5,002 research outputs found
Spatially Resolved Images of Dust Belt(s) Around the Planet-hosting Subgiant Kappa CrB
We present Herschel spatially resolved images of the debris disc orbiting the
subgiant Kappa CrB. Not only are these the first resolved images of a debris
disc orbiting a subgiant, but Kappa CrB is a rare example of an intermediate
mass star where a detailed study of the structure of the planetary system can
be made, including both planets and planetesimal belt(s). The only way to
discover planets around such stars using the radial velocity technique is to
observe 'retired' A stars, which are cooler and slower rotators compared to
their main-sequence counterparts. A planetary companion has already been
detected orbiting the subgiant Kappa CrB, with revised parameters of m sin i =
2.1MJ and apl = 2.8AU (Johnson et al. 2008a). We present additional Keck I
HIRES radial velocity measurements that provide evidence for a second planetary
companion, alongside Keck II AO imaging that places an upper limit on the mass
of this companion. Modelling of our Herschel images shows that the dust is
broadly distributed, but cannot distinguish between a single wide belt (from 20
to 220AU) or two narrow dust belts (at around 40 and 165AU). Given the
existence of a second planetary companion beyond approximately 3AU it is
possible that the absence of dust within approximately 20AU is caused by
dynamical depletion, although the observations are not inconsistent with
depletion of these regions by collisional erosion, which occurs at higher rates
closer to the star.Comment: Updated abstrac
Randomised, controlled trial of alternating pressure mattresses compared with alternating pressure overlays for the prevention of pressure ulcers : PRESSURE (pressure relieving support surfaces) trial
Objective To compare whether differences exist between alternating pressure overlays and alternating pressure mattresses in the development of new pressure ulcers, healing of existing pressure ulcers, and patient acceptability. Design Pragmatic, open, multicentre, randomised controlled trial. Setting 11 hospitals in six NHS trusts. Participants 1972 people admitted to hospital as acute or elective patients. Interventions Participants were randomised to an alternating pressure mattress (n = 982) of- an alternating pressure overlay (n = 990). Main outcome measures The proportion of participants developing a new pressure ulcer of grade 2 or worse; time to development of new pressure ulcers; proportions of participants developing a new ulcer within 30 days; healing of existing pressure ulcers; and patient acceptability Results Intention to treat analysis found no difference in the proportions of participants developing a new pressure ulcer of grade 2 or worse (10.7% overlay patients, 10.3% mattress patients; difference 0.4%, 95% confidence interval - 23% to 3.1%, P = 0.75). More overlay patients requested change owing to dissatisfaction (23.3%) than mattress patients (18.9%, P = 0.02). Conclusion No difference was found between alternating pressure mattresses and alternating pressure overlays in the proportion of people who develop a pressure ulcer
Montage: a grid portal and software toolkit for science-grade astronomical image mosaicking
Montage is a portable software toolkit for constructing custom, science-grade
mosaics by composing multiple astronomical images. The mosaics constructed by
Montage preserve the astrometry (position) and photometry (intensity) of the
sources in the input images. The mosaic to be constructed is specified by the
user in terms of a set of parameters, including dataset and wavelength to be
used, location and size on the sky, coordinate system and projection, and
spatial sampling rate. Many astronomical datasets are massive, and are stored
in distributed archives that are, in most cases, remote with respect to the
available computational resources. Montage can be run on both single- and
multi-processor computers, including clusters and grids. Standard grid tools
are used to run Montage in the case where the data or computers used to
construct a mosaic are located remotely on the Internet. This paper describes
the architecture, algorithms, and usage of Montage as both a software toolkit
and as a grid portal. Timing results are provided to show how Montage
performance scales with number of processors on a cluster computer. In
addition, we compare the performance of two methods of running Montage in
parallel on a grid.Comment: 16 pages, 11 figure
Synthesis and Characterization of Azole Isoflavone Inhibitors of Aromatase
The synthesis and biological evaluation of a series of 2-azole and 2-thioazole isoflavones as potential aromatase inhibitors are described. Differences in inhibitory activity of triazole and imidazole inhibitors are rationalized with density functional theory to expose a key difference in the electronic structure of these molecules. In addition, difference binding spectra of inhibitors to immunoaffinity-purified aromatase produces classical Type II spectra consistent with coordination of the nitrogen lone pair electrons to the aromatase P450 heme
Synthesis and Characterization of Azole Isoflavone Inhibitors of Aromatase
The synthesis and biological evaluation of a series of 2-azole and 2-thioazole isoflavones as potential aromatase inhibitors are described. Differences in inhibitory activity of triazole and imidazole inhibitors are rationalized with density functional theory to expose a key difference in the electronic structure of these molecules. In addition, difference binding spectra of inhibitors to immunoaffinity-purified aromatase produces classical Type II spectra consistent with coordination of the nitrogen lone pair electrons to the aromatase P450 heme
A microscopic model for d-wave charge carrier pairing and non-Fermi-liquid behavior in a purely repulsive 2D electron system
We investigate a microscopic model for strongly correlated electrons with
both on-site and nearest neighbor Coulomb repulsion on a 2D square lattice.
This exhibits a state in which electrons undergo a ``somersault'' in their
internal spin-space (spin-flux) as they traverse a closed loop in external
coordinate space. When this spin-1/2 antiferromagnetic (AFM) insulator is
doped, the ground state is a liquid of charged, bosonic meron-vortices, which
for topological reasons are created in vortex-antivortex pairs. The magnetic
exchange energy of the distorted AFM background leads to a logarithmic
vortex-antivortex attraction which overcomes the direct Coulomb repulsion
between holes localized on the vortex cores. This leads to the appearance of
pre-formed charged pairs. We use the Configuration Interaction (CI) Method to
study the quantum translational and rotational motion of various charged
magnetic solitons and soliton pairs. The CI method systematically describes
fluctuation and quantum tunneling corrections to the Hartree-Fock Approximation
(HFA). We find that the lowest energy charged meron-antimeron pairs exhibit
d-wave rotational symmetry, consistent with the symmetry of the cuprate
superconducting order parameter. For a single hole in the 2D AFM plane, we find
a precursor to spin-charge separation in which a conventional charged
spin-polaron dissociates into a singly charged meron-antimeron pair. This model
provides a unified microscopic basis for (i) non-Fermi-liquid transport
properties, (ii) d-wave preformed charged carrier pairs, (iii) mid-infrared
optical absorption, (iv) destruction of AFM long range order with doping and
other magnetic properties, and (v) certain aspects of angled resolved
photo-emission spectroscopy (ARPES).Comment: 14 pages, 17 figure
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