229 research outputs found
In the Service of Citizenship: A Study of Student Involvement in Community Service
I learn more through my volunteer work than I ever do in any of my classes at school. Talking to people from diverse backgrounds provides so much insight that people just can\u27t imagine. I study all these different theories in political science and sociology, but until you get a chance to see how the social world influences people\u27s everyday lives, it just doesn\u27t have that much meaning.
I have been involved in volunteer work ever since I was in high school, and I\u27ll probably continue to do stuff like Habitat [for Humanity] until I\u27m old and gray. I get a lot out of working to serve others, and it\u27s a good feeling to know that I have helped someone even if it\u27s in some small way. It helps me to cherish people more and understand what life is all about
The Dynamic Tensions of Service Learning in Higher Education: A Philosophical Perspective
Senior faculty in a peace and justice program at a small liberal arts college reject the efforts of a student affairs professional to help the faculty connect their teaching to practice through service activities in the local community. One faculty member openly wonders how out-of-class activities such as community service have anything to do with interdisciplinary theories of social justice. A director of an office of community service is upset because the provost has decided to develop a Center for Community Service Learning. The director sees this as an attempt to usurp the good work of student affairs and feels that attempts to engage faculty will be difficult, if not futile. A department chair in an American Thought and Language program at a large research university asks an associate professor being considered for promotion to full professor to explain in writing to the promotion and tenure committee the relevance of his research on service learning. Both the chair and the committee are apprehensive about service learning as a legitimate area of scholarly inquiry. And finally, a local social service agency in a university town has had its till of student volunteers after repeatedly receiving complaints from clients about patronizing attitudes expressed by the students
Growth and predation activity at deep-sea hydrothermal vents along the Galápagos Rift
Growth rates of unclassified mussels collected from hydrothermal vents on the Pacific Ocean (2500 m) are among the highest recorded for deep-sea species. Mature mussels have mean growth rates of about 1 cm yr-1 which are comparable to growth rates of shallow water mussels...
Metallicities of Emission-Line Galaxies from HST ACS PEARS and HST WFC3 ERS Grism Spectroscopy at 0.6 < z < 2.4
Galaxies selected on the basis of their emission line strength show low
metallicities, regardless of their redshifts. We conclude this from a sample of
faint galaxies at redshifts between 0.6 < z < 2.4, selected by their prominent
emission lines in low-resolution grism spectra in the optical with the Advanced
Camera for Surveys (ACS) on the Hubble Space Telescope (HST) and in the
near-infrared using Wide-Field Camera 3 (WFC3). Using a sample of 11 emission
line galaxies (ELGs) at 0.6 < z < 2.4 with luminosities of -22 < M_B < -19,
which have [OII], H\beta, and [OIII] line flux measurements from the
combination of two grism spectral surveys, we use the R23 method to derive the
gas-phase oxygen abundances: 7.5 < 12+log(O/H) < 8.5. The galaxy stellar masses
are derived using Bayesian based Markov Chain Monte Carlo (\piMC^2) fitting of
their Spectral Energy Distribution (SED), and span the mass range 8.1 <
log(M_*/M_\sun) < 10.1. These galaxies show a mass-metallicity (M-L) and
Luminosity-Metallicity (L-Z) relation, which is offset by --0.6 dex in
metallicity at given absolute magnitude and stellar mass relative to the local
SDSS galaxies, as well as continuum selected DEEP2 samples at similar
redshifts. The emission-line selected galaxies most resemble the local "green
peas" galaxies and Lyman-alpha galaxies at z~0.3 and z~2.3 in the M-Z and L-Z
relations and their morphologies. The G-M_{20} morphology analysis shows that
10 out of 11 show disturbed morphology, even as the star-forming regions are
compact. These galaxies may be intrinsically metal poor, being at early stages
of formation, or the low metallicities may be due to gas infall and accretion
due to mergers.Comment: 24 pages with 7 figure
Hubble Space Telescope Imaging of Lyman Alpha Emission at z=4.4
We present the highest redshift detections of resolved Lyman alpha emission,
using Hubble Space Telescope/ACS F658N narrowband-imaging data taken in
parallel with the Wide Field Camera 3 Early Release Science program in the
GOODS CDF-S. We detect Lyman alpha emission from three spectroscopically
confirmed z = 4.4 Lyman alpha emitting galaxies (LAEs), more than doubling the
sample of LAEs with resolved Lyman alpha emission. Comparing the light
distribution between the rest-frame ultraviolet continuum and narrowband
images, we investigate the escape of Lyman alpha photons at high redshift.
