793 research outputs found
The galaxy environment in GAMA G3C groups using the Kilo Degree Survey Data Release 3
We aim to investigate the galaxy environment in GAMA Galaxy Groups Catalogue
(G3C) using a volume-limited galaxy sample from the Kilo Degree Survey Data
Release 3. The k-Nearest Neighbour technique is adapted to take into account
the probability density functions (PDFs) of photometric redshifts in our
calculations. This algorithm was tested on simulated KiDS tiles, showing its
capability of recovering the relation between galaxy colour, luminosity and
local environment. The characterization of the galaxy environment in G3C groups
shows systematically steeper density contrasts for more massive groups. The red
galaxy fraction gradients in these groups is evident for most of group mass
bins. The density contrast of red galaxies is systematically higher at group
centers when compared to blue galaxy ones. In addition, distinct group center
definitions are used to show that our results are insensitive to center
definitions. These results confirm the galaxy evolution scenario which
environmental mechanisms are responsible for a slow quenching process as
galaxies fall into groups and clusters, resulting in a smooth observed colour
gradients in galaxy systems.Comment: 14 pages, Accepted to MNRA
The VOICE Survey : VST Optical Imaging of the CDFS and ES1 Fields
Indexación: Scopus.We present the VST Optical Imaging of the CDFS and ES1 Fields (VOICE) Survey, a VST INAF Guaranteed Time program designed to provide optical coverage of two 4 deg2 cosmic windows in the Southern hemisphere. VOICE provides the first, multi-band deep optical imaging of these sky regions, thus complementing and enhancing the rich legacy of longer-wavelength surveys with VISTA, Spitzer, Herschel and ATCA available in these areas and paving the way for upcoming observations with facilities such as the LSST, MeerKAT and the SKA. VOICE exploits VST's OmegaCAM optical imaging capabilities and completes the reduction of WFI data available within the ES1 fields as part of the ESO-Spitzer Imaging Extragalactic Survey (ESIS) program providing ugri and uBVR coverage of 4 and 4 deg2 areas within the CDFS and ES1 field respectively. We present the survey's science rationale and observing strategy, the data reduction and multi-wavelength data fusion pipeline. Survey data products and their future updates will be released at http://www.mattiavaccari.net/voice/ and on CDS/VizieR.https://pos.sissa.it/275/026/pd
SUDARE-VOICE variability-selection of Active Galaxies in the Chandra Deep Field South and the SERVS/SWIRE region
One of the most peculiar characteristics of Active Galactic Nuclei (AGN) is
their variability over all wavelengths. This property has been used in the past
to select AGN samples and is foreseen to be one of the detection techniques
applied in future multi-epoch surveys, complementing photometric and
spectroscopic methods.
In this paper, we aim to construct and characterise an AGN sample using a
multi-epoch dataset in the r band from the SUDARE-VOICE survey.
Our work makes use of the VST monitoring program of an area surrounding the
Chandra Deep Field South to select variable sources. We use data spanning a six
month period over an area of 2 square degrees, to identify AGN based on their
photometric variability.
The selected sample includes 175 AGN candidates with magnitude r < 23 mag. We
distinguish different classes of variable sources through their lightcurves, as
well as X-ray, spectroscopic, SED, optical and IR information overlapping with
our survey.
We find that 12% of the sample (21/175) is represented by SN. Of the
remaining sources, 4% (6/154) are stars, while 66% (102/154) are likely AGNs
based on the available diagnostics. We estimate an upper limit to the
contamination of the variability selected AGN sample of about 34%, but we point
out that restricting the analysis to the sources with available
multi-wavelength ancillary information, the purity of our sample is close to
80% (102 AGN out of 128 non-SN sources with multi-wavelength diagnostics). Our
work thus confirms the efficiency of the variability selection method in
agreement with our previous work on the COSMOS field; in addition we show that
the variability approach is roughly consistent with the infrared selection.Comment: Published in A & A, 15 pages, 6 figure
Optically variable active galactic nuclei in the 3 yr VST survey of the COSMOS field
The analysis of the variability of active galactic nuclei (AGNs) at different
wavelengths and the study of possible correlations among different spectral
windows are nowadays a major field of inquiry. Optical variability has been
largely used to identify AGNs in multivisit surveys. The strength of a
selection based on optical variability lies in the chance to analyze data from
surveys of large sky areas by ground-based telescopes. However the
effectiveness of optical variability selection, with respect to other
multiwavelength techniques, has been poorly studied down to the depth expected
from next generation surveys. Here we present the results of our r-band
analysis of a sample of 299 optically variable AGN candidates in the VST survey
of the COSMOS field, counting 54 visits spread over three observing seasons
spanning > 3 yr. This dataset is > 3 times larger in size than the one
presented in our previous analysis (De Cicco et al. 2015), and the observing
baseline is ~8 times longer. We push towards deeper magnitudes (r(AB) ~23.5
mag) compared to past studies; we make wide use of ancillary multiwavelength
catalogs in order to confirm the nature of our AGN candidates, and constrain
the accuracy of the method based on spectroscopic and photometric diagnostics.
