242 research outputs found
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Examining the Career Pathways of Educators with Superintendent Certification
Purpose: We used gatekeeping theory to frame our examination of whether and when educators with superintendent certification become superintendents, and how their likelihood of making that transition is influenced by race, sex, and other characteristics. Further, we sought to identify variation in career pathways to the superintendency.
Data and Method: We analyzed 26,071 observations of 4,813 unique individuals, representing the entire population of Texas public school educators who obtained their first superintendent certificate between the 2000-01 and 2014-15 school years. We constructed alluvial diagrams to visualize these educators’ career pathways. In addition to compiling a life table and visual displays of hazard, we utilized a discrete-time hazard model to control for individual and contextual characteristics associated with transitions into the superintendency.
Findings: Educators are most likely to enter the superintendency in the academic year immediately following that in which they obtained the requisite certification. Further, pathways to the superintendency differ greatly based on educator sex and race, as well as the level and locale employment setting. Finally, we determined that age, experience, education, level of employment, and sex all have statistically significant impacts on the likelihood of becoming a superintendent.
Implications for Research and Practice: We discuss the role that researchers must play in coordinating with practitioners to ensure more equitable opportunity for aspiring superintendents. We also emphasize the important role that preparation programs play in preparing candidates for the job market. Finally, we ponder further expansions of similar pre-superintendency research, as well as more robust applications of alluvial diagrams.
KEYWORDS: superintendents, intersectionality, alluvial, career pathways, certification, gatekeeping, school district leadershi
Constraining churning and blurring in the Milky Way using large spectroscopic surveys -- an exploratory study
We have investigated the possibilities to quantify how much stars move in the
Milky Way stellar disk due to diffuse processes (i.e. so called blurring) and
due to influences from spiral arms and the bar (i.e. so called churning). To
this end we assume that it is possible to infer the formation radius of a star
if we know their elemental abundances and age as well as the metallicity
profile of the interstellar medium at the time of the formation of the star.
Using this information, coupled with orbital information derived from Gaia DR2
data and radial velocities from large spectroscopic surveys, we show that it is
possible to isolate stellar samples such that we can start to quantify how
important the role of churning is. We use data from APOGEE DR14, parallaxes
from Gaia and stellar ages based on C and N elemental abundances in the stars.
In our sample, we find that about half of the stars have experienced some sort
of radial migration (based solely on their orbital properties), 10 % have
likely have suffered only from churning, whilst a modest 5-7 % of stars have
never experienced either churning or blurring making them ideal tracers of the
original properties of the cool stellar disk. Our investigation shows that it
is possible to put up a framework where we can begin to quantify churning and
blurring an important. Important aspects for future work would include to
investigate how selection effects should be accounted for.Comment: Paper submitted to MNRAS. Comments are welcom
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Pathways to the Principalship: An Event History Analysis of the Careers of Teachers With Principal Certification
Utilizing rich data on nearly 11,000 educators over 17 academic years in a highly diverse context, we examine the career paths of teachers to determine whether and when they transition into the principalship. We utilize a variety of event history analyses, including discrete-time hazard modeling, to determine how an individual’s race, gender, and their combination—among other characteristics—contribute to their likelihood of making this transition. We found that inequitable pathways to the principalship are not explained by systematic differences in personal and contextual characteristics along lines of race and gender but rather that the selection of school leaders may be a process influenced by systemic bias
High-throughput discovery of rare human nucleotide polymorphisms by Ecotilling
Human individuals differ from one another at only ∼0.1% of nucleotide positions, but these single nucleotide differences account for most heritable phenotypic variation. Large-scale efforts to discover and genotype human variation have been limited to common polymorphisms. However, these efforts overlook rare nucleotide changes that may contribute to phenotypic diversity and genetic disorders, including cancer. Thus, there is an increasing need for high-throughput methods to robustly detect rare nucleotide differences. Toward this end, we have adapted the mismatch discovery method known as Ecotilling for the discovery of human single nucleotide polymorphisms. To increase throughput and reduce costs, we developed a universal primer strategy and implemented algorithms for automated band detection. Ecotilling was validated by screening 90 human DNA samples for nucleotide changes in 5 gene targets and by comparing results to public resequencing data. To increase throughput for discovery of rare alleles, we pooled samples 8-fold and found Ecotilling to be efficient relative to resequencing, with a false negative rate of 5% and a false discovery rate of 4%. We identified 28 new rare alleles, including some that are predicted to damage protein function. The detection of rare damaging mutations has implications for models of human disease
PARALLAX of GALACTIC CEPHEIDS from SPATIALLY SCANNING the WIDE FIELD CAMERA 3 on the HUBBLE SPACE TELESCOPE: The CASE of SS CANIS MAJORIS
A rotating three component perfect fluid source and its junction with empty space-time
The Kerr solution for empty space-time is presented in an ellipsoidally
symmetric coordinate system and it is used to produce generalised ellipsoidal
metrics appropriate for the generation of rotating interior solutions of
Einstein's equations. It is shown that these solutions are the familiar static
perfect fluid cases commonly derived in curvature coordinates but now endowed
with rotation. The resulting solutions are also discussed in the context of
T-solutions of Einstein's equations and the vacuum T-solution outside a
rotating source is presented. The interior source for these solutions is shown
not to be a perfect fluid but rather an anisotropic three component perfect
fluid for which the energy momentum tensor is derived. The Schwarzschild
interior solution is given as an example of the approach.Comment: 14 page
Cluster Cepheids with High Precision Gaia Parallaxes, Low Zeropoint Uncertainties, and Hubble Space Telescope Photometry
We present HST photometry of 17 Cepheids in open clusters and their mean
parallaxes from Gaia EDR3. These parallaxes are more precise than those from
individual Cepheids (G<8 mag) previously used to measure the Hubble constant
because they are derived from an average of >300 stars per cluster. Cluster
parallaxes also have smaller systematic uncertainty because their stars lie in
the range (G>13 mag) where the Gaia parallax calibration is most comprehensive.
Cepheid photometry employed in the period--luminosity relation was measured
using the same instrument(WFC3) and filters(F555W,F814W,F160W) as extragalactic
Cepheids in SNIa hosts. We find no evidence of residual parallax offset in this
magnitude range, zp=-3+/-4 muas, consistent with Lindegren:2021b and most
studies. The Cepheid luminosity (P=10d, solar-metallicity) in the HST
near-infrared, Wesenheit system derived from the cluster sample is
M_{H,1}^W=-5.902+/-0.025 and -5.890+/-0.018 mag with or without simultaneous
determination of a parallax offset, respectively. These results are similar to
measurements from field Cepheids, confirming the accuracy of the Gaia
parallaxes over a broad range of magnitudes. The SH0ES distance ladder
calibrated solely from this sample gives H_0=72.8+/-1.3 and H_0=73.2+/-1.1
km/s/Mpc with or without offset marginalization; combined with all anchors we
find H_0=73.01+/-0.99 and 73.15+/-0.97, respectively, a 5% or 7% reduction in
the uncertainty and a 5.3 sigma Hubble Tension relative to Planck+LambdaCDM. It
appears increasingly difficult to reconcile two of the best measured cosmic
scales, parallaxes from Gaia and the angular size of the acoustic scale of the
CMB, using the simplest form of LambdaCDM to join the two.Comment: 12 pages, submitted to ApJ, comments welcom
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