.Comment: 11 pages, LaTeX, no figure

    Study of chirally motivated low-energy KK^- optical potentials

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    The KK^- optical potential in the nuclear medium is evaluated self consistently from a free-space KNK^-N tt matrix constructed within a coupled-channel chiral approach to the low-energy KˉN\bar K N data. The chiral-model parameters are fitted to a select subset of the low-energy data {\it plus} the KK^- atomic data throughout the periodic table. The resulting attractive KK^- optical potentials are relatively `shallow', with central depth of the real part about 55 MeV, for a fairly reasonable reproduction of the atomic data with χ2/N2.2\chi^2 / N \approx 2.2. Relatively `deep' attractive potentials of depth about 180 MeV, which result in other phenomenological approaches with χ2/N1.5\chi^2 / N \approx 1.5, are ruled out within chirally motivated models. Different physical data input is required to distinguish between shallow and deep KK^- optical potentials. The (Kstop,πK^{-}_{\rm stop},\pi) reaction could provide such a test, with exclusive rates differing by over a factor of three for the two classes of potentials. Finally, forward (K,pK^-,p) differential cross sections for the production of relatively narrow deeply bound KK^- {\it nuclear} states are evaluated for deep KK^- optical potentials, yielding values considerably lower than those estimated before.Comment: 22 pages, 3 figures, minor revisions, Nucl. Phys. A in pres

    Hydrodynamic bidimensional stability of detonation wave solutions for reactive mixtures

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    The structure of a planar detonation wave is analyzed for an Eulerian mixture of ideal gases undergoing the symmetric reversible explosive reaction A1 + A1 = A2 + A2. The chemical rate law is derived from the reactive Boltzmann equation, showing a detailed chemical kinetics in terms of a second-order reaction rate. The hydrodynamic bidimensional stability of the detonation wave is also investigated using a normal mode approach, when small time-space transverse disturbances affect the shock wave location. A suitable numerical technique is here proposed in order to solve the stability problem and numerical results are provided illustrating the detonation wave structure and its instability spectrum.The paper is partially supported by Brazilian Research Council (CNPq), by Italian Research Council GNFM-INdAM, and by Portuguese Funds of FCT, CMAT project UID/MAT/00013/2013

    First draft genome of \u3ci\u3eThecaphora frezii\u3c/i\u3e, causal agent of peanut smut disease

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    Objectives: The fungal pathogen Thecaphora frezii Carranza & Lindquist causes peanut smut, a severe disease currently endemic in Argentina. To study the ecology of T. frezii and to understand the mechanisms of smut resistance in peanut plants, it is crucial to know the genetics of this pathogen. The objective of this work was to isolate the pathogen and generate the first draft genome of T. frezii that will be the basis for analyzing its potential genetic diversity and its interaction with peanut cultivars. Our research group is working to identify peanut germplasm with smut resistance and to understand the genetics of the pathogen. Knowing the genome of T. frezii will help analyze potential variants of this pathogen and contribute to develop enhanced peanut germplasm with broader and long-lasting resistance. Data description: Thecaphora frezii isolate IPAVE 0401 (here referred as T.f.B7) was obtained from a single hyphal-tip culture, its DNA was sequenced using Pacific Biosciences Sequel II (PacBio) and Illumina NovaSeq6000 (Nova). Data from both sequencing platforms were combined and the de novo assembling estimated a 29.3 Mb genome size. Completeness of the genome examined using Benchmarking Universal Single-Copy Orthologs (BUSCO) showed the assembly had 84.6% of the 758 genes in fungi_odb10

    Testing maximal electron and muon neutrino oscillations with sub-GeV SuperKamiokande atmospheric neutrino data

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    Motivated by the Exact Parity Model and other theories, the hypothesis that each of the known neutrinos oscillates maximally with a sterile partner has been put forward as an explanation of the atmospheric and solar neutrino anomalies. We provide detailed predictions for muon and electron flux ratios induced in the Kamiokande and SuperKamiokande detectors by sub-GeV atmospheric neutrinos. Several different, carefully chosen cuts on momentum and zenith angle are proposed, emphasizing the role of up-down flux asymmetries.Comment: LaTeX, 8 figures, 17 pages, version to appear in Phys. Rev. D Rapid Communication

    Solutions of the atmospheric, solar and LSND neutrino anomalies from TeV scale quark-lepton unification

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    There is a unique SU(4)SU(2)LSU(2)RSU(4) \otimes SU(2)_L \otimes SU(2)_R gauge model which allows quarks and leptons to be unified at the TeV scale. It is already known that the neutrino masses arise radiatively in the model and are naturally light. We study the atmospheric, solar and LSND neutrino anomalies within the framework of this model.Comment: Minor changes, 31 page

    Lanthanide Induced Photoluminescence in Lead-Free Cs₂AgBiBr₆ Bulk Perovskite: Insights From Optical and Theoretical Investigations

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    The search for materials substituting toxic lead in metal halide perovskites has recently placed emphasis on the Cs2AgBiBr6 double perovskite as a possible candidate. The poor light-emissive features of this species, mainly associated to the indirect nature of the band gap and the strongly bound exciton, however, currently make it unsuitable for solid-state lighting applications. Doping with lanthanides is an established strategy to implement luminescence in poorly emissive materials, with the additional advantage of tuning the wavelength of emission independently from the host band structure. We discuss here the impact of Eu- and Yb-doping on the absorption and emission properties of Cs2AgBiBr6 polycrystalline thin films, obtained from solution-processing of hydrothermally synthesized bulk crystalline powders, by combining experiments and density functional theory calculations. Eu(III) incorporation does not lead to the characteristic 5D0→7F2 emission feature at 2 eV, while only a weak sub band-gap radiative emission ascribed to a trap-assisted recombination process is reported. On the other hand, we demonstrate that Yb(III) incorporated in the bulk double perovskite leads to an intense and exclusive photoluminescence emission in the near-infrared (NIR) from thin films, as a result of the efficient sensitization of the lanthanide centered 2F5/2→2F7/2 transition, with favorable mid-gap energetic position. Yb-doping may be thus exploited for the future development of stable and sustainable perovskite NIR-light emitters
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