596 research outputs found
Effect of methyl jasmonate in gene expression, and in hormonal and phenolic profiles of holm oak embryogenic lines before and after infection with Phytophthora Cinnamomi
The dieback syndrome affecting Quercus ilex and other oak species impels the search for tolerant plant genotypes, as well as methods of plant immunization against such infections. Elicitation treatments can be an effective strategy to activate plant defense response and embryogenic lines represent a promising tool to generate new tolerant genotypes and also to study early markers involved in defense response. The aim of the presented work was to investigate changes in gene expression, and in hormonal and phenolic profiles induced in three holm oak embryogenic lines (ELs) elicited with methyl jasmonate (MeJA) before and after infection with the oomycete Phytophthora cinnamomi, which is the main biotic agent involved in this pathogenic process. The three ELs, derived from three genotypes, showed different basal profiles in all tested parameters, noting that the VA5 naïve genotype from a scape tree was characterized by a basal higher expression in NADPH-dependent cinnamyl alcohol dehydrogenase (CAD) and chalcone synthase (CHS) genes and also by higher caffeic acid content. Our work also identifies changes triggered by MeJA elicitation in holm oak embryogenic lines, such as increases in ABA and JA contents, as well as in levels of most of the determined phenolic compounds, especially in caffeic acid in Q8 and E00 ELs, but not in their biosynthesis genes. Irrespective of the EL, the response to oomycete infection in holm oak elicited plant material was characterized by a further increase in JA. Since JA and phenols have been described as a part of the Q. ilex defense response against P. cinnamomi, we propose that MeJA may act as an induced resistance (IR) stimulus and that in our embryogenic material induced both direct (detected prior to any challenge) and primed (detected after subsequent challenge) defense responses. Copyright © 2022 Morcillo, Sales, Corredoira, Martínez, Segura and Arrillaga
A major star formation region in the receding tip of the stellar Galactic bar. II. Supplementary information and evidence that the bar is not the same structure as the triaxial bulge previouly reported
This paper is the second part of Garzon et al. (1997: ApJ 491, L31) in which
we presented an outline of the analysis of 60 spectra from a follow-up program
to the Two Micron Galactic Survey (TMGS) project in the l=27 deg., b=0 deg.
area. In this second part, we present a more detailed explanation of the
analysis as well a library of the spectra for more complete information for
each of the 60 stars, and further discussions on the implications for the
structure of the Galaxy.
This region contains a prominent excess in the flux distribution and star
counts previously observed in several spectral ranges, notably in the TMGS.
More than 50% of the spectra of the stars detected with m_K<5.0 mag, within a
very high confidence level, correspond to stars of luminosity class I, and a
significant proportion of the remainder are very late giants which must also be
rapidly evolving. We make the case, using all the available evidence, that we
are observing a region at the nearer end of the Galactic bar, where the Scutum
spiral arm breaks away, and that this is powerful evidence for the presence of
the bar. Alternative explanations do not give nearly such a satisfactory
account of the observations.
The space localization of one and, a fortiori, of both ends of the bar allows
us to infer a position angle for the bar of around 75 deg. with respect to the
Sun-Galactic centre line. The angle is different from that given by other
authors for the bar and this, we think, is because they refer to the triaxial
bulge and not to the bar as detected here.Comment: 21 pages, 1 table, 9 figures, accepted in A
Angular size test on the expansion of the Universe
Assuming the standard cosmological model as correct, the average linear size
of galaxies with the same luminosity is six times smaller at z=3.2 than at z=0,
and their average angular size for a given luminosity is approximately
proportional to 1/z. Neither the hypothesis that galaxies which formed earlier
have much higher densities nor their luminosity evolution, mergers ratio, or
massive outflows due to a quasar feedback mechanism are enough to justify such
a strong size evolution. Also, at high redshift, the intrinsic ultraviolet
surface brightness would be prohibitively high with this evolution, and the
velocity dispersion much higher than observed. We explore here another
possibility to overcome this problem by considering different cosmological
scenarios that might make the observed angular sizes compatible with a weaker
evolution.
One of the models explored, a very simple phenomenological extrapolation of
the linear Hubble law in a Euclidean static universe, fits the angular size vs.
redshift dependence quite well, which is also approximately proportional to 1/z
with this cosmological model. There are no free parameters derived ad hoc,
although the error bars allow a slight size/luminosity evolution. The type Ia
supernovae Hubble diagram can also be explained in terms of this model with no
ad hoc fitted parameter.
WARNING: I do not argue here that the true Universe is static. My intention
is just to discuss which theoretical models provide a better fit to the data of
observational cosmology.Comment: 44 pages, accepted to be published in Int. J. Mod. Phys.
Accurate placement of epiescleral plaque in brachytherapy of choroideal melanoma
Salvadó Jassans, JosepPla general de l'obra: A Lluís Millet. Es veu la figura, en bronze,
del músic i fundador de l'Orfeó Català, en el gest de dirigir.
