6,896 research outputs found
2D kinematics of the edge-on spiral galaxy ESO 379-G006
We present a kinematical study of the nearly edge-on galaxy ESO 379-G006 that
shows the existence of extraplanar ionized gas. With Fabry-Perot spectroscopy
at H-alpha, we study the kinematics of ESO 379-G006 using velocity maps and
position-velocity diagrams parallel to the major and to the minor axis of the
galaxy. We build the rotation curve of the disk and discuss the role of
projection effects due to the fact of viewing this galaxy nearly edge-on. The
twisting of the isovelocities in the radial velocity field of the disk of ESO
379-G006 as well as the kinematic asymmetries found in some position-velocity
diagrams parallel to the minor axis of the galaxy suggest the existence of
deviations to circular motions in the disk that can be modeled and explained
with the inclusion of a radial inflow probably generated by a bar or by spiral
arms. We succeeded in detecting extraplanar Diffuse Ionized Gas in this galaxy.
At the same time, from the analysis of position-velocity diagrams, we found
some evidence that the extraplanar gas could lag in rotation velocity with
respect to the midplane rotation.Comment: 61 pages, 15 figures. Accepted for publication in A
"Magnetoscan": A Modified Hall Probe Scanning Technique for the Detection of Inhomogeneities in Bulk High Temperature Superconductors
We present a novel technique for the investigation of local variations of the
critical current density in large bulk superconductors. In contrast to the
usual Hall probe scanning technique, the sample is not magnetized as a whole
before the scan, but locally by a small permanent magnet, which is fixed near
the Hall probe, during the scanning process. The resulting signal can be
interpreted as a qualitative measure of the local shielding currents flowing at
the surface.Comment: 8 pages, 4 figure
El problema inverso de la hidrologÃa subterránea: estado del arte y método de solución
El problema inverso de la hidrologÃa subterránea, que consiste en la obtención de los parámetros hidraúlicos de un acuÃfero a partir de datos de niveles piezométricos, ha sido objeto de un intenso proceso de investigación en los últimos años. En la primera parte de este artÃculo, se pasa revista a los trabajos más relevantes de dicho proceso. Ello da pie, en la segunda parte, a proponer un método, basado en la teorÃa máxima verosimilitud, que permite obtener transmisividades, coeficientes de almacenamiento y goteo en recarga y caudales y niveles en los contornos, con datos en régimen transitorio y/o estacionario en dominios bi- o cuasitri-dimensionales. El metodo se basa en la teorÃa del estado adjunto, lo cual se traduce en un ahorro considerable de memoria y tiempo de ordenador. La eficacia del algoritmo se muestra con un ejemplo.Peer Reviewe
Spatially resolved LMC star formation history: I. Outside in evolution of the outer LMC disk
We study the evolution of three fields in the outer LMC disk Rgc=3.5-6.2 Kpc.
Their star formation history indicates a stellar populations gradient such that
younger stellar populations are more centrally concentrated. We identify two
main star forming epochs, separated by a period of lower activity between ~7
and ~4 Gyr ago. Their relative importance varies from a similar amount of stars
formed in the two epochs in the innermost field, to only 40% of the stars
formed in the more recent epoch in the outermost field. The young star forming
epoch continues to the present time in the innermost field, but lasted only
till ~0.8 and 1.3 Gyr ago at Rgc=5.5 degrees and 7.1 degrees, respectively.
This gradient is correlated with the measured HI column density and implies an
outside-in quenching of the star formation, possibly related to a variation of
the size of the HI disk. This could either result from gas depletion due to
star formation or ram-pressure stripping, or from to the compression of the gas
disk as ram-pressure from the Milky Way halo acted on the LMC interstellar
medium. The latter two situations may have occurred when the LMC first
approached the Milky Way.Comment: 15 pages, 13 figures, 4 tables. MNRAS, in pres
ICES. 2016. Report of the Workshop on Atlantic Sardine (WKSAR), 26–30 September 2016, Lisbon, Portugal. ICES CM 2016/ACOM:41. 351 pp.
The Workshop on Atlantic Sardine (WKSAR), chaired by Alexandra Silva (Portugal) and Lionel Pawlowski (France), met in Lisbon, 26–30 September to (i) review infor-mation on stock identification, connectivity and migrations of sardine within European Atlantic waters (Area 7 to Subdivision 9.a)and, (ii) collate, standardize and analyse survey, fishery and biological data collected in the region, (iii) propose scenarios of stock structure and dynamics and (iv) methods/models for stock assessment (ToRs, Annex 5).
There were 18 participants from the UK, France, Portugal and Spain, including one representative from PONG-PESCA (NGO, Portugal) and two chair-invited experts on genetics (Annex 1). A WebEx meeting was organized with stakeholders to facilitate their effective involvement in the benchmark process, clarifying what their role is, and to promote their contribution. To that purpose a questionnaire was written, translated into French, Spanish and Portuguese, and sent to stakeholders with questions regard-ing their perception of the various aspects of the Northern and Southern stocks, the fisheries, the monitoring and their management (Annex 2).
Information on stock identification, connectivity and migrations has been compiled in Section 3 to be reviewed by SIMWG.
The group agreed to set the deadline to compile final datasets (all) at 5th December in order for people to start running assessment in preparation for the ICES benchmark meeting in February 2017
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