The Macroeconomic Impact of Skilled Emigration from South Africa: A CGE Analysis

South Africa faces the dual problem of large inflows of illegal immigrants and outflows of skilled emigrants. This situation potentially has serious implications for the domestic labour market and economy as a whole. In this paper we measure the impact of skilled emigration and the subsequent loss in primary factor productivity on the South African economy using a dynamic computable general equilibrium (CGE) model. Results indicate that skilled emigration in the absence of any programmes to counter this flow of workers has a generally negative effect on the economy. Industries with the greatest exposure to the investment and export sectors as well as those with the highest concentration of skilled workers are shown to be most affected. We also use simple and intuitive back-of-the-envelope equations to enhance our understanding of the mechanisms driving the model’s macroeconomic results. These results justify the government’s current efforts to retain and attract skilled labour as part of the ASGISA framework.

Multilayer infrared beamsplitter film system

Multilayer infrared beamsplitter film system on a potassium bromide crystal substrate is operational over a wavelength range of 2.5 to 25 microns with nearly equal broadband reflectance and transmittance. It is useful in optical coating, vacuum deposition, radiometry, interferometry, and spectrometry

Persistent currents in continuous one-dimensional disordered rings within the Hartree--Fock approximation

We present numerical results for the zero temperature persistent currents carried by interacting spinless electrons in disordered one dimensional continuous rings. The disorder potential is described by a collection of delta-functions at random locations and strengths. The calculations are performed by a self-consistent Hartree-Fock (H-F) approximation. Because the H-F approximation retains the concept of single-electron levels, we compare the statistics of energy levels of noninteracting electrons with those of interacting electrons as well as of the level persistent currents. We find that the e-e interactions alters the levels and samples persistent currents and introduces a preffered diamagnetic current direction. In contrast to the analogous calculations that recently appeared in the literature for interacting spinless electrons in the presence of moderate disorder in tight-binding models we find no suppression of the persistent currents due to the e-e interactions.Comment: 10 RevTex pages including 11 figures, minor updated ref'

An assessment of sphere drag coefficient data

Wind tunnel test data for falling sphere drag coefficient determinatio

High-speed ultrasound imaging in dense suspensions reveals impact-activated solidification due to dynamic shear jamming

A remarkable property of dense suspensions is that they can transform from liquid-like at rest to solid-like under sudden impact. Previous work showed that this impact-induced solidification involves rapidly moving jamming fronts; however, details of this process have remained unresolved. Here we use high-speed ultrasound imaging to probe non-invasively how the interior of a dense suspension responds to impact. Measuring the speed of sound we demonstrate that the solidification proceeds without a detectable increase in packing fraction, and imaging the evolving flow field we find that the shear intensity is maximized right at the jamming front. Taken together, this provides direct experimental evidence for jamming by shear, rather than densification, as driving the transformation to solid-like behavior. Based on these findings we propose a new model to explain the anisotropy in the propagation speed of the fronts and delineate the onset conditions for dynamic shear jamming in suspensions.Comment: 9 pages, 3 figure

High efficiency optical beamsplitter designed for operation in the infrared region

Beamsplitter system uses potassium bromide as substrate for operating in the spectral region between 5 and 30 microns and calcium fluoride for narrowband applications. It uses a 13-layer film which yields nearly equal broadband infrared reflectance and transmittance

Magnetic relaxation in metallic films: Single and multilayer structures

The intrinsic magnetic relaxations in metallic films will be discussed. It will be shown that the intrinsic damping mechanism in metals is caused by incoherent scattering of itinerant electron-hole pair excitations by phonons and magnons. Berger [L. Berger, Phys. Rev. B 54, 9353 (1996)] showed that the interaction between spin waves and itinerant electrons in multilayers can lead to interface Gilbert damping. Ferromagnetic resonance (FMR) studies were carried out using magnetic single and double layer films. The FMR linewidth of the Fe films in the double layer structures was found to always be larger than the FMR linewidth measured for the single Fe films having the same thickness. The increase in the FMR linewidth scaled inversely with the film thickness, and was found to be linearly dependent on the microwave frequency. These results are in agreement with Berger's predictions. (C) 2002 American Institute of Physics

Role of dynamic capsomere supply for viral capsid self-assembly

Many viruses rely on the self-assembly of their capsids to protect and transport their genomic material. For many viral systems, in particular for human viruses like hepatitis B, adeno or human immunodeficiency virus, that lead to persistent infections, capsomeres are continuously produced in the cytoplasm of the host cell while completed capsids exit the cell for a new round of infection. Here we use coarse-grained Brownian dynamics simulations of a generic patchy particle model to elucidate the role of the dynamic supply of capsomeres for the reversible self-assembly of empty T1 icosahedral virus capsids. We find that for high rates of capsomere influx only a narrow range of bond strengths exists for which a steady state of continuous capsid production is possible. For bond strengths smaller and larger than this optimal value, the reaction volume becomes crowded by small and large intermediates, respectively. For lower rates of capsomere influx a broader range of bond strengths exists for which a steady state of continuous capsid production is established, although now the production rate of capsids is smaller. Thus our simulations suggest that the importance of an optimal bond strength for viral capsid assembly typical for in vitro conditions can be reduced by the dynamic influx of capsomeres in a cellular environment.Comment: Revtex, 26 pages, 7 EPS figure