11,614 research outputs found
Low EUV Luminosities Impinging on Protoplanetary Disks
The amount of high-energy stellar radiation reaching the surface of
protoplanetary disks is essential to determine their chemistry and physical
evolution. Here, we use millimetric and centimetric radio data to constrain the
EUV luminosity impinging on 14 disks around young (~2-10Myr) sun-like stars.
For each object we identify the long-wavelength emission in excess to the dust
thermal emission, attribute that to free-free disk emission, and thereby
compute an upper limit to the EUV reaching the disk. We find upper limits lower
than 10 photons/s for all sources without jets and lower than photons/s for the three older sources in our sample. These latter
values are low for EUV-driven photoevaporation alone to clear out
protoplanetary material in the timescale inferred by observations. In addition,
our EUV upper limits are too low to reproduce the [NeII] 12.81 micron
luminosities from three disks with slow [NeII]-detected winds. This indicates
that the [NeII] line in these sources primarily traces a mostly neutral wind
where Ne is ionized by 1 keV X-ray photons, implying higher photoevaporative
mass loss rates than those predicted by EUV-driven models alone. In summary,
our results suggest that high-energy stellar photons other than EUV may
dominate the dispersal of protoplanetary disks around sun-like stars.Comment: Accepted for publication to The Astrophysical Journa
Environmental effects on galaxy evolution. II: quantifying the tidal features in NIR-images of the cluster Abell 85
This work is part of a series of papers devoted to investigate the evolution
of cluster galaxies during their infall. In the present article we imaged in
NIR a selected sample of galaxies through- out the massive cluster Abell 85 (z
= 0.055). We obtained (JHK) photometry for 68 objects, reaching 1 mag/arcsec^2
deeper than 2MASS. We use these images to unveil asymmetries in the outskirts
of a sample of bright galaxies and develop a new asymmetry index, alpha_An,
which allows to quantify the degree of disruption by the relative area occupied
by the tidal features on the plane of the sky. We measure the asymmetries for a
subsample of 41 large area objects finding clear asymmetries in ten galaxies,
most of them being in groups and pairs projected at different clustercentric
distances, some of them located beyond R500 . Combining information on the
Hi-gas content of blue galaxies and the distribution of sub-structures across
Abell 85, with the present NIR asymmetry analysis, we obtain a very powerful
tool to confirm that tidal mechanisms are indeed present and are currently
affecting a fraction of galaxies in Abell 85. However, when comparing our deep
NIR images with UV-blue images of two very disrupted (jellyfish) galaxies in
this cluster, we discard the presence of tidal 1 interactions down to our
detection limit. Our results suggest that ram-pressure stripping is at the
origin of such spectacular disruptions. We conclude that across a complex
cluster like Abell 85, environment mechanisms, both gravitational and
hydrodynamical, are playing an active role in driving galaxy evolution.Comment: 30 pages, 13 figures, Accepted for Publication in A
La Inquisició a debat
Los profesores J. Contreras, J.-P. Dedieu, H. Kamen, F. Tomás y Valiente y R. García cárcel debaten el tema inquisitorial a partir de cuatro cuestiones fundamentales: ¿fue la Inquisición el resultado de una superestructura impuesta artificialmente a la sociedad o, por el contrario, emanó de la propia sociedad?, ¿represión inquisitorial teórica o efectiva?, ¿fue excepcional la Inquisición española en el marco europeo?, ¿cuál es la naturaleza de la Inquisición, religiosa o política?.In this transcription, Contreras, Dedieu, Kamen, Tomás y Valiente and García Cárcel debate the Inquisition focusing on four main questions: the Inquisition as a result of un artificially imposed to the society superstructure or, on the contrary, as an emanation of that society; the inquisitorial repression as merely theoretical or really effective; the supposed exceptionality, in an European context, of Spanish Inquisition and the real nature, religious or political, of the Inquisition
On the geometry of mixed states and the Fisher information tensor
In this paper, we will review the co-adjoint orbit formulation of finite
dimensional quantum mechanics, and in this framework, we will interpret the
notion of quantum Fisher information index (and metric). Following previous
work of part of the authors, who introduced the definition of Fisher
information tensor, we will show how its antisymmetric part is the pullback of
the natural Kostant-Kirillov-Souriau symplectic form along some natural
diffeomorphism. In order to do this, we will need to understand the symmetric
logarithmic derivative as a proper 1-form, settling the issues about its very
