The Revealing Dust: Mid-Infrared Activity in Hickson Compact Group Galaxy Nuclei

We present a sample of 46 galaxy nuclei from 12 nearby (z<4500 km/s) Hickson Compact Groups (HCGs) with a complete suite of 1-24 micron 2MASS+Spitzer nuclear photometry. For all objects in the sample, blue emission from stellar photospheres dominates in the near-IR through the 3.6 micron IRAC band. Twenty-five of 46 (54%) galaxy nuclei show red, mid-IR continua characteristic of hot dust powered by ongoing star formation and/or accretion onto a central black hole. We introduce alpha_{IRAC}, the spectral index of a power-law fit to the 4.5-8.0 micron IRAC data, and demonstrate that it cleanly separates the mid-IR active and non-active HCG nuclei. This parameter is more powerful for identifying low to moderate-luminosity mid-IR activity than other measures which include data at rest-frame lambda<3.6 micron that may be dominated by stellar photospheric emission. While the HCG galaxies clearly have a bimodal distribution in this parameter space, a comparison sample from the Spitzer Nearby Galaxy Survey (SINGS) matched in J-band total galaxy luminosity is continuously distributed. A second diagnostic, the fraction of 24 micron emission in excess of that expected from quiescent galaxies, f_{24D}, reveals an additional 3 nuclei to be active at 24 micron. Comparing these two mid-IR diagnostics of nuclear activity to optical spectroscopic identifications from the literature reveals some discrepancies, and we discuss the challenges of distinguishing the source of ionizing radiation in these and other lower luminosity systems. We find a significant correlation between the fraction of mid-IR active galaxies and the total HI mass in a group, and investigate possible interpretations of these results in light of galaxy evolution in the highly interactive system of a compact group environment.Comment: 20 pages, 17 figures (1 color), uses emulateapj. Accepted for publication by Ap

Star Clusters in the Tidal Tails of Interacting Galaxies: Cluster Populations Across a Variety of Tail Environments

We have searched for compact stellar structures within 17 tidal tails in 13 different interacting galaxies using F606W- and F814W- band images from the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). The sample of tidal tails includes a diverse population of optical properties, merging galaxy mass ratios, HI content, and ages. Combining our tail sample with Knierman et al. (2003), we find evidence of star clusters formed in situ with Mv < -8.5 and V-I < 2.0 in 10 of 23 tidal tails; we are able to identify cluster candidates to Mv = -6.5 in the closest tails. Three tails offer clear examples of "beads on a string" star formation morphology in V-I color maps. Two tails present both tidal dwarf galaxy (TDG) candidates and cluster candidates. Statistical diagnostics indicate that clusters in tidal tails may be drawn from the same power-law luminosity functions (with logarithmic slopes ~ -2 - -2.5) found in quiescent spiral galaxies and the interiors of interacting systems. We find that the tail regions with the largest number of observable clusters are relatively young (< 250 Myr old) and bright (V < 24 mag arcsec^(-2)), probably attributed to the strong bursts of star formation in interacting systems soon after periapse. Otherwise, we find no statistical difference between cluster-rich and cluster-poor tails in terms of many observable characteristics, though this analysis suffers from complex, unresolved gas dynamics and projection effects.Comment: Accepted for publication in the Astrophysical Journal. 27 pages, 8 figure

New Evidence of the Lower Miocene Age of the Blacktail Deer Creek Formation in Montana

193-204http://deepblue.lib.umich.edu/bitstream/2027.42/48250/2/ID089.pd

Principles And Practices Fostering Inclusive Excellence: Lessons From The Howard Hughes Medical Institute’s Capstone Institutions

Best-practices pedagogy in science, technology, engineering, and mathematics (STEM) aims for inclusive excellence that fosters student persistence. This paper describes principles of inclusivity across 11 primarily undergraduate institutions designated as Capstone Awardees in Howard Hughes Medical Institute’s (HHMI) 2012 competition. The Capstones represent a range of institutional missions, student profiles, and geographical locations. Each successfully directed activities toward persistence of STEM students, especially those from traditionally underrepresented groups, through a set of common elements: mentoring programs to build community; research experiences to strengthen scientific skill/identity; attention to quantitative skills; and outreach/bridge programs to broaden the student pool. This paper grounds these program elements in learning theory, emphasizing their essential principles with examples of how they were implemented within institutional contexts. We also describe common assessment approaches that in many cases informed programming and created traction for stakeholder buy-in. The lessons learned from our shared experiences in pursuit of inclusive excellence, including the resources housed on our companion website, can inform others’ efforts to increase access to and persistence in STEM in higher education

