70 research outputs found
The Outer Disks of Early-Type Galaxies. I. Surface-Brightness Profiles of Barred Galaxies
We present a study of 66 barred, early-type (S0-Sb) disk galaxies, focused on
the disk surface brightness profile outside the bar region and the nature of
Freeman Type I and II profiles, their origins, and their possible relation to
disk truncations. This paper discusses the data and their reduction, outlines
our classification system, and presents -band profiles and classifications
for all galaxies in the sample.
The profiles are derived from a variety of different sources, including the
Sloan Digital Sky Survey (Data Release 5). For about half of the galaxies, we
have profiles derived from more than one telescope; this allows us to check the
stability and repeatability of our profile extraction and classification. The
vast majority of the profiles are reliable down to levels of mu_R ~ 27 mag
arcsec^-2; in exceptional cases, we can trace profiles down to mu_R > 28. We
can typically follow disk profiles out to at least 1.5 times the traditional
optical radius R_25; for some galaxies, we find light extending to ~ 3 R_25.
We classify the profiles into three main groups: Type I (single-exponential),
Type II (down-bending), and Type III (up-bending). The frequencies of these
types are approximately 27%, 42%, and 24%, respectively, plus another 6% which
are combinations of Types II and III. We further classify Type II profiles by
where the break falls in relation to the bar length, and in terms of the
postulated mechanisms for breaks at large radii ("classical trunction" of star
formation versus the influence of the Outer Lindblad Resonance of the bar). We
also classify the Type III profiles by the probable morphology of the outer
light (disk or spheroid). Illustrations are given for all cases. (Abridged)Comment: 41 pages, 26 PDF figures. To appear in the Astronomical Journal.
Version with full-resolution figures available at
http://www.mpe.mpg.de/~erwin/research
Transcriptional repression of the glycoprotein hormone alpha subunit gene by androgen may involve direct binding of androgen receptor to the proximal promoter.
Testicular androgens suppress the synthesis and secretion of the pituitary gonadotropins, in particular, luteinizing hormone. This suppressive effect includes transcription of both the common a subunit gene and the unique β subunit genes. Herein, we demonstrate that 1600 base pairs (bp) of proximal 5'-flanking region derived from the human α subunit gene and a shorter 315-bp segment of the bovine α subunit gene confer negative regulation by androgen to the gene encoding bacterial chloramphenicol acetyltransferase in transgenic mice.Testicular androgens suppress the synthesis and secretion of the pituitary gonadotropins, in particular, luteinizing hormone. This suppressive effect includes transcription of both the common a subunit gene and the unique β subunit genes. Herein, we demonstrate that 1600 base pairs (bp) of proximal 5'-flanking region derived from the human α subunit gene and a shorter 315-bp segment of the bovine α subunit gene confer negative regulation by androgen to the gene encoding bacterial chloramphenicol acetyltransferase in transgenic mice
Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
We review internal processes of secular evolution in galaxy disks,
concentrating on the buildup of dense central features that look like
classical, merger-built bulges but that were made slowly out of disk gas. We
call these pseudobulges. As an existence proof, we review how bars rearrange
disk gas into outer rings, inner rings, and gas dumped into the center. In
simulations, this gas reaches high densities that plausibly feed star
formation. In the observations, many SB and oval galaxies show central
concentrations of gas and star formation. Star formation rates imply plausible
pseudobulge growth times of a few billion years. If secular processes built
dense central components that masquerade as bulges, can we distinguish them
from merger-built bulges? Observations show that pseudobulges retain a memory
of their disky origin. They have one or more characteristics of disks: (1)
flatter shapes than those of classical bulges, (2) large ratios of ordered to
random velocities indicative of disk dynamics, (3) small velocity dispersions,
(4) spiral structure or nuclear bars in the bulge part of the light profile,
(5) nearly exponential brightness profiles, and (6) starbursts. These
structures occur preferentially in barred and oval galaxies in which secular
evolution should be rapid. So the cleanest examples of pseudobulges are
recognizable. Thus a large variety of observational and theoretical results
contribute to a new picture of galaxy evolution that complements hierarchical
clustering and merging.Comment: 92 pages, 21 figures in 30 Postscript files; to appear in Annual
Review of Astronomy and Astrophysics, Vol. 42, 2004, in press; for a version
with full resolution figures, see
http://chandra.as.utexas.edu/~kormendy/ar3ss.htm
Gene Transcription Changes in Asthmatic Chronic Rhinosinusitis with Nasal Polyps and Comparison to Those in Atopic Dermatitis
Asthmatic chronic rhinosinusitis with nasal polyps (aCRSwNP) is a common disruptive eosinophilic disease without effective medical treatment. Therefore, we sought to identify gene expression changes, particularly those occurring early, in aCRSwNP. To highlight expression changes associated with eosinophilic epithelial inflammation, we further compared the changes in aCRSwNP with those in a second eosinophilic epithelial disease, atopic dermatitis (AD), which is also closely related to asthma.Genome-wide mRNA levels measured by exon array in both nasosinus inflamed mucosa and adjacent polyp from 11 aCRSwNP patients were compared to those in nasosinus tissue from 17 normal or rhinitis subjects without polyps. Differential expression of selected genes was confirmed by qRT-PCR or immunoassay, and transcription changes common to AD were identified. Comparison of aCRSwNP inflamed mucosa and polyp to normal/rhinitis tissue identified 447 differentially transcribed genes at > or = 2 fold-change and adjusted p-value < 0.05. These included increased transcription of chemokines localized to chromosome 17q11.2 (CCL13, CCL2, CCL8, and CCL11) that favor eosinophil and monocyte chemotaxis and chemokines (CCL18, CCL22, and CXCL13) that alternatively-activated monocyte-derived cells have been shown to produce. Additional transcription changes likely associated with Th2-like eosinophilic inflammation were prominent and included increased IL1RL1 (IL33 receptor) and EMR1&3 and decreased CRISP2&3. A down-regulated PDGFB-centric network involving several smooth muscle-associated genes was also implicated. Genes at 17q11.2, genes associated with alternative activation or smooth muscle, and the IL1RL1 gene were also differentially transcribed in AD.Our data implicate several genes or gene sets in aCRSwNP and eosinophilic epithelial inflammation, some that likely act in the earlier stages of inflammation. The identified gene expression changes provide additional diagnostic and therapeutic targets for aCRSwNP and other eosinophilic epithelial diseases
An immune dysfunction score for stratification of patients with acute infection based on whole-blood gene expression
Dysregulated host responses to infection can lead to organ dysfunction and sepsis, causing millions of global deaths each year. To alleviate this burden, improved prognostication and biomarkers of response are urgently needed. We investigated the use of whole-blood transcriptomics for stratification of patients with severe infection by integrating data from 3149 samples from patients with sepsis due to community-acquired pneumonia or fecal peritonitis admitted to intensive care and healthy individuals into a gene expression reference map. We used this map to derive a quantitative sepsis response signature (SRSq) score reflective of immune dysfunction and predictive of clinical outcomes, which can be estimated using a 7- or 12-gene signature. Last, we built a machine learning framework, SepstratifieR, to deploy SRSq in adult and pediatric bacterial and viral sepsis, H1N1 influenza, and COVID-19, demonstrating clinically relevant stratification across diseases and revealing some of the physiological alterations linking immune dysregulation to mortality. Our method enables early identification of individuals with dysfunctional immune profiles, bringing us closer to precision medicine in infection.peer-reviewe
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