definition and explicit computation. Moreover, the fibration of co-adjoint
orbits, seen as spaces of mixed states, is also discussed.Comment: 27 pages; Accepted Manuscrip
Tracing the Conversion of Gas into Stars in Young Massive Cluster Progenitors
Whilst young massive clusters (YMCs; 10 M, age
100 Myr) have been identified in significant numbers, their
progenitor gas clouds have eluded detection. Recently, four extreme molecular
clouds residing within 200 pc of the Galactic centre have been identified as
having the properties thought necessary to form YMCs. Here we utilise far-IR
continuum data from the Herschel Infrared Galactic Plane Survey (HiGAL) and
millimetre spectral line data from the Millimetre Astronomy Legacy Team 90 GHz
Survey (MALT90) to determine their global physical and kinematic structure. We
derive their masses, dust temperatures and radii and use virial analysis to
conclude that they are all likely gravitationally bound -- confirming that they
are likely YMC progenitors. We then compare the density profiles of these
clouds to those of the gas and stellar components of the Sagittarius B2 Main
and North proto-clusters and the stellar distribution of the Arches YMC. We
find that even in these clouds -- the most massive and dense quiescent clouds
in the Galaxy -- the gas is not compact enough to form an Arches-like ( =
2x10 M, R = 0.4 pc) stellar distribution. Further
dynamical processes would be required to condense the resultant population,
indicating that the mass becomes more centrally concentrated as the
(proto)-cluster evolves. These results suggest that YMC formation may proceed
hierarchically rather than through monolithic collapse.Comment: 12 pages, 8 figures, 1 table. Accepted by MNRA
Electronic States in Diffused Quantum Wells
In the present study we calculate the energy values and the spatial
distributions of the bound electronic states in some diffused quantum wells.
The calculations are performed within the virtual crystal approximation, spin dependent empirical tight-binding model and the surface Green
function matching method. A good agreement is found between our results and
experimental data obtained for AlGaAs/GaAs quantum wells with thermally induced
changes in the profile at the interfaces. Our calculations show that for
diffusion lengths {\AA} the transition (C3-HH3) is not
sensitive to the diffusion length, but the transitions (C1-HH1), (C1-LH1),
(C2-HH2) and (C2-LH2) display large "blue shifts" as L_{D} increases. For
diffusion lengths {\AA} the transitions (C1-HH1) and (C1-LH1)
are less sensitive to the L_{D} changes than the (C3-HH3) transition. The
observed dependence is explained in terms of the bound states spatial
distributions.Comment: ReVTeX file, 7pp., no macros, 4 figures available on the reques
Desarrollo de materiales online de apoyo para la realización del Trabajo de Fin de Grado
Depto. de Trabajo Social y Servicios SocialesFac. de Trabajo SocialFALSEsubmitte
Robustness of spatial Penning trap modes against environment-assisted entanglement
The separability of the spatial modes of a charged particle in a Penning trap
in the presence of an environment is studied by means of the positive partial
transpose (PPT) criterion. Assuming a weak Markovian environment, described by
linear Lindblad operators, our results strongly suggest that the environmental
coupling of the axial and cyclotron degrees of freedom does not lead to
entanglement at experimentally realistic temperatures. We therefore argue that,
apart from unavoidable decoherence, the presence of such an environment does
not alter the effectiveness of recently suggested quantum information protocols
in Penning traps, which are based on the combination of a spatial mode with the
spin of the particle.Comment: 11 pages, 2 figure
The rubric as an assessment strategy in the mathematical argumentation process
The article shares the proposal of an analytical rubric as a strategy for the assessment and monitoring of learning outcomes in students who develop an argumentative plot from the mathematics field, to solve any problem situation in daily life. The study was based on the theory of mathematical argumentation proposed by Duval and the contributions of León and Calderón, as well as the dimensions presented to us by the logical frameworks in the design of analytical rubrics. The research was developed under the social critical paradigm through the design of pedagogical action research, and the focus group technique was used for the collection of information composed by five professors from the department of basic sciences. As a result, a collective rubric that, in addition to generating processes of self-assessment and self-training in teachers, evidences a decrease in the existent subjectivity of the evaluation processes, thus strengthening its objectivity
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