A near-infrared study of the star forming region RCW 34

We report the results of a near-infrared imaging study of a $7.8 \times 7.8$ arcmin$^2$ region centered on the 6.7 GHz methanol maser associated with the RCW 34 star forming region using the 1.4m IRSF telescope at Sutherland. A total of 1283 objects were detected simultaneously in J, H, and K for an exposure time of 10800 seconds. The J-H, H-K two-colour diagram revealed a strong concentration of more than 700 objects with colours similar to what is expected of reddened classical T Tauri stars. The distribution of the objects on the K {\it vs} J-K colour-magnitude diagram is also suggestive that a significant fraction of the 1283 objects is lower mass pre-main sequence stars. We also present the luminosity function for the subset of about 700 pre-main sequence stars and show that it suggests ongoing star formation activity for about $10^7$ years. An examination of the spatial distribution of the pre-main sequence stars shows that the fainter (older) part of the population is more dispersed over the observed region and the brighter (younger) subset is more concentrated around the position of the O8.5V star. This suggests that the physical effects of the O8.5V star and the two early B-type stars on the remainder of the cloud out of which they formed, could have played a role in the onset of the more recent episode of star formation in RCW 34.Comment: Accepted for publication in The Astronomical Journa

Optometric management of the pterygium

Optometric management of the pterygiu

Dr. H.J. van der Bijl se filosofiese denkraamwerk - ’n histories-fllosofiese oorsig

The philosophical cognitive framework of dr. H.J. van der Bijl - a historicphilosophical overview The great achievements of H.J. van der Bijl on the industrial scene in South Africa as a whole and in Vanderbijlpark in particular are widely known. What is less commonly known is that the vision and ideals on which these achievements are based, are grounded in the humanist-scientistic philosophy of the Renaissance a n d the Enlightenment. From a Christian-Reformational point of view it will be a rgued that the deepest ideals of Van der Bijl were never realised, and can never be realised. From a Reformational point of view the basic reason why Van der B ijl’s ideals were not realised, is to be found in a lack of a biblically orientated life a n d worldview, and especially a biblically orientated anthropology. Because of his scientism Van der Bijl overrated human abilities to create an utopia on the basis of scientific knowledge and he underrated the effect o f sin on human nature. Van der Bijl also ignored God’s will for humanity and society; he judged the human being as autonomous and ignored the fact that man is merely a steward of God's properly and not the owner

‘Doing’ health policy analysis: methodological and conceptual reflections and challenges

The case for undertaking policy analysis has been made by a number of scholars and practitioners. However, there has been much less attention given to how to do policy analysis, what research designs, theories or methods best inform policy analysis. This paper begins by looking at the health policy environment, and some of the challenges to researching this highly complex phenomenon. It focuses on research in middle and low income countries, drawing on some of the frameworks and theories, methodologies and designs that can be used in health policy analysis, giving examples from recent studies. The implications of case studies and of temporality in research design are explored. Attention is drawn to the roles of the policy researcher and the importance of reflexivity and researcher positionality in the research process. The final section explores ways of advancing the field of health policy analysis with recommendations on theory, methodology and researcher reflexivity

Controlled epitaxial graphene growth within amorphous carbon corrals

Structured growth of high quality graphene is necessary for technological development of carbon based electronics. Specifically, control of the bunching and placement of surface steps under epitaxial graphene on SiC is an important consideration for graphene device production. We demonstrate lithographically patterned evaporated amorphous carbon corrals as a method to pin SiC surface steps. Evaporated amorphous carbon is an ideal step-flow barrier on SiC due to its chemical compatibility with graphene growth and its structural stability at high temperatures, as well as its patternability. The amorphous carbon is deposited in vacuum on SiC prior to graphene growth. In the graphene furnace at temperatures above 1200$^\circ$C, mobile SiC steps accumulate at these amorphous carbon barriers, forming an aligned step free region for graphene growth at temperatures above 1330$^\circ$C. AFM imaging and Raman spectroscopy support the formation of quality step-free graphene sheets grown on SiC with the step morphology aligned to the carbon grid

Direct NN-body code on low-power embedded ARM GPUs

This work arises on the environment of the ExaNeSt project aiming at design and development of an exascale ready supercomputer with low energy consumption profile but able to support the most demanding scientific and technical applications. The ExaNeSt compute unit consists of densely-packed low-power 64-bit ARM processors, embedded within Xilinx FPGA SoCs. SoC boards are heterogeneous architecture where computing power is supplied both by CPUs and GPUs, and are emerging as a possible low-power and low-cost alternative to clusters based on traditional CPUs. A state-of-the-art direct $N$-body code suitable for astrophysical simulations has been re-engineered in order to exploit SoC heterogeneous platforms based on ARM CPUs and embedded GPUs. Performance tests show that embedded GPUs can be effectively used to accelerate real-life scientific calculations, and that are promising also because of their energy efficiency, which is a crucial design in future exascale platforms.Comment: 16 pages, 7 figures, 1 table, accepted for publication in the Computing Conference 2019 proceeding

The 2008 Super Tuesday Tornado Outbreak: Synthetic Dual Doppler Analysis of Contrasting Tornadic Storm Types

During the Super Tuesday Tornado Outbreak on 5-6 February, a significant number of storms passed within about 40 km of WSR-88D radars. This distance, combined with the significant motion vector (from the southwest at 20-25 m per second) of relatively steady storms, is amenable to a synthetic dual Doppler analysis during the times when the storms passed the WSR-88D locations. Nine storms will be analyzed using the SDD technique. The following table provides their general characteristics and nearest approach to the 88D radars. For this data set, storm structure ranges from isolated supercell to QLCS. Each storm will be analyzed for a 40-60 min period during passage by the WSR-88D radar to determine general storm properties. Analysis of high-resolution single Doppler data around the time of passage (plus or minus 30 min), combined with 1-2 SDD analyses, will be used to examine the kinematic structure of low-level circulations (e.g., mesocyclone, downdraft) and the relation to the parent storm. This analysis may provide insights on the fundamental differences between cyclonic circulations in supercell storms and those within QCLS's

Electronic Cooling via Interlayer Coulomb Coupling in Multilayer Epitaxial Graphene

In van der Waals bonded or rotationally disordered multilayer stacks of two-dimensional (2D) materials, the electronic states remain tightly confined within individual 2D layers. As a result, electron-phonon interactions occur primarily within layers and interlayer electrical conductivities are low. In addition, strong covalent in-plane intralayer bonding combined with weak van der Waals interlayer bonding results in weak phonon-mediated thermal coupling between the layers. We demonstrate here, however, that Coulomb interactions between electrons in different layers of multilayer epitaxial graphene provide an important mechanism for interlayer thermal transport even though all electronic states are strongly confined within individual 2D layers. This effect is manifested in the relaxation dynamics of hot carriers in ultrafast time-resolved terahertz spectroscopy. We develop a theory of interlayer Coulomb coupling containing no free parameters that accounts for the experimentally observed trends in hot-carrier dynamics as temperature and the number of layers is varied.Comment: 54 pages, 15 figures, uses documentclass{achemso}, M.T.M. and J.R.T. contributed equally to this wor