5,338 research outputs found
Phase diagram and influence of defects in the double perovskites
The phase diagram of the double perovskites of the type Sr_{2-x} La_x Fe Mo
O_6 is analyzed, with and without disorder due to antisites. In addition to an
homogeneous half metallic ferrimagnetic phase in the absence of doping and
disorder, we find antiferromagnetic phases at large dopings, and other
ferrimagnetic phases with lower saturation magnetization, in the presence of
disorder.Comment: 4 pages, 3 postscript figures, some errata correcte
Antecedentes motivacionales de los comportamientos prosociales y antisociales en el contexto deportivo
A microscopic model for a class of mixed-spin quantum antiferromagnets
We propose a microscopic model that describes the magnetic behavior of the
mixed-spin quantum systems RBaNiO (R= magnetic rare earth). An
evaluation of the properties of this model by Quantum Monte Carlo simulations
shows remarkable good agreement with the experimental data and provides new
insight into the physics of mixed-spin quantum magnets.Comment: revised version to be published in Phys. Rev.
First detection of the 448 GHz H2O transition in space
We present the first detection of the ortho-H2O 4_23-3_30 transition at 448
GHz in space. We observed this transition in the local (z = 0.010) luminous
infrared (IR) galaxy ESO 320-G030 (IRAS F11506-3851) using the Atacama Large
Millimeter/submillimeter Array (ALMA). The water 4_23-3_30 emission, which
originates in the highly obscured nucleus of this galaxy, is spatially resolved
over a region of ~65 pc in diameter and shows a regular rotation pattern
compatible with the global molecular and ionized gas kinematics. The line
profile is symmetric and well fitted by a Gaussian with an integrated flux of
37.0 +- 0.7 Jy km s-1 . Models predict this water transition as a potential
collisionally excited maser transition. On the contrary, in this galaxy, we
find that the 4_23-3_30 emission is primarily excited by the intense far-IR
radiation field present in its nucleus. According to our modeling, this
transition is a probe of deeply buried galaxy nuclei thanks to the high dust
optical depths (tau_100{\mu}m > 1, N_H > 1e24 cm-2) required to efficiently
excite it.Comment: Accepted for publication in A&A Letters; 4 pages, 5 figure
Use of water troughs by wild rabbits (Oryctolagus cuniculus) in a farmland area of north–west Spain
Uso de bebederos por parte del conejo de monte (Oryctolagus cuniculus) en un paisaje agrícola en el noroeste de EspañaEn la península Ibérica, los bebederos son una herramienta de gestión de hábitat muy frecuente para incrementar las densidades de especies de caza menor, aunque el comportamiento de ingestión de agua de las especies “diana” no se ha estudiado en profundidad, como es el caso del conejo de monte (Oryctolagus cuniculus). Estudiamos el uso de bebederos por parte de conejos de monte durante 228 períodos de una semana en tres períodos consecutivos (junio–octubre) de 2008, 2009 y 2010 en un paisaje agrícola de noroeste de España, utilizando cámaras de fototrampeo. Los conejos utilizaron el 43% de los bebederos y se observó un número significativamente mayor de conejos bebiendo en bebederos rodeados por cobertura vegetal en comparación con bebederos situados en campos abiertos sin dicha cobertura vegetal. La mayoría de los conejos que bebieron fueron fotografiados de julio a septiembre (98%), si bien la utilización de bebederos no se relacionó claramente con la climatología. Los conejos bebieron principalmente durante la mañana (52% de los conejos) no tanto durante la tarde y noche, y raramente durante el mediodía. Los conejos se fotografiaron junto con perdices rojas (Alectoris rufa) en el 6% de las fotografías. Estos hallazgos sugieren que los bebederos son útiles para el conejo y otras especies con necesidades hídricas similares y que debieran ser colocados cerca de zonas con cobertura vegetal arbustiva.Installation of water troughs is a common approach to increase densities of small game species in the Iberian peninsula but little is known about the watering patterns of target species, such as the wild rabbit (Oryctolagus cuniculus). Using camera trapping, we monitored the use of water troughs by wild rabbits over 228 weeks in three consecutive periods, from June to October in 2008, 2009 and 2010, on farmland in north–west Spain. Wild rabbits used 43% of the water troughs. A significantly higher number of rabbits were observed drinking at troughs surrounded by shrub cover than at those in open fields. Most drinking events were recorded from July to September (98%), though the use of water troughs was not clearly related to weather. Wild rabbits drank mainly during the morning (52% of rabbits), less so in the evening and at night, and rarely in the afternoon. Wild rabbits were photographed together with red–legged partridges (Alectoris rufa) in 6% of photographs. These findings suggest water troughs are useful for species such as wild rabbits and should be