Està situada a l'exterior del Palau de la Música Catalana
Two-particle angular correlations in the search for new physics at future colliders
The analysis of angular particle correlations can yield valuable insights
into the initial state of matter in high-energy collisions, thereby potentially
revealing the existence of Beyond the Standard Model scenarios such as Hidden
Valley (HV). In this study, we focus on a QCD-like hidden sector with
relatively massive HV quarks (~GeV) which might enlarge and
strengthen azimuthal correlations of final-state SM hadrons. In particular, we
study the formation and possible observation of \textit{ridge-like} structures
in the angular two-particle correlation function at future colliders,
with a much cleaner environment than in hadron colliders, such as the LHC.Comment: Talk presented at the International Workshop on Future Linear
Colliders (LCWS 2023), 15-19 May 2023. C23-05-15.
A major star formation region in the receding tip of the stellar Galactic bar
We present an analysis of the optical spectroscopy of 58 stars in the
Galactic plane at \arcdeg, where a prominent excess in the flux
distribution and star counts have been observed in several spectral regions, in
particular in the Two Micron Galactic Survey (TMGS) catalog. The sources were
selected from the TMGS, to have a magnitude brighter than +5 mag and be
within 2 degrees of the Galactic plane. More than 60% of the spectra correspond
to stars of luminosity class I, and a significant proportion of the remainder
are very late giants which would also be fast evolving. This very high
concentration of young sources points to the existence of a major star
formation region in the Galactic plane, located just inside the assumed origin
of the Scutum spiral arm. Such regions can form due to the concentrations of
shocked gas where a galactic bar meets a spiral arm, as is observed at the ends
of the bars of face-on external galaxies. Thus, the presence of a massive star
formation region is very strong supporting evidence for the presence of a bar
in our Galaxy.Comment: 13 pages (latex) + 4 figures (eps), accepted in ApJ Let
La construcción de la imagen femenina en la literatura de la Cruzada
Premi UAB de l'Observatori per a la Igualtat als millors Treballs de Fi de Grau amb perspectiva de gènere. 4a Edició, curs 2018-2019La tradición historiográfica sobre la Guerra Civil ha tendido a relegar el papel de las mujeres a la pasividad política. Este trabajo pretende demostrar a las féminas como sujetos activos con una importancia tal que el Nuevo Estado estableció como una de sus prioridades la activación de un gran mecanismo con el objetivo de redefinir la feminidad y relegarla de nuevo al ámbito doméstico.La tradició historiogràfica sobre la Guerra Civil ha tendit a relegar el paper de les dones a la passivitat política. Aquest treball pretén demostrar a les fèmines com a subjectes actius amb una importància tal que el Nou Estat va establéixer com a una de les seves prioritats l'activació d'un gran mecanisme amb l'objectiu de redefinir la feminitat i relegar-la de nou a l'àmbit domèstic
Another cluster of red supergiants close to RSGC1
Recent studies have revealed massive star clusters in a region of the Milky
Way close to the tip of the Long Bar. These clusters are heavily obscured and
are characterised by a population of red supergiants. We analyse a previously
unreported concentration of bright red stars ~16' away from the cluster RSGC1.
We utilised near IR photometry to identify candidate red supergiants and then
K-band spectroscopy of a sample to characterise their properties.
We find a compact clump of eight red supergiants and five other candidates at
some distance, one of which is spectroscopically confirmed as a red supergiant.
These objects must form an open cluster, which we name Alicante 8. Because of
the high reddening and strong field contamination, the cluster sequence is not
clearly seen in 2MASS or UKIDSS near-IR photometry. From the analysis of the
red supergiants, we infer an extinction and an age close
to 20 Myr. Though this cluster is smaller than the three known previously, its
properties still suggest a mass in excess of 10 000 M_{\sun}. Its discovery
corroborates the hypothesis that star formation in this region has happened on
a wide scale between ~10 and ~20 Myr ago.Comment: Accepted for publication in Astronomy & Astrophysics. Figure 1
degraded and changed to B&W, Figure 2 degraded to meet size requirement
A third red supergiant rich cluster in the Scutum-Crux arm
Aims. We aim to characterise the properties of a third massive, red supergiant dominated galactic cluster.
Methods. To accomplish this we utilised a combination of near/mid-IR photometry and spectroscopy to identify and classify the properties of cluster members, and statistical arguments to determine the mass of the cluster.
Results. We found a total of 16 strong candidates for cluster membership, for which formal classification of a subset yields spectral types from K3-M4 Ia and luminosities between log(L/L-circle dot) similar to 4.5-4.8 for an adopted distance of 6 +/- 1 kpc. For an age in the range of 16-20 Myr, the implied mass is 2-4 x 10(4) M-circle dot, making it one of the most massive young clusters in the Galaxy. This discovery supports the hypothesis that a significant burst of star formation occurred at the base of Scutum-Crux arm between 10-20 Myr ago, yielding a stellar complex comprising at least similar to 10(5) M-circle dot of stars (noting that since the cluster identification criteria rely on the presence of RSGs, we suspect that the true stellar yield will be significantly higher). We highlight the apparent absence of X-ray binaries within the star formation complex and finally, given the physical association of at least two pulsars with this region, discuss the implications of this finding for stellar evolution and the production and properties of neutron stars
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