338 research outputs found
Are Debris Disks and Massive Planets Correlated?
Using data from the Spitzer Space Telescope Legacy Science Program
``Formation and Evolution of Planetary Systems'' (FEPS), we have searched for
debris disks around 9 FGK stars (2-10 Gyr), known from radial velocity (RV)
studies to have one or more massive planets. Only one of the sources, HD 38529,
has excess emission above the stellar photosphere; at 70 micron the
signal-to-noise ratio in the excess is 4.7 while at wavelengths < 30 micron
there is no evidence of excess. The remaining sources show no excesses at any
Spitzer wavelengths. Applying survival tests to the FEPS sample and the results
for the FGK survey published in Bryden et al. (2006), we do not find a
significant correlation between the frequency and properties of debris disks
and the presence of close-in planets. We discuss possible reasons for the lack
of a correlation.Comment: 24 pages, 3 figures. Accepted to Astrophysical Journa
Formation and Evolution of Planetary Systems: Cold Outer Disks Associated with Sun-like stars
We present the discovery of debris systems around three solar mass stars
based upon observations performed with the Spitzer Space Telescope as part of a
Legacy Science Program, ``the Formation and Evolution of Planetary Systems''
(FEPS). We also confirm the presence of debris around two other stars. All the
stars exhibit infrared emission in excess of the expected photospheres in the
70 micron band, but are consistent with photospheric emission at <= 33 micron.
This restricts the maximum temperature of debris in equilibrium with the
stellar radiation to T < 70 K. We find that these sources are relatively old in
the FEPS sample, in the age range 0.7 - 3 Gyr. Based on models of the spectral
energy distributions, we suggest that these debris systems represent materials
generated by collisions of planetesimal belts. We speculate on the nature of
these systems through comparisons to our own Kuiper Belt, and on the likely
planet(s) responsible for stirring the system and ultimately releasing dust
through collisions. We further report observations of a nearby star HD 13974 (d
=11 pc) that is indistinguishable from a bare photosphere at both 24 micron and
70 micron. The observations place strong upper limits on the presence of any
cold dust in this nearby system (L_IR/L_* < 10^{-5.2}).Comment: 31 pages, 9 figures, accepted for publication in Ap
Soft, collinear and non-relativistic modes in radiative decays of very heavy quarkonium
We analyze the end-point region of the photon spectrum in semi-inclusive
radiative decays of very heavy quarkonium (m alpha_s^2 >> Lambda_QCD). We
discuss the interplay of the scales arising in the Soft-Collinear Effective
Theory, m, m(1-z)^{1/2} and m(1-z) for z close to 1, with the scales of heavy
quarkonium systems in the weak coupling regime, m, m alpha_s and m alpha_s^2.
For 1-z \sim alpha_s^2 only collinear and (ultra)soft modes are seen to be
relevant, but the recently discovered soft-collinear modes show up for 1-z <<
alpha_s^2. The S- and P-wave octet shape functions are calculated. When they
are included in the analysis of the photon spectrum of the Upsilon (1S) system,
the agreement with data in the end-point region becomes excellent. The NRQCD
matrix elements and
are also obtained.Comment: Revtex, 11 pages, 6 figures. Minor improvements and references added.
Journal versio
Estimating prevalence of overweight and obesity at the neighborhood level: the value of maternal height and weight data available on birth certificate records
<p>Abstract</p> <p>Objective</p> <p>To determine the value of maternal height and weight data on birth certificate records when estimating prevalence of overweight and obese adults at the neighborhood level.</p> <p>Research Design and Methods</p> <p>Regression analysis was used to determine how much variation in the percentage of the adult population with a body mass index (BMI) of ≥ 25 (based on survey data) could be accounted for by the percentage of mothers with BMI ≥ 25 (based on birth certificate data) -- alone and in combination with other sociodemographic characteristics of census tracts.</p> <p>Results</p> <p>Alone, the percentage of mothers with BMI ≥ 25 explained more than half (R<sup>2 </sup>= .52) of the variation in the percentage of all residents in census tracts with BMI ≥ 25; in combination with several measures of the sociodemographic characteristics of the census tracts, 75% ( R<sup>2 </sup>= 75.2) of the variation is explained.</p> <p>Conclusions</p> <p>Maternal height and weight data available from birth certificate records may be useful for identifying neighborhoods with relatively high or low prevalence of adult residents who are overweight or obese. This is especially true if used in combination with readily available census data.</p
Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas
Although theMYConcogene has been implicated incancer, a systematic assessment of alterations ofMYC, related transcription factors, and co-regulatoryproteins, forming the proximal MYC network (PMN),across human cancers is lacking. Using computa-tional approaches, we define genomic and proteo-mic features associated with MYC and the PMNacross the 33 cancers of The Cancer Genome Atlas.Pan-cancer, 28% of all samples had at least one ofthe MYC paralogs amplified. In contrast, the MYCantagonists MGA and MNT were the most frequentlymutated or deleted members, proposing a roleas tumor suppressors.MYCalterations were mutu-ally exclusive withPIK3CA,PTEN,APC,orBRAFalterations, suggesting that MYC is a distinct onco-genic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such asimmune response and growth factor signaling; chro-matin, translation, and DNA replication/repair wereconserved pan-cancer. This analysis reveals insightsinto MYC biology and is a reference for biomarkersand therapeutics for cancers with alterations ofMYC or the PMN
Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context
Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts
Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas
This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing
molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin
Spatial Organization and Molecular Correlation of Tumor-Infiltrating Lymphocytes Using Deep Learning on Pathology Images
Beyond sample curation and basic pathologic characterization, the digitized H&E-stained images
of TCGA samples remain underutilized. To highlight this resource, we present mappings of tumorinfiltrating lymphocytes (TILs) based on H&E images from 13 TCGA tumor types. These TIL
maps are derived through computational staining using a convolutional neural network trained to
classify patches of images. Affinity propagation revealed local spatial structure in TIL patterns and
correlation with overall survival. TIL map structural patterns were grouped using standard
histopathological parameters. These patterns are enriched in particular T cell subpopulations
derived from molecular measures. TIL densities and spatial structure were differentially enriched
among tumor types, immune subtypes, and tumor molecular subtypes, implying that spatial
infiltrate state could reflect particular tumor cell aberration states. Obtaining spatial lymphocytic
patterns linked to the rich genomic characterization of TCGA samples demonstrates one use for
the TCGA image archives with insights into the tumor-immune microenvironment
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