3,260 research outputs found

    A new record of the invasive seaweed Caulerpa cylindracea Sonder in the South Adriatic Sea

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    The green alga Caulerpa cylindracea Sonder is one of the most infamous and threatening invasive species in the Mediterranean Sea. Since 1985, it started rapidly spreading to all Mediterranean regions causing many ecological changes on natural communities. In the present study, we present an example of this proliferation with the first record in the Marine Protected Area of Tremiti Island (MPATI) in the South Adriatic Sea. Fifteen sites along the coast and 5 different depths have been investigated. Our results provide eveidence of a wide invasion of this pest in three islands, San Domino, San Nicola and Capraia. This study fills a particular data gap in the ongoing biomonitoring of invasive seaweeds in the Mediterranean Sea representing a base line of this invasive species for the MPATI

    Genetic relationships within and among Iberian fescues (Festuca L.) based on PCR-amplified markers

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    The genus Festuca comprises approximately 450 species and is widely distributed around the world. The Iberian Penninsula, with more than 100 taxa colonizing very diverse habitats, is one of its main centers of diversification. This study was conducted to assess molecular genetic variation and genetic relatedness among 91 populations of 31 taxa of Iberian fescues, based on several molecular markers (random amplified polymorphic DNA, amplified fragment length polymorphisms, and trnL sequences). The analyses showed the paraphyletic origin of the broad-leaved (subgenus Festuca, sections Scariosae and Subbulbosae, and subgenus Schedonorus) and the fine-leaved fescues (subgenus Festuca, sections Aulaxyper, Eskia, and Festuca). Schedonorus showed a weak relationship with Lolium rigidum and appeared to be the most recent of the broad-leaved clade. Section Eskia was the most ancient and Festuca the most recent of the fine-leaved clade. Festuca and Aulaxyper were the most related sections, in concordance with their taxonomic affinities. All taxa grouped into their sections, except F. ampla and F. capillifolia (section Festuca), which appeared to be more closely related to Aulaxyper and to a new independent section, respectively. Most populations clustered at the species level, but some subspecies and varieties mixed their populations. This study demonstrated the value in combining different molecular markers to uncover hidden genetic relationships between populations of Festuca

    Predictions for Triple Stars with and without a Pulsar in Star Clusters

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    Though about 80 pulsar binaries have been detected in globular clusters so far, no pulsar has been found in a triple system in which all three objects are of comparable mass. Here we present predictions for the abundance of such triple systems, and for the most likely characteristics of these systems. Our predictions are based on an extensive set of more than 500 direct simulations of star clusters with primordial binaries, and a number of additional runs containing primordial triples. Our simulations employ a number N_{tot} of equal mass stars from N_{tot}=512 to N_{tot}=19661 and a primordial binary fraction from 0-50%. In addition, we validate our results against simulations with N=19661 that include a mass spectrum with a turn-off mass at 0.8 M_{sun}, appropriate to describe the old stellar populations of galactic globular clusters. Based on our simulations, we expect that typical triple abundances in the core of a dense cluster are two orders of magnitude lower than the binary abundances, which in itself already suggests that we don't have to wait too long for the first comparable-mass triple with a pulsar to be detected.Comment: 11 pages, minor changes to match MNRAS accepted versio

    Dissolving star cluster candidates

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    We present a list of 34 neglected entries from star cluster catalogues located at relatively high galactic latitudes (b>|b| > 15^{\circ}) which appear to be candidate late stages of star cluster dynamical evolution. Although underpopulated with respect to usual open clusters, they still present a high number density contrast as compared to the galactic field. This was verified by means of (i) predicted model counts from different galactic subsystems in the same direction, and (ii) Guide Star Catalog equal solid angle counts for the object and surrounding fields. This suggests that the objects are physical systems, possibly star clusters in the process of disruption or their fossil remains. The sample will be useful for followup studies in view of verifying their physi cal nature.Comment: manuscript in LATEX with 7 pages, 7 figures .ps Accepted for Astronomy and Astrophysics main journa

    Procedimiento de preparación y materiales conformados basados en compuestos eutécticos binarios o ternarios de circonia

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    Referencia OEPM: P9600891.-- Fecha de solicitud: 19/04/1996.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).Procedimiento de preparación y materiales conformados basados en compuestos eutécticos binarios o ternarios de circonia. La presente invención está relacionada con la preparación de materiales con estructuras eutécticas micrométricas basados en mezclas de óxidos, conformados con dimensiones mili y submilimétricas mediante fusión zonal por láser con diferentes sistemas ópticos de focalización y control de los haces de los láseres. Su utilización es en el sector de la producción y conservación de energía, como elementos calefactores, refractarios, cátodos para plasmas de aire, electrodos, en componentes para celdas de combustión, microsensores de gas oxígeno, etc.Peer reviewe

    Contingency tables: developing virtual teaching materials

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    En la actualidad encontramos numerosas herramientas didácticas en Internet, sin embargo su utilidad potencial depende de los conocimientos que proporcionan y su uso por parte del profesor. En este trabajo, se describe un curso desarrollado para la enseñanza de las tablas de contingencia y los conceptos y procedimientos relacionados, en particular la asociación y la independencia, la prueba Chi cuadrado y algunos coeficientes de asociación. Este curso ha sido experimentado en asignaturas de la licenciatura de Psicología

    Respuesta fisiológica al estrés agudo en conejos alimentados con dietas enriquecidas con ácidos grasos poliinsaturados n-3

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    A total of 700 kits were randomly distributed in flatdeck group cages avoiding litter effect. They were fed 2 isofibrous, isoenergetic and isoproteic diets formulated with 2 different sources of fat: mixed fat (control group, C, n=350) and a supplement of salmon oil rich in polyunsaturated fatty acids (PUFAs) n-3 (PUFA group, P, n=350)

    Physical characterization of 2020 AV2, the first known asteroid orbiting inside Venus orbit

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    The first known asteroid with the orbit inside that of Venus is 2020~AV2_{2}. This may be the largest member of a new population of small bodies with the aphelion smaller than 0.718~au, called Vatiras. The surface of 2020~AV2_{2} is being constantly modified by the high temperature, by the strong solar wind irradiation that characterizes the innermost region of the Solar system, and by high-energy micrometeorite impacts. The study of its physical properties represents an extreme test-case for the science of near-Earth asteroids. Here, we report spectroscopic observations of 2020~AV2_{2} in the 0.5-1.5~μm\mu m wavelength interval. These were performed with the Nordic Optical Telescope and the William Herschel Telescope. Based on the obtained spectra, we classify 2020~AV2_{2} as a Sa-type asteroid. We estimate the diameter of this Vatira to be 1.500.65+1.101.50_{-0.65}^{+1.10} km by considering the average albedo of A-type and S-complex asteroids (pV=0.230.08+0.11p_V=0.23_{-0.08}^{+0.11}), and the absolute magnitude (H=16.40±0.7816.40\pm0.78 mag). The wide spectral band around 1~μm\mu m shows the signature of an olivine rich composition. The estimated band centre BIC=1.08±0.02 μmBIC = 1.08 \pm 0.02~\mu m corresponds to a ferroan olivine mineralogy similar to that of brachinite meteorites.Comment: Accepted for publication in MNRAS. 10 pages, 5 figures
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