138 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

    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

    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

    Single Collateral Reconstructions Reveal Distinct Phases of Corticospinal Remodeling after Spinal Cord Injury

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    Injuries to the spinal cord often result in severe functional deficits that, in case of incomplete injuries, can be partially compensated by axonal remodeling. The corticospinal tract (CST), for example, responds to a thoracic transection with the formation of an intraspinal detour circuit. The key step for the formation of the detour circuit is the sprouting of new CST collaterals in the cervical spinal cord that contact local interneurons. How individual collaterals are formed and refined over time is incompletely understood

    CIBERER : Spanish national network for research on rare diseases: A highly productive collaborative initiative

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    Altres ajuts: Instituto de Salud Carlos III (ISCIII); Ministerio de Ciencia e Innovación.CIBER (Center for Biomedical Network Research; Centro de Investigación Biomédica En Red) is a public national consortium created in 2006 under the umbrella of the Spanish National Institute of Health Carlos III (ISCIII). This innovative research structure comprises 11 different specific areas dedicated to the main public health priorities in the National Health System. CIBERER, the thematic area of CIBER focused on rare diseases (RDs) currently consists of 75 research groups belonging to universities, research centers, and hospitals of the entire country. CIBERER's mission is to be a center prioritizing and favoring collaboration and cooperation between biomedical and clinical research groups, with special emphasis on the aspects of genetic, molecular, biochemical, and cellular research of RDs. This research is the basis for providing new tools for the diagnosis and therapy of low-prevalence diseases, in line with the International Rare Diseases Research Consortium (IRDiRC) objectives, thus favoring translational research between the scientific environment of the laboratory and the clinical setting of health centers. In this article, we intend to review CIBERER's 15-year journey and summarize the main results obtained in terms of internationalization, scientific production, contributions toward the discovery of new therapies and novel genes associated to diseases, cooperation with patients' associations and many other topics related to RD research

    Estudo fitoquímico de folhas de Solanum lycocarpum A. St.-Hil (Solanaceae) e sua aplicação na alelopatia

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    (Phytochemistry of Solanum lycocarpum A.St.–Hil (Solanaceae) leaves and their application in allelopathy). Solanum lycocarpum A.St.-Hil (Solanaceae) is a typical shrub in the Cerrado of central Brazil. The allelopathic activity of aqueous extracts of the leaves and fruits of this species has already been proven in previous studies. The goal of this work was to verify the allelopathic activity of different leaf extracts of S. lycocarpum on the germination and growth of four target species. The leaves were collected, dried, triturated and submitted to two distinct methods of extraction: 1- liquid--liquid (ethyl acetate and dichloromethane) from the aqueous extract and 2- with solvents of increasing polarities (hexane, dichloromethane, ethyl acetate, acetone, methanol and water) directly from the leaves. Each extraction was made with ultrasound equipment for one hour, filtered and evaporated. From these extracts, solutions of 800, 400 and 200 ppm were prepared, and water and Logran® were used as positive and negative controls, respectively. Each solution, as well as the controls, was dissolved in DMSO for the bioassays. The target species used were lettuce, watercress, tomato and onion. To each plate, 20 seeds were added and 1 mL of the tested solutions (with 4 repetitions). The plates were incubated at 25 oC without light, and the shoots and roots of the seedlings were then measured and the percentage of germination and the inhibition of each extract were calculated. Tomato was the most sensitive to the extracts, followed by watercress, onion and lettuce. The extracts with stronger activity were AcOEt, acetone and the liquid-liquid extraction, indicating the fractions that may contain the active principles of the leaves in this species
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