32 research outputs found
Keys to Reducing Summer Regression: The Reader, Routine, and Relationship
This study utilized a mixed-methods, quasi-experimental design to investigate the impact of parent development and home-based summer reading on summer reading regression (as measured by oral reading fluency) at three Title I elementary schools in North Carolina. Title I parents and students participated in a parent development and communicated throughout the summer. Quantitative and qualitative methods (QUAN-qual) were used to collect and analyze data in order to answer four research questions related to the parent development seminar and reading routines. Quantitative data were collected using a pretest/posttest, reading logs, contact logs, and questionnaires. Qualitative data were collected from the questionnaire responses, parent contact logs, and reading logs. Based on the results of this study, the researcher identified three keys to reducing summer regression: the reader, routine, and relationship
A Correlational Study of School Report Card Grades and Degrees of Poverty
This study explores the ways in which public schools are evaluated and the results are reported in North Carolina. Currently using a formula that calculates a summative score based on academic achievement and academic growth, the impact of poverty and the complexity of school evaluation is investigated using demographic and testing data from schools across the state. Furthermore, recommendations to alter current practices of school evaluation and reporting as well as suggestions for future research are discussed based on this study’s findings
Summer Reading Loss: A Mixed-Methods Study of Parent Development and Home-Based Summer Reading
This dissertation utilized a mixed-methods, quasi-experimental design to investigate the impact of parent development on rising third graders\u27 summer reading losses as measured by the difference in May and August oral reading fluency scores. Title I parents and students from three schools in a rural North Carolina school district participated in a parent development session that focused on reading strategies to use at home. Parents and Title I teachers were in contact during the summer via telephone or face-to-face and students kept a reading log in order to collect data regarding reading routines. Quantitative data were collected using a pretest/posttest method using the end-of-year second-grade oral reading fluency assessment using Dynamic Indicators of Basic Early Literacy Skills (DIBELS Next). Quantitative data from reading logs and questionnaires were also used to analyze the impact of parent development and a home-based summer reading program on summer reading loss as measured by oral reading fluency (rate). Qualitative data were collected from questionnaires, parent contact logs, and reading logs. Quantitative and qualitative methods (QUAN-qual) were used to collect and analyze data in order to answer four research questions: (1) What is the impact of the parent development seminar on parents\u27 abilities to demonstrate mastery of reading strategies? (2) What is the impact of summer reading volume (number of books initially and repeatedly read) on summer reading loss as measured by the difference in May and August oral reading fluency scores? (3): What is the impact of reading strategies (echo, NIM, shared, and repeated readings) on summer reading loss as measured by the difference in May and August oral reading fluency scores? (4) What is the impact of parent development and home-based summer reading on summer reading loss as measured by the difference in May and August oral reading fluency scores? The researcher found that parent development and home-based summer reading had a positive impact on struggling readers\u27 (red zone) and home literacy routines. This study also found that repeated readings (within the same day) and face-to-face communication were effective strategies to target summer reading loss. Recommendations for future research include a larger sample size and a focus on the type of parent communication students receive (face-to-face or telephone). Additional recommendations include revisions to the reading log to emphasize repeated readings and to improve self-reporting methods
Real-Time Support: Using eCoaching to Increase Preservice Teachers’ Confidence to Teach
The role of teacher education preparation programs is to equip preservice teachers (PSTs) with the knowledge and skills to support the development of all students. To do this, university faculty must establish and monitor PST’s progress toward quality standards for teaching. eCoaching is a professional learning tool that provides real-time feedback to PSTs during instruction. In this article, the authors present eCoaching as a professional learning strategy. An overview of eCoaching logistics, perceived impact of eCoaching on PSTs, a description of eCoaching in action, and an explanation of how it meshes with current support practices are provided
Galaxy interactions II: High density environments
With the aim to assess the role of dense environments in galaxy interactions,
properties we present an analysis of close galaxy pairs in groups and clusters,
obtained from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). We
identified pairs that reside in groups by cross-correlating the total galaxy
pair catalogue with the SDSS-DR7 group catalogue from Zapata et al. (2009). We
classify pair galaxies according to the intensity of interaction. We analysed
the effect of high density environments on different classes of galaxy-galaxy
interactions and we have also studied the impact of the group global
environment on pair galaxies. We find that galaxy pairs are more concentrated
towards the group centres with respect to the other group galaxy members, and
disturbed pairs show a preference to contain the brightest galaxy in the
groups. The color-magnitude relation exhibits significant differences between
pair galaxies and the control sample, consisting in color tails with a clear
excess of extremely blue and red galaxies for merging systems. In addition,
pair galaxies show a significant excess of young stellar populations with
respect to galaxies in the control sample; this finding suggests that, in dense
environments, strong interactions produce an important effect in modifying
galaxy properties. We find that the fraction of star forming galaxies decreases
