Implementation of Grootboom: Implications for the enforcement of socio--economic rights

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The origin of a1g_{1g} and eg_g' orderings in Nax_xCoO2_2

It has often been suggested that correlation effects suppress the small e_g' Fermi surface pockets of NaxCoO_2 that are predicted by LDA, but absent in ARPES measurements. It appears that within the dynamical mean field theory (DMFT) the ARPES can be reproduced only if the on-site energy of the eg' complex is lower than that of the a1g complex at the one-electron level, prior to the addition of local correlation effects. Current estimates regarding the order of the two orbital complexes range from -200 meV to 315 meV in therms of the energy difference. In this work, we perform density functional theory calculations of this one-electron splitting \Delta= \epsilon_a1g-\epsilon_e_g' for the full two-layer compound, Na2xCo2O4, accounting for the effects of Na ordering, interplanar interactions and octahedral distortion. We find that \epsilon a_1g-\epsilon e_g' is negative for all Na fillings and that this is primarily due to the strongly positive Coulomb field created by Na+ ions in the intercalant plane. This field disproportionately affects the a_1g orbital which protrudes farther upward from the Co plane than the e_g' orbitals. We discuss also the secondary effects of octahedral compression and multi-orbital filling on the value of \Delta as a function of Na content. Our results indicate that if the e_g' pockets are indeed suppressed that can only be due to nonlocal correlation