30,853 research outputs found
America's Online Pursuits: The Changing Picture of Who's Online and What They Do
Provides a broad analysis of survey data collected between March 2000 and August 2003, to illustrate shifting trends in Internet use. Looks at participation by age, gender, race, income, and education level
Older Adults and Social Media
Presents survey findings on the growing use of social networking sites among Americans age 50 and older, as well as their other online activities, and considers possible factors behind the trend. Compares trends by age group and broadband access
Effects of Massive Star Formation on the ISM of Dwarf Galaxies
We are studying star formation effects on the properties of the ISM in low
metallicity environments using mid-infrared (MIR) and far-infrared (FIR)
observations of starbursting dwarf galaxies taken with the Infrared Space
Observatory (ISO) and the Kuiper Airborne Observatory (KAO). Effects of the
hard pervasive radiation field on the gas and dust, due to the dust-poor
environments are apparent in both the dust and gas components. From a 158
micron [CII] survey we find enhanced I[CII]/FIR ratios in dwarf galaxies and
I[CII]/I(CO) ratios up to 10 times higher than those for normal metallicity
starburst galaxies. We consider MIR observations in understanding the star
formation properties of dwarf galaxies and constraints on the stellar SED.
Notably, the strong MIR [NeIII]/[NeII] ratios reveal the presence of current
massive stellar populations < 5 My old in NGC1569, NGC1140 and IIZw40. The MIR
unidentified infrared bands (UIBs) are weak, if present at all, as a general
characteristic in low metallicity environments, revealing the destruction of
the smallest carbon particles (e.g. PAHs) over large spatial scales. This is
confirmed with our dust modeling: mass fractions of PAHs are almost negligible
compared to the larger silicate grains emitting in the FIR as well as the small
carbon grains emitting in the MIR, which appear to be the source of the
photoelectric gas heating in these galaxies, in view of the [CII] cooling.Comment: To appear in New Astronomy Reviews, Eds. D. Schaerer & R.
Delgado-Gonzalez. Proceedings for JENAM99: "The Interplay between Massive
Stars and the ISM" 13 pages including 5 color figure
Artists, Musicians and the Internet
Presents findings from a national survey of self-described artists and an online survey of 2,755 musicians that assess how artists and musicians use the Internet, what they think about copyright issues, and how they feel about online file sharing
Modeling the Dust Spectral Energy Distributions of Dwarf Galaxies
Recent efforts on the modeling of the infrared spectral energy distributions
(SEDs) of dwarf galaxies are summarised here. The characterisation of the dust
properties in these low metallicity environments is just unfolding, as a result
of recently available mid-infrared to millimetre observations. From the limited
cases we know to date, it appears that the hard radiation fields that are
present in these star-bursting dwarf galaxies, as well as the rampent
energetics of supernovae shocks and winds have modified the dust properties, in
comparison with those in the Galaxy, or other gas and dust rich galaxies. The
sophistication of the SED models is limited by the availability of detailed
data in the mid infrared and particularly in the submillimetre to millimetre
regime, which will open up in the near future with space-based missions, such
as Herschel.Comment: 8 pages presented at "The Spectral Energy Distribution of Gas-Rich
Galaxies: Confronting Models with Data" Heidelberg (Germany), October 2004.
To be published in The Spectral Energy Distribution of Gas-Rich Galaxies, ed.
C. Popescu & R. Tuffs (Melville:AIP) in pres
Takings Clause Analysis of Utility Ratemaking Decisions: Measuring Hope’s Investor Interest Factor
Charles Taliaferro, Jil Evans. The Image in Mind: Theism, Naturalism, and the Imagination. Continuum, 2011
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