toward the group centre; however, galaxy pairs show a more efficient star
formation activity than galaxies without a close companion. We have also found
that pair galaxies prefer groups with low density global environments with
respect to galaxies of the corresponding control sample. Blue, young stellar
population galaxies prefer groups within low density global environments.Comment: 10 pages, 11 figures, accepted for publication in A&
SN 2010ay is a Luminous and Broad-lined Type Ic Supernova within a Low-metallicity Host Galaxy
We report on our serendipitous pre-discovery detection and detailed follow-up
of the broad-lined Type Ic supernova (SN) 2010ay at z = 0.067 imaged by the
Pan-STARRS1 3pi survey just ~4 days after explosion. The SN had a peak
luminosity, M_R ~ -20.2 mag, significantly more luminous than known GRB-SNe and
one of the most luminous SNe Ib/c ever discovered. The absorption velocity of
SN 2010ay is v_Si ~ 19,000 km/s at ~40 days after explosion, 2-5 times higher
than other broad-lined SNe and similar to the GRB-SN 2010bh at comparable
epochs. Moreover, the velocity declines ~2 times slower than other SNe Ic-BL
and GRB-SNe. Assuming that the optical emission is powered by radioactive
decay, the peak magnitude implies the synthesis of an unusually large mass of
56 Ni, M_Ni = 0.9 M_solar. Modeling of the light-curve points to a total ejecta
mass, M_ej ~ 4.7 M_sol, and total kinetic energy, E_K ~ 11x10^51 ergs. The
ratio of M_Ni to M_ej is ~2 times as large for SN 2010ay as typical GRB-SNe and
may suggest an additional energy reservoir. The metallicity (log(O/H)_PP04 + 12
= 8.19) of the explosion site within the host galaxy places SN 2010ay in the
low-metallicity regime populated by GRB-SNe, and ~0.5(0.2) dex lower than that
typically measured for the host environments of normal (broad-lined) Ic
supernovae. We constrain any gamma-ray emission with E_gamma < 6x10^{48} erg
(25-150 keV) and our deep radio follow-up observations with the Expanded Very
Large Array rule out relativistic ejecta with energy, E > 10^48 erg. We
therefore rule out the association of a relativistic outflow like those which
accompanied SN 1998bw and traditional long-duration GRBs, but place
less-stringent constraints on a weak afterglow like that seen from XRF 060218.
These observations challenge the importance of progenitor metallicity for the
production of a GRB, and suggest that other parameters also play a key role.Comment: 19 pages, 10 figures, V3 has revisions following referee's report;
more information at
http://www.cfa.harvard.edu/~nsanders/papers/2010ay/summary.htm
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Discovery of a Cosmological, Relativistic Outburst via its Rapidly Fading Optical Emission
We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R_peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g' – R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection of incoherent radio emission at such distances implies a large emitting region, from which we infer the presence of relativistic ejecta. The observed properties are all consistent with the population of long-duration gamma-ray bursts (GRBs), marking the first time such an outburst has been discovered in the distant universe independent of a high-energy trigger. We searched for possible high-energy counterparts to PTF11agg, but found no evidence for associated prompt emission. We therefore consider three possible scenarios to account for a GRB-like afterglow without a high-energy counterpart: an "untriggered" GRB (lack of satellite coverage), an "orphan" afterglow (viewing-angle effects), and a "dirty fireball" (suppressed high-energy emission). The observed optical and radio light curves appear inconsistent with even the most basic predictions for off-axis afterglow models. The simplest explanation, then, is that PTF11agg is a normal, on-axis long-duration GRB for which the associated high-energy emission was simply missed. However, we have calculated the likelihood of such a serendipitous discovery by PTF and find that it is quite small (≈2.6%). While not definitive, we nonetheless speculate that PTF11agg may represent a new, more common (>4 times the on-axis GRB rate at 90% confidence) class of relativistic outbursts lacking associated high-energy emission. If so, such sources will be uncovered in large numbers by future wide-field optical and radio transient surveys
Meiosis genes in Daphnia pulex and the role of parthenogenesis in genome evolution
<p>Abstract</p> <p>Background</p> <p>Thousands of parthenogenetic animal species have been described and cytogenetic manifestations of this reproductive mode are well known. However, little is understood about the molecular determinants of parthenogenesis. The <it>Daphnia pulex </it>genome must contain the molecular machinery for different reproductive modes: sexual (both male and female meiosis) and parthenogenetic (which is either cyclical or obligate). This feature makes <it>D. pulex </it>an ideal model to investigate the genetic basis of parthenogenesis and its consequences for gene and genome evolution. Here we describe the inventory of meiotic genes and their expression patterns during meiotic and parthenogenetic reproduction to help address whether parthenogenesis uses existing meiotic and mitotic machinery, or whether novel processes may be involved.</p> <p>Results</p> <p>We report an inventory of 130 homologs representing over 40 genes encoding proteins with diverse roles in meiotic processes in the genome of <it>D. pulex</it>. Many genes involved in cell cycle regulation and sister chromatid cohesion are characterized by expansions in copy number. In contrast, most genes involved in DNA replication and homologous recombination are present as single copies. Notably, <it>RECQ2 </it>(which suppresses homologous recombination) is present in multiple copies while <it>DMC1 </it>is the only gene in our inventory that is absent in the <it>Daphnia </it>genome. Expression patterns for 44 gene copies were similar during meiosis <it>versus </it>parthenogenesis, although several genes displayed marked differences in expression level in germline and somatic tissues.</p> <p>Conclusion</p> <p>We propose that expansions in meiotic gene families in <it>D. pulex </it>may be associated with parthenogenesis. Taking into account our findings, we provide a mechanistic model of parthenogenesis, highlighting steps that must differ from meiosis including sister chromatid cohesion and kinetochore attachment.</p