1,933 research outputs found
An investigative study of a spectrum-matching imaging system Final report
Evaluation system for classification of remote objects and materials identified by solar and thermal radiation emissio
Relativistic models of magnetars: the twisted-torus magnetic field configuration
We find general relativistic solutions of equilibrium magnetic field
configurations in magnetars, extending previous results of Colaiuda et al.
(2008). Our method is based on the solution of the relativistic Grad-Shafranov
equation, to which Maxwell's equations can be reduced in some limit. We obtain
equilibrium solutions with the toroidal magnetic field component confined into
a finite region inside the star, and the poloidal component extending to the
exterior. These so-called twisted-torus configurations have been found to be
the final outcome of dynamical simulations in the framework of Newtonian
gravity, and appear to be more stable than other configurations. The solutions
include higher order multipoles, which are coupled to the dominant dipolar
field. We use arguments of minimal energy to constrain the ratio of the
toroidal to the poloidal field.Comment: 13 pages, 12 figures. Minor changes to match the version published on
MNRA
The MiMeS Project: Magnetism in Massive Stars
The Magnetism in Massive Stars (MiMeS) Project is a consensus collaboration
among the foremost international researchers of the physics of hot, massive
stars, with the basic aim of understanding the origin, evolution and impact of
magnetic fields in these objects. The cornerstone of the project is the MiMeS
Large Program at the Canada-France-Hawaii Telescope, which represents a
dedication of 640 hours of telescope time from 2008-2012. The MiMeS Large
Program will exploit the unique capabilities of the ESPaDOnS spectropolarimeter
to obtain critical missing information about the poorly-studied magnetic
properties of these important stars, to confront current models and to guide
theory.Comment: 6 pages, 3 figures, proceedings of IAUS 259: Cosmic Magnetic Field
Recommended from our members
Visualising gas heating from an RF plasma loudspeaker
In an electro-acoustic transduction mechanism, an ac modulation (here in the audio frequency range) of the electric field in an atmospheric pressure air plasma gives rise to a rapid increase in the gas temperature and dimensions of the gas volume. As in natural lightning, the rapid expansion in the ionised column though the air produces external pressure variations at the modulation frequency.
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Spatial and temporal measurement of the gas temperature can identify the nature of the thermal expansion and provide a direct approach to understanding its relationship to the sound pressure wave that is generated. However, the established method through spectroscopic measurement of rotational line emission from nitrogen molecules is limited to the main current channel where relaxation and subsequent optical emission of the excited nitrogen molecules occurs. The wider picture is revealed through the use of the Schlieren method where the refractive index gradients caused by gas heating in the plasma are imaged
Development and application of an indicator assessment tool for measuring health services accreditation programs
© 2015 Mumford et al. Background: Hospital accreditation programs are internationally widespread and consume increasingly scarce health resources. However, we lack tools to consistently identify suitable indicators to assess and monitor accreditation outcomes. We describe the development and validation of such a tool. Results: Using Australian accreditation standards as our reference point we: reviewed the research evidence for potential indicators; looked for links with existing external indicators; and assessed relevant state and federal policies. We allocated provisional scores, on a five point Likert scale, to the five accountability criteria in the tool: research; accuracy; proximity; no adverse effects; and specificity. An expert panel validated the use of the purpose designed indicator assessment tool. The panel identified hand hygiene compliance rates as a suitable process indicator, and hospital acquired Staphylococcus aureus infection (SAB) rates as an outcome indicator, with the hypothesis that improved hand hygiene compliance rates and lower SAB rates would correlate with accreditation performance. Conclusions: This new tool can be used to identify, analyse, and compare accreditation indicators. Using infection control indicators such as hand hygiene compliance and SAB rates to measure accreditation effectiveness has merit, and their efficacy can be determined by comparing accreditation scores with indicator outcomes. To verify the tool as a robust instrument, testing is needed in other health service domains, both in Australia and internationally. This tool provides health policy makers with an important means for assessing the accreditation programs which form a critical part of the national patient safety and quality framework
The aetiology of rickets-like lower limb deformities in Malawian children
Summary: Debilitating rickets-like lower limb deformities are common in children throughout the world, particularly in Malawi, Africa where the causes are unknown. We have identified that Blount disease and calcium deficiency rickets are the likely causes of these deformities and propose calcium supplementation as a potential treatment of Malawian rickets.
