398 research outputs found
Conservation implications of past and present nesting habitat selection of the endangered Osprey Pandion haliaetus population of the Canary Islands
We studied nesting habitat selection of the endangered
non-migratory Osprey Pandion haliaetus population of
the Canary Islands and evaluated the effect of human
expansion in recent decades. Compared with randomly
selected potential nest-sites, Osprey nests were more
frequently found on taller, southwest-facing cliffs, char-
acterized by lower human pressure and closer to Yel-
low-legged Gull Larus michahellis colonies and Barbary
Falcon Falco pelegrinoides breeding sites. Furthermore,
changes in some breeding habitat features have been
detected in recent decades. According to our predictive
models, large areas of suitable habitat are available but
unoccupied in the Canaries, and human activities are probably limiting the settlement and dispersion of new
pairs.Peer reviewe
Percepción de justicia en procesos de selección según Género y Resultado
Máster Universitario en Desarrollo y Gestión de Recursos Humanos Por la UllEl objetivo del presente estudio es analizar cómo es percibida la justicia
organizacional en el proceso de selección en función del género y el resultado,
poniendo el foco de atención en la justicia distributiva. La muestra estuvo compuesta
por 21 personas; 14 mujeres y 7 hombres. Además, 13 de los participantes en este
estudio obtuvieron como resultado de la selección No apto frente a 8 Aptos. Los
resultados muestran que el género no modera la percepción de justicia. Sin
embargo, se encontró un efecto significativo del resultado obtenido en la selección
sobre la percepción de justicia. Como consecuencia, podemos afirmar que la
percepción de justicia de los candidatos disminuye cuando obtienen un resultado
desfavorable, pero no aparecen diferencias en función del géneroThe aim of this study was to analyze how distributive justice is perceived
in the selection process, dependingon gender and the process result. A total of 21
people participated in the study, of which 14 women and 7 men. In addition, 13 of the
participants in this study obtained as a result of the selection ineligible versus 8 apt.
The results show that gender does not moderate the perception of justice. However,
there is a significant effect of selection result on the perception of justice. As a
consequence, it can be stated that candidates' perception of fairness decreases
when they obtain an unfavorable result, but there are no differences based on
gender
Surges and Si IV bursts in the solar atmosphere. Understanding IRIS and SST observations through RMHD experiments
Surges often appear as a result of the emergence of magnetized plasma from
the solar interior. Traditionally, they are observed in chromospheric lines
such as H 6563 \AA and Ca II 8542 \AA. However, whether there is a
response to the surge appearance and evolution in the Si IV lines or, in fact,
in many other transition region lines has not been studied. In this paper we
analyze a simultaneous episode of an H surge and a Si IV burst that
occurred on 2016 September 03 in active region AR12585. To that end, we use
coordinated observations from the Interface Region Imaging Spectrograph (IRIS)
and the Swedish 1-m Solar Telescope (SST). For the first time, we report
emission of Si IV within the surge, finding profiles that are brighter and
broader than the average. Furthermore, the brightest Si IV patches within the
domain of the surge are located mainly near its footpoints. To understand the
relation between the surges and the emission in transition region lines like Si
IV, we have carried out 2.5D radiative MHD (RMHD) experiments of magnetic flux
emergence episodes using the Bifrost code and including the non-equilibrium
ionization of silicon. Through spectral synthesis we explain several features
of the observations. We show that the presence of Si IV emission patches within
the surge, their location near the surge footpoints and various observed
spectral features are a natural consequence of the emergence of magnetized
plasma from the interior to the atmosphere and the ensuing reconnection
processes.Comment: 13 pages, 8 figures. The Astrophysical Journal (Accepted
Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere
We investigate the effects of interactions between ions and neutrals on the
chromosphere and overlying corona using 2.5D radiative MHD simulations with the
Bifrost code. We have extended the code capabilities implementing ion-neutral
interaction effects using the Generalized Ohm's Law, i.e., we include the Hall
term and the ambipolar diffusion (Pedersen dissipation) in the induction
equation. Our models span from the upper convection zone to the corona, with
the photosphere, chromosphere and transition region partially ionized. Our
simulations reveal that the interactions between ionized particles and neutral
particles have important consequences for the magneto-thermodynamics of these
modeled layers: 1) ambipolar diffusion increases the temperature in the
chromosphere; 2) sporadically the horizontal magnetic field in the photosphere
is diffused into the chromosphere due to the large ambipolar diffusion; 3)
ambipolar diffusion concentrates electrical currents leading to more violent
jets and reconnection processes, resulting in 3a) the formation of longer and
faster spicules, 3b) heating of plasma during the spicule evolution, and 3c)
decoupling of the plasma and magnetic field in spicules. Our results indicate
that ambipolar diffusion is a critical ingredient for understanding the
magneto-thermo-dynamic properties in the chromosphere and transition region.
