Universiẗat, Diss., 1999--Kaiserslautern.

Techn. Universiẗat, Diss., 2002--Clausthal.

We test the galactic outflow model by probing associated galaxies of four strong intergalactic C IV absorbers at z = 5-6 using the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) ramp narrowband filters. The four strong C IV absorbers reside at z = 5.74, 5.52, 4.95, and 4.87, with column densities ranging from N-C IV = 10(13.8) to 10(14.8) cm(-2). At z = 5.74, we detect an i-dropout Ly alpha emitter (LAE) candidate with a projected impact parameter of 42 physical kpc from the C IV absorber. This LAE candidate has a Ly alpha-based star formation rate (SFRLy alpha) of 2 M-circle dot yr(-1) and a UV-based SFR of 4 M-circle dot yr(-1). Although we cannot completely rule out that this i-dropout emitter may be an [O II] interloper, its measured properties are consistent with the C IV powered galaxy at z = 5.74. For C IV absorbers at z = 4.95 and z = 4.87, although we detect two LAE candidates with impact parameters of 160 and 200 kpc, such distances are larger than that predicted from the simulations. Therefore, we treat them as nondetections. For the system at z = 5.52, we do not detect LAE candidates, placing a 3 sigma upper limit of SFRLy alpha approximate to 1.5 M-circle dot yr(-1). In summary, in these four cases, we only detect one plausible C IV source at z = 5.74. Combining the modest SFR of the one detection and the three nondetections, our HST observations strongly support that smaller galaxies (SFRLy alpha less than or similar to 2 M-circle dot yr(-1)) are main sources of intergalactic C IV absorbers, and such small galaxies play a major role in the metal enrichment of the intergalactic medium at z greater than or similar to 5.

This research identified the critical success factors in the growth of small businesses in South Africa against the theories of small business growth. The study applied both quantitative and qualitative research methodology to identify which factors contributed most to the growth of the sample of 131 small businesses in Gauteng province. This was done by (1) identifying the mean characteristics of small businesses that had experienced their first disruption to growth after establishment, (2) identifying the dominant reasons for the growth challenges, (3) identifying the tools and/or actions employed to transgress the first challenge to growth and (4) comparing these actions to small businesses that had not experienced challenges to their growth. Small businesses facing growth challenges were found to be between one and three years old, have 36 staff, have sales revenue of R13,5 million and sales growing at 25% per annum. The most common mitigation tools and/or actions were to hire more staff, hire competent professional management, source external professional assistance in the form of a mentor and restructure reporting lines. This research found that the focus of small business development should focus on these types of businesses because of their propensity to grow faster and employ more staff. This study also emphasised the growth aspirations of the owner/ manager. Lastly a management model for small businesses was presented. / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

This body of research investigates the capability and propensity of a selection of inks and coatings manufacturing micro-, small- and medium enterprises, based in and around Cape Town in the Western Cape, to export product Academic literature reviewed emphasised the fact that the size of the organisation and the level of education resident in the organisation was an important enabler for the business to be export- ready. The evidence- based research conducted in this study found that networks linking businesses to concerns already involved in exporting was the greatest enabler. Previous export experience amongst the management certainly influenced the alacrity with which the business took to exporting (a matter of knowing the pitfalls and being able to mitigate risk beforehand). However, this was not a deterrent to entering the export market. A champion was needed to keep the export process on track The size of the business in now way impeded that business from exploiting the opportunities when they were presented. The academic literature reviewed also alluded to the poor skills available in the labour poor. The study found that businesses were able to work around these hindrances (not obstacles). The professional qualifications tended to be resident within the senior management team, which pulled the company through the exporting process. This has worked well in the short term. However it could prove a disabling factor in the long term if suitable qualified candidates could not be found to absorb and take on the running of the business after the incumbent management team leaves or retires. / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

No description available.

The problem under consideration is that of obtaining a representation of the permeability of a porous medium which is heterogeneous and anisotropic from limited information. To solve this inverse problem we propose the use of two different pieces that work together. A simulated annealing algorithm is presented and coupled with an homogenization technique; together these solve the problem which was posed. Further, numerical simulation results are presented illustrating the use of the simulated annealing algorithm as well as a coupling with the homoginization technique. This study illustrates that the performance of the annealing algorithm is enhanced with usage of homogenization.