allocated close to shrub areas.Uso de bebederos por parte del conejo de monte (Oryctolagus cuniculus) en un paisaje agrícola en el noroeste de EspañaEn la península Ibérica, los bebederos son una herramienta de gestión de hábitat muy frecuente para incrementar las densidades de especies de caza menor, aunque el comportamiento de ingestión de agua de las especies “diana” no se ha estudiado en profundidad, como es el caso del conejo de monte (Oryctolagus cuniculus). Estudiamos el uso de bebederos por parte de conejos de monte durante 228 períodos de una semana en tres períodos consecutivos (junio–octubre) de 2008, 2009 y 2010 en un paisaje agrícola de noroeste de España, utilizando cámaras de fototrampeo. Los conejos utilizaron el 43% de los bebederos y se observó un número significativamente mayor de conejos bebiendo en bebederos rodeados por cobertura vegetal en comparación con bebederos situados en campos abiertos sin dicha cobertura vegetal. La mayoría de los conejos que bebieron fueron fotografiados de julio a septiembre (98%), si bien la utilización de bebederos no se relacionó claramente con la climatología. Los conejos bebieron principalmente durante la mañana (52% de los conejos) no tanto durante la tarde y noche, y raramente durante el mediodía. Los conejos se fotografiaron junto con perdices rojas (Alectoris rufa) en el 6% de las fotografías. Estos hallazgos sugieren que los bebederos son útiles para el conejo y otras especies con necesidades hídricas similares y que debieran ser colocados cerca de zonas con cobertura vegetal arbustiva
Generation of a novel three-dimensional scaffold-based model of the bovine endometrium
Bovine in vitro endometrial models that resemble tissue function in vivo are needed to study infertility, long-term uterine alterations induced by pathogens and impact of endocrine disruptor chemicals on reproductive function and other reproductive system complications that cause high economic losses in livestock species. The present study aimed to generate an innovative, reproducible, and functional 3D scaffold-based model of the bovine endometrium structurally robust for long term-culture. We developed a multicellular model containing both endometrial epithelial and stromal cells. Epithelial cells organized to form a luminal-like epithelial layer on the surface of the scaffold. Stromal cells produced their own extracellular matrix forming a stable subepithelial compartment that physiologically resembles the normal endometrium. Both cell types released prostaglandin E2 and prostaglandin F2α following a treatment with oxytocin and arachidonic acid. Additionally signal pathways mediating oxytocin and arachidonic acid stimulation of prostaglandin synthesis were analyzed by real time PCR (RT-PCR). Oxytocin receptor (OXTR), prostaglandin E2 receptor 2 (EP2), prostaglandin E2 receptor 4 (EP4), prostaglandin F receptor (PTGFR), prostaglandin E synthase (PTGES), PGF-synthase (PGFS) and prostaglandin-endoperoxide synthase 2 (COX-2) expression was detected in both control and treatment groups, however, only significant changes in abundance of OXTR mRNA transcripts were found. The results obtained by this study are a step forward in bovine in vitro culture technology. This 3D scaffold-based model provides a platform to study regulatory mechanisms involved in endometrial physiology and can set the basis for a broader tool for designing and testing novel therapeutic strategies for recurrent uterine pathologies
An experimental measurement of the staggered magnetization curve for a Haldane spin chain
Long-range magnetic ordering in R_2 Ba Ni O_5 (R=magnetic rare earth)
quasi-1-dimensional mixed-spin antiferromagnets is described by a simple
mean-field model that is based on the intrinsic staggered magnetization
function of isolated Haldane spin chains for the Ni-subsystem, and single-ion
magnetization functions for the rare earth ions. The model is applied to new
experimental results obtained in powder diffraction experiments on Nd_2 Ba Ni
O_5 and Nd Y Ba Ni O_5, and to previously published diffraction data for Er_2
Ba Ni O_5. From this analysis we extract the bare staggered magnetization curve
for Haldane spin chains in these compounds.Comment: some revisions in text and figures 5 pages, 2 figures, PRL accepted
for publicatio
The nuclear and extended infrared emission of the Seyfert galaxy NGC 2992 and the interacting system Arp 245
We present subarcsecond resolution infrared (IR) imaging and mid-IR
spectroscopic observations of the Seyfert 1.9 galaxy NGC 2992, obtained with
the Gemini North Telescope and the Gran Telescopio CANARIAS (GTC). The N-band
image reveals faint extended emission out to ~3 kpc, and the PAH features
detected in the GTC/CanariCam 7.5-13 micron spectrum indicate that the bulk of
this extended emission is dust heated by star formation. We also report
arcsecond resolution MIR and far-IR imaging of the interacting system Arp 245,
taken with the Spitzer Space Telescope and the Herschel Space Observatory.
