1,288 research outputs found
Strategies for Systemic Change:Youth Community Organizing to Disruptthe School-to-Prison Nexus
The school disciplinary landscape across the United States changed significantly through the enactment of policies that criminalize studentsâ behaviors during the 1990s and 2000s. Schools began to involve the police and criminal legal system in school disciplinary issues that used to be handled by school administrators. This shift led youth of Color1 to increasingly come into contact with the juvenile legal system through school suspensions, expulsions, and referrals to alternative schoolsâwhat we characterize as the school-toprison nexus.
Conceptualizing the school-to-prison pipeline as a nexus, or interlocking system of power over youth, allows us to understand how the criminalization of youth is a systemic problem that demands structural change and interventions across multiple levels of analysis and settings, including local schools, school districts, police departments, and state policies. Although important research has documented the ways that Black and Latino youth are referred to the juvenile legal system through punitive school policies, there has been less attention to the actions youth are taking to critique and dismantle these policies. Youth community organizing (YCO) against the school-to-prison nexus represents an arena of youth activism that deserves further attention and analysis. In this chapter, we define YCO as groups that create spaces for young people to think critically about their everyday social conditions, identify root causes of social problems, and build political power and voice to create policy solutions and change in their communities (Ginwright, Noguera, & Cammarota, 2006; Kirshner, 2015; Watts, Griffith, & Abdul- Adil, 1999)
Formulae for Growth Factors In Expanding Universes Containing Matter and a Cosmological Constant
Formulae are presented for the linear growth factor D/a and its logarithmic
derivative dlnD/dlna in expanding Friedmann-Robertson-Walker Universes with
arbitrary matter and vacuum densities. The formulae permit rapid and stable
numerical evaluation. A fortran program is available at
http://casa.colorado.edu/~ajsh/growl/ .Comment: 7 pages, including 3 embedded PostScript figures. Minor changes to
agree with version accepted for publication in MNRAS. Fortran package
growl.tar.gz available at http://casa.colorado.edu/~ajsh/growl
Long Gamma-Ray Bursts and Type Ic Core Collapse Supernovae Have Similar Locations in Hosts
When the afterglow fades at the site of a long-duration gamma-ray burst
(LGRB), Type Ic supernovae (SN Ic) are the only type of core collapse supernova
observed. Recent work found that a sample of LGRB in high-redshift galaxies had
different environments from a collection of core-collapse environments, which
were identified from their colors and light curves. LGRB were in the brightest
regions of their hosts, but the core-collapse sample followed the overall
distribution of the galaxy light. Here we examine 504 supernovae with types
assigned based on their spectra that are located in nearby (z < 0.06) galaxies
for which we have constructed surface photometry from the Sloan Digital Sky
Survey (SDSS). The distributions of the thermonuclear supernovae (SN Ia) and
some varieties of core-collapse supernovae (SN II and SN Ib) follow the galaxy
light, but the SN Ic (like LGRB) are much more likely to erupt in the brightest
regions of their hosts. The high-redshift hosts of LGRB are overwhelmingly
irregulars, without bulges, while many low redshift SN Ic hosts are spirals
with small bulges. When we remove the bulge light from our low-redshift sample,
the SN Ic and LGRB distributions agree extremely well. If both LGRB and SN Ic
stem from very massive stars, then it seems plausible that the conditions
necessary for forming SN Ic are also required for LGRB. Additional factors,
including metallicity, may determine whether the stellar evolution of a massive
star leads to a LGRB with an underlying broad-lined SN Ic, or simply a SN Ic
without a gamma-ray burst.Comment: Accepted by the Astrophysical Journal, 12 pages, 3 tables, 4 figures,
SN sample size increases from 263 to 504 in v2, varying host magnitude and
distance shown not to introduce systematic error in measurement
âThis was 1976 reinventedâ: The role of framing in the development of a South African youth movement
The literature on contemporary youth organizing has documented psychological benefits associated with participation and some evidence of local political impact. But how do local organizing campaigns transform into regional or national movements? This is a practical question facing youth organizers and one that calls for attention from researchers. In this article, we draw on 3 years of ethnographic fieldwork with South Africa\u27s Equal Education (EE) to analyze collective action frames that enabled EE youth to assert legitimacy and construct shared aims across locales. Our findings focus on how youth constructed historical continuity frames that lent them legitimacy as upholders of the South African freedom struggle and flexible problem frames that linked young people\u27s local struggles, such as inadequate sanitation or broken windows at their schools, to a national policy agenda. We discuss connections to other youth movements and implications for the interdisciplinary youth organizing field
The Environment of ``E+A'' Galaxies
The violent star formation history of ``E+A'' galaxies and their detection
almost exclusively in distant clusters is frequently used to link them to the
``Butcher-Oemler effect'' and to argue that cluster environment influences
galaxy evolution. From 11113 spectra in the Las Campanas Redshift Survey, we
have obtained a unique sample of 21 nearby ``E+A" galaxies. Surprisingly, a
large fraction (about 75%) of these ``E+A''s lie in the field. Therefore,
interactions with the cluster environment, in the form of the ICM or cluster
potential, are not essential for ``E+A'' formation. If one mechanism is
responsible for ``E+A''s, their existence in the field and the tidal features
in at least 5 of the 21 argue that galaxy-galaxy interactions and mergers are
that mechanism. The most likely environments for such interactions are poor
groups, which have lower velocity dispersions than clusters and higher galaxy
densities than the field. In hierarchical models, groups fall into clusters in
greater numbers at intermediate redshifts than they do today. Thus, the
Butcher-Oemler effect may reflect the typical evolution of galaxies in groups
and in the field rather than the influence of clusters on star formation in
galaxies. This abstract is abridged.Comment: 39 uuencoded, compressed pages (except Fig 1), complete preprint at
ftp://ociw.edu/pub/aiz/eplusa.ps, ApJ, submitte
A Local Hubble Bubble from SNe Ia?
