189 research outputs found

    On the rr-stability of spacelike hypersurfaces

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    In this paper we study the strong stability of spacelike hypersurfaces with constant rr-th mean curvature in Generalized Robertson-Walker spacetimes of constant sectional curvature. In particular, we treat the case in which the ambient spacetime is the de Sitter space

    The mean curvature of cylindrically bounded submanifolds

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    We give an estimate of the mean curvature of a complete submanifold lying inside a closed cylinder B(r)×RB(r)\times\R^{\ell} in a product Riemannian manifold Nn×RN^{n-\ell}\times\R^{\ell}. It follows that a complete hypersurface of given constant mean curvature lying inside a closed circular cylinder in Euclidean space cannot be proper if the circular base is of sufficiently small radius. In particular, any possible counterexample to a conjecture of Calabion complete minimal hypersurfaces cannot be proper. As another application of our method, we derive a result about the stochastic incompleteness of submanifolds with sufficiently small mean curvature.Comment: First version (December 2008). Final version, including new title (February 2009). To appear in Mathematische Annale

    Marginally Trapped Surfaces in the Nonsymmetric Gravitational Theory

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    We consider a simple, physical approach to the problem of marginally trapped surfaces in the Nonsymmetric Gravitational Theory (NGT). We apply this approach to a particular spherically symmetric, Wyman sector gravitational field, consisting of a pulse in the antisymmetric field variable. We demonstrate that marginally trapped surfaces do exist for this choice of initial data.Comment: REVTeX 3.0 with epsf macros and AMS symbols, 3 pages, 1 figur

    Los depósitos de ceniza volcánica del Pleistoceno Superior-Holoceno de la región de Tafí del Valle-Cafayate, noroeste de Argentina

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    [EN]We identified volcanic ash deposits, whose thickness can exceed sometimes the 4 m, in the southeastern margin of La Puna and neighbouring areas (Provinces of Tucuman and Salta, Argentina). These Late Pleistocene and Holocene deposits show the existence of a highly explosive volcanism only some few thousand years ago, without comparison with any historical volcanic episode in northwestern Argentina. We have characterized the size distribution of ash (laser diffraction), morphology of particles (SEM), mineralogy (XRD) and the geochemistry of major and trace elements in bulk sample using mass spectrometry (HR-ICP-MS). The information provided by these deposits is of great interest to size adequately the geochemical impact models of ashfall in future volcanic eruptions in the Central Volcanic Zone of the Andes, quantifying the contribution of volcanic ash to the regional geochemical balances, both with respect to nutrients (e.g., Ca and Fe) and potentially toxic elements (e.g., As and F), among other elements of interest.[ES] Se han localizado diversos depósitos de ceniza volcánica, cuyos espesores llegan a superar en ocasiones los 4 m al suroeste de La Puna y áreas limítrofes (Provincias de Tucumán y Salta, Argentina). Estos depósitos son de edad Pleistoceno Superior y Holoceno y muestran la existencia hace pocos miles de años de volcanismo altamente explosivo, sin comparación con ningún episodio volcánico histórico en el noroeste de Argentina. Se han caracterizado la distribución granulométrica de la ceniza (difracción laser), la morfología de las partículas (microscopía electrónica de barrido), mineralogía (difracción de rayos X) y la geoquímica de elementos mayores y trazas en muestra total mediante espectrometría de masas (HR-ICP-MS). La información suministrada por estos depósitos tiene gran interés a la hora de dimensionar los modelos de impacto geoquímico de la caída de ceniza de futuras erupciones volcánicas en la Zona Volcánica Central de los Andes, cuantificando la contribución de la ceniza volcánica a los balances geoquímicos regionales, tanto por lo que respecta a nutrientes (p. ej., Ca y Fe), como de elementos potencialmente tóxicos (p. ej., As y F), entre otros elementos de interés.Agradecemos el apoyo técnico del labGEOTOP (infraestructura cofinanciada por FEDER, CSIC08-4E-001) del ICTJA-CSIC; de los Grupos PEGEFA (2009-SGR-972) y GEOVOL y fue financiado por el Proyecto QUECA (CGL2011-23307).Peer reviewe

    Preservation and Promotion of Opera Cultural Heritage: The Experience of La Scala Theatre

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    This paper focuses on music and music-related cultural heritage typically preserved by opera houses, starting from the experience achieved during the long-lasting collaboration between La Scala theater and the Laboratory of Music Informatics of the University of Milan. First, we will mention the most significant results achieved by the project in the fields of preservation, information retrieval and dissemination of cultural heritage through computer-based approaches. Moreover, we will discuss the possibilities offered by new technologies applied to the conservative context of an opera house, including: the multi-layer representation of music information to foster the accessibility of musical content also by non-experts; the adoption of 5G networks to deliver spherical videos of live events, thus opening new scenarios for cultural heritage enjoyment and dissemination; deep learning approaches both to improve internal processes (e.g., back-office applications for music information retrieval) and to offer advanced services to users (e.g., highly-customized experiences)

