1,680 research outputs found
Welcome to the Profession: Exploring Perceptions of New Teacher Retention Supports
Numerous studies have identified a research to practice gap regarding teacher retention (Hagaman & Casey, 2018; Carver, 2003; CCSESA, 2016). In Minnesota, teacher retention is a concern as 51.32% of professional licensed teachers were not working as a public or charter school teacher during the 2019-2020 school year. (PELSB, 2021). The objective of our ongoing phenomenological study is to identify and address what common themes exist across multiple groups of educational professionals regarding retention rates of Minnesota teachers new to the profession. Our study employs grounded theory to analyze educational professionalsâ reflective writings to expand insights regarding why half of the stateâs fully licensed teachers are leaving the field, examine supports provided to new teachers, and determine what supports would be most beneficial for retention. This study compares the perceptions of beginning teacher supports through three different lenses (pre-service, in-service, and administrative). Insights gained from this study will inform preparation program content, alleviate the research to practice gap, and empower education professionals to be agents of change for improved teacher retention rates
Trapping of Ultracold Atoms in a Hollow-core Photonic Crystal Fiber
Ultracold sodium atoms have been trapped inside a hollow-core optical fiber.
The atoms are transferred from a free space optical dipole trap into a trap
formed by a red-detuned gaussian light mode confined to the core of the fiber.
We show that at least 5% of the atoms held initially in the free space trap can
be loaded into the core of the fiber and retrieved outside.Comment: 4 pages, 3 figures, corrected author list, added refs, changed figs,
changed content, accepted by PR
Reforming HMRC : Making it Fit for the Twenty-First Century - First Stage Report
Her Majestyâs Revenue & Customs (HMRC) performs a vital task in collecting taxes, enforcing lax laws and delivering services to taxpayers. Against a background of reductions in resources, it has experienced considerable difficulties in meeting the service expectation of taxpayers and challenging organised tax avoidance. This policy paper investigates the difficulties and makes recommendations to strengthen HMRC and its public accountability
Cancer risk in relation to body fat distribution, evaluated by DXA-scans, in postmenopausal women â the Prospective Epidemiological Risk Factor (PERF) study
Abstract Studies with direct measures of body fat distribution are required to explore the association between central and general obesity to cancer risk in postmenopausal women. This study investigates the association between central obesity and general obesity to overall/site-specific cancer risk in postmenopausal women. The analysis included 4,679 Danish postmenopausal women. Body fat distribution was evaluated by whole-body dual-energy X-ray absorptiometry scanners. Cancer diagnoses were extracted from the Danish Cancer Registry and multivariable Cox regression models explored the association between cancer risk and central obesity after adjusting for BMI. Our results showed that high central obese women had a 50% increased risk of overall cancer relative to low central obese women (Q1vs.Q4: [HR:1.50, CI:1.20â1.88]). For site-specific cancers, central obesity was significantly associated with Respiratory (Q1vs.Q4: [HR:2.01, CI:1.17â3.47]), Gastrointestinal (Q1vs.Q4: [HR:1.55, CI:0.99â2.41]) and Female genital organs (Q1vs.Q4: [HR:1.95, CI:1.00â3.78]) cancer diagnoses. Sub-analyses stratified by smoking-habits found a significant association between central obesity and a cancer diagnosis for current (Q1vs.Q4: [HR:1.93, CI:1.25â2.99]) and former smokers (Q1vs.Q4: [HR:1.90, CI:1.23â2.94]). These analyses suggest that central obesity is associated with some cancers in postmenopausal women independent of BMI
Detection strategies for scalar gravitational waves with interferometers and resonant spheres
We compute the response and the angular pattern function of an interferometer
for a scalar component of gravitational radiation in Brans-Dicke theory. We
examine the problem of detecting a stochastic background of scalar GWs and
compute the scalar overlap reduction function in the correlation between an
interferometer and the monopole mode of a resonant sphere. While the
correlation between two interferometers is maximized taking them as close as
possible, the interferometer-sphere correlation is maximized at a finite value
of f*d, where `f' is the resonance frequency of the sphere and `d' the distance
between the detectors. This defines an optimal resonance frequency of the
sphere as a function of the distance. For the correlation between the Virgo
interferometer located near Pisa and a sphere located in Frascati, near Rome,
we find an optimal resonance frequency f=590 Hz. We also briefly discuss the
difficulties in applying this analysis to the dilaton and moduli fields
predicted by string theory.Comment: 26 pages, Latex, 4 Postscript figures. Various minor improvements,
misprint in eqs. 42, 127, 138 corrected, references adde
Catalytic enantioselective nucleophilic desymmetrization of phosphonate esters
