3,963 research outputs found
Performance Management in Portfolio School Districts
Explores the challenges of performance-based oversight of portfolio districts -- districts trying to provide diverse types of schools with common standards and accountability -- and the capacities needed. Includes profiles and best practices
Some notes on the Kruskal - Szekeres completion
The Kruskal - Szekeres (KS) completion of the Schwarzschild spacetime is open
to Synge's methodological criticism that the KS procedure generates "good"
coordinates from "bad". This is addressed here in two ways: First I generate
the KS coordinates from Israel coordinates, which are also "good", and then I
generate the KS coordinates directly from a streamlined integration of the
Einstein equations.Comment: One typo correcte
Signatures of the Milky Way's Dark Disk in Current and Future Experiments
In hierarchical structure formation models of disk galaxies, a dark matter
disk forms as massive satellites are preferentially dragged into the disk-plane
where they dissolve. Here, we quantify the importance of this dark disk for
direct and indirect dark matter detection. The low velocity of the dark disk
with respect to the Earth enhances detection rates in direct detection
experiments at low recoil energy. For WIMP masses M_{WIMP} >~ 50 GeV, the
detection rate increases by up to a factor of 3 in the 5 - 20 keV recoil energy
range. Comparing this with rates at higher energy is sensitive to M_{WIMP},
providing stronger mass constraints particularly for M_{WIMP}>~100 GeV. The
annual modulation signal is significantly boosted by the dark disk and the
modulation phase is shifted by ~3 weeks relative to the dark halo. The
variation of the observed phase with recoil energy determines M_{WIMP}, once
the dark disk properties are fixed by future astronomical surveys. The low
velocity of the particles in the dark disk with respect to the solar system
significantly enhances the capture rate of WIMPs in the Sun, leading to an
increased flux of neutrinos from the Sun which could be detected in current and
future neutrino telescopes. The dark disk contribution to the muon flux from
neutrino back conversion at the Earth is increased by a factor of ~5 compared
to the SHM, for rho_d/rho_h=0.5.Comment: 5 pages, 7 figures, To appear in the proceedings of Identification of
Dark Matter 2008 (IDM2008), Stockholm, 18-22 August 2008; corrected one
referenc
Maximally extended, explicit and regular coverings of the Schwarzschild - de Sitter vacua in arbitrary dimension
Maximally extended, explicit and regular coverings of the Schwarzschild - de
Sitter family of vacua are given, first in spacetime (generalizing a result due
to Israel) and then for all dimensions (assuming a sphere). It is
shown that these coordinates offer important advantages over the well known
Kruskal - Szekeres procedure.Comment: 12 pages revtex4 5 figures in color. Higher resolution version at
http://www.astro.queensu.ca/~lake/regularcoordinates.pd
Evolution of antiferromagnetic domains in the all-in-all-out ordered pyrochlore NdZrO
We report the observation of magnetic domains in the exotic,
antiferromagnetically ordered all-in-all-out state of NdZrO,
induced by spin canting. The all-in-all-out state can be realized by Ising-like
spins on a pyrochlore lattice and is established in NdZrO below
0.31 K for external magnetic fields up to 0.14 T. Two different spin
arrangements can fulfill this configuration which leads to the possibility of
magnetic domains. The all-in-all-out domain structure can be controlled by an
external magnetic field applied parallel to the [111] direction. This is a
result of different spin canting mechanism for the two all-in-all-out
configurations for such a direction of the magnetic field. The change of the
domain structure is observed through a hysteresis in the magnetic
susceptibility. No hysteresis occurs, however, in case the external magnetic
field is applied along [100].Comment: Accepted for publication in Phys. Rev. B, 6 pages, 6 figure
How the nursing associate role is viewed by different stakeholders: a qualitative research study
Background:
The nursing associate role was created following a review by Health Education England in 2015 that examined nurse education and training so that capacity and improvements could be made to the provision of care in England.
Objective:
To explore different stakeholder perspectives of how the nursing associate role has been embedded within local healthcare practice.
Design:
The study was designed to explore and evaluate the role of the nursing associate in practice from the perspectives of those stakeholders who have experience of working with the nursing associate.
Setting(s):
Online semi-structured interviews.
Participants:
9 stakeholder participants who had direct contact with the nursing associate or trainee nursing associate in the practice setting.
Methods:
A mixed-methods qualitative approach was used, which included a creative methodological approach in the form of photo-elicitation and semi-structured interviews to explore the lived experience of participants.
Results:
Analysis revealed 2 superordinate themes: (1) the contribution of the nursing associate; (2) real-work perspectives of the role.
Conclusions:
The findings demonstrated that the role was important to the provision of care, but that there were challenges related to communication, support and education provision throughout the organisations
Observation of long range magnetic ordering in pyrohafnate Nd2Hf2O7: A neutron diffraction study
We have investigated the physical properties of a pyrochlore hafnate Nd2Hf2O7
using ac magnetic susceptibility \chi_ac(T), dc magnetic susceptibility
\chi(T), isothermal magnetization M(H) and heat capacity C_p(T) measurements,
and determined the magnetic ground state by neutron powder diffraction study.
An upturn is observed below 6 K in C_p(T)/T, however both C_p(T) and \chi(T) do
not show any clear anomaly down to 2 K. The \chi_ac(T) shows a well pronounced
anomaly indicating an antiferromagnetic transition at T_N = 0.55 K. The long
range antiferromagnetic ordering is confirmed by neutron diffraction. The
refinement of neutron diffraction pattern reveals an all-in/all-out
antiferromagnetic structure, where for successive tetrahedra, the four Nd3+
magnetic moments point alternatively all-into or all-out-of the tetrahedron,
with an ordering wavevector k = (0, 0, 0) and an ordered state magnetic moment
of m = 0.62(1) \mu_B/Nd at 0.1 K. The ordered moment is strongly reduced
reflecting strong quantum fluctuations in ordered state.Comment: 10 pages, 9 figures and 2 tables; to appear in Phys. Rev.
New Wrinkles on an Old Model: Correlation Between Liquid Drop Parameters and Curvature Term
The relationship between the volume and surface energy coefficients in the
liquid drop A^{-1/3} expansion of nuclear masses is discussed. The volume and
surface coefficients in the liquid drop expansion share the same physical
origin and their physical connection is used to extend the expansion with a
curvature term. A possible generalization of the Wigner term is also suggested.
This connection between coefficients is used to fit the experimental nuclear
masses. The excellent fit obtained with a smaller number of parameters
validates the assumed physical connection.Comment: 6 pages, 2 figure
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