3,740 research outputs found
Sobre la autonomía constitucional del Servicio Electoral y el control judicial del Tribunal Calificador de Elecciones
Este comentario analiza el alcance de la sentencia del Tribunal Calificador de Elecciones sobre el recurso de queja interpuesto por el pacto electoral “Nueva Mayoría” en contra de la resolución de la Directora (s) del SERVEL ante la negativa de esta de inscribir dicho pacto para las elecciones primarias de Alcalde 2016. La sentencia además de concluir que el Servicio Electoral actuó erradamente al requerir la comparecencia personal de todos los presidentes y secretarios de los partidos políticos, se pronunció sobre la procedencia del recurso de queja ante las actuaciones de dicho Servicio y la sujeción del mismo, como parte de la Administración, al control judicial. El comentario también analiza la forma en que el Tribunal Calificador de Elecciones apreció la prueba en el caso
Exploring the electron density in plasmas induced by extreme ultraviolet radiation in argon
The new generation of lithography tools use high energy EUV radiation which
ionizes the present background gas due to photoionization. To predict and
understand the long term impact on the highly delicate mirrors It is essential
to characterize these kinds of EUV-induced plasmas. We measured the electron
density evolution in argon gas during and just after irradiation by a short
pulse of EUV light at 13.5 nm by applying microwave cavity resonance
spectroscopy. Dependencies on EUV pulse energy and gas pressure have been
explored over a range relevant for industrial applications.
Our experimental results show that the maximum reached electron density
depends linearly on pulse energy. A quadratic dependence - caused by
photoionization and subsequent electron impact ionization by free electrons -
is found from experiments where the gas pressure is varied. This is
demonstrated by our theoretical estimates presented in this manuscript as well.Comment: submitted to J. Phys. D. 16 pages, 8 figure
The substellar mass function in sigma Orionis. II. Optical, near-infrared and IRAC/Spitzer photometry of young cluster brown dwarfs and planetary-mass objects
We investigate the mass function in the substellar domain down to a few
Jupiter masses in the young sigma Orionis open cluster (3+/-2 Ma, d =
360^+70_-60 pc). We have performed a deep IJ-band search, covering an area of
790 arcmin^2 close to the cluster centre. This survey was complemented with an
infrared follow-up in the HKs- and Spitzer 3.6-8.0 mum-bands. Using
colour-magnitude diagrams, we have selected 49 candidate cluster members in the
magnitude interval 16.1 mag < I < 23.0 mag. Accounting for flux excesses at 8.0
mum and previously known spectral features of youth, 30 objects are bona fide
cluster members. Four are first identified from our optical-near infrared data.
Eleven have most probable masses below the deuterium burning limit and are
classified as planetary-mass object candidates. The slope of the substellar
mass spectrum (Delta N / Delta M = a M^-alpha) in the mass interval 0.11 Msol M
< 0.006 Msol is alpha = +0.6+/-0.2. Any opacity mass-limit, if these objects
form via fragmentation, may lie below 0.006 Msol. The frequency of sigma
Orionis brown dwarfs with circumsubstellar discs is 47+/-15 %. The continuity
in the mass function and in the frequency of discs suggests that very low-mass
stars and substellar objects, even below the deuterium-burning mass limit, may
share the same formation mechanism.Comment: Accepted for publication in A&A (12/04/2007). It has not been edited
for language ye
A near-infrared survey for new low-mass members in Alpha Per
We present a near-infrared (K'-band) survey of 0.7 square degree area in the
Alpha Persei open cluster (age = 90 Myr, distance = 182 pc) carried out with
the Omega-Prime camera on the Calar Alto 3.5-m telescope. Combining optical
data (Rc and Ic) obtained with the KPNO/MOSA detector and presented in Stauffer
et al. (1999) with the K' observations, a sample of new candidate members has
been extracted from the optical-infrared colour-magnitude diagram. The location
of these candidates in the colour-colour diagram suggests that two-thirds of
them are actually reddened background giants. About 20 new candidate members
with masses between 0.3 and 0.04 Msun are added to the 400 known Alpha Per
cluster members. If they are indeed Alpha Per members, four of the new
candidates would be brown dwarfs. We discuss the advantages and drawbacks of
