4,367 research outputs found
Tidal streams around galaxies in the SDSS DR7 archive
Context. Models of hierarchical structure formation predict the accretion of
smaller satellite galaxies onto more massive systems and this process should be
accompanied by a disintegration of the smaller companions visible, e.g., in
tidal streams. Aims. In order to verify and quantify this scenario we have
developed a search strategy for low surface brightness tidal structures around
a sample of 474 galaxies using the Sloan Digital Sky Survey DR7 archive.
Methods. Calibrated images taken from the SDSS archive were processed in an
automated manner and visually inspected for possible tidal streams. Results. We
were able to extract structures at surface brightness levels ranging from \sim
24 down to 28 mag arcsec-2. A significant number of tidal streams was found and
measured. Their apparent length varies as they seem to be in different stages
of accretion. Conclusions. At least 6% of the galaxies show distinct stream
like features, a total of 19% show faint features. Several individual cases are
described and discussed.Comment: 15 pages, 21 figures. Accepted for publication in A&
Discovery of tidal tails around the distant globular cluster Palomar 14
We report the detection of a pair of degree-long tidal tails associated with
the globular cluster Palomar 14, using images obtained at the CFHT. We reveal a
power-law departure from a King profile at large distances to the cluster
center. The density map constructed with the optimal matched filter technique
shows a nearly symmetrical and elongated distribution of stars on both sides of
the cluster, forming a S-shape characteristic of mass loss. This evidence may
be the telltale signature of tidal stripping in action. This, together with its
large Galactocentric distance, imposes strong constraints on its orbit and/or
origin: i) it must follow an external orbit confined to the peripheral region
of the Galactic halo and/or ii) it formed in a satellite galaxy later accreted
by the Milky Way.Comment: 8 pages, 9 figures, accepted for publication by Ap
Preliminary study of the genetic differentiation between two variety of cuban creole pig
It is admitted an Iberian origin for the Cuban Creole Pig breed. Inside this breed there exist varieties morphologically very well defined, as the Unhaired and Middlehaired types. The existence of these types is traditionally admitted by Cuban producers, researchers and by the society in general. To confirmate the genetic differentiation of these two morphological types, we have analyzed 93 samples of the breed, with representation of the middlehaired (MD) type (58 animals) and unhaired (UH) type (35 animals) taken from several Cuba provinces. We have used a test of 20 microsatellites of the recommended by FAO/ISAG. The obtained values for the parameters GST (0.74 and 0.12 percent) are extremely low. All these results are showing a no existence of varieties inside the Cuban Creole Pig breed.Al cerdo Criollo Cubano (cCC) se le atribuye un origen ibérico. Dentro de este último existen variedades bien definidas, como la Lampiña y la Entrepelada, las cuales han tenido representación al menos morfológica dentro del cCC. La existencia de estos dos tipos es aceptada en Cuba por productores, investigadores y por la sociedad en general. Con el objetivo de determinar la existencia o no de diferenciación genética entre ellos, se analizaron 93 animales, de ellos, 58 entrepelados y 35 lampiños. Se emplearon 20 microsatélites recomendados por la FAO/ISAG (International Society of Animal Genetics) para estudios de biodiversidad porcina. Los microsatélites se amplificaron mediante la Reacción en Cadena de la Polimerasa (PCR) y los fragmentos amplificados se separaron mediante electroforesis en un secuenciador automático. Los valores que se obtienen en los parámetros GST, 0,74 p.100 y 0,12 p.100 son extremadamente bajos, lo que demuestra que dentro del cCC no existe subdivisión varietal
Remnants of Sagittarius Dwarf Spheroidal Galaxy around the young globular cluster Palomar 12
Photometry of a large field around the young globular cluster Palomar 12 has
revealed the main-sequence of a low surface-brightness stellar system. This
main-sequence is indicative of a stellar population that varies significantly
in metallicity and/or age, but in the mean is more metal poor than Pal 12.
Under different assumptions for the properties of this population, we find
distances from the Sun in the range 17-24 kpc, which encompasses the distance
to Pal 12, kpc. The stellar system is also detected in a field
2\arcdeg North of Pal 12, which indicates it has a minimum diameter of
kpc. The orbit of Pal 12 (Dinescu et al. 2000), the color-magnitude
diagram of the stellar system, their positions on the sky, and their distances
suggest that they are debris from the tidal disruption of the Sgr dSph galaxy.
