533 research outputs found
Teaching Metalinguistic Skills To Enhance Early Reading Instruction
This article focuses on practical classroom ideas for enhancing early literacy learning by teaching a broad range of metalinguistic skills. These skills include phonemic and word awareness, but focus largely on syntactic and pragmatic skills in order to give children a richer understanding of language and its functions. Theoretical background is provided along with activities that can be used in the primary classroom
Correlation Between Phase Competition and the Nucleation of a Griffiths Phase in (La1-yPry)0.7Ca0.3Mn16/18O3
Detailed analyses of the temperature-dependent zero field ac susceptibility
of prototypical phase-separated (La1-yPry)0.7Ca0.3Mn16/18O3, 0 < y < 1, reveal
features consistent with the presence of a Griffiths phase (GP), viz., an
inverse susceptibility characterized by power law with 0.05 < lamda < 0.33 as y
decreases towards yc < 0.85. Beyond yc = 0.85, the GP is suppressed. These
data, combined with previous neutron diffraction measurements, enable a phase
diagram summarizing the evolution of the GP with composition to be constructed
for this system; in particular, it shows that the disorder relevant for the
establishment of such a phase is linked closely to the relative volume
fractions of the phase separated antiferromagnetic and ferromagnetic
components, even when the recently estimated double exchange (DE) linked
percolation threshold is exceeded. The influence of electron-phonon coupling
can also be seen through oxygen isotope effects.Comment: 4 page
The Next Generation Virgo Cluster Survey (NGVS). XVIII. Measurement and Calibration of Surface Brightness Fluctuation Distances for Bright Galaxies in Virgo (and Beyond)
We describe a program to measure surface brightness fluctuation (SBF)
distances to galaxies observed in the Next Generation Virgo Cluster Survey
(NGVS), a photometric imaging survey covering of the Virgo cluster
in the bandpasses with the Canada-France Hawaii Telescope. We
describe the selection of the sample galaxies, the procedures for measuring the
apparent -band SBF magnitude , and the calibration of the absolute
as a function of observed stellar population properties. The
multi-band NGVS data set provides multiple options for calibrating the SBF
distances, and we explore various calibrations involving individual color
indices as well as combinations of two different colors. Within the color range
of the present sample, the two-color calibrations do not significantly improve
the scatter with respect to wide-baseline, single-color calibrations involving
. We adopt the calibration as reference for the present
galaxy sample, with an observed scatter of 0.11 mag. For a few cases that lack
good photometry, we use an alternative relation based on a combination
of and colors, with only a slightly larger observed scatter of
0.12 mag. The agreement of our measurements with the best existing distance
estimates provides confidence that our measurements are accurate. We present a
preliminary catalog of distances for 89 galaxies brighter than
mag within the survey footprint, including members of the background M and W
Clouds at roughly twice the distance of the main body of the Virgo cluster. The
extension of the present work to fainter and bluer galaxies is in progress.Comment: ApJ accepte
Reducing Maternal and Child Health Disparities among Latino Immigrants in South Carolina Through a Tailored, Culturally Appropriate and Participant-Driven Initiative
Newly arrived Latino immigrants in South Carolina (SC), especially Latina mothers, experience many health related barriers including a general lack of health services information. The PASOs program, which means âstepsâ in Spanish, uses education, outreach, partnerships and advocacy to empower Latino families to utilize available health care services throughout SC. PASOs is a community-based program conducted by college trained bilingual/bicultural facilitators with the support from community health care workers (promotores de salud). Participants (n=523) were expectant mothers with an average age of 27 (SD=6) years, mostly from Mexico (69%), with an average of 9 (SD=4) years of education and 7 (SD=5) years living in the US. Repeated measures analyses from pre-test to post-test indicated significant knowledge improvement (p<0.005) regarding the importance of prenatal care, signs of preterm delivery, benefits of breastfeeding, and the importance of folic acid intake during periconception. By the end of the course, the majority of the Latinas (93%; p<0.0001) were able to name a birth control method they planned to use following their current pregnancy. Results of this study emphasize the benefits associated with the implementation of a culturally-appropriate program with newly arrived Latino immigrants, including an increase on preconception, pregnancy, and post-pregnancy knowledge
The CFHT Legacy Survey: The Morphology-Density Relation of Galaxies out to Z~1
We study the relationships between galaxy total luminosity (M_g), morphology,
color and environment as a function of redshift. We use a magnitude-limited
sample of 65,624 galaxies in the redshift range 0<z<1.3 taken from one of the
Canada-France-Hawaii Telescope Legacy Survey Deep Fields. We parametrize galaxy
morphology according to the Sersic index n. Our n>2 number fractions at z=0.1
agree well with those based on SDSS galaxies. We find that the n>2 galaxy
number fraction is constant with redshift in the field. However, for overdense
environments this fraction is larger and increases towards lower redshifts,
higher densities and higher luminosities. Rest-frame color-magnitude diagrams
show that the color distribution is bimodal out to our redshift limit of z~1
with a prominent red-sequence of galaxies at 0.2<z<0.4 and a large blue-peak
dominance at 0.8<z<1. We use this bimodality to define a red galaxy fraction
(rest-frame u-g>1). For all environments, this fraction increases towards lower
redshifts and higher luminosities. The red fraction within cluster-like regions
changes 60% faster with redshift as compared to the field for M_g<-19.5. Using,
for the first time, observations across many cluster-field interfaces
distributed over a single, large volume, we trace the large-scale
morphology-density relation and the Butcher-Oemler effect over a period of
