530 research outputs found
Alignment of the central galaxies with the environment
In this work, we combine ellipticity and major axis position angle
measurements from the Sloan Digital Sky Server Data Release 16 (SDSS DR16) with
the group finder algorithm of Rodriguez \& Merch\'an to determine the alignment
of the central galaxies with the surrounding structures and satellite galaxies
lying in their group. We use two independent methods: A modified version of the
two-point cross-correlation function and the angle between the central galaxy
orientation and the satellite galaxies relative position. The first method
allows us to study the inner and outer regions of the cluster, while the second
method provides information within the halos. Our results show that central
galaxies present anysotropy in the correlation function up to , which becomes 10\% stronger for the brightest ones
(). When we split the galaxy sample by colour, we find that
red central galaxies are the main contributors to this anisotropy. We also show
that this behaviour does not depend on the group mass or central galaxy
ellipticity. Finally, our results are in agreement with previous findings,
showing that the two-point cross-correlation function is a best tracer of the
galaxy alignments using all galaxies and not only those of the group to which
it belongs. In addition, this feature allows us to explore the behaviour of the
alignment on larger scales.Comment: 10 pages, 9 figures, sent to MNRA
Excited states of the water molecule : Analysis of the valence and Rydberg character
The excited states of the water molecule have been analyzed by using the extended quantum-chemical multistate CASPT2 method, namely, MS-CASPT2, in conjunction with large one-electron basis sets of atomic natural orbital type. The study includes 13 singlet and triplet excited states, both valence and 3s-, 3p-, and 3d-members of the Rydberg series converging to the lowest ionization potential and the 3s- and 3p-Rydberg members converging to the second low-lying state of the cation, 1 math. The research has been focused on the analysis of the valence or Rydberg character of the low-lying states. The computation of the 1 math state of water at different geometries indicates that it has a predominant 3s-Rydberg character at the equilibrium geometry of the molecule but it becomes progressively a valence state described mainly by the one-electron 1b1→4a1 promotion, as expected from a textbook of general chemistry, upon elongation of the O–H bonds. The described valence-Rydberg mixing is established to be originated by a molecular orbital (MO) Rydbergization process, as suggested earlier by R. S. Mulliken [Acc. Chem. Res. 9, 7 (1976)] . The same phenomenon occurs also for the 1 math state whereas a more complex behavior has been determined for the 2 math state, where both MO Rydbergization and configurational mixing take place. Similar conclusions have been obtained for the triplet states of the [email protected] [email protected] [email protected]
Transient Down-Regulation of Sound-Induced c-Fos Protein Expression in the Inferior Colliculus after Ablation of the Auditory Cortex
We tested whether lesions of the excitatory glutamatergic projection from the auditory cortex (AC) to the inferior colliculus (IC) induce plastic changes in neurons of this nucleus. Changes in neuronal activation in the IC deprived unilaterally of the cortico-collicular projection were assessed by quantitative c-Fos immunocytochemistry. Densitometry and stereology measures of sound-induced c-Fos immunoreactivity in the IC showed diminished labeling at 1, 15, 90, and 180 days after lesions to the AC suggesting protein down-regulation, at least up to 15 days post-lesion. Between 15 and 90 days after the lesion, c-Fos labeling recovers, approaching control values at 180 days. Thus, glutamatergic excitation from the cortex maintains sound-induced activity in neurons of the IC. Subdivisions of this nucleus receiving a higher density of cortical innervation such as the dorsal cortex showed greater changes in c-Fos immunoreactivity, suggesting that the anatomical strength of the projection correlates with effect strength. Therefore, after damage of the corticofugal projection, neurons of the IC down-regulate and further recover sound-induced c-Fos protein expression. This may be part of cellular mechanisms aimed at balancing or adapting neuronal responses to altered synaptic inputs
The Relation Between Halo Shape, Velocity Dispersion and Formation Time
We use dark matter haloes identified in the MareNostrum Universe and galaxy
groups identified in the Sloan Data Release 7 galaxy catalogue, to study the
relation between halo shape and halo dynamics, parametrizing out the mass of
the systems. A strong shape-dynamics, independent of mass, correlation is
present in the simulation data, which we find it to be due to different halo
formation times. Early formation time haloes are, at the present epoch, more
spherical and have higher velocity dispersions than late forming-time haloes.