We discuss briefly the implications for the evolution of Sgr and the Galactic
halo.Comment: 16 pages, 2 figures, accepted for ApJ Letters. Some importante
changes after revision, including a new figur
Treatment of Social Media in Person Name Disambiguation in the Web
En este trabajo presentamos dos heurÃsticas para tratar páginas web correspondientes a redes sociales en el problema de desambiguación de nombres de persona en la Web. Este problema consiste en agrupar las páginas web proporcionadas por un motor de búsqueda al consultar un nombre de persona según el individuo al que se refieren. Aunque estas páginas web pueden afectar negativamente en la agrupación de los resultados, la mayorÃa de sistemas del estado del arte no tienen en cuenta su papel en este problema. Hemos evaluado nuestras heurÃsticas con dos colecciones que contienen este tipo de páginas web. Para agrupar las páginas web hemos utilizado una extensión de un algoritmo del estado del arte. Ambas heurÃsticas obtienen mejoras cuando hay un número elevado de páginas sociales y el algoritmo propuesto es más independiente del nivel de ambigüedad de los nombres de persona que otros propuestos por el estado del arte.In this work, we present two heuristics to treat web pages from social networks for person name disambiguation in the Web. This problem consists in clustering the results provided by a search engine when the query is a person name according to the individual they refer to. Although these web pages could negatively affect when grouping the results, most of the systems in the state-of-the-art do not take into account their role in this problem. We have evaluated our heuristics with two collections that contain this kind of web pages. We have used an extension of an algorithm of the state of the art to cluster the web pages. Both heuristics get improvements when there is a high number of social web pages, and the proposed algorithm is more independent with respect to the ambiguity degree of person names than other ones in the state of the art.Este trabajo ha sido subvencionado por el Ministerio de Ciencia e Innovación [MED-RECORD Project, TIN2013-46616-C2-2-R] y el grupo CVIP de la URJC
Analysis of Silage Fermentation Characteristics Using Transflectance Measurements by Near Infrared Spectroscopy
The fermentation end products as lactic acid, volatile fatty acids and ammonia-nitrogen, are important indicators of the efficiency of silage fermentation and are closely related to nutritive value of them (Jaster, 1995). Drying is problematic in the case of silage as many fermentation products are volatile and may get lost during the drying process. This may be a reason why NIR technology is being little used for the evaluation of silage fermentation characteristics. The feasibility of using near infrared transflectance spectroscopy to evaluate the content in fermentation end products of grass and maize fresh silage was investigated in this study
Predicción de amputación mediante MESS (Mangled Extremity Severity Score) en pacientes con lesión traumática vascular grave
En este estudio retrospectivo y ciego se analizan las historias clÃnicas de 60 pacientes
(63 miembros inferiores), que ingresaron en nuestro hospital desde 1978 a 1992 a
causa de una lesión traumática vascular grave; en este grupo no se incluyeron los pacientes con
traumatismo vascular localizado por encima de la cadera o debajo del tobillo. El objetivo del
estudio ha sido investigar si el MESS (Mangled extremity severity score) es un sistema útil para
decidir entre la amputación precoz o el intento de reconstrucción en este tipo de pacientes. De
36 miembros que terminaron en amputación, 34 tuvieron un MESS de 7 o más, demostrando
una sensibilidad del test del 94,4%. De 27 miembros que se salvaron, 22 tuvieron un MESS de
6 o menos, demostrando una especificidad del 81,4%. Asà pues, el MESS es un test útil para
predecir la necesidad o no de amputar un miembro con lesión vascular traumática grave, pero
no es absolutamente fiable. Parece más fiable cuando se aplica a pacientes con traumatismo
vascular grave que cuando se aplica a pacientes con traumatismo, tengan o no lesión vascular.60 patients (63 limbs) suffering from a severe vascular injury of the lower extremities
between 1978-1992 have been retrospectively reviewed. Those cases wherein vascular injury
was located above the hip level or under the ankle level were not included. The aim of this study
was to investÃgate whether the Mangled Extremity Severity Score (MESS) is a useful test to decide
between limb salvage or early amputation in this type of patients. Among 36 amputated limbs. 34
had a score equal or greater than 7, the rate of sensitivity of the test was 94,4%. Among 27 salvaged
limbs, 22 had a score equal or lower than 6, showing a rate of specificity of 81,4%. The MESS
seems to be a very useful test for prediction of limb salvage versus amputation with severe vascular
injury, although it is not totally reliable. It seems better when applied to patients with vascular injury,
rather than to those with mangled extremity, with or without vascular injury
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