    Practical guidelines to manage discordant situations of SMN2 copy number in patients with spinal muscular atrophy

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    Objective Assessment of SMN2 copy number in patients with spinal muscular atrophy (SMA) is essential to establish careful genotype-phenotype correlations and predict disease evolution. This issue is becoming crucial in the present scenario of therapeutic advances with the perspective of SMA neonatal screening and early diagnosis to initiate treatment, as this value is critical to stratify patients for clinical trials and to define those eligible to receive medication. Several technical pitfalls and interindividual variations may account for reported discrepancies in the estimation of SMN2 copy number and establishment of phenotype-genotype correlations. Methods We propose a management guide based on a sequence of specified actions once SMN2 copy number is determined for a given patient. Regardless of the method used to estimate the number of SMN2 copies, our approach focuses on the manifestations of the patient to recommend how to proceed in each case. Results We defined situations according to SMN2 copy number in a presymptomatic scenario of screening, in which we predict the possible evolution, and when a symptomatic patient is genetically confirmed. Unexpected discordant cases include patients having a single SMN2 copy but noncongenital disease forms, 2 SMN2 copies compatible with type II or III SMA, and 3 or 4 copies of the gene showing more severe disease than expected. Conclusions Our proposed guideline would help to systematically identify discordant SMA cases that warrant further genetic investigation. The SMN2 gene, as the main modifier of SMA phenotype, deserves a more in-depth study to provide more accurate genotype-phenotype correlations

    Monitoreo y simulaciones de desempeño térmico de aulas de la Facultad de Arquitectura de la UNNE en días de verano y condiciones reales de uso

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    Se exponen los resultados del monitoreo térmico, contrastado con simulaciones mediante ECOTECT, de seis aulas del edificio de la Facultad de Arquitectura y Urbanismo (FAU) de la Universidad Nacional del Nordeste (UNNE), durante un período de 15 días de verano, en la ciudad de Resistencia, Chaco. El objetivo fue detectar posibles problemas de disconfort y completar un diagnóstico de situación higrotérmica, cuya primera etapa la constituyó el monitoreo y simulaciones previas del mismo edificio, durante Julio de 2011, así como validar los resultados de las simulaciones. Por los resultados obtenidos, el edificio monitoreado, que constituye una tipología constructiva tradicional representativa de muchos edificios institucionales de la década del ’50 (en servicio activo en varias provincias del país), constituye un caso de desempeño térmico deficiente durante días de verano típicos de la zona “Ib”, con temperaturas interiores por encima del límite superior confortable definido, durante el 95% del tiempo de monitoreo.This work presents the thermal monitoring’s results, contrasted with simulations by ECOTECT, of six classrooms of the building of Architecture and Urbanism Faculty (FAU) of Northeast National University (UNNE) during a period of 15 summer days, in Resistencia city. The objective was to validate the results of the simulations and to detect potential thermal discomfort problems and complete a diagnosis of hygrothermal situation, whose first stage was the previous monitoring and simulations of the same building during a period of July 2011. As the results, the monitored building, which is a traditional building type, representative of many institutional buildings of the ´50s (on active duty in several argentine provinces), is a case of poor thermal performance during typical summer days in the "Ib" zone, with indoor temperatures above the upper defined comfort limit , during 95% of monitoring time.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

    Volatile diterpene emission by two Mediterranean Cistaceae shrubs

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    Mediterranean vegetation emits a wide range of biogenic volatile organic compounds (BVOCs) among which isoprenoids present quantitatively the most important compound class. Here, we investigated the isoprenoid emission from two Mediterranean Cistaceae shrubs, Halimium halimifolium and Cistus ladanifer, under controlled and natural conditions, respectively. For the first time, diurnal emission patterns of the diterpene kaurene were detected in real-time by Proton-Transfer-Reaction-Timeof- Flight-Mass-Spectrometer. Kaurene emissions were strongly variable among H. halimifolium plants, ranging from 0.01 ± 0.003 to 0.06 ± 0.01 nmol m−2 s−1 in low and high emitting individuals, respectively. They were in the same order of magnitude as monoterpene (0.01 ± 0.01 to 0.11 ± 0.04 nmol m−2 s−1) and sesquiterpene (0.01 ± 0.01 to 0.52 nmol m−2 s−1) emission rates. Comparable range and variability was found for C. ladanifer under natural conditions. Labelling with 13C-pyruvate suggested that emitted kaurene was not derived from de novo biosynthesis. The high kaurene content in leaves, the weak relationship with ecophysiological parameters and the tendency of higher emissions with increasing temperatures in the field indicate an emission from storage pools. This study highlights significant emissions of kaurene from two Mediterranean shrub species, indicating that the release of diterpenes into the atmosphere should probably deserve more attention in the futureinfo:eu-repo/semantics/publishedVersio

