407 research outputs found
Chemical enrichment of the complex hot ISM of the Antennae galaxies: I. Spatial and spectral analysis of the diffuse X-ray emission
We present an analysis of the properties of the hot interstellar medium (ISM)
in the merging pair of galaxies known as The Antennae (NGC 4038/39), performed
using the deep, coadded ~411 ks Chandra ACIS-S data set. These deep X-ray
observations and Chandra's high angular resolution allow us to investigate the
properties of the hot ISM with unprecedented spatial and spectral resolution.
Through a spatially resolved spectral analysis, we find a variety of
temperatures (from 0.2 to 0.7 keV) and Nh (from Galactic to 2x10^21 cm^-2).
Metal abundances for Ne, Mg, Si, and Fe vary dramatically throughout the ISM
from sub-solar values (~0.2) up to several times solar.Comment: 33 pages, 18 figures, revised version accepted by Astrophysical
Journal Supplement Serie
Preventie op de camping:Resultaten van twee pilots in West-Brabant in het souterrain van de woningmarkt
Vanwege tekorten op de woningmarkt enerzijds en de moeizame exploitatie van recreatieparken anderzijds, is permanente bewoning op recreatieparken een structureel maatschappelijk verschijnsel geworden. Permanente bewoning is wettelijk niet toegestaan en kan samengaan met diverse vormen van sociale problematiek. De sociale crisis die ontstond op camping Fort Oranje is voor de GGD WestBrabant aanleiding geweest preventieve werkwijzen voor recreatieparken te ontwikkelen. Dit artikel beschrijft twee pilots die in dit verband werden opgezet. De ambitie was bewoners van recreatieparken in beeld te krijgen en waar nodig te ondersteunen, en om een stem te geven aan hun verhaal
Chemical enrichment of the complex hot ISM of the Antennae Galaxies: II. Physical properties of the hot gas and supernova feedback
We investigate the physical properties of the interstellar medium (ISM) in
the merging pair of galaxies known as The Antennae (NGC 4038/39), using the
deep coadded ~411 ks Chandra ACIS-S data set. The method of analysis and some
of the main results from the spectral analysis, such as metal abundances and
their variations from ~0.2 to ~20-30 times solar, are described in Paper I
(Baldi et al. submitted). In the present paper we investigate in detail the
physics of the hot emitting gas, deriving measures for the hot-gas mass (~10^
M_sun), cooling times (10^7-10^8 yr), and pressure (3.5x10^-11-2.8x10^-10 dyne
cm^-2). At least in one of the two nuclei (NGC 4038) the hot-gas pressure is
significantly higher than the CO pressure, implying that shock waves may be
driven into the CO clouds. Comparison of the metal abundances with the average
stellar yields predicted by theoretical models of SN explosions points to SNe
of Type II as the main contributors of metals to the hot ISM. There is no
evidence of any correlation between radio-optical star-formation indicators and
the measured metal abundances. Although due to uncertainties in the average gas
density we cannot exclude that mixing may have played an important role, the
short time required to produce the observed metal masses (<=2 Myr) suggests
that the correlations are unlikely to have been destroyed by efficient mixing.
