1,680 research outputs found
The ALHAMBRA photometric system
This paper presents the characterization of the optical range of the ALHAMBRA
photometric system, a 20 contiguous, equal-width, medium-band CCD system with
wavelength coverage from 3500A to 9700A. The photometric description of the
system is done by presenting the full response curve as a product of the
filters, CCD and atmospheric transmission curves, and using some first and
second order moments of this response function. We also introduce the set of
standard stars that defines the system, formed by 31 classic spectrophotometric
standard stars which have been used in the calibration of other known
photometric systems, and 288 stars, flux calibrated homogeneously, from the
Next Generation Spectral Library (NGSL). Based on the NGSL, we determine the
transformation equations between Sloan Digital Sky Survey (SDSS) ugriz
photometry and the ALHAMBRA photometric system, in order to establish some
relations between both systems. Finally we develop and discuss a strategy to
calculate the photometric zero points of the different pointings in the
ALHAMBRA project.Comment: Astronomical Journal on the 14th of January 201
High redshift AGNs from the 1Jy catalogue and the magnification bias
We have found a statistically significant (99.1 \%) excess of red ()
galaxies with photographic magnitudes , taken from the APM Sky
Catalogue around radiosources from the 1Jy catalogue. The amplitude,
scale and dependence on galaxy colours of the observed overdensity are
consistent with its being a result of the magnification bias caused by the weak
gravitational lensing of large scale structures at redshift
and are hardly explained by other causes, as obscuration by dust.Comment: uuencoded file containing 3 ps files: the main text, a table and a
figure. To appear in ApJ Letter
Fast Integrated Spectra Analyzer: A New Computational Tool For Age and Reddening Determination of Small Angular Diameter Open Clusters
We present a new algorithm called 'Fast Integrated Spectra Analyzer" (FISA)
that permits fast and reasonably accurate age and reddening determinations for
small angular diameter open clusters by using their integrated spectra in the
(3600-7400) \AA \ range and currently available template spectrum libraries.
This algorithm and its implementation help to achieve astrophysical results in
shorter times than from other methods. A brief review is given of the
integrated spectroscopic technique applied to the study of open clusters as
well as the basic assumptions that justify its use. We describe the numerical
algorithm employed in detail, show examples of its application, and provide a
link to the code. Our method has successfully been applied to integrated
spectroscopy of open clusters, both in the Galaxy and in the Magellanic Clouds,
to determine ages and reddenings.Comment: 27 Pages, 7 Figures, 1 table. Accepted to PAS
The ALHAMBRA Project: A large area multi medium-band optical and NIR photometric survey
(ABRIDGED) We describe the first results of the ALHAMBRA survey which
provides cosmic tomography of the evolution of the contents of the Universe
over most of Cosmic history. Our approach employs 20 contiguous, equal-width,
medium-band filters covering from 3500 to 9700 A, plus the JHKs bands, to
observe an area of 4 sqdeg on the sky. The optical photometric system has been
designed to maximize the number of objects with accurate classification by SED
and redshift, and to be sensitive to relatively faint emission lines. The
observations are being carried out with the Calar Alto 3.5m telescope using the
cameras LAICA and O-2000. The first data confirm that we are reaching the
expected magnitude limits of AB<~25 mag in the optical filters from the blue to
8300 A, and from AB=24.7 to 23.4 for the redder ones. The limit in the NIR is
(Vega) K_s~20, H~21, J~22. We expect to obtain accurate redshift values, Delta
z/(1+z) <~ 0.03 for about 5x10^5 galaxies with I<~25 (60% complete), and
z_med=0.74. This accuracy, together with the homogeneity of the selection
function, will allow for the study of the redshift evolution of the large scale
structure, the galaxy population and its evolution with redshift, the
identification of clusters of galaxies, and many other studies, without the
need for any further follow-up. It will also provide targets for detailed
studies with 10m-class telescopes. Given its area, spectral coverage and its
depth, apart from those main goals, the ALHAMBRA-Survey will also produce
valuable data for galactic studies.Comment: Accepted to the Astronomical Journal. 43 pages, 18 figures. The
images have been reduced in resolution to adapt to standard file sizes.
Readers can find the full-resolution version of the paper at the ALHAMBRA web
site (http://www.iaa.es/alhambra) under the "Publications" lin
The Cluster Lensing and Supernova Survey with Hubble (CLASH): Strong Lensing Analysis of Abell 383 from 16-Band HST WFC3/ACS Imaging
We examine the inner mass distribution of the relaxed galaxy cluster Abell
383 in deep 16-band HST/ACS+WFC3 imaging taken as part of the CLASH multi-cycle
treasury program. Our program is designed to study the dark matter distribution
in 25 massive clusters, and balances depth with a wide wavelength coverage to
better identify lensed systems and generate precise photometric redshifts. This
information together with the predictive strength of our strong-lensing
analysis method identifies 13 new multiply-lensed images and candidates, so
that a total of 27 multiple-images of 9 systems are used to tightly constrain
the inner mass profile, (r<160 kpc).