We analyze the monopole in the peculiar velocities of 44 Type Ia supernovae
(SNe Ia) to test for a local void. The sample extends from 20 to 300 Mpc/h,
with distances, deduced from light-curve shapes, accurate to ~6%. Assuming
Omega_m=1 and Omega_lambda=0, the most significant deviation we find from the
Hubble law is an outwards flow of (6.6+/-2.2)% inside a sphere of radius 70
Mpc/h as would be produced by a void of ~20% underdensity surrounded by a dense
shell. This shell roughly coincides with the local Great Walls. Monte Carlo
analyses, using Gaussian errors or bootstrap resampling, show the probability
for chance occurrence of this result out of a pure Hubble flow to be ~2%. The
monopole could be contaminated by higher moments of the velocity field,
especially a quadrupole, which are not properly probed by the current limited
sky coverage. The void would be less significant if Omega_m is low and
Omega_lambda is high. It would be more significant if one outlier is removed
from the sample, or if the size of the void is constrained a-priori. This
putative void is not in significant conflict with any of the standard
cosmological scenarios. It suggests that the Hubble constant as determined
within 70 Mpc/h could be overestimated by ~6% and the local value of Omega may
be underestimated by ~20%. While the present evidence for a local void is
marginal in this data set, the analysis shows that the accumulation of SNe Ia
distances will soon provide useful constraints on elusive and important aspects
of regional cosmic dynamics.Comment: 21 pages, 3 figures. Slightly revised version. To appear in ApJ, 503,
Aug. 20, 199
Probabilistic Assessment of Drought Characteristics using a Hidden Markov Model
Droughts are evaluated using drought indices that measure the departure of meteorological and hydrological variables such as precipitation and stream flow from their long-term averages. While there are many drought indices proposed in the literature, most of them use pre-defined thresholds for identifying drought classes ignoring the inherent uncertainties in characterizing droughts. In this study, a hidden Markov model (HMM) [1] is developed for probabilistic classification of drought states. The HMM captures space and time dependence in the data. The proposed model is applied to assess drought characteristics in Indiana using monthly precipitation and stream flow data. The comparison of HMM based drought index with standard precipitation index (SPI) [2] suggests that the HMM index provides more intuitive results
The Peculiar Type Ic Supernova 1997ef: Another Hypernova
SN 1997ef has been recognized as a peculiar supernova from its light curve
and spectral properties. The object was classified as a Type Ic supernova (SN
Ic) because its spectra are dominated by broad absorption lines of oxygen and
iron, lacking any clear signs of hydrogen or helium line features. The light
curve is very different from that of previously known SNe Ic, showing a very
broad peak and a slow tail. The strikingly broad line features in the spectra
of SN 1997ef, which were also seen in the hypernova SN 1998bw, suggest the
interesting possibility that SN 1997ef may also be a hypernova. The light curve
and spectra of SN 1997ef were modeled first with a standard SN~Ic model
assuming an ordinary kinetic energy of explosion erg. The
explosion of a CO star of mass gives a
reasonably good fit to the light curve but clearly fails to reproduce the broad
spectral features. Then, models with larger masses and energies were explored.
Both the light curve and the spectra of SN 1997ef are much better reproduced by
a C+O star model with 8 \e{51} erg and .
Therefore, we conclude that SN 1997ef is very likely a hypernova on the basis
of its kinetic energy of explosion. Finally, implications for the deviation
from spherical symmetry are discussed in an effort to improve the light curve
and spectral fits.Comment: "To appear in the Astrophysical Journal, Vol.534 (2000)
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