More likely, a significant fraction of SN II ejecta may be in a cool phase, in
grains, or escaping in hot winds. In each case, any such fraction of the ejecta
would remain undetectable with soft X-ray observations.Comment: 29 pages, 6 figures, accepted by the Astrophysical Journa
KRAB-Induced Heterochromatin Effectively Silences <i>PLOD2</i> Gene Expression in Somatic Cells and is Resilient to TGFβ1 Activation
Epigenetic editing, an emerging technique used for the modulation of gene expression in mammalian cells, is a promising strategy to correct disease-related gene expression. Although epigenetic reprogramming results in sustained transcriptional modulation in several in vivo models, further studies are needed to develop this approach into a straightforward technology for effective and specific interventions. Important goals of current research efforts are understanding the context-dependency of successful epigenetic editing and finding the most effective epigenetic effector(s) for specific tasks. Here we tested whether the fibrosis- and cancer-associated PLOD2 gene can be repressed by the DNA methyltransferase M.SssI, or by the non-catalytic Krüppel associated box (KRAB) repressor directed to the PLOD2 promoter via zinc finger- or CRISPR-dCas9-mediated targeting. M.SssI fusions induced de novo DNA methylation, changed histone modifications in a context-dependent manner, and led to 50%-70% reduction in PLOD2 expression in fibrotic fibroblasts and in MDA-MB-231 cancer cells. Targeting KRAB to PLOD2 resulted in the deposition of repressive histone modifications without DNA methylation and in almost complete PLOD2 silencing. Interestingly, both long-term TGFβ1-induced, as well as unstimulated PLOD2 expression, was completely repressed by KRAB, while M.SssI only prevented the TGFβ1-induced PLOD2 expression. Targeting transiently expressed dCas9-KRAB resulted in sustained PLOD2 repression in HEK293T and MCF-7 cells. Together, these findings point to KRAB outperforming DNA methylation as a small potent targeting epigenetic effector for silencing TGFβ1-induced and uninduced PLOD2 expression
New Observations of Extra-Disk Molecular Gas in Interacting Galaxy Systems, Including a Two-Component System in Stephan's Quintet
We present new CO (1 - 0) observations of eleven extragalactic tails and
bridges in nine interacting galaxy systems, almost doubling the number of such
features with sensitive CO measurements. Eight of these eleven features were
undetected in CO to very low CO/HI limits, with the most extreme case being the
NGC 7714/5 bridge. This bridge contains luminous H II regions and has a very
high HI column density (1.6 X 10^21 cm^-2 in the 55" CO beam), yet was
undetected in CO to rms T(R)* = 2.4 mK. The HI column density is higher than
standard H2 and CO self-shielding limits for solar-metallicity gas, suggesting
that the gas in this bridge is metal-poor and has an enhanced N(H2)/I(CO) ratio
compared to the Galactic value. Only one of the eleven features in our sample
was unambiguously detected in CO, a luminous HI-rich star formation region near
an optical tail in the compact group Stephan's Quintet. We detect CO at two
widely separated velocities in this feature, at ~6000 km/s and ~6700 km/s. Both
of these components have HI and H-alpha counterparts. These velocities
correspond to those of galaxies in the group, suggesting that this gas is
material that has been removed from two galaxies in the group. The
CO/HI/H-alpha ratios for both components are similar to global values for
spiral galaxies.Comment: 39 pages, Latex, 15 figures, Astronomical Journal, in pres
KRAB-Induced Heterochromatin Effectively Silences <i>PLOD2</i> Gene Expression in Somatic Cells and is Resilient to TGFβ1 Activation
IRAC Observations of M81
IRAC images of M81 show three distinct morphological constituents: a smooth
distribution of evolved stars with bulge, disk, and spiral arm components; a
clumpy distribution of dust emission tracing the spiral arms; and a pointlike
nuclear source. The bulge stellar colors are consistent with M-type giants, and
the disk colors are consistent with a slightly younger population. The dust
emission generally follows the blue and ultraviolet emission, but there are
large areas that have dust emission without ultraviolet and smaller areas with
ultraviolet but little dust emission. The former are presumably caused by
extinction, and the latter may be due to cavities in the gas and dust created
by supernova explosions. The nucleus appears fainter at 8 um than expected from
ground-based 10 um observations made four years ago.Comment: ApJS in press (Spitzer special issue); 15 pages, 3 figures. Changes:
