3,220 research outputs found
Electronic structure and magnetism in two-dimensional hexagonal 5d transition metal carbides, Tan+1Cn (n=1,2,3)
Density functional calculations are used to investigate the electronic
structure of two-dimensional 5d tantalum carbides with honeycomb-like lattice
structures. We focus on changes in the low-energy bands near the Fermi level
with dimensionality. We find that the Ta 5d states dominate, but the extended
nature of the wavefunctions makes them weakly correlated. The carbide sheets
are prone to long range magnetic order. We evaluate the stability of these
states to enhanced electron--electron interactions through a Hubbard U
correction. Lastly, we find spin orbit interactions strongly renormalize the
band structure for n=2, but play a minor role in n=1 and 3.Comment: 4 pages, 4 figure
Health-related quality of life measurement in pediatric clinical practice: An appraisal and precept for future research and application
Health-related quality of life (HRQOL) measurement has emerged as an important health outcome in clinical trials, clinical practice improvement strategies, and healthcare services research and evaluation. HRQOL measures are also increasingly proposed for use in clinical practice settings to inform treatment decisions. In settings where HRQOL measures have been utilized with adults, physicians report such measures as useful, some physicians alter their treatment based on patient reports on such instruments, and patients themselves generally feel the instruments to be helpful. However, there is a dearth of studies evaluating the clinical utility of HRQOL measurement in pediatric clinical practice. This paper provides an updated review of the literature and proposes a precept governing the application of pediatric HRQOL measurement in pediatric clinical practice. Utilizing HRQOL measurement in pediatric healthcare settings can facilitate patient-physician communication, improve patient/parent satisfaction, identify hidden morbidities, and assist in clinical decision-making. Demonstrating the utility of pediatric HRQOL measurement in identifying children with the greatest needs, while simultaneously demonstrating the cost advantages of providing timely, targeted interventions to address those needs, may ultimately provide the driving force for incorporating HRQOL measurement in pediatric clinical practice
Mississippian stratotypes
Working Group on the Mississippian of the U.S.A.Ope
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Phase Coexistence of Ferroelectric Vortices and Classical a1/a2 Domains in PbTiO3/SrTiO3 Superlattices.
A catalogue of Galactic GEMS: Globular cluster Extra-tidal Mock Stars
This work presents the Globular cluster Extra-tidal Mock Star (GEMS)
catalogue of extra-tidal stars and binaries created via three-body dynamical
encounters in globular cluster cores. Using the particle-spray code Corespray,
we sample N=50,000 extra-tidal stars and escaped recoil binaries for 159
Galactic globular clusters. Sky positions, kinematics, stellar properties and
escape information are provided for all simulated stars. Stellar orbits are
integrated in seven different static and time-varying Milky Way gravitational
potential models where the structure of the disc, perturbations from the Large
Magellanic Cloud and the mass and sphericity of the Milky Way's dark matter
halo are all investigated. We find that the action coordinates of the mock
extra-tidal stars are largely Galactic model independent, where minor offsets
and broadening of the distributions between models are likely due to
interactions with substructure. Importantly, we also report the first evidence
for stellar stream contamination by globular cluster core stars and binaries
for clusters with pericentre radii larger than five kiloparsecs. Finally, we
provide a quantitative tool that uses action coordinates to match field stars
to host clusters with probabilities. Ultimately, combining data from the GEMS
catalogue with information of observed stars will allow for association of
extra-tidal field stars with any Galactic globular cluster; a requisite tool
for understanding population-level dynamics and evolution of clusters in the
Milky Way.Comment: 23 pages, 12 figures, 1 table. Accepted for publication in Monthly
Notices of the Royal Astronomical Society. For the associated GEMS catalogue,
please visit https://zenodo.org/records/843670
Extrasolar planet science with the Antarctic planet interferometer
The primary limitation to ground based astronomy is the Earth's atmosphere. The atmosphere above the Antarctic plateau is different in many regards compared to the atmosphere at temperate sites. The extreme altitude, cold and low humidity offer a uniquely transparent atmosphere at many wavelengths. Studies at the South Pole have shown additionally that the turbulence properties of the night time polar atmosphere are fundamentally different to mid latitudes. Despite relatively strong ground layer turbulence, the lack of high altitude turbulence combined with low wind speeds presents favorable conditions for interferometry. The unique properties of the polar atmosphere can be exploited for Extrasolar Planet studies with differential astrometry, differential phase and nulling intereferometers. This paper combines the available data on the properties of the atmosphere at the South Pole and other Antarctic plateau sites for Extrasolar Planet science with interferometry
The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)
AST/RO, a 1.7 m diameter telescope for astronomy and aeronomy studies at
wavelengths between 200 and 2000 microns, was installed at the South Pole
during the 1994-1995 Austral summer. The telescope operates continuously
through the Austral winter, and is being used primarily for spectroscopic
studies of neutral atomic carbon and carbon monoxide in the interstellar medium
of the Milky Way and the Magellanic Clouds. The South Pole environment is
unique among observatory sites for unusually low wind speeds, low absolute
humidity, and the consistent clarity of the submillimeter sky. Four heterodyne
receivers, an array receiver, three acousto-optical spectrometers, and an array
spectrometer are installed. A Fabry-Perot spectrometer using a bolometric array
and a Terahertz receiver are in development. Telescope pointing, focus, and
calibration methods as well as the unique working environment and logistical
requirements of the South Pole are described.Comment: 57 pages, 15 figures. Submitted to PAS
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