6,204 research outputs found
Improving a Satellite Mission System by means of a Semantic Grid Architecture
The use of a semantic grid architecture can make easier the
deployment of complex applications, in which several organizations are involved and diverse resources are shared. This paper presents the application of the architecture defined in the Ontogrid project (S-OGSA) into a scenario for the analysis of the quality of the products of satellite missions
Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties
Understanding the nature of spiral structure in disk galaxies is one of the
main, and still unsolved questions in galactic astronomy. However, theoretical
works are proposing new testable predictions whose detection is becoming
feasible with recent development in instrumentation. In particular, streaming
motions along spiral arms are expected to induce azimuthal variations in the
chemical composition of a galaxy at a given galactic radius. In this letter we
analyse the gas content in NGC 6754 with VLT/MUSE data to characterise its 2D
chemical composition and H line-of-sight velocity distribution. We find
that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of
tangentially-slower, radially-outward (tangentially-faster, radially-inward)
streaming motions of metal-rich (poor) gas over a large range of radii. These
results show direct evidence of gas radial migration for the first time. We
compare our results with the gas behaviour in a -body disk simulation
showing spiral morphological features rotating with a similar speed as the gas
at every radius, in good agreement with the observed trend. This indicates that
the spiral arm features in NGC 6754 may be transient and rotate similarly as
the gas does at a large range of radii.Comment: 8 pages, 4 figures, accepted for publication in ApJL 2016 September
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Water and socioeconomic dependencies: a multiregional model
River basins often extend over several regions connected by both water flows and socioeconomic factors. Therefore, water policy and diverse hydrological scenarios can affect socioeconomic variables in other parts of a river basin. This paper proposes a tool combining hydro-economic and input–output models to analyze the socioeconomic impacts of different hydrologic scenarios from a multiregional standpoint. To this end, we have built a monthly-basis hydro-economic model to fit a multiregional input–output table to estimate direct and indirect impacts on value added and employment, bringing together data on water flow and regional demand, sector-based economic analysis and macroeconomic impacts. In a given hydrological scenario, the hydro-economic model determines the output of irrigated farmland in each region and the value added generated by each crop. These data are then processed using the multiregional input–output model to determine socio-economic impacts in each of the regions forming the river basin. This methodology allows evaluation of different water policies, providing a tool for policymakers to estimate socio-economic impacts. Finally, we apply this methodology in two scenarios reflecting the opportunity costs of diverse hydrological scenarios in terms of value added and employment terms to demonstrate its excellent analytic capacity. Graphic abstract: [Figure not available: see fulltext.]
The complex structure of HH 110 as revealed from Integral Field Spectroscopy
HH 110 is a rather peculiar Herbig-Haro object in Orion that originates due
to the deflection of another jet (HH 270) by a dense molecular clump, instead
of being directly ejected from a young stellar object. Here we present new
results on the kinematics and physical conditions of HH 110 based on Integral
Field Spectroscopy. The 3D spectral data cover the whole outflow extent (~4.5
arcmin, ~0.6 pc at a distance of 460 pc) in the spectral range 6500-7000 \AA.
We built emission-line intensity maps of H, [NII] and [SII] and of
their radial velocity channels. Furthermore, we analysed the spatial
distribution of the excitation and electron density from [NII]/H,
[SII]/H, and [SII] 6716/6731 integrated line-ratio maps, as well as
their behaviour as a function of velocity, from line-ratio channel maps. Our
results fully reproduce the morphology and kinematics obtained from previous
imaging and long-slit data. In addition, the IFS data revealed, for the first
time, the complex spatial distribution of the physical conditions (excitation
and density) in the whole jet, and their behaviour as a function of the
kinematics. The results here derived give further support to the more recent
model simulations that involve deflection of a pulsed jet propagating in an
inhomogeneous ambient medium. The IFS data give richer information than that
provided by current model simulations or laboratory jet experiments. Hence,
they could provide valuable clues to constrain the space parameters in future
theoretical works.Comment: 12 pages, 15 figures Accepted in MNRA
Integral Field Spectroscopy of HH 262: The Spectral Atlas
HH 262 is a group of emitting knots displaying an "hour-glass" morphology in
the Halpha and [SII] lines, located 3.5' to the northeast of the young stellar
object L1551-IRS5, in Taurus. We present new results of the kinematics and
physical conditions of HH 262 based on Integral Field Spectroscopy covering a
field of 1.5'x3', which includes all the bright knots in HH 262. These data
show complex kinematics and significant variations in physical conditions over
the mapped region of HH 262 on a spatial scale of <3". A new result derived
from the IFS data is the weakness of the [NII] emission (below detection limit
in most of the mapped region of HH 262), including the brightest central knots.
Our data reinforce the association of HH 262 with the redshifted lobe of the
evolved molecular outflow L1551-IRS5. The interaction of this outflow with a
younger one, powered by L1551 NE, around the position of HH 262 could give rise
to the complex morphology and kinematics of HH 262.Comment: Accepted for publication in MNRA
G 112-29 (=NLTT 18149), a Very Wide Companion to GJ 282 AB with a Common Proper Motion, Common Parallax, Common Radial Velocity and Common Age
We have made a search for common proper motion (CPM) companions to the wide
binaries in the solar vicinity. We found that the binary GJ 282AB has a very
distant CPM companion (NLTT 18149) at a separation s=1.09 \arcdeg. Improved
spectral types and radial velocities are obtained, and ages determined for the
three components. The Hipparcos trigonometric parallaxes and the new radial
velocities and ages turn out to be very similar for the three stars, and
provide strong evidence that they form a physical system. At a projected
separation of 55733AU from GJ 282AB, NLTT 18149 ranks among the widest physical
companions known.Comment: 13 pages, 3 figures, submmited to Ap
EstimaciĂłn de CO2 acumulado por los manglares de la BahĂa de Chame, mediante análisis de cenizas de Avicennia germinans y Rhizophora mangle.
Este estudio realizĂł para determinar el 002 acumulado por los manglares de la BahĂa de Chame, estimado mediante un análisis de cenizas de Avicennia germinans y Rhizophora mangle el sitio exacto del estudio está ubicado en La Tembladera (BahĂa Chame) corregimiento de Cermeño, comunidad de Monte Oscuro en el distrito de Capira, en la provincia de Panamá Oeste. Se seleccionĂł una zona de manglar rivereño que se dividiĂł en tres zonas de marea: chica, media y grande. Por cada zona de marea, se tomaron dos especies de mangle. De cada especie se seleccionaron al azar tres árboles para tomar las muestras de hoja, tronco y raĂz. El procesamiento se llevĂł acabo en el Laboratorio de suelo de la Facultad de Ciencias Agropecuarias de la Universidad de Panamá. Los resultados obtenidos demuestran que Rhizophora mangle acumula mayor cantidad de 002 que Avicennia germinans. La zona de marea chica obtuvo mayor porcentaje de 002 acumulado y el tronco es la estructura vegetal que acumula mayor cantidad de CO2
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