almost 8 Gyr.Comment: Accepted by Ap
Limits on Quaoar's Atmosphere
Here we present high cadence photometry taken by the Acquisition Camera on Gemini South, of a close passage by the ~540 km radius Kuiper belt object, (50000) Quaoar, of a r' = 20.2 background star. Observations before and after the event show that the apparent impact parameter of the event was 0."019 ± 0."004, corresponding to a close approach of 580 ± 120 km to the center of Quaoar. No signatures of occultation by either Quaoar's limb or its potential atmosphere are detectable in the relative photometry of Quaoar and the target star, which were unresolved during closest approach. From this photometry we are able to put constraints on any potential atmosphere Quaoar might have. Using a Markov chain Monte Carlo and likelihood approach, we place pressure upper limits on sublimation supported, isothermal atmospheres of pure N_2, CO, and CH_4. For N_2 and CO, the upper limit surface pressures are 1 and 0.7 Όbar, respectively. The surface temperature required for such low sublimation pressures is ~33 K, much lower than Quaoar's mean temperature of ~44 K measured by others. We conclude that Quaoar cannot have an isothermal N_2 or CO atmosphere. We cannot eliminate the possibility of a CH_4 atmosphere, but place upper surface pressure and mean temperature limits of ~138 nbar and ~44 K, respectively
The Next Generation Virgo Cluster Survey. VII. The intrinsic shapes of low-luminosity galaxies in the core of the Virgo cluster, and a comparison with the Local Group
(Abridged) We investigate the intrinsic shapes of low-luminosity galaxies in
the central 300 kpc of the Virgo cluster using deep imaging obtained as part of
the NGVS. We build a sample of nearly 300 red-sequence cluster members in the
yet unexplored magnitude range. The observed distribution of
apparent axis ratios is then fit by families of triaxial models with
normally-distributed intrinsic ellipticities and triaxialities. We develop a
Bayesian framework to explore the posterior distribution of the model
parameters, which allows us to work directly on discrete data, and to account
for individual, surface brightness-dependent axis ratio uncertainties. For this
population we infer a mean intrinsic ellipticity E=0.43, and a mean triaxiality
T=0.16. This implies that faint Virgo galaxies are best described as a family
of thick, nearly oblate spheroids with mean intrinsic axis ratios 1:0.94:0.57.
We additionally attempt a study of the intrinsic shapes of Local Group
satellites of similar luminosities. For the LG population we infer a slightly
larger mean intrinsic ellipticity E=0.51, and the paucity of objects with round
apparent shapes translates into more triaxial mean shapes, 1:0.76:0.49. We
finally compare the intrinsic shapes of NGVS low-mass galaxies with samples of
more massive quiescent systems, and with field, star-forming galaxies of
similar luminosities. We find that the intrinsic flattening in this
low-luminosity regime is almost independent of the environment in which the
galaxy resides--but there is a hint that objects may be slightly rounder in
denser environments. The comparable flattening distributions of low-luminosity
galaxies that have experienced very different degrees of environmental effects
suggests that internal processes are the main drivers of galaxy structure at
low masses--with external mechanisms playing a secondary role.Comment: Accepted to ApJ. 18 pages, 12 figure
Col-OSSOS: The Colours of the Outer Solar System Origins Survey
The Colours of the Outer Solar System Origins Survey (Col-OSSOS) is acquiring
near-simultaneous , , and photometry of unprecedented precision with
the Gemini North Telescope, targeting nearly a hundred trans-Neptunian objects
(TNOs) brighter than mag discovered in the Outer Solar System
Origins Survey. Combining the optical and near-infrared photometry with the
well-characterized detection efficiency of the Col-OSSOS target sample will
provide the first flux-limited compositional dynamical map of the outer Solar
System. In this paper, we describe our observing strategy and detail the data
reduction processes we employ, including techniques to mitigate the impact of
rotational variability. We present optical and near-infrared colors for 35
TNOs. We find two taxonomic groups for the dynamically excited TNOs, the
neutral and red classes, which divide at . Based on simple
albedo and orbital distribution assumptions, we find that the neutral class
outnumbers the red class, with a ratio of 4:1 and potentially as high as 11:1.
Including in our analysis constraints from the cold classical objects, which
are known to exhibit unique albedos and colors, we find that within our
measurement uncertainty, our observations are consistent with the primordial
Solar System protoplanetesimal disk being neutral-class-dominated, with two
major compositional divisions in color space.Comment: Accepted to ApJS; on-line supplemental files will be available with
the AJS published version of the pape
The Next Generation Virgo Cluster Survey. IX. Estimating the Efficiency of Galaxy Formation on the Lowest-Mass Scales
The Next Generation Virgo Cluster Survey has recently determined the
luminosity function of galaxies in the core of the Virgo cluster down to
unprecedented magnitude and surface brightness limits. Comparing simulations of
cluster formation to the derived central stellar mass function, we attempt to
estimate the stellar-to-halo-mass ratio (SHMR) for dwarf galaxies, as it would
have been before they fell into the cluster. This approach ignores several
details and complications, e.g., the contribution of ongoing star formation to
the present-day stellar mass of cluster members, and the effects of adiabatic
contraction and/or violent feedback on the subhalo and cluster potentials. The
final results are startlingly simple, however; we find that the trends in the
SHMR determined previously for bright galaxies appear to extend down in a
scale-invariant way to the faintest objects detected in the survey. These
results extend measurements of the formation efficiency of field galaxies by
two decades in halo mass, or five decades in stellar mass, down to some of the
least massive dwarf galaxies known, with stellar masses of .Comment: 18 pages, 12 figures; published in ApJ July 1st 201
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