139 research outputs found
Reining in Punitive Discipline: Recent Trends in Exclusionary School Discipline Disparities
Concerns around disparities in suspensions and expulsions from schools in the United States have resulted in a concerted effort to reduce the use of exclusionary school discipline. In this article, the authors describe trends in the use of exclusionary discipline in Indiana and Oregon, two U.S. states with different school discipline policy climates. The findings point to a substantial decline in the use of suspensions and other forms of exclusionary discipline in both states. The authors further find that racial and socioeconomic disparities have recently narrowed in both states, though Black students and students who were identified as economically disadvantaged remain likely to be disproportionately exposed to exclusionary discipline. These trends, and their timing, illustrate the broad-based change in disciplinary norms that has occurred in the U.S. over the past decade
ć暩珏1æă«ăăăăąăăăăă”ăŒăžăźćčæ ïŒ ćçŁć©Š6ćç”çŁć©Š4ćă«ćźæœăăŠ
The article of record as published may be located at http://dx.doi.org/10.2514/6.2008-7012AIAA Guidance, Navigation and Control Conference and Exhibit ; Paper no. AIAA-2008-7012, Honolulu, Hawaii, 2008Minimum-time solutions are developed for the rest-to-rest reorientation of an asymmetric rigid-body. The optimality of the open-loop solutions are demonstrated by application of Pontryagin's Minimum Principle. Bellman's theory is used to further demonstrate optimality while extending open-loop theory to real-time application. The open-loop time optimal control is, next, used to construct the closed-loop Caratheodory- control solution for a similar maneuver. Closed-loop results presented for the system with and without parameter uncertainties verify the successful implementation of the method in practical applications
neutron strength in the isotones and the Cr()Cr reaction
We performed a measurement of the CrCr reaction at 16 MeV
using the Florida State University Super-Enge Split-Pole Spectrograph (SE-SPS)
and observed 26 states. While all of the states observed here had been seen in
previous experiments, we changed five assignments from those
reported previously and determined values for nine states that had not had
such assignments made previously.
The neutron strength observed in Cr in the present work and
in the isotones Ca, Ti, and Fe via
reactions is much smaller than the sum rule for this strength. Most of the
observed strength in these nuclei is located in states near 4 MeV
excitation energy. The remaining strength may be located in the
continuum or may be fragmented among many bound states. A covariant density
functional theory calculation provides support for the hypothesis that the
neutron orbit is unbound in Cr. The (He) reaction
may provide a more sensitive probe for the missing neutron strength.
In addition, particle- coincidence experiments may help resolve some
remaining questions in this nucleus.Comment: 15 pages, 5 figures. arXiv admin note: text overlap with
arXiv:2212.0438
Terrestrial biosphere changes over the last 120âŻkyr
A new global synthesis and biomization of long (>âŻ40âŻkyr) pollen-data records is presented and used with simulations from the HadCM3 and FAMOUS climate models and the BIOME4 vegetation model to analyse the dynamics of the global terrestrial biosphere and carbon storage over the last glacialâinterglacial cycle. Simulated biome distributions using BIOME4 driven by HadCM3 and FAMOUS at the global scale over time generally agree well with those inferred from pollen data. Global average areas of grassland and dry shrubland, desert, and tundra biomes show large-scale increases during the Last Glacial Maximum, between ca. 64 and 74âŻka BP and cool substages of Marine Isotope Stage 5, at the expense of the tropical forest, warm-temperate forest, and temperate forest biomes. These changes are reflected in BIOME4 simulations of global net primary productivity, showing good agreement between the two models. Such changes are likely to affect terrestrial carbon storage, which in turn influences the stable carbon isotopic composition of seawater as terrestrial carbon is depleted in 13C
Search for Eccentric Black Hole Coalescences during the Third Observing Run of LIGO and Virgo
Despite the growing number of confident binary black hole coalescences
observed through gravitational waves so far, the astrophysical origin of these
binaries remains uncertain. Orbital eccentricity is one of the clearest tracers
of binary formation channels. Identifying binary eccentricity, however, remains
challenging due to the limited availability of gravitational waveforms that
include effects of eccentricity. Here, we present observational results for a
waveform-independent search sensitive to eccentric black hole coalescences,
covering the third observing run (O3) of the LIGO and Virgo detectors. We
identified no new high-significance candidates beyond those that were already
identified with searches focusing on quasi-circular binaries. We determine the
sensitivity of our search to high-mass (total mass ) binaries
covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to
compare model predictions to search results. Assuming all detections are indeed
quasi-circular, for our fiducial population model, we place an upper limit for
the merger rate density of high-mass binaries with eccentricities at Gpc yr at 90\% confidence level.Comment: 24 pages, 5 figure
Incidence and Characterisation of Methicillin-Resistant Staphylococcus aureus (MRSA) from Nasal Colonisation in Participants Attending a Cattle Veterinary Conference in the UK
We sought to determine the prevalence of nasal colonisation with methicillin-resistant Staphylococcus aureus among cattle veterinarians in the UK. There was particular interest in examining the frequency of colonisation with MRSA harbouring mecC, as strains with this mecA homologue were originally identified in bovine milk and may represent a zoonotic risk to those in contact with dairy livestock. Three hundred and seven delegates at the British Cattle Veterinarian Association (BCVA) Congress 2011 in Southport, UK were screening for nasal colonisation with MRSA. Isolates were characterised by whole genome sequencing and antimicrobial susceptibility testing. Eight out of three hundred and seven delegates (2.6%) were positive for nasal colonisation with MRSA. All strains were positive for mecA and none possessed mecC. The time since a delegateâs last visit to a farm was significantly shorter in the MRSA-positive group than in MRSA-negative counterparts. BCVA delegates have an increased risk of MRSA colonisation compared to the general population but their frequency of colonisation is lower than that reported from other types of veterinarian conference, and from that seen in human healthcare workers. The results indicate that recent visitation to a farm is a risk factor for MRSA colonisation and that mecC-MRSA are rare among BCVA delegates (<1% based on sample size). Contact with livestock, including dairy cattle, may still be a risk factor for human colonisation with mecC-MRSA but occurs at a rate below the lower limit of detection available in this study
- âŠ