The numerical simulations have been made publicly available, similar to
previous Bifrost simulations. This will allow the community to study realistic
numerical simulations with a wider range of magnetic field configurations and
physics modules than previously possible.Comment: 13 figures. Accepted to be published in Ap
A comparative study of resistivity models for simulations of magnetic reconnection in the solar atmosphere
Magnetic reconnection is a fundamental mechanism in astrophysics. A common
challenge in mimicking this process numerically in particular for the Sun is
that the solar electrical resistivity is small compared to the diffusive
effects caused by the discrete nature of codes. We aim to study different
anomalous resistivity models and their respective effects on simulations
related to magnetic reconnection in the Sun. We used the Bifrost code to
perform a 2D numerical reconnection experiment in the corona that is driven by
converging opposite polarities at the solar surface. This experiment was run
with three different commonly used resistivity models: 1) the hyper-diffusion
model originally implemented in Bifrost, 2) a resistivity proportional to the
current density, and 3) a resistivity proportional to the square of the
electron drift velocity. The study was complemented with a 1D experiment of a
Harris current sheet with the same resistivity models. The 2D experiment shows
that the three resistivity models are capable of producing results in
satisfactory agreement with each other in terms of the current sheet length,
inflow velocity, and Poynting influx. Even though Petschek-like reconnection
occurred with the current density-proportional resistivity while the other two
cases mainly followed plasmoid-mediated reconnection, the large-scale evolution
of thermodynamical quantities such as temperature and density are quite similar
between the three cases. For the 1D experiment, some recalibration of the
diffusion parameters is needed to obtain comparable results. Specifically the
hyper-diffusion and the drift velocity-dependent resistivity model needed only
minor adjustments, while the current density-proportional model needed a
rescaling of several orders of magnitude.Comment: 15 pages, 8 figures, 1 movi
Factors affecting the spatial distribution and breeding habitat of an insular cliff-nesting raptor community
The specific spatial distribution and habitat association—strongly influenced by environmental factors
or competitive interactions—are major issues in ecology and conservation. We located and
georeferenced nesting sites of five cliff-nesting raptors (Egyptian vulture Neophron percnopterus
[a locally extinct species], common buzzard Buteo buteo, osprey Pandion haliaetus, common kestrel
Falco tinnunculus, Barbary falcon Falco peregrinus pelegrinoides), and common raven Corvus
corax on one of the most biodiverse hotspot within the Canary Islands (Teno, Tenerife). We used
generalized linear models to evaluate the factors affecting abundance, richness, and intra- and
interspecific interactions. Raptor abundance increased with slope, shrub-covered area, and habitat
diversity, and decreased with altitude, and forested and grassed areas. Richness increased with
slope and decreased with altitude. Threatened species (osprey, Barbary falcon, and raven) occupied
cliffs farther away from houses and roads, and more rugged areas than the non-threatened
species. The models suggested that the probability of cliff occupation by buzzards, falcons, and ravens
depended only on inter-specific interactions. Buzzard occupation increased with the distance to
the nearest raven and kestrel nests, whereas falcons and ravens seek proximity to each other. Teno
holds between 75% and 100% of the insular breeding populations of the most endangered species
(osprey and raven), indicating the high conservation value of this area. Our study suggests that the
preservation of rugged terrains and areas of low human pressure are key factors for raptor conservation
and provide basic knowledge on the community structure and habitat associations to develop
appropriated management actions for these fragile island populationsPeer reviewe
El síndrome de burnout en los profesionales de enfermería de las unidades de cuidados críticos.
Luminescent materials with spectral conversion for renewable energies: photocatalysis and artificial photosynthesis
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