Reddening and the Extinction Law at High Galactic Latitude

We present near-infrared (JHKL) photometry of 103 southern stars located behind translucent interstellar clouds at high Galactic latitude. Our data are combined with visual photometry and spectral type information from the literature in a detailed analysis of the wavelength dependence of interstellar extinction by dust in these high-latitude clouds. We investigate the shape of the near-infrared extinction curve and evaluate the total line-of-sight extinction ( AV) and ratio of total-to-selective extinction ( RV) in each line of sight. Sources of uncertainty in RV arising from photometric errors and spectral classification errors are carefully assessed and quantified as functions of the line-of-sight reddening. We detect appreciable differences in our results compared with the average extinction curve for dust in the diffuse interstellar medium ( ISM) close to the Galactic plane. Assuming a power-law form in the near-infrared, we find the mean for high-latitude clouds to be well described by [Aλ] α λ-2.3, somewhat steeper than that for the diffuse ISM ([Aλ] α λ-1.8). Our sample includes a substantial number of lines of sight with low RV values (47% with RV \u3c 2.8) relative to the diffuse ISM average of 3.05 ± 0.15. We conclude that many high-latitude clouds have enhanced abundances of relatively small grains

Low-Mass Proto-Planet Migration in T-Tauri Alpha-Disks

We present detailed estimates of ''type-I'' migration rates for low-mass proto-planets embedded in steady-state T-Tauri alpha-disks, based on Lindblad torque calculations ignoring feedback on the disk. Differences in migration rates for several plausible background disk models are explored and we contrast results obtained using the standard two dimensional formalism of spiral density wave theory with those obtained from a simple treatment of three-dimensional effects. Opacity transitions in the disk result in sudden radial variations of the migration rates. Regions with minimal migration rates may be preferred sites of gravitational interactions between proto-planets. Three-dimensional torques are significantly weaker than two-dimensional ones and they are sensitive to the surface density profile of the background disk. We find that migration times in excess of runaway envelope accretion times or T-Tauri disk lifetimes are possible for Earth-mass proto-planets in some background disk models, even at sub-AU distances. We conclude that an understanding of the background disk structure and ''viscosity'', as well as a proper treatment of three-dimensional effects in torque calculations, are necessary to obtain reliable estimates of ``type-I'' migration rates.Comment: Minor revisions, 31 pages, 7 figures, accepted for publication in Ap

The Size Distribution of Dust toward HD 210121 as Determined from Extinction

Several observations suggest that the molecular cloud toward HD 210121 contains an enhanced relative abundance of small dust grains. In particular, the value of the ratio of total-to-selective extinction (Rv) is unusually low. In this paper, we estimate the size distribution of dust grains in this line of sight from the extinction curve observed in the near-infrared through the ultraviolet. We use the maximum entropy method (MEM) to find the smoothest possible size distribution consistent within a χ2 confidence level fit to the extinction data. While MEM has been shown to be a powerful tool in modeling average extinction curves, we show in this paper that MEM can also be a useful technique in modeling individual lines of sight that differ significantly from Galactic averages. We review existing data for HD 210121 and calculate the dust-to-gas ratio in order to constrain the amount of material used in the grain model. We present size distributions for both two-component models of silicate and graphite and three-component models that include amorphous carbon. We compare HD 210121 with the average diffuse interstellar medium and with three other high-latitude lines of sight. The grain-size distribution toward HD 210121 contains a relative excess of grains with radius ɑ\u3c 0.1 µm as well as a relative deficiency of grains with radius ɑ \u3e 0.1 µm as compared with the average diffuse interstellar medium and other clouds at high latitude

Training of Instrumentalists and Development of New Technologies on SOFIA

This white paper is submitted to the Astronomy and Astrophysics 2010 Decadal Survey (Astro2010)1 Committee on the State of the Profession to emphasize the potential of the Stratospheric Observatory for Infrared Astronomy (SOFIA) to contribute to the training of instrumentalists and observers, and to related technology developments. This potential goes beyond the primary mission of SOFIA, which is to carry out unique, high priority astronomical research. SOFIA is a Boeing 747SP aircraft with a 2.5 meter telescope. It will enable astronomical observations anywhere, any time, and at most wavelengths between 0.3 microns and 1.6 mm not accessible from ground-based observatories. These attributes, accruing from the mobility and flight altitude of SOFIA, guarantee a wealth of scientific return. Its instrument teams (nine in the first generation) and guest investigators will do suborbital astronomy in a shirt-sleeve environment. The project will invest $10M per year in science instrument development over a lifetime of 20 years. This, frequent flight opportunities, and operation that enables rapid changes of science instruments and hands-on in-flight access to the instruments, assure a unique and extensive potential - both for training young instrumentalists and for encouraging and deploying nascent technologies. Novel instruments covering optical, infrared, and submillimeter bands can be developed for and tested on SOFIA by their developers (including apprentices) for their own observations and for those of guest observers, to validate technologies and maximize observational effectiveness.Comment: 10 pages, no figures, White Paper for Astro 2010 Survey Committee on State of the Professio

