10,930 research outputs found
H3K4me3 - dependent epigenetic memory regulates transcriptional reactivation in the oocyte
SELECTED ORAL COMMUNICATIONS, SESSION 52: EPIGENETIC PATTERN IN OOCYTE AND EMBRYO, Tuesday 16 June 2015. This article/study appears in: Abstract book of the 31st ESHRE Annual Meeting, Lisbon, Portugal, 14-17 June 2015.Study question: How does the oocyte regulate its transcriptional activity in light of its prolonged meiotic arrest?
Summary answer: A histone methylation-mediated epigenetic memory programed by the demethylase KDM5 is required for the correct temporal reactivation of the oocyte's transcriptional activity.
What is known already: During oogenesis oocytes transit from stages of transcriptional activity to those of transcriptional quiescence, and such transitions are believed to be essential for proper gamete formation. Although the temporal regulation of these transitions has been well documented across diverse organisms, the molecular mechanisms underlying these processes remain largely unknown.Funding by national/international organization(s) – Partly funded by Fundação para a Ciência e a Tecnologia
Star Cluster collisions - a formation scenario for the Extended Globular Cluster Scl-dE1 GC1
Recent observations of the dwarf elliptical galaxy Scl-dE1 (Sc22) in the
Sculptor group of galaxies revealed an extended globular cluster (Scl-dE1 GC1),
which exhibits an extremely large core radius of about 21.2 pc. The authors of
the discovery paper speculated on whether this object could reside in its own
dark matter halo and/or if it might have formed through the merging of two or
more star clusters. In this paper, we present N-body simulations to explore
thoroughly this particular formation scenario. We follow the merger of two star
clusters within dark matter haloes of a range of masses (as well as in the
absence of a dark matter halo). In order to obtain a remnant which resembles
the observed extended star cluster, we find that the star formation efficiency
has to be quite high (around 33 per cent) and the dark matter halo, if present
at all, has to be of very low mass, i.e. raising the mass to light ratio of the
object within the body of the stellar distribution by at most a factor of a
few. We also find that expansion of a single star cluster following mass loss
provides another viable formation path. Finally, we show that future
measurements of the velocity dispersion of this system may be able to
distinguish between the various scenarios we have explored.Comment: accepted by MNRAS, 9 pages, 2 figures, 9 table
Study of the Sextans dwarf spheroidal galaxy from the DART CaII triplet survey
We use VLT/FLAMES intermediate resolution (R~6500) spectra of individual red
giant branch stars in the near-infrared CaII triplet (CaT) region to
investigate the wide-area metallicity properties and internal kinematics of the
Sextans dwarf spheroidal galaxy (dSph). Our final sample consists of 174
probable members of Sextans with accurate line-of-sight velocities (+- 2 km/s)
and CaT [Fe/H] measurements (+- 0.2 dex). We use the MgI line at 8806.8 \AA\,
as an empirical discriminator for distinguishing between probable members of
the dSph (giant stars) and probable Galactic contaminants (dwarf stars).
Sextans shows a similar chemo-dynamical behaviour to other Milky Way dSphs,
with its central regions being more metal rich than the outer parts and with
the more metal-rich stars displaying colder kinematics than the more metal-poor
stars. Hints of a velocity gradient are found along the projected major axis
and along an axis at P.A.=191 deg, however a larger and more spatially extended
sample may be necessary to pin down the amplitude and direction of this
gradient. We detect a cold kinematic substructure at the centre of Sextans,
consistent with being the remnant of a disrupted very metal poor stellar
cluster. We derive the most extended line-of-sight velocity dispersion profile
for Sextans, out to a projected radius of 1.6 deg. From Jeans modelling of the
observed line-of-sight velocity dispersion profile we find that this is
consistent with both a cored dark matter halo with large core radius and cuspy
halo with low concentration. The mass within the last measured point is in the
range 2-4 x 10^8 M_sun, giving very large mass-to-light ratios, from 460 to 920
(M/L)_(V,sun).Comment: 30 pages, 17 figures; 4 tables. Accepted for publication in MNRAS.
Table 4 will appear as online material in the published version of the
manuscript. Typo correcte
Análise econômica exploratória da olivicultura no Brasil e Espanha.
Exploratory economic analysis of olive growing in Brazil and Spain
Coastal observatories for monitoring of fish behaviour and their responses to environmental changes
The inclusion of behavioral components in the analysis of a community can be of paramount importance in marine ecology. Diel (i.e., 24-h based), seasonal activity rhythms, or longer durational in behavioral responses can result in shifts in populations, and therefore on measurable abundances. Here, we review the value of developing cabled video observatory technology for the remote, long-term, and high-frequency monitoring of fish and their environments in coastal temperate areas. We provide details on the methodological requirements and constraints for the appropriate measurement of fish behavior over various seasonal scales (24 h, seasonal, annual) with camera systems mounted at fixed observatory locations. We highlight the importance of using marine sensors to simultaneously collect relevant environmental data in parallel to image data acquisition. Here we present multiparametric video, oceanographic, and meteorological data collected from the Mediterranean observatory platform, OBSEA (www.obsea.es; 20 m water depth). These data are reviewed in relation to ongoing and future developments of cabled observatory science. Two key approaches for the future improvement of cabled observatory technology are: (1) the application of Artificial Intelligence to aid in the analysis of increasingly large, complex, and highly interrelated biological and environmental data sets, and (2) the development of geographical observational networks to enable the reliable spatial analysis of observed populations over extended distances
The hidden burden of adult allergic rhinitis : UK healthcare resource utilisation survey
Funding Funding for this survey was provided by Meda Pharma.Peer reviewedPublisher PD
ATLAS silicon module assembly and qualification tests at IFIC Valencia
ATLAS experiment, designed to probe the interactions of particles emerging
out of proton proton collisions at energies of up to 14 TeV, will assume
operation at the Large Hadron Collider (LHC) at CERN in 2007. This paper
discusses the assembly and the quality control tests of forward detector
modules for the ATLAS silicon microstrip detector assembled at the Instituto de
Fisica Corpuscular (IFIC) in Valencia. The construction and testing procedures
are outlined and the laboratory equipment is briefly described. Emphasis is
given on the module quality achieved in terms of mechanical and electrical
stability.Comment: 23 pages, 38 EPS figures, uses JINST LaTeX clas
Orientation bias of optically selected galaxy clusters and its impact on stacked weak-lensing analyses
Weak-lensing measurements of the averaged shear profiles of galaxy clusters binned by some proxy for cluster mass are commonly converted to cluster mass estimates under the assumption that these cluster stacks have spherical symmetry. In this paper, we test whether this assumption holds for optically selected clusters binned by estimated optical richness. Using mock catalogues created from N-body simulations populated realistically with galaxies, we ran a suite of optical cluster finders and estimated their optical richness. We binned galaxy clusters by true cluster mass and estimated optical richness and measure the ellipticity of these stacks. We find that the processes of optical cluster selection and richness estimation are biased, leading to stacked structures that are elongated along the line of sight. We show that weak-lensing alone cannot measure the size of this orientation bias. Weak-lensing masses of stacked optically selected clusters are overestimated by up to 3–6 per cent when clusters can be uniquely associated with haloes. This effect is large enough to lead to significant biases in the cosmological parameters derived from large surveys like the Dark Energy Survey, if not calibrated via simulations or fitted simultaneously. This bias probably also contributes to the observed discrepancy between the observed and predicted Sunyaev–Zel’dovich signal of optically selected clusters
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