    Anales de Edafología y Agrobiología Tomo 36 Número 1-2

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    Duración efectiva del índice de sequedad, por M. P. Garmendía y J. Garmendía.-- Adsorción y evolución de manganeso en arcillas, por O. Carpena, I. Tovar, A. Lax y F. Costa.-- Ecología de leguminosas en relación con algunos factores ambientales en Guadalajara. I. Aspectos florísticos y relación con la clase ele suelo, por M. Morey.-- Variaciones del contenido de nitrógeno en una plantación de Lolium perenne,por Esther Simón Martínez.-- Predicción de temperaturas máximas diarias, por E. Hernández, J. A. Hernández, J. F. Sánchez y J. Garmendía.-- Efectos del almacenaje sobre las propiedades físicas y biológicas de muestras tamizadas de suelos orgánicos, por F. Díaz-Fierros Viqueiro.-- Morfometría del cuarzo y circón aplicada al estudio genético de un suelo policíclico, por M. C. Villar Celorio.-- Contribución al estudio de la terra rossa española. II. Mineralogía de la fracción arcilla, por L. J. Alías, M. Nieto y J. Albaladejo.-- Entisoles del Campo de Cartagena (Murcia). Características generales y mineralógicas, por L. J. Alías y R. Ortiz Silla.-- Estudio sobre la composición química de variedades de almendra del sureste español, por F. Romojaro, J. F. García y F. J. López Andreu.-- Componentes del plátano canario y sus variaciones durante la maduración, por A. Carlos Blesa, M. A. Rodríguez Raymond y A. Maestre.-- Contribución al estudio de la platanera canaria. Relación entre la actividad respiratoria y la maduración de los plátanos, por A. Carlos Blesa, M. A Rodríguez Raymoud, C. D. Lorenzo e Isabel López.-- Notas.-- Reestructuración del C. S. I. C.-- Nombramiento del Prof. Casas Peláez como Presidente del C. S. I. C. 1.-- Carta del Presidente del C. S. I. C. al personal del mismo.-- Nombramiento del Prof. Snárez y Suárez como Director general de Educación Bastea.-- 6.° Curso Internacional de Fertilidad de Suelos y Nutrición Vegetal.—8ª Reunión Internacional de Micromorfología de Suelos.—19ª Conferencia General de la UNESCO.-- Sociedad Española de Ciencia del Suelo.-- Nombramiento de Secretario del Centro de Edafología y Biología Aplicada de Salamanca.-- Dimisión del Director del Centre de Edafología y Biología Aplicada del Cuarto (Sevilla).-- Propuesta de Director del Centro de Edafología y Biología Aplicada del Cuarto.-- Viaje del Prof. Troncoso.-- Grupo Español de Trabajo del Cuaternario.-- Autorizaciones para realizar función docente.-- Invitaciones a Profesores extranjeros.-- Programa de cooperación internacional con lberoamérica: bolsas de estudio y viaje .-- Conferencia del Prof. Salerno.-- Viaje realizado a Hispanoamérica por el Dr. D. Francisco Girela Vilchez.-- Creación del Centro de Formaci.ón y Promoción de Personal del C. S. I. C. (C. F. P. P.)Peer reviewed2019-08.- CopyBook.- Libnova.- Biblioteca ICA

    High-Throughput Sequencing of RNA Silencing-Associated Small RNAs in Olive (Olea europaea L.)

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    Small RNAs (sRNAs) of 20 to 25 nucleotides (nt) in length maintain genome integrity and control gene expression in a multitude of developmental and physiological processes. Despite RNA silencing has been primarily studied in model plants, the advent of high-throughput sequencing technologies has enabled profiling of the sRNA component of more than 40 plant species. Here, we used deep sequencing and molecular methods to report the first inventory of sRNAs in olive (Olea europaea L.). sRNA libraries prepared from juvenile and adult shoots revealed that the 24-nt class dominates the sRNA transcriptome and atypically accumulates to levels never seen in other plant species, suggesting an active role of heterochromatin silencing in the maintenance and integrity of its large genome. A total of 18 known miRNA families were identified in the libraries. Also, 5 other sRNAs derived from potential hairpin-like precursors remain as plausible miRNA candidates. RNA blots confirmed miRNA expression and suggested tissue- and/or developmental-specific expression patterns. Target mRNAs of conserved miRNAs were computationally predicted among the olive cDNA collection and experimentally validated through endonucleolytic cleavage assays. Finally, we use expression data to uncover genetic components of the miR156, miR172 and miR390/TAS3-derived trans-acting small interfering RNA (tasiRNA) regulatory nodes, suggesting that these interactive networks controlling developmental transitions are fully operational in olive
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