The Milky Way Bulge extra-tidal star survey: BH 261 (AL 3)

The Milky Way Bulge extra-tidal star survey (MWBest) is a spectroscopic survey with the goal of identifying stripped globular cluster stars from inner Galaxy clusters. In this way, an indication of the fraction of metal-poor bulge stars that originated from globular clusters can be determined. We observed and analyzed stars in and around BH 261, an understudied globular cluster in the bulge. From seven giants within the tidal radius of the cluster, we measured an average heliocentric radial velocity of = -61 +- 2.6 km/s with a radial velocity dispersion of \sigma = 6.1 +- 1.9 km/s. The large velocity dispersion may have arisen from tidal heating in the cluster's orbit about the Galactic center, or because BH 261 has a high dynamical mass as well as a high mass-to-light ratio. From spectra of five giants, we measure an average metallicity of = -1.1 +- 0.2 dex. We also spectroscopically confirm an RR Lyrae star in BH 261, which yields a distance to the cluster of 7.1 +- 0.4~kpc. Stars with 3D velocities and metallicities consistent with BH 261 reaching to ~0.5 degrees from the cluster are identified. A handful of these stars are also consistent with the spatial distribution of that potential debris from models focussing on the most recent disruption of the cluster.Comment: accepted for publication in The Astronomical Journa

Continental-scale homogenization of residential lawn plant communities

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Landscape and Urban Planning 165 (2017): 54-63, doi:10.1016/j.landurbplan.2017.05.004.Residential lawns are highly managed ecosystems that occur in urbanized landscapes across the United States. Because they are ubiquitous, lawns are good systems in which to study the potential homogenizing effects of urban land use and management together with the continental-scale effects of climate on ecosystem structure and functioning. We hypothesized that similar homeowner preferences and management in residential areas across the United States would lead to low plant species diversity in lawns and relatively homogeneous vegetation across broad geographical regions. We also hypothesized that lawn plant species richness would increase with regional temperature and precipitation due to the presence of spontaneous, weedy vegetation, but would decrease with household income and fertilizer use. To test these predictions, we compared plant species composition and richness in residential lawns in seven U.S. metropolitan regions. We also compared species composition in lawns with understory vegetation in minimally-managed reference areas in each city. As expected, the composition of cultivated turfgrasses was more similar among lawns than among reference areas, but this pattern also held among spontaneous species. Plant species richness and diversity varied more among lawns than among reference areas, and more diverse lawns occurred in metropolitan areas with higher precipitation. Native forb diversity increased with precipitation and decreased with income, driving overall lawn diversity trends with these predictors as well. Our results showed that both management and regional climate shaped lawn species composition, but the overall homogeneity of species regardless of regional context strongly suggested that management was a more important driver.This research was supported by the Macrosystems Biology Program in the Emerging Frontiers Division of the Biological Sciences Directorate at the National Science Foundation (NSF) under grants EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, and 121238320

Ecological homogenization of urban USA

Author Posting. © Ecological Society of America, 2014. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Frontiers in Ecology and the Environment 12 (2014): 74-81, doi:10.1890/120374.A visually apparent but scientifically untested outcome of land-use change is homogenization across urban areas, where neighborhoods in different parts of the country have similar patterns of roads, residential lots, commercial areas, and aquatic features. We hypothesize that this homogenization extends to ecological structure and also to ecosystem functions such as carbon dynamics and microclimate, with continental-scale implications. Further, we suggest that understanding urban homogenization will provide the basis for understanding the impacts of urban land-use change from local to continental scales. Here, we show how multi-scale, multi-disciplinary datasets from six metropolitan areas that cover the major climatic regions of the US (Phoenix, AZ; Miami, FL; Baltimore, MD; Boston, MA; Minneapolis–St Paul, MN; and Los Angeles, CA) can be used to determine how household and neighborhood characteristics correlate with land-management practices, land-cover composition, and landscape structure and ecosystem functions at local, regional, and continental scales.We thank the MacroSystems Biology Program in the Emerging Frontiers Division of the Biological Sciences Directorate at NSF for support. The “Ecological Homogenization of Urban America” project was supported by a series of collaborative grants from this program (EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, 121238320). The work arose from research funded by grants from the NSF Long Term Ecological Research Program supporting work in Baltimore (DEB-0423476), Phoenix (BCS-1026865, DEB-0423704 and DEB-9714833), Plum Island (Boston) (OCE-1058747 and 1238212), Cedar Creek (Minneapolis–St Paul) (DEB-0620652), and Florida Coastal Everglades (Miami) (DBI-0620409)

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