The halo shape-dynamics correlation, albeit weaker, survives the projection in
2D (ie., among projected shape and 1-D velocity dispersion). A similar
shape-dynamics correlation, independent of mass, is also found in the SDSS DR7
groups of galaxies and in order to investigate its cause we have tested and
used, as a proxy of the group formation time, a concentration parameter. We
have found, as in the case of the simulated haloes, that less concentrated
groups, corresponding to late formation times, have lower velocity dispersions
and higher elongations than groups with higher values of concentration,
corresponding to early formation times.Comment: MNRAS in press (10 pages, 10 figures
Anisotropic correlation functions as tracers of central galaxy alignments in simulations
Motivated by observational results, we use IllustrisTNG hydrodynamical
numerical simulations to study the alignment of the central galaxies in groups
with the surrounding structures. This approach allows us to analyse galaxy and
group properties not available in observations. To perform this analysis, we
use a modified version of the two-point cross-correlation function and a
measure of the angle between the semi-major axes of the central galaxies and
the larger structures. Overall, our results reproduce observational ones, as we
find large-scale anisotropy, which is dominated by the red central galaxies. In
addition, the latter is noticeably more aligned with their group than the blue
ones. In contrast to the observations, we find a strong dependence of the
anisotropy on the central galaxy with mass, probably associated with the
inability of observational methods to determine them. This result allows us to
link the alignment to the process of halo assembly and the well-known
dependence of halo anisotropy on mass. When we include the dark matter
distribution in our analysis, we conclude that the galaxy alignment found in
simulations (and observations) can be explained by a combination of physical
processes at different scales: the central galaxy aligns with the dark matter
halo it inhabits, and this, in turn, aligns with the surrounding structures at
large scales.Comment: 9 pages, 11 figures, Accepted by MNRA
Desempeño en un procedimiento de igualación a la muestra en función del tipo de relación entrenada y la variabilidad en los estÃmulos de segundo orden.
10 h.Se presentan los resultados de tres experimentos en los cuales se evalúo el efecto del tipo de relación a entrenar y la variación/no variación de los estÃmulos de segundo orden sobre el desempeño en pruebas de transferencia. En el experimento 1, se conformaron tres grupos experimentales (a) identidad (b) diferencia y (c) semejanza por color y forma. Se encontró que el grupo entrenado en la relación de semejanza tuvo desempeños significativamente más altos en pruebas de transferencia. En el experimento 2, se evaluó el efecto de la relación de semejanza por color sin variación formal en los estÃmulos de segundo orden en dos grupos experimentales, los cuales diferÃan en la relación a probar (identidad o diferencia). Se observó un desempeño bajo en los dos grupos en pruebas de transferencia. En el experimento 3, se manipuló el tipo de relación y se implementó una variación ensayo a ensayo de los estÃmulos de segundo orden. Se encontró que en el grupo entrenado en semejanza se presentaron puntajes significativamente más altos en las pruebas de transferencia. Los hallazgos generales indican que el entrenamiento en la relación de semejanza y la variación de los estÃmulos de segundo orden tienen un papel facilitador sobre el desempeño efectivo en las pruebas de transferencia extrarrelacional y extrarrelacional-extramodal-extrainstancia (ERMI).Incluye referencias bibliográficasPsicologoPregrad
Comparison of Pretectal Genoarchitectonic Pattern between Quail and Chicken Embryos
Regionalization of the central nervous system is controlled by local networks of transcription factors that establish and maintain the identities of neuroepithelial progenitor areas and their neuronal derivatives. The conserved cerebral Bauplan of vertebrates must result essentially from conserved patterns of developmentally expressed transcription factors. We have previously produced detailed molecular maps for the alar plate of prosomere 1 (the pretectal region) in chicken (Ferran et al., 2007, 2008, 2009). Here we compare the early molecular signature of the pretectum of two closely related avian species of the family Phasianidae, Coturnix japonica (Japanese quail) and Gallus gallus (chicken), aiming to test conservation of the described pattern at a microevolutionary level. We studied the developmental pretectal expression of Bhlhb4, Dbx1, Ebf1, Gata3, Gbx2, Lim1, Meis1, Meis2, Pax3, Pax6, Six3, Tal2, and Tcf7l2 (Tcf4) mRNA, using in situ hybridization, and PAX7 immunohistochemistry. The genoarchitectonic profile of individual pretectal domains and strata was produced, using comparable section planes. Remarkable conservation of the combinatorial genoarchitectonic code was observed, fundamented in a tripartite anteroposterior subdivision. However, we found that at corresponding developmental stages the pretectal region of G. gallus was approximately 30% larger than that of C. japonica, but seemed relatively less mature. Altogether, our results on a conserved genoarchitectonic pattern highlight the importance of early developmental gene networks that causally underlie the production of homologous derivatives in these two evolutionarily closely related species. The shared patterns probably apply to sauropsids in general, as well as to more distantly related vertebrate species
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