Older adults place lower value on choice relative to young adults

Choice is highly valued in modern society, from the supermarket to the hospital; however, it remains unknown whether older and younger adults place the same value on increased choice. The current investigation tested whether 53 older ( M age = 75.44 years) versus 53 younger adults ( M age = 19.58 years) placed lower value on increased choice by examining the monetary amounts they were willing to pay for increased prescription drug coverage options — important given the recently implemented Medicare prescription drug program. Results indicate that older adults placed lower value on increasing choice sets relative to younger adults, who placed progressively higher value on increasingly larger choice sets. These results are discussed regarding their implications for theory and policy

U.S. GLOBAL CHANGE RESEARCH PROGRAM CLIMATE SCIENCE SPECIAL REPORT (CSSR)

Fifth-Order Draft Table of Contents Front Matter About This Report........................................................................................ 1 Guide to the Report......................................................................................4 Executive Summary ................................................................................... 12 Chapters 1. Our Globally Changing Climate .......................................................... 38 2. Physical Drivers of Climate Change ................................................... 98 3. Detection and Attribution of Climate Change .................................... 160 4. Climate Models, Scenarios, and Projections .................................... 186 5. Large-Scale Circulation and Climate Variability ................................ 228 6. Temperature Changes in the United States ...................................... 267 7. Precipitation Change in the United States ......................................... 301 8. Droughts, Floods, and Hydrology ......................................................... 336 9. Extreme Storms ....................................................................................... 375 10. Changes in Land Cover and Terrestrial Biogeochemistry ............ 405 11. Arctic Changes and their Effects on Alaska and the Rest of the United States..... 443 12. Sea Level Rise ....................................................................................... 493 13. Ocean Acidification and Other Ocean Changes .............................. 540 14. Perspectives on Climate Change Mitigation .................................... 584 15. Potential Surprises: Compound Extremes and Tipping Elements .......... 608 Appendices A. Observational Datasets Used in Climate Studies ............................. 636 B. Weighting Strategy for the Fourth National Climate Assessment ................ 642 C. Detection and Attribution Methodologies Overview ............................ 652 D. Acronyms and Units ................................................................................. 664 E. Glossary ...................................................................................................... 66

U.S. GLOBAL CHANGE RESEARCH PROGRAM CLIMATE SCIENCE SPECIAL REPORT (CSSR)

Fifth-Order Draft Table of Contents Front Matter About This Report........................................................................................ 1 Guide to the Report......................................................................................4 Executive Summary ................................................................................... 12 Chapters 1. Our Globally Changing Climate .......................................................... 38 2. Physical Drivers of Climate Change ................................................... 98 3. Detection and Attribution of Climate Change .................................... 160 4. Climate Models, Scenarios, and Projections .................................... 186 5. Large-Scale Circulation and Climate Variability ................................ 228 6. Temperature Changes in the United States ...................................... 267 7. Precipitation Change in the United States ......................................... 301 8. Droughts, Floods, and Hydrology ......................................................... 336 9. Extreme Storms ....................................................................................... 375 10. Changes in Land Cover and Terrestrial Biogeochemistry ............ 405 11. Arctic Changes and their Effects on Alaska and the Rest of the United States..... 443 12. Sea Level Rise ....................................................................................... 493 13. Ocean Acidification and Other Ocean Changes .............................. 540 14. Perspectives on Climate Change Mitigation .................................... 584 15. Potential Surprises: Compound Extremes and Tipping Elements .......... 608 Appendices A. Observational Datasets Used in Climate Studies ............................. 636 B. Weighting Strategy for the Fourth National Climate Assessment ................ 642 C. Detection and Attribution Methodologies Overview ............................ 652 D. Acronyms and Units ................................................................................. 664 E. Glossary ...................................................................................................... 66