unused references removed, numbers and labels in Table 1 change
Star Formation Thresholds in Galactic Disks
We report the first results of a detailed study of the star formation law in
a sample of 32 nearby spiral galaxies with well-measured rotation curves, HI
and H (as traced by CO) surface density profiles, and new \Ha CCD
photometry. Our results strongly support the view that the formation of
gravitationally bound interstellar clouds regulates the onset of widespread
star formation -- at least in the outer regions of galactic disks.Comment: Will appear in July 1 ApJ. Abbreviated abstract. Postscript version
available at http://www.astro.caltech.edu/~clm
A Kinematic Link between Boxy Bulges, Stellar Bars, and Nuclear Activity in NGC 3079 & NGC 4388
We present direct kinematic evidence for bar streaming motions in two active
galaxies with boxy stellar bulges. The Hawaii Imaging Fabry-Perot
Interferometer was used on the Canada-France-Hawaii 3.6-m telescope and the
University of Hawaii 2.2-m telescope to derive the two-dimensional velocity
field of the line-emitting gas in the disks of the Sc galaxy NGC 3079 and the
Sb galaxy NGC 4388. In contrast to previous work based on long-slit data, the
detection of the bar potential from the Fabry-Perot data does not rely on the
existence of inner Lindblad resonances or strong bar-induced shocks. Simple
kinematic models which approximate the intrinsic gas orbits as nonintersecting,
inclined elliptical annuli that conserve angular momentum characterize the
observed velocity fields. Box-shaped bulges in both NGC 3079 and NGC 4388 are
confirmed using new near-infrared images to reduce dust obscuration.
Morphological analysis of starlight in these galaxies is combined with the gas
kinematics derived from the Fabry-Perot spectra to test evolutionary models of
stellar bars that involve transitory boxy bulges, and to quantify the
importance of such bars in fueling active nuclei. Our data support the
evolutionary bar models, but fail to prove convincingly that the stellar bars
in NGC 3079 and NGC 4388 directly trigger or sustain the nuclear activity.
(abridged)Comment: 31 pages, 18 figures, Latex, requires aaspp4.sty. Accepted for the
Astronomical Journal (November issue
Epigenetic Regulation of S100A9 and S100A12 Expression in Monocyte-Macrophage System in Hyperglycemic Conditions
The number of diabetic patients in Europe and world-wide is growing. Diabetes confers a 2-fold higher risk for vascular disease. Lack of insulin production (Type 1 diabetes, T1D) or lack of insulin responsiveness (Type 2 diabetes, T2D) causes systemic metabolic changes such as hyperglycemia (HG) which contribute to the pathology of diabetes. Monocytes and macrophages are key innate immune cells that control inflammatory reactions associated with diabetic vascular complications. Inflammatory programming of macrophages is regulated and maintained by epigenetic mechanisms, in particular histone modifications. The aim of our study was to identify the epigenetic mechanisms involved in the hyperglycemia-mediated macrophage activation. Using Affymetrix microarray profiling and RT-qPCR we identified that hyperglycemia increased the expression of S100A9 and S100A12 in primary human macrophages. Expression of S100A12 was sustained after glucose levels were normalized. Glucose augmented the response of macrophages to Toll-like receptor (TLR)-ligands Palmatic acid (PA) and Lipopolysaccharide (LPS) i.e., pro-inflammatory stimulation. The abundance of activating histone Histone 3 Lysine 4 methylation marks (H3K4me1, H3K4me3) and general acetylation on histone 3 (AceH3) with the promoters of these genes was analyzed by chromatin immunoprecipitation. Hyperglycemia increased acetylation of histones bound to the promoters of S100A9 and S100A12 in M1 macrophages. In contrast, hyperglycemia caused a reduction in total H3 which correlated with the increased expression of both S100 genes. The inhibition of histone methyltransferases SET domain-containing protein (SET)7/9 and SET and MYND domain-containing protein (SMYD)3 showed that these specifically regulated S100A12 expression. We conclude that hyperglycemia upregulates expression of S100A9, S100A12 via epigenetic regulation and induces an activating histone code on the respective gene promoters in M1 macrophages. Mechanistically, this regulation relies on action of histone methyltransferases SMYD3 and SET7/9. The results define an important role for epigenetic regulation in macrophage mediated inflammation in diabetic conditions
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