Vroee woordelyste en woordeboeke in verband met Afrikaans

Die begin van die professionele leksikografie in Suid-Afrika kan teruggevoer word na 1926 toe prof. J.J. Smith amptelik met die werk aan Die Afri/caanse Woordeboek Gater ook bekend as die Woordeboek mn die Afrikaanse Taal) begin het. In hierdie artikel word daar ingegaan op die stand van die Afrikaanse leksikografie teen daardie tyd en op die Afrikaanse en voor-Afrikaanse woordelyste en woordeboeke wat voor 1926 verskyn het. Werke wat van 1844 tot 1925 gepubliseer is, word bespreek. Van die vroee leksikografiese baanbrekers was Nederlanders wat hulle in Suid-Afrika gevestig het. Hulle werk het nog 'n sterk Nederlandse karakter gehad. Eers deur die invloed van die sogenaamde Tweede Afrikaanse Taalbeweging nil 1905 en die werk van die ZuidAfrikaanse Akademie voor Taal, Letteren en Kunst wat in 1909 tot stand gekom het, is die Afrikaanse leksikografiese produkte in 'n groot mate van hierdie Nederlandse inslag ges.,uwer. Teen 1926 was die grondslag van 'n leksikografiese tradisie in Suid-Afrika gele, maar die Afrikaanse verk1arende leksikografie was nog 'n onbekende en onverkende terrein.Sleutelwoorde: afrikaans, vroee woordelyste en woordeboeke, professionele leksikografi

Hadronic parity violation and neutron capture reactions

The hadronic weak interaction remains one of the most poorly understood sectors of the Standard Model; for obvious reasons. On the one hand, the initial and final states involve strongly bound systems of particles, for which the theoretical description (e.g. QCD) is insufficient itself and all of the current alternative or hybrid approaches are phenomenological and therefore depend on experimental input. On the other hand, experimental tests are notoriously difficult because the weak interaction observables are suppressed by the strong interaction and very high statistics measurements are needed to reach a meaningful accuracy, which in turn requires tight control of systematic uncertainties. All of this is true for both strangeness-conserving (ΔS = 0) and strangeness-changing (ΔS = 1) nonleptonic interactions. In the former category, new high intensity neutron facilities and the experiments that are proposed or are in preparation there promise sensitivities that could finally see non-zero parity violating (PV) effects in systems that have a theoretically clean interpretation. This paper provides a brief description of the physics issues and various models and introduces a few experimental efforts that are currently underway

A reduced coupled-mode description for the electron-ion energy relaxation in dense matter

We present a simplified model for the electron-ion energy relaxation in dense two-temperature systems that includes the effects of coupled collective modes. It also extends the standard Spitzer result to both degenerate and strongly coupled systems. Starting from the general coupled-mode description, we are able to solve analytically for the temperature relaxation time in warm dense matter and strongly coupled plasmas. This was achieved by decoupling the electron-ion dynamics and by representing the ion response in terms of the mode frequencies. The presented reduced model allows for a fast description of temperature equilibration within hydrodynamic simulations and an easy comparison for experimental investigations. For warm dense matter, both fluid and solid, the model gives a slower electron-ion equilibration than predicted by the classical Spitzer result

All-optical formation of a Bose-Einstein condensate for applications in scanning electron microscopy

We report on the production of a F=1 spinor condensate of 87Rb atoms in a single beam optical dipole trap formed by a focused CO2 laser. The condensate is produced 13mm below the tip of a scanning electron microscope employing standard all-optical techniques. The condensate fraction contains up to 100,000 atoms and we achieve a duty cycle of less than 10s.Comment: 5 pages, 4 figure

Probing the hydrogen melting line at high pressures by dynamic compression

We investigate the capabilities of dynamic compression by intense heavy ion beams to yield information about the high pressure phases of hydrogen. Employing ab initio simulations and experimental data, a new wide range equation of state for hydrogen is constructed. The results show that the melting line up to its maximum as well as the transition from molecular fluids to fully ionized plasmas can be tested with the beam parameters soon to be available. We demonstrate that x-ray scattering can distinguish between phases and dissociation states

Quantitative adsorbate structure determination under catalytic reaction conditions

Current methods allow quantitative local structure determination of adsorbate geometries on surfaces in ultrahigh vacuum (UHV) but are incompatible with the higher pressures required for a steady-state catalytic reactions. Here we show that photoelectron diffraction can be used to determine the structure of the methoxy and formate reaction intermediates during the steady-state oxidation of methanol over Cu(110) by taking advantage of recent instrumental developments to allow near-ambient pressure x-ray photoelectron spectroscopy. The local methoxy site differs from that under static UHV conditions, attributed to the increased surface mobility and dynamic nature of the surface under reaction conditions

Structure of strongly coupled, multi-component plasmas

We investigate the short-range structure in strongly coupled fluidlike plasmas using the hypernetted chain approach generalized to multicomponent systems. Good agreement with numerical simulations validates this method for the parameters considered. We found a strong mutual impact on the spatial arrangement for systems with multiple ion species which is most clearly pronounced in the static structure factor. Quantum pseudopotentials were used to mimic diffraction and exchange effects in dense electron-ion systems. We demonstrate that the different kinds of pseudopotentials proposed lead to large differences in both the pair distributions and structure factors. Large discrepancies were also found in the predicted ion feature of the x-ray scattering signal, illustrating the need for comparison with full quantum calculations or experimental verification