Using these data, we obtain nuclear fluxes using different methods and find
that we can only recover the nuclear fluxes obtained from the subarcsecond data
at 20-25 micron, where the AGN emission dominates. We fitted the nuclear IR
spectral energy distribution of NGC 2992, including the GTC/CanariCam nuclear
spectrum (~50 pc), with clumpy torus models. We then used the best-fitting
torus model to decompose the Spitzer/IRS 5-30 spectrum (~630 pc) in AGN and
starburst components, using different starburst templates. We find that,
whereas at shorter mid-IR wavelengths the starburst component dominates (64% at
6 micron), the AGN component reaches 90% at 20 micron. We finally obtained dust
masses, temperatures and star formation rates for the different components of
the Arp 245 system and find similar values for NGC 2992 and NGC 2993. These
measurements are within those reported for other interacting systems in the
first stages of the interaction.Comment: 20 pages, 12 figures, accepted by MNRA
Influencia de la atmósfera de sinterización en la estabilidad térmica de cerámicas de hidroxiapatita reforzadas con zircona
En este trabajo se estudia la influencia de la atmósfera de sinterización sobre la estabilidad térmica de cerámicas de hidroxiapatita (HA) reforzadas con partículas de circona parcialmente estabilizada con magnesia (Mg-PSZ). Los cuerpos verdes fueron obtenidos por prensado uniaxial y las sinterizaciones se realizaron en aire y en oxígeno húmedo. El estudio por difracción de rayos-X y espectroscopía infrarroja permitió comprobar que la atmósfera húmeda evita la descomposición de la hidroxiapatita, todo lo contrario a lo que sucede en aire donde es evidente la presencia del zirconato cálcico (CZ) en la interfaz entre la partícula de circona y la matriz de HA. La caracterización microestructural de los materiales por Microscopía Electrónica de Barrido permitió apreciar el desarrollo de tamaño de grano de los materiales sinterizados. El estudio del comportamiento mecánico mediante ensayos de indentación reveló un aumento de la tenacidad a la fractura en el caso de los materiales que presentaban Mg-PSZ con respecto a la HA pura
Generalization of the K-SVD algorithm for minimization of ß-divergence
[EN] In this paper, we propose, describe, and test a modification of the K-SVD algorithm. Given a set of training data, the proposed algorithm computes an overcomplete dictionary by minimizing the ß-divergence () between the data and its representation as linear combinations of atoms of the dictionary, under strict sparsity restrictions. For the special case , the proposed algorithm minimizes the Frobenius norm and, therefore, for the proposed algorithm is equivalent to the original K-SVD algorithm. We describe the modifications needed and discuss the possible shortcomings of the new algorithm. The algorithm is tested with random matrices and with an example based on speech separation.This work has been partially supported by the EU together with the Spanish Government through TEC2015-67387-C4-1-R (MINECO/FEDER) and by Programa de FPU del Ministerio de Educacion, Cultura y Deporte FPU13/03828 (Spain).García Mollá, VM.; San Juan-Sebastian, P.; Virtanen, T.; Vidal Maciá, AM.; Alonso-Jordá, P. (2019). Generalization of the K-SVD algorithm for minimization of ß-divergence. Digital Signal Processing. 92:47-53. https://doi.org/10.1016/j.dsp.2019.05.001S47539
- …