Molecules that contain a stereogenic phosphorus atom are crucial to medicine, agrochemistry and catalysis. While methods are available for the selective construction of various chiral organophosphorus compounds, catalytic enantioselective approaches for their synthesis are far less common. Given the vastness of possible substituent combinations around a phosphorus atom, protocols for their preparation should also be divergent, providing facile access not only to one but to many classes of phosphorus compounds. Here we introduce a catalytic and enantioselective strategy for the preparation of an enantioenriched phosphorus(V) centre that can be diversified enantiospecifically to a wide range of biologically relevant phosphorus(V) compounds. The process, which involves an enantioselective nucleophilic substitution catalysed by a superbasic bifunctional iminophosphorane catalyst, can accommodate a wide range of carbon substituents at phosphorus. The resulting stable, yet versatile, synthetic intermediates can be combined with a multitude of medicinally relevant O-, N- and S-based nucleophiles
Defect-Engineering by Solvent Mediated Mild Oxidation as a Tool to Induce Exchange Bias in Metal Doped Ferrites
The crystal site occupancy of different divalent ions and the induction of lattice defects represent an additional tool for modifying the intrinsic magnetic properties of spinel ferrites nanoparticles. Here, the relevance of the lattice defects is demonstrated in the appearance of exchangeâbias and in the improvement of the magnetic properties of doped ferrites of 20Â nm, obtained from the mild oxidation of core@shell (wĂŒstite@ferrite) nanoparticles. Three types of nanoparticles (Fe0.95O@Fe3O4, [email protected] and [email protected]) are oxidized. As a result, the core@shell morphology is removed and transformed in a spinelâlike nanoparticle, through a topotactic transformation. This study shows that most of the induced defects in these nanoparticles and their magnetic properties are driven by the inability of the Co(II) ions at the octahedral sites to migrate to tetrahedral sites, at the chosen mild oxidation temperature. In addition, the appearance of crystal defects and antiphase boundaries improves the magnetic properties of the starting compounds and leads to the appearance of exchange bias at room temperature. These results highlight the validity of the proposed method to impose novel magnetic characteristics in the technologically relevant class of nanomaterials such as spinel ferrites, expanding their potential exploitation in several application fields
Into the Lyα jungle: exploring the circumgalactic medium of galaxies at z ⌠4 â 5 with MUSE
We present a study of the galaxy environment of 9 strong H I+C IV absorption line systems (16.2 < log(N(HI)) < 21.2) spanning a wide range in metallicity at z ⌠4 â 5, using MUSE integral field and X-Shooter spectroscopic data collected in a z â 5.26 quasar field. We identify galaxies within a 250 kpc and ±1000 km sâ1 window for 6 out of the 9 absorption systems, with 2 of the absorption line systems showing multiple associated galaxies within the MUSE field of view. The space density of Lyα emitting galaxies (LAEs) around the H I and C IV systems is â10 â 20 times the average sky density of LAEs given the flux limit of our survey, showing a clear correlation between the absorption and galaxy populations. Further, we find that the strongest C IV systems in our sample are those that are most closely aligned with galaxies in velocity space, i.e. within velocities of ±500 km sâ1. The two most metal poor systems lie in the most dense galaxy environments, implying we are potentially tracing gas that is infalling for the first time into star-forming groups at high redshift. Finally, we detect an extended Lyα nebula around the z â 5.26 quasar, which extends up to â50 kpc at the surface brightness limit of 3.8 Ă 10â18 erg sâ1 cmâ2 arcsecâ2. After scaling for surface brightness dimming, we find that this nebula is centrally brighter, having a steeper radial profile than the average for nebulae studied at z ⌠3 and is consistent with the mild redshift evolution seen from z â 2
Directly imaging damped Lyman-alpha galaxies at z>2. I: Methodology and First Results
We present the methodology for, and the first results from, a new imaging
program aimed at identifying and characterizing the host galaxies of damped
Lyman-alpha absorbers (DLAs) at z>2. We target quasar sightlines with multiple
optically-thick HI absorbers and use the higher-redshift system as a "blocking
filter" (via its Lyman-limit absorption) to eliminate all far-ultraviolet (FUV)
emission from the quasar. This allows us to directly image the rest-frame FUV
continuum emission of the lower-redshift DLA, without any quasar contamination
and with no bias towards large impact parameters. We introduce a formalism
based on galaxy number counts and Bayesian statistics with which we quantify
the probability that a candidate is the DLA host galaxy. This method will allow
the identification of a bona fide sample of DLAs that are too faint to be
spectroscopically confirmed. The same formalism can be adopted to the study of
other quasar absorption line systems (e.g. MgII absorbers). We have applied
this imaging technique to two QSO sightlines. For the z~2.69 DLA towards
J073149+285449, a galaxy with impact parameter b=1.54"=11.89 kpc and implied
star formation rate (SFR) of ~5 M/yr is identified as the most reliable
candidate. In the case of the z~2.92 DLA towards J211444-005533, no likely host
is found down to a 3-sigma SFR limit of 1.4 M/yr. Studying the HI column
density as a function of the impact parameter, including 6 DLAs with known
hosts from the literature, we find evidence that the observed HI distribution
is more extended than what is generally predicted from numerical simulation.Comment: 22 pages, 13 figures. Accepted for publication in MNRAS. Typos
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