2,153 research outputs found
An evaluation of management measures to control invasive organisms during annual takeovers at sub-Antarctic Marion island
Opening the doors of learning: Increasing access to music degrees
This article is contextualized for Music and is a response to the CHE (2013) Report that proposes a flexible curriculum structure for undergraduate degrees in South Africa, to address student under preparedness. Research states that music graduates need well developed identities in music, as well as generic, transferable skills to ensure lifelong employment and that a bachelor of music degree is best suited for this. However, in the South African context, the bachelor of music degree qualification is not accessible to the majority of prospective students as they are under prepared to study music at tertiary level. Only a minority of learners receive quality music education at school, while the majority of learners, including those from low socio-economic communities, do not receive formal music education. Under preparedness to study music, has traditionally been addressed through certificates and diploma qualifications in music. A discussion, and interpretation of the literature, has led to the researcher to develop an alternate framework to both improve student access to music degrees and manage under preparedness. The proposed approach advocates that music departments at universities adopt the framework of the national certificate vocation as an alternative to certificates and diplomas. The alternative curriculum structure for music, would be a more cost effective way to address under preparedness, improve academic success and lead to high skill levels.
The study is situated in a constructivist, interpretive worldview, with a qualitative research design. Purposive sampling in the form of the choice of literature for the theoretical framework was adopted. While this theoretical study is contextualized for music, it is applicable to other fields
Application of the Cubed-Sphere Grid to Tilted Black-Hole Accretion Disks
In recent work we presented the first results of global general relativistic
magnetohydrodynamic (GRMHD) simulations of tilted (or misaligned) accretion
disks around rotating black holes. The simulated tilted disks showed dramatic
differences from comparable untilted disks, such as asymmetrical accretion onto
the hole through opposing "plunging streams" and global precession of the disk
powered by a torque provided by the black hole. However, those simulations used
a traditional spherical-polar grid that was purposefully underresolved along
the pole, which prevented us from assessing the behavior of any jets that may
have been associated with the tilted disks. To address this shortcoming we have
added a block-structured "cubed-sphere" grid option to the Cosmos++ GRMHD code,
which will allow us to simultaneously resolve the disk and polar regions. Here
we present our implementation of this grid and the results of a small suite of
validation tests intended to demonstrate that the new grid performs as
expected. The most important test in this work is a comparison of identical
tilted disks, one evolved using our spherical-polar grid and the other with the
cubed-sphere grid. We also demonstrate an interesting dependence of the
early-time evolution of our disks on their orientation with respect to the grid
alignment. This dependence arises from the differing treatment of current
sheets within the disks, especially whether they are aligned with symmetry
planes of the grid or not.Comment: 15 pages, 11 figures, submitted to Ap
GRMHD prediction of coronal variability in accreting black holes
On the basis of data from an energy-conserving 3D general relativistic MHD
simulation, we predict the statistical character of variability in the coronal
luminosity from accreting black holes. When the inner boundary of the corona is
defined to be the electron scattering photosphere, its location depends only on
the mass accretion rate in Eddington units (\dot{M}). Nearly independent of
viewing angle and \dot{M}, the power spectrum over the range of frequencies
from approximately the orbital frequency at the innermost stable circular orbit
(ISCO) to ~100 times lower is well approximated by a power-law with index -2,
crudely consistent with the observed power spectra of hard X-ray fluctuations
in AGN and the hard states of Galactic binary black holes. The underlying
physical driver for variability in the light curve is variations in the
accretion rate caused by the chaotic character of MHD turbulence, but the power
spectrum of the coronal light output is significantly steeper. Part of this
contrast is due to the fact that the mass accretion rate can be significantly
modulated by radial epicyclic motions that do not result in dissipation, and
therefore do not drive luminosity fluctuations. The other part of this contrast
is due to the inward decrease of the characteristic inflow time, which leads to
decreasing radial coherence length with increasing fluctuation frequency.Comment: Accepted for publication in ApJ, 35 pages, 11 figures (8 color and 3
greyscale), AASTEX. High-resolution versions can be found at the following
links: [PS] http://www.pha.jhu.edu/~scn/papers/grmhd_var.ps [PDF]
http://www.pha.jhu.edu/~scn/papers/grmhd_var.pd
The use of the road to health card in monitoring child health
Objectives:
The Road to Health Chart (RTHC) provides a simple, cheap, practical and convenient method of monitoring child health. The RTHC could assist with vaccine compliance and early identification of growth faltering, to improve general health. The purpose of the study was to assess whether the RTHCs were adequately completed and interpreted at primary, secondary and tertiary care levels in South Africa.