Introduction: Surgical correction of rickets-like lower limb deformities is the most common paediatric operation performed at Beit Cure Orthopaedic Hospital, Malawi. The aim of this study was to investigate the aetiology of these deformities.
Methods: Children with a tibio-femoral angle of deformity >20° were enrolled (n = 42, 3.0–15.0 years). Anthropometric and early life and well-being data were collected. Early morning serum and urine samples were collected on the morning of the operation for markers of calcium and phosphate homeostasis. Knee radiographs were obtained, and the children were diagnosed with either Blount (BD, n = 22) or evidence of rickets disease (RD, n = 20). As BD is a mechanical rather than metabolic disease, BD were assumed to be biochemically representative of the local population and thus used as a local reference for RD.
Results: There were no differences in anthropometry or early life experiences between BD and RD. Parathyroid hormone (PTH), 1,25-dihydroxyvitamin D, total alkaline phosphatase and urinary phosphate were significantly higher and serum phosphate, 25-hydroxyvitamin D (25OHD) and tubular maximal reabsorption of phosphate significantly lower in RD than BD. There was no difference in serum calcium, fibroblast growth factor 23 or markers of iron status between groups. All children had 25OHD > 25 nmol/L.
Conclusions: Vitamin D deficiency is not implicated in the aetiology of RD or BD in Malawian children. The cause of RD in Malawi is likely to be dietary calcium deficiency leading to elevated PTH resulting in increased losses of phosphate from the bone and glomerular filtrate. The causes of BD remain unclear; there was no evidence in support of previously suggested risk factors such as being overweight or starting to walk early. Prior to surgical intervention, supplementation with calcium should be considered for children with RD
Stakeholder perspectives on implementing accreditation programs: A qualitative study of enabling factors
Background: Accreditation programs are complex, system-wide quality and safety interventions. Despite their international popularity, evidence of their effectiveness is weak and contradictory. This may be due to variable implementation in different contexts. However, there is limited research that informs implementation strategies. We aimed to advance knowledge in this area by identifying factors that enable effective implementation of accreditation programs across different healthcare settings. Methods. We conducted 39 focus groups and eight interviews between 2011 and 2012, involving 258 diverse healthcare stakeholders from every Australian State and Territory. Interviews were semi-structured and focused on the aims, implementation and consequences of three prominent accreditation programs in the aged, primary and acute care sectors. Data were thematically analysed to distil and categorise facilitators of effective implementation. Results: Four factors were identified as critical enablers of effective implementation: the accreditation program is collaborative, valid and uses relevant standards; accreditation is favourably received by health professionals; healthcare organisations are capable of embracing accreditation; and accreditation is appropriately aligned with other regulatory initiatives and supported by relevant incentives. Conclusions: Strategic implementation of accreditation programs should target the four factors emerging from this study, which may increase the likelihood of accreditation being implemented successfully. © 2013 Hinchcliff et al.; licensee BioMed Central Ltd
CP and related phenomena in the context of Stellar Evolution
We review the interaction in intermediate and high mass stars between their
evolution and magnetic and chemical properties. We describe the theory of
Ap-star `fossil' fields, before touching on the expected secular diffusive
processes which give rise to evolution of the field. We then present recent
results from a spectropolarimetric survey of Herbig Ae/Be stars, showing that
magnetic fields of the kind seen on the main-sequence already exist during the
pre-main sequence phase, in agreement with fossil field theory, and that the
origin of the slow rotation of Ap/Bp stars also lies early in the pre-main
sequence evolution; we also present results confirming a lack of stars with
fields below a few hundred gauss. We then seek which macroscopic motions
compete with atomic diffusion in determining the surface abundances of AmFm
stars. While turbulent transport and mass loss, in competition with atomic
diffusion, are both able to explain observed surface abundances, the interior
abundance distribution is different enough to potentially lead to a test using
asterosismology. Finally we review progress on the turbulence-driving and
mixing processes in stellar radiative zones.Comment: Proceedings of IAU GA in Rio, JD4 on Ap stars; 10 pages, 7 figure
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