9,106 research outputs found
Expanded Very Large Array Observations of the Nebula Around G79.29+0.46
We have observed the radio nebula surrounding the Galactic luminous blue variable candidate G79.29+0.46 with the Expanded Very Large Array (EVLA) at 6 cm. These new radio observations allow a morphological comparison between the radio emission, which traces the ionized gas component, and the mid-IR emission, a tracer of the dust component. The InfraRed Array Camera (8 ÎĽm) and the Multiband Imaging Photometer for Spitzer (24 ÎĽm and 70 ÎĽm) images have been reprocessed and compared with the EVLA map. We confirm the presence of a second shell at 24 ÎĽm and also provide evidence for its detection at 70 ÎĽm. The differences between the spatial morphology of the radio and mid-IR maps indicate the existence of two dust populations, the cooler one emitting mostly at longer wavelengths. Analysis of the two dusty, nested shells have provided us with an estimate of the characteristic timescales for shell ejection, providing important constraints for stellar evolutionary models. Finer details of the ionized gas distribution can be appreciated thanks to the improved quality of the new 6 cm image, most notably the highly structured texture of the nebula. Evidence of interaction between the nebula and the surrounding interstellar medium can be seen in the radio map, including brighter features that delineate regions where the shell structure is locally modified. In particular, the brighter filaments in the southwest region appear to frame the shocked southwestern clump reported from CO observations
Evaluación cuantitativa de la influencia de los espacios de color para la detección automática de células
En este artĂculo proponemos el estudio de los espacios de color en el marco de la segmentaciĂłn automática de
estructuras celulares. En contraste con estudios neuro-fĂsicos orientados a describir la percepciĂłn humana del
color nosotros desarrollamos un análisis cuantitativo tomando como referencia el resultado de algoritmos de
segmentaciĂłn y plantillas generadas manualmente. Los resultados obtenidos demuestran que el color tiene una
influencia considerable sobre la capacidad de análisis de una imagen y que los espacios de color que además de
separar la cromaticidad y luminancia procuran la normalizaciĂłn de las distancias entre colores proveen una
mejor representaciĂłn de la informaciĂłn presente en la imagen a diferencia de los espacios de color tales como el
RGB y HSI que han dominado la literatura de procesamiento de imágenes biomédicas en el pasadoIn this paper we study color spaces in the framework of automatic segmentation of cellular structures. In contrast
to neuro-physical studies focused on human perception of color we resort to a quantitative evaluation of such
impact using as reference segmentation outputs and ground truth images. The results show that color
representation has a considerable influence in the capabilities of such algorithms and color spaces that separate
chromaticity and luminance components, and normalize color differences, provide a representation of image data
better than color spaces such as RGB and HSI used extensively in the field of biomedical image processing in the
past
New Variable Jet Models for HH 34
We consider newly derived proper motions of the HH 34 jet to reconstruct the evolution of this outflow. We first extrapolate ballistic trajectories for the knots (starting from their present-day positions and velocities) and find that at ~1000 yr in the future most of them will merge to form a larger-mass structure. This mass structure will be formed close to the present-day position of the HH 34S bow shock. We then carry out a fit to the ejection velocity versus time reconstructed from the observed proper motions (assuming that the past motion of the knots was ballistic) and use this fit to compute axisymmetric jet simulations. We find that the intensity maps predicted from these simulations do indeed match reasonably well the [S II] structure of HH 34 observed in Hubble Space Telescope images
Local superconducting density of states of ErNi2B2C
We present local tunnelling microscopy and spectroscopy measurements at low
temperatures in single crystalline samples of the magnetic superconductor
ErNi2B2C. The electronic local density of states shows a striking departure
from s-wave BCS theory with a finite value at the Fermi level, which amounts to
half of the normal phase density of states.Comment: 9 pages, 3 figure
Modeling of the Sub-Tg Relaxation Spectrum of Pd42.5Ni7.5Cu30P20 Metallic Glass
In this work we study the mechanical relaxation spectrum of Pd42.5Ni7.5Cu30P20
metallic glass. The effect of aging on the relaxation behavior is analyzed by measuring the
internal friction during consecutive heating runs. The mechanical relaxation of the wellannealed
glass state is modeled by fitting susceptibility functions to the primary and
secondary relaxations of the system. The model is able to reproduce the mechanical
relaxation spectrum below the glass transition temperature (sub-Tg) in the frequency-
temperature ranges relevant for the high temperature physical properties and forming
ability of metallic glasses. The model reveals a relaxation spectrum composed by the
overlapping of primary and secondary processes covering a wide domain of times but with
a relatively narrow range of activation energies.Postprint (author's final draft
Strain mapping and nanocrystallite size determination by neutron diffraction in an aluminum alloy (AA5083) severely plastically deformed through equal channel angular pressing
Six specimens of an aluminum alloy (AA-5083) extruded by Equal Channel Angular Pressing following two different routes plus a blank sample were examined with a neutron radiation of 1.5448 Å. Macrostrain maps from the (311) reflection were obtained. A clear difference about accumulated macrostrain with the extrusion cycles between the two routes is shown. The diffraction data of annealed specimens did permit to estimate crystallite sizes that range between 89 nm and 115 nm depending on the routes
PND8 COST-EFFECTIVENESS AND BUDGET IMPACT ANALYSIS OF SUBCUTANEOUS INTERFERON BETA-1A FOR RELAPSING-REMITTING MULTIPLE SCLEROSIS IN SPAIN
Band gap control via tuning of inversion degree in CdInS spinel
Based on theoretical arguments we propose a possible route for controlling
the band-gap in the promising photovoltaic material CdInS. Our
\textit{ab initio} calculations show that the experimental degree of inversion
in this spinel (fraction of tetrahedral sites occupied by In) corresponds
approximately to the equilibrium value given by the minimum of the theoretical
inversion free energy at a typical synthesis temperature. Modification of this
temperature, or of the cooling rate after synthesis, is then expected to change
the inversion degree, which in turn sensitively tunes the electronic band-gap
of the solid, as shown here by accurate screened hybrid functional
calculations.Comment: In press in Applied Physics Letters (2012); 4 pages, 2 figures, 1
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