While our data do not support a positional offset between the Lyman alpha and
rest-frame ultraviolet (UV) continuum emission, the half-light radii in two out
of the three galaxies are significantly larger in Lyman alpha than in the
rest-frame UV continuum. This result is confirmed when comparing object sizes
in a stack of all objects in both bands. Additionally, the narrowband flux
detected with HST is significantly less than observed in similar filters from
the ground. These results together imply that the Lyman alpha emission is not
strictly confined to its indigenous star-forming regions. Rather, the Lyman
alpha emission is more extended, with the missing HST flux likely existing in a
diffuse outer halo. This suggests that the radiative transfer of Lyman alpha
photons in high-redshift LAEs is complicated, with the interstellar-medium
geometry and/or outflows playing a significant role in galaxies at these
redshifts.Comment: Submitted to the Astrophysical Journal. 11 pages, 10 figure
Metallicities of Emission-Line Galaxies from HST ACS PEARS and HST WFC3 ERS Grism Spectroscopy at 0.6 is less than z is less than 2.4
Galaxies selected on the basis of their emission line strength. show low metallicities, regardless of their redshifts. We conclude this from a sample of faint galaxies at redshifts between 0.6 < z < 2.4, selected by their prominent emission lines in low resolution grism spectra in the optiCa.i with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) and in the near-infrared using Wide-Field Camera 3 (WFC3). Using a sample of 11 emission line galaxies (ELGs) at 0.6 < z < 2.4 with luminosities of -22 approx < MB approx -19 which have [OII], H-Beta, and [OIII] line flux measurements from the combination of two grism spectral surveys, we use the R23 method to derive the gas-phase oxygen abundances: 7.5 <12+log(0/H)<8.5. The galaxy stellar masses are derived using Bayesian based Markov Chain Monte Carlo (pi MC(exp 2)) fitting of their Spectral Energy Distribution (SED), and span the mass range 8.1 < log(M(stellar)/M(solar)) < 10.1. These galaxies show a mass-metal1icity (M-L) and Luminosity-Metallicity (LZ) relation, which is offset by -<J.6 dex in meta1licity at given absolute magnitude and stellar mass relative to the local SDSS galaxies, as well as continuum selected DEEP2 samples at similar redshifts. The emission-line selected galaxies most resemble the local "green peas" galaxies and Lyman-alpha galaxies at z approx = 0.3 and z approx = 2.3 in the M-Z and L-Z relations and their morphologies. The G - M(sub 20) morphology analysis shows that 10 out of 11 show disturbed morphology, even as the star-forming regions are compact. These galaxies may be intrinsically metal poor, being at early stages of formation, or the low metallicities may be due to gas infall and accretion due to mergers
FIGS -- Faint Infrared Grism Survey: Description and Data Reduction
The Faint Infrared Grism Survey (FIGS) is a deep Hubble Space Telescope (HST)
WFC3/IR (Wide Field Camera 3 Infrared) slitless spectroscopic survey of four
deep fields. Two fields are located in the Great Observatories Origins Deep
Survey-North (GOODS-N) area and two fields are located in the Great
Observatories Origins Deep Survey-South (GOODS-S) area. One of the southern
fields selected is the Hubble Ultra Deep Field. Each of these four fields were
observed using the WFC3/G102 grism (0.8-1.15 continuous coverage)
with a total exposure time of 40 orbits (~ 100 kilo-seconds) per field. This
reaches a 3 sigma continuum depth of ~26 AB magnitudes and probes emission
lines to . This paper details the four
FIGS fields and the overall observational strategy of the project. A detailed
description of the Simulation Based Extraction (SBE) method used to extract and
combine over 10000 spectra of over 2000 distinct sources brighter than
m_F105W=26.5 mag is provided. High fidelity simulations of the observations is
shown to significantly improve the background subtraction process, the spectral
contamination estimates, and the final flux calibration. This allows for the
combination of multiple spectra to produce a final high quality, deep,
1D-spectra for each object in the survey.Comment: 21 Pages. 17 Figures. To appear in Ap
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