650 research outputs found
Revealing the large nuclear dust structures in NGC 1068 with MIDI/VLTI
To understand the relation between the small "obscuring torus" and dusty
structures at larger scales (5-10 pc) in NGC 1068, we use ESO's Mid-Infrared
Interferometer (MIDI) with the 1.8 m Auxiliary Telescopes to achieve the
necessary spatial resolution (~ 20-100 millarcsec). We use the chromatic phases
in the data to improve the spatial fidelity of the analysis. We present
interferometric data for NGC 1068 obtained in 2007 and 2012. We find no
evidence of source variability. Many (u,v) points show non-zero chromatic
phases indicating significant asymmetries. Gaussian model fitting of the
correlated fluxes and chromatic phases provides a 3-component best fit with
estimates of sizes, temperatures and positions of the components. A large,
warm, off-center component is required at a distance approximately 90 mas to
the north-west at a PA ~ -18 deg. The dust at 5-10 pc in the polar region
contributes 4 times more to the mid-infrared flux at 12 um than the dust
located at the center. This dust may represent the inner wall of a dusty cone.
If similar regions are heated by the direct radiation from the nucleus, then
they will contribute substantially to the classification of many Seyfert
galaxies as Type 2. Such a region is also consistent in other Seyfert galaxies
(the Circinus galaxy, NGC 3783 and NGC 424).Comment: 21 pages, 10 figures; Accepted for publication on A&
NGC 1068: No change in the mid-IR torus structure despite X-ray variability
Context. Recent NuSTAR observations revealed a somewhat unexpected increase
in the X-ray flux of the nucleus of NGC 1068. We expect the infrared emission
of the dusty torus to react on the intrinsic changes of the accretion disk.
Aims. We aim to investigate the origin of the X-ray variation by
investigating the response of the mid-infrared environment.
Methods. We obtained single-aperture and interferometric mid-infrared
measurements and directly compared the measurements observed before and
immediately after the X-ray variations. The average correlated and
single-aperture fluxes as well as the differential phases were directly
compared to detect a possible change in the structure of the nuclear emission
on scales of 2 pc.
Results. The flux densities and differential phases of the observations
before and during the X-ray variation show no significant change over a period
of ten years. Possible minor variations in the infrared emission are
8 %.
Conclusions. Our results suggest that the mid-infrared environment of NGC
1068 has remained unchanged for a decade. The recent transient change in the
X-rays did not cause a significant variation in the infrared emission. This
independent study supports previous conclusions that stated that the X-ray
variation detected by NuSTAR observations is due to X-ray emission piercing
through a patchy section of the dusty region.Comment: 6 pages, 5 figures, 3 tables. Accepted for publication on A&
Cystic adenomatoid malformations are induced by localized FGF10 overexpression in fetal rat lung
Fibroblast growth factor-10 (FGF10) is a mesenchymal growth factor, involved in epithelial and mesenchymal interactions during lung branching morphogenesis. In the present work, FGF10 overexpression was transiently induced in a temporally and spatially restricted manner, during the pseudoglandular or canalicular stages of rat lung development, by trans-uterine ultrasound-guided intraparenchymal microinjections of adenoviral vector encoding the rfgf10 transgene. The morphologic and histologic classification of the resulting malformations were dependent upon developmental stage and location. Overexpression of FGF10 restricted to the proximal tracheobronchial tree during the pseudoglandular phase resulted in large cysts lined by tall columnar epithelium composed primarily of Clara cells with a paucity of Type II pneumocytes, resembling bronchiolar type epithelium. In contrast, FGF10 overexpression in the distal lung parenchyma during the canalicular phase resulted in small cysts lined by cuboidal epithelial cells composed of primarily Type II pneumocytes resembling acinar epithelial differentiation. The cystic malformations induced by FGF10 overexpression appear to closely recapitulate the morphology and histology of the spectrum of human congenital cystic adenomatoid malformation (CCAM). These findings support a role for FGF10 in the induction of human CCAM and provide further mechanistic insight into the role of FGF10 in normal and abnormal lung development.This project was in part funded by proceeds from the Ruth and Tristram C. Colket
Jr. Chair in Pediatric Surgery (A.W.F.), and the Fundação para a Ciência e
Tecnologia (POCI/SAUOBS/56428/2004). S.G. was supported by FCT grant ref.
SFRH/BD/15260/2004
Targeted gene transfer to fetal rat lung interstitium by ultrasound-guided intrapulmonary injection
In utero gene transfer to the developing lung may have clinical or research applications. In this study, we developed a new method for specifically targeting the fetal rat lung with adeno and lentiviral vectors encoding the enhanced green fluorescence protein (EGFP) marker gene at E15.5 using ultrasound biomicroscopy (UBM). Survival rate, morphometric parameters, viral biodistribution, and lung transduction efficiency were analyzed and compared to the intra-amniotic route of administration. Expression of EGFP started as early as 24 and 72 h after the injection of adenoviral and lentiviral vectors, respectively. Both vectors transduced lung parenchyma with gene expression limited to interstitial cells of the injected region, in contrast to intra-amniotic injection, which targeted the pulmonary epithelium. Expression of EGFP was most intense at E18.5 and E21.5 for adenoviral and lentiviral vectors, respectively. In contrast to lentivirus, adenoviral expression significantly declined until final analysis at 1 week of age. This study demonstrates the feasibility of targeting the fetal rat lung interstitium with viral vectors under UBM guidance during the pseudoglandular stage. This model system may facilitate in vivo studies of dynamic lung morphogenesis and could provide insight into the efficacy of prenatal gene transfer strategies for treatment of specific lung disorders.FCT Grant (SFRH/BD/15260/2004) on behalf of the FCT Grant POCI/SAU-OBS/56428/200
Surface Brightness Profiles of Composite Images of Compact Galaxies at z~4-6 in the HUDF
The Hubble Ultra Deep Field (HUDF) contains a significant number of B, V and
i'-band dropout objects, many of which were recently confirmed to be young
star-forming galaxies at z~4-6. These galaxies are too faint individually to
accurately measure their radial surface brightness profiles. Their average
light profiles are potentially of great interest, since they may contain clues
to the time since the onset of significant galaxy assembly. We separately
co-add V, i' and z'-band HUDF images of sets of z~4,5 and 6 objects,
pre-selected to have nearly identical compact sizes and the roundest shapes.
From these stacked images, we are able to study the averaged radial structure
of these objects at much higher signal-to-noise ratio than possible for an
individual faint object. Here we explore the reliability and usefulness of a
stacking technique of compact objects at z~4-6 in the HUDF. Our results are:
(1) image stacking provides reliable and reproducible average surface
brightness profiles; (2) the shape of the average surface brightness profiles
show that even the faintest z~4-6 objects are resolved; and (3) if late-type
galaxies dominate the population of galaxies at z~4-6, as previous HST studies
have shown, then limits to dynamical age estimates for these galaxies from
their profile shapes are comparable with the SED ages obtained from the
broadband colors. We also present accurate measurements of the sky-background
in the HUDF and its associated 1-sigma uncertainties.Comment: 10 pages, 9 figures, 2 tables, emulateapj; Accepted for publication
in The Astronomical Journa
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