We also perform tests aimed at assessing the relevance of dense sampling in
view of future wide-field surveys. We demonstrate that the method allows the
selection of high-purity (> 86%) samples. We take advantage of the longer
observing baseline to achieve great improvement in the completeness of our
sample with respect to X-ray and spectroscopically confirmed samples of AGNs
(59%, vs. ~15% in our previous work), as well as in the completeness of
unobscured and obscured AGNs. The effectiveness of the method confirms the
importance to develop future, more refined techniques for the automated
analysis of larger datasets.Comment: 21 pages, 10 figures; accepted for publication in A&
The Fornax Deep Survey with VST. II. Fornax A: a two-phase assembly caught on act
As part of the Fornax Deep Survey with the ESO VLT Survey Telescope, we
present new and bands mosaics of the SW group of the Fornax cluster. It
covers an area of square degrees around the central galaxy
NGC1316. The deep photometry, the high spatial resolution of OmegaCam and the
large covered area allow us to study the galaxy structure, to trace stellar
halo formation and look at the galaxy environment. We map the surface
brightness profile out to 33arcmin (kpc ) from the galaxy
centre, down to mag arcsec and mag
arcsec. This allow us to estimate the scales of the main components
dominating the light distribution, which are the central spheroid, inside 5.5
arcmin ( kpc), and the outer stellar envelope. Data analysis suggests
that we are catching in act the second phase of the mass assembly in this
galaxy, since the accretion of smaller satellites is going on in both
components. The outer envelope of NGC1316 still hosts the remnants of the
accreted satellite galaxies that are forming the stellar halo. We discuss the
possible formation scenarios for NGC1316, by comparing the observed properties
(morphology, colors, gas content, kinematics and dynamics) with predictions
from cosmological simulations of galaxy formation. We find that {\it i)} the
central spheroid could result from at least one merging event, it could be a
pre-existing early-type disk galaxy with a lower mass companion, and {\it ii)}
the stellar envelope comes from the gradual accretion of small satellites.Comment: Accepeted for publication in Ap
Efectos del vibrado del pino piñonero (Pinus pinea L.) en el vigor de los árboles: densidad de copa, crecimiento de guías y parásitos de debilidad
In the Northwest of Spain the mechanized harvesting of pine cones is more and more frequenIn order to quantify the effects of vibration on the vigor of the trees, parcels of stone pine were planted in plateau and countryside. Both the mechanized and manual harvests were analyzed in adult and young trees. The growth of the tree shoots was measured. The presence and abundance of three insect plagues was analyzed in those same trees: Tomicus piniperda, Rhyacionia buoliana and Thaumetopoea pityocampa. The average shoot length of those trees manually harvested was superior to that of those mechanically harvested. The difference was very significant in young trees (40-50 years old) in the countryside and in adult trees (more than 80 years) on the plateau. Rhyacionia buoliana was more abundant in adult trees that young trees, but the relation of its abundance with the harvest method was not seen. The presence of Tomicus piniperda was rare and was only detected in mechanically harvested stands. Thaumetopoea pityocampa was more frequent in trees harvested by hand than those harvested mechanically and was more abundant in young stands. The percentage tree of defoliation was low in all stands independent of harvest method.En el noroeste de España es cada vez más frecuente la recolección mecanizada de piña. Para cuantificar los efectos del vibrado sobre el vigor de los árboles se instalaron en montes de páramo y de campiña parcelas donde se realizó cosecha mecanizada y manual en arbolado adulto y joven. Se midió el crecimiento de los brotes y se analizó la presencia y abundancia de tres insectos plaga sobre estos árboles, Tomicus piniperda y Rhyacionia buoliana, considerados parásitos de debilidad, así como Thaumetopoea pityocampa. La longitud media de los brotes fue superior en árboles cosechados manualmente. La diferencia es importante en árboles jóvenes (40-50 años) de campiñas y en árboles adultos (más de 80 años) de páramos. Rhyacionia buoliana fue más abundante en árboles adultos que en arbolado joven, pero no se vio relación de su abundancia con el método de cosecha. Tomicus piniperda fue escaso y sólo se detectó en rodales cosechados mecanizadamente. Thaumetopoea pityocampa es más frecuente en rodales cosechados manualmente, y en rodales jóvenes lo que indica que selecciona los árboles de crecimiento más vigoroso para alimentarse. Los porcentajes de defoliación fueron bajos en todas las parcelas