We find consistency with the standard distance-redshift relation for the full
range spanned by the lensed images, 1.01<z<6.03, with the higher redshift
sources deflected through larger angles as expected. The inner mass profile
derived here is consistent with the results of our independent weak-lensing
analysis of wide-field Subaru images, with good agreement in the region of
overlap. The overall mass profile is well fitted by an NFW profile with
M_{vir}=(5.37^{+0.70}_{-0.63}\pm 0.26) x 10^{14}M_{\odot}/h and a relatively
high concentration, c_{vir}=8.77^{+0.44}_{-0.42}\pm 0.23, which lies above the
standard c-M relation similar to other well-studied clusters. The critical
radius of Abell 383 is modest by the standards of other lensing clusters,
r_{E}\simeq16\pm2\arcsec (for z_s=2.55), so the relatively large number of
lensed images uncovered here with precise photometric redshifts validates our
imaging strategy for the CLASH survey. In total we aim to provide similarly
high-quality lensing data for 25 clusters, 20 of which are X-ray selected
relaxed clusters, enabling a precise determination of the representative mass
profile free from lensing bias. (ABRIDGED)Comment: 15 pages, 14 figures, 2 tabels; V3 matches the submitted version
later published in Ap
Physical capacity in youth football players of a profesional club
Las características físicas del fútbol son muy diversas, aunque se reconocen como muy importantes la capacidad de realizar esfuerzos de alta intensidad y la de retrasar la fatiga en la mayor medida posible en esfuerzos intermitentes. Son diversos los trabajos que analizan dichas características en el fútbol profesional, aunque son menores los que analizan las categorías de
formación. En el presente estudio se analiza la evolución por categorías de pruebas de salto, velocidad, agilidad y resistencia aeróbica específica, en jugadores de fútbol jóvenes de la cantera de un club profesional de la liga española. Se produjo un incremento de las marcas con la edad, aunque no se observaron diferencias significativas en grupos de edad cercanos, produciéndose una meseta en el rendimiento en la fuerza explosiva y velocidad de aceleración a partir de los 17 años y en la velocidad de desplazamiento y agilidad a los 15 añosPhysical characteristics of football are very different, but are recognized as very important the ability to perform high-intensity efforts and to delay fatigue as much as possible in intermittent efforts. There are several studies that analyze these characteristics in professional football but are less those who analyze the categories of training. In the present study analyzes the evolution of categories of jumping, speed, agility and specific endurance in young soccer players from a professional club of the Spanish league. There was an increase of the marks with age, although no significant differences in age groups encircle. Producing a plateau in performance in explosive strength and acceleration speed from 17 years and in speed and agility at age of 1
Three-dimensional printed polycaprolactone-microcrystalline cellulose scaffolds
Microcrystalline cellulose (MCC) is proposed in this study as an additive in polycaprolactone (PCL) matrices to obtain three-dimensional (3D) printed scaffolds with improved mechanical and biological properties. Improving the mechanical behavior and the biological performance of polycaprolactone-based scaffolds allows to increase the potential of these structures for bone tissue engineering. Different groups of samples were evaluated in order to analyze the effect of the additive in the properties of the PCL matrix. The concentrations of MCC in the groups of samples were 0, 2, 5, and 10% (w/w). These combinations were subjected to a thermogravimetric analysis in order to evaluate the influence of the additive in the thermal properties of the composites. 3D printed scaffolds were manufactured with a commercial 3D printer based on fused deposition modelling. The operation conditions have been established in order to obtain scaffolds with a 0/90° pattern with pore sizes between 450 and 500 µm and porosity values between 50 and 60%. The mechanical properties of these structures were measured in the compression and flexural modes. The scaffolds containing 2 and 5% MCC have higher flexural and compression elastic modulus, although those containing 10% do not show this reinforcement effect. On the other hand, the proliferation of sheep bone marrow cells on the proposed scaffolds was evaluated over 8 days. The results show that the proliferation is significantly better (p < 0.05) on the group of samples containing 2% MCC. Therefore, these scaffolds (PCL:MCC 98:2) have suitable properties to be further evaluated for bone tissue engineering applications
Sinovitis villonodular pigmentada difusa: Revisión de 13 casos
Se hace un estudio retrospectivo de trece pacientes con Sinovitis Villonodular pigmentada, seis localizadas en la rodilla, dos en la muñeca y pie, y uno en tobillo, cadera y codo respectivamente. En cinco de los casos existía una afectación del hueso. Se hace una revisión bibliográfica sobre la etiopatogenia, radiología, métodos diagnósticos y tratamientoA retrospective study of thirteen patients with pigmented villonodular synovitis was made. Six cases were localized in the knee, two in the wrist and feet, and one in ankle, hip and elbow. Five case showed bone invasion, the pathogenesis, radiographical appearance, diagnosis and treatment are discussed
- …