the near-infrared survey as compared to the optical selection method. We also
describe the outcome of optical spectroscopy obtained with the Twin
spectrograph on the Calar Alto 3.5-m telescope for about 30 candidates,
including selected members from the optical sample presented in Barrado y
Navascues et al. (2002) and from our joint optical/infrared catalogue. These
results argue in favour of the optical selection method for this particular
cluster.Comment: 13 pages, 10 figures, 3 tables and 1 electronic table, accepted for
publication in A&
Effects of Liposomes Contained in Thermosensitive Hydrogels as Biomaterials Useful in Neural Tissue Engineering
Indexación: Scopus.Advances in the generation of suitable thermosensitive hydrogels for the delivery of cells in neural tissue engineering demonstrate a delicate relationship between physical properties and capabilities to promote cell proliferation and differentiation. To improve the properties of these materials, it is possible to add liposomes for the controlled release of bioactive elements, which in turn can affect the physical and biological properties of the hydrogels. In the present investigation, different hydrogels based on Pluronic F127 have been formulated with the incorporation of chitosan and two types of liposomes of two different sizes. The rheological and thermal properties and their relation with the neurite proliferation and growth of the PC12 cell line were evaluated. Our results show that the incorporation of liposomes modifies the properties of the hydrogels dependent on the concentration of chitosan and the lipid type in the liposomes, which directly affect the capabilities of the hydrogels to promote the viability and differentiation of PC12 cells. © 2017 by the authors.http://www.mdpi.com/1996-1944/10/10/112
VLT X-shooter spectroscopy of the nearest brown dwarf binary
The aim of the project is to characterise both components of the nearest
brown dwarf sytem to the Sun, WISE J104915.57-531906.1 (=Luhman16AB) at optical
and near-infrared wavelengths. We obtained high signal-to-noise
intermediate-resolution (R~6000-11000) optical (600-1000 nm) and near-infrared
(1000-2480nm) spectra of each component of Luhman16AB, the closest brown dwarf
binary to the Sun, with the X-Shooter instrument on the Very Large Telescope.
We classify the primary and secondary of the Luhman16 system as L6-L7.5 and
T0+/-1, respectively, in agreement with previous measurements published in the
literature. We present measurements of the lithium pseudo-equivalent widths,
which appears of similar strength on both components (8.2+/-1.0 Angstroms and
8.4+/-1.5 Angstroms for the L and T components, respectively). The presence of
lithium (Lithium 7) in both components imply masses below 0.06 Msun while
comparison with models suggests lower limits of 0.04 Msun. The detection of
lithium in the T component is the first of its kind. Similarly, we assess the
strength of other alkali lines (e.g. pseudo-equivalent widths of 6-7 Angstroms
for RbI and 4-7 Angstroms for CsI) present in the optical and near-infrared
regions and compare with estimates for L and T dwarfs. We also derive effective
temperatures and luminosities of each component of the binary: -4.66+/-0.08 dex
and 1305(+180)(-135) for the L dwarf and -4.68+/-0.13 dex and 1320(+185)(-135)
for the T dwarf, respectively. Using our radial velocity determinations, the
binary does not appear to belong to any of the well-known moving group. Our
preliminary theoretical analysis of the optical and J-band spectra indicates
that the L- and T-type spectra can be reproduced with a single temperature and
gravity but different relative chemical abundances which impact strongly the
spectral energy distribution of L/T transition objects.Comment: 12 pages, 9 figure, 3 tables, accepted to A&
Variability in the Lambda Orionis cluster substellar domain
We present the first results on variability of very low mass stars and brown
dwarfs belonging to the 5 Myr Lambda Orionis cluster (Collinder 69). We have
monitored almost continuously in the J filter a small area of the cluster which
includes 12 possible members of the cluster during one night. Some members have
turned to be short-term variable. One of them, LOri167, has a mass close to the
planetary mass limit and its variability might be due to instabilities produced
by the deuterium burning, although other mechanism cannot be ruled out.Comment: Accepted for Astronomische Nachrichten. Workshop "Ultra-low-mass star
formation and evolution", La Palma June 200
- …