Inconsistencies among testing methods and results in previous research prompted this study that builds upon a systematic usability testing research framework to better understand how interface medium influences users’ abilities to detect usability flaws in applications. Medium was tested to identify its effects on users’ perceptions of usability and abilities to detect usability problems and severe usability problems. Also explored was the relationship between users’ perceptions of usability and abilities to detect usability problems. Results indicated that medium has no effect on users’ abilities to detect usability problems or perceptions of usability. However, results did indicate an interaction between medium and the tested application in which users were able to identify significantly more usability problems on a higher fidelity medium using a particular application. Results also indicated that as users’ perceptions of an application’s usability increases, the users are less able to detect usability problems in that application.

This dissertation presents spectroscopic studies of gas in galaxy halos and large-scale structures through high-resolution quasar absorption lines. The broad goal of this effort is to learn how galaxies acquire their gas and how they return it to the intergalactic medium, or more generally, how galaxies interact with their environment. The study of the absorption lines due to the extraplanar 21cm "Outer Arm'' (OA) of the Milky Way toward two quasars, H1821+643 and HS0624+6907, provides valuable insight into the gas accretion processes. It yields the following results. (1) The OA is a multiphase cloud and high ions show small but significant offsets in velocity and are unlikely to be cospatial with the low ions. (2) The overall metallicity of the OA is Z=0.3-0.5 of the solar abundance, but nitrogen is underabundant. (3) The abundance of N, O, and S derived are roughly consistent with outer-galaxy emission-line abundances and the metallicity gradient derived from H II regions. The similarity of the OA kinematics to several nearby high velocity clouds (HVCs, e.g. Complexes C, G, and H) suggests that these clouds could be detritus from a merging satellite galaxy. To test this hypothesis, we build up a simple model including tidal tripping, ram-pressure stripping, and dynamical friction to consider whether the OA could be debris affiliated with the Monoceros Ring. Our model can roughly reproduce the spatial and velocity characteristics of the OA. Moreover, the metallicity of the OA is similar to the higher metallcities measured in the younger stellar components of the Monoceros Ring and the progenitor candidate, the CMa overdensity. However, both our model and the Galactic warp scenario can not explain other HVCs that are likely to be related to the OA. Instead of acquiring gas, some galaxies have their gas removed through various physical processes. Ram-pressure stripping and tidal interaction are important mechanisms for galaxies to loose their gas. The high-resolution spectrum of Mrk205 combined with H I 21 cm, CO emission, and infrared observations is utilized to study a unique transforming galaxy NGC4319. We find: (1) the object has lost most of its diffuse interstellar H I. (2) molecular hydrogen remains in the disk of the galaxy. The molecular hydrogen column density is low, but the molecular gas fraction is extraordinarily high. CO emission is also clearly detected, but only from the barred central region. (3) There is very little evidence of recent star formation in the galaxy. The results appears to match many of the predictions of Quilis et al. (2000), suggesting NGC4319 is undergoing a transformation from a spiral into an S0 due to ram-pressure stripping, possibly in tandem with tidal stripping. To understand the characteristics of gas (especially warm-hot intergalactic medium) in large scale structures, similar high resolution spectra of 31 quasars were selected based on the galaxy density showing in the 2MASS map. They provide a unbiased sample for the study of the correlation between O VI/H I absorbers and galaxies and 2MASS galaxy groups at low redshift (z<0.04). We totally discover 52 \lya\ absorbers and 7 O VI absorbers, and O VI is clearly detected using the stacking and "pixel optical depth'' techniques for nearby galaxies along the sightlines. It seems that the locations of the O VI absorbers do not correlated with the spacial distribution of large-scale structures manifested by galaxy groups, but more closely associated with individual galaxies. It indicates that the galactic winds and "feedback'' plays important role in polluting the IGM with O VI. Finally, we perform an extra investigation on the variable O VI and N V emission from the black hole binary LMC X-3 in our original absorption line study of the hot Galactic halo and the ISM of the LMC using LMC X-3 as a background source. We observe significant velocity and intensity variation in both O VI and N V emission. Their trends suggest that illumination of the B-star atmosphere by the intense X-ray emission from the accreting black hole creates a hot spot on one side of the B star, and this hot spot is the origin of the O VI and N V emission.

No description available.