Periodontal regeneration in clinical practice
The regeneration or restitution of lost supporting tissue has always been considered the ideal objective of periodontal therapy. However, attempts to convert this intention into solid clinical practice can become tremendously complex, the results of which are very different from the original intention. The aim of this article is to offer an up-to-date, general perspective on periodontal regeneration, orienting the clinician within the global strategy for oral treatment. To this end, we revise the healing process of periodontal injury, the different therapeutic approaches, the interpretation of the results, and finally, limiting factors in periodontal regeneration
Supernova rates from the SUDARE VST-Omegacam search II. Rates in a galaxy sample
This is the second paper of a series in which we present measurements of the
Supernova (SN) rates from the SUDARE survey. In this paper, we study the trend
of the SN rates with the intrinsic colours, the star formation activity and the
mass of the parent galaxies. We have considered a sample of about 130000
galaxies and a SN sample of about 50 events. We found that the SN Ia rate per
unit mass is higher by a factor of six in the star-forming galaxies with
respect to the passive galaxies. The SN Ia rate per unit mass is also higher in
the less massive galaxies that are also younger. These results suggest a
distribution of the delay times (DTD) less populated at long delay times than
at short delays. The CC SN rate per unit mass is proportional to both the sSFR
and the galaxy mass. The trends of the Type Ia and CC SN rates as a function of
the sSFR and the galaxy mass that we observed from SUDARE data are in agreement
with literature results at different redshifts. The expected number of SNe Ia
is in agreement with the observed one for all four DTD models considered both
in passive and star-forming galaxies so we can not discriminate between
different progenitor scenarios. The expected number of CC SNe is higher than
the observed one, suggesting a higher limit for the minimum progenitor mass. We
also compare the expected and observed trends of the SN Ia rate with the
intrinsic U - J colour of the parent galaxy, assumed as a tracer of the age
distribution. While the slope of the relation between the SN Ia rate and the U
- J color in star-forming galaxies can be reproduced well by all four DTD
models considered, only the steepest of them is able to account for the rates
and colour in star-forming and passive galaxies with the same value of the SN
Ia production efficiency.Comment: A& A accepte
Homenaje a Ramón y Cajal en el centenario de la concesión del Premio Nobel
Scientific Meeting: Honoring to Ramon and Cajal in the centenary of the grant of the Nobel Prize.Mesa Redonda: Homenaje a Ramón y Cajal en el centenario de la concesión del Premio Nobe
Liquid fructose downregulates SIRT1 expression and activity and impairs the oxidation of fatty acids in rat and human liver cells
Fructose ingestion is associated with the production of hepatic steatosis and hypertriglyceridemia. For fructose to attain these effects in rats, simultaneous induction of fatty acid synthesis and inhibition of fatty acid oxidation is required. We aimed to determine the mechanism involved in the inhibition of fatty acid oxidation by fructose and whether this effect occurs also in human liver cells. Female rats were supplemented or not with liquid fructose (10% w/v) for 7 or 14 days; rat (FaO) and human (HepG2) hepatoma cells, and human hepatocytes were incubated with fructose 25 mM for 24 h. The expression and activity of the enzymes and transcription factors relating to fatty acid β-oxidation were evaluated. Fructose inhibited the activity of fatty acid β-oxidation only in livers of 14-day fructose-supplemented rats, as well as the expression and activity of peroxisome proliferator activated receptor α (PPARα). Similar results were observed in FaO and HepG2 cells and human hepatocytes. PPARα downregulation was not due to an osmotic effect or to an increase in protein-phosphatase 2A activity caused by fructose. Rather, it was related to increased content in liver of inactive and acetylated peroxisome proliferator activated receptor gamma coactivator 1α, due to a reduction in sirtuin 1 expression and activity. In conclusion, fructose inhibits liver fatty acid oxidation by reducing PPARα expression and activity, both in rat and human liver cells, by a mechanism involving sirtuin 1 down-regulation
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