Methods:
The study was carried out at a primary, secondary and tertiary care centre. A questionnaire was administered to 100 subjects from each; seeking demographic information, whether the RTHC was brought along, and if not why it was not brought.
Results:
Most children were brought by their mothers. The RTHC was not brought to 48% of the consultations; of those, about 72% thought that bringing the RTHC along was not necessary. Health workers seldom asked to see the RTHC at the primary and secondary care settings, but 50% of them did so at Ga-Rankuwa Hospital (p = 0,002). In only 8 cases overall were the children below the 3rd percentile of weight-for-age. Approximately 20% had incomplete immunisations.
Conclusions: Many parents believe that the RTHC is only required for Well-baby-clinic visits, not for consultations. The RTHC is not often asked for at consultations; the fact that this is more often done at the tertiary care centre may be that much of the service is supplied by paediatricians-in-training. Health workers should ask to see the RTHC, in order for mothers to understand the importance of the information. The study showed that the RTHC is not used to its full potential.
South African Family Practice Vol. 49 (1) 2007: pp. 1
Books
Neurobiology Neurobiology: 2 ed. Ed. by Gordon M. Shepherd. Pp. xiv + 689. Illustrared. R74,50. Oxford: Oxford Universiry Press. 1988.Medical physiology Textbook of Medical Physiology. Ed. by A. C. Guyton. Pp. xli + 1014. Illustrated. Kent: Harcourt, Brace, Jovanovich. 1991.Bilingual heart and stress booklets The Healthy HeartlDie Gesonde Hart. Ed. by G. Jackson. Coping with Stress/Oorwin Stres. Ed. by T. Trauer. pp. 77. Illustrated. RI9,95. Cape Town: Tafelberg. 1990
Global General Relativistic Magnetohydrodynamic Simulations of Accretion Tori
This paper presents an initial survey of the properties of accretion flows in
the Kerr metric from three-dimensional, general relativistic
magnetohydrodynamic simulations of accretion tori. We consider three fiducial
models of tori around rotating, both prograde and retrograde, and nonrotating
black holes; these three fiducial models are also contrasted with axisymmetric
simulations and a pseudo-Newtonian simulation with equivalent initial
conditions to delineate the limitations of these approximations.Comment: Submitted to ApJ. 30 pages, 21 figures. Animations and
high-resolution version of figures available at
http://www.astro.virginia.edu/~jd5
B4GALNT2 and xenotransplantation: A newly appreciated xenogeneic antigen
Analysis of non-Gal antibody induced after pig-to-baboon cardiac xenotransplantation identified the glycan produced by porcine beta-1,4-N-acetyl-galactosaminyltransferase 2 (B4GALNT2) as an immunogenic xenotransplantation antigen. The porcine B4GALNT2 enzyme is homologous to the human enzyme, which synthesizes the human SDa blood group antigen. Most humans produce low levels of anti-SDa IgM which polyagglutinates red blood cells from rare individuals with high levels of SDa expression. The SDa glycan is also present on GM2 gangliosides. Clinical GM2 vaccination studies for melanoma patients suggest that a human antibody response to SDa can be induced. Expression of porcine B4GALNT2 in human HEK293 cells results in increased binding of anti-SDa antibody and increased binding of Dolichos biflorus agglutinin (DBA), a lectin commonly used to detect SDa. In pigs, B4GALNT2 is expressed by vascular endothelial cells and endothelial cells from a wide variety of pig backgrounds stain with DBA, suggesting that porcine vascular expression of B4GALNT2 is not polymorphic. Mutations in B4GALNT2 have been engineered in mice and pigs. In both species, the B4GALNT2-KO animals are apparently normal and no longer show evidence of SDa antigen expression. Pig tissues with a mutation in B4GALNT2, added to a background of alpha-1,3-galactosyltransferase deficient (GGTA1-KO) and cytidine monophosphate-N-acetylneuraminic acid hydroxylase deficient (CMAH-KO), show reduced antibody binding, confirming the presence of B4GALNT2-dependent antibodies in both humans and non-human primates. Preclinical xenotransplantation using B4GALNT2-deficient donors has recently been reported. Elimination of this source of immunogenic pig antigen should minimize acute injury by preformed anti-pig antibody and eliminate an induced clinical immune response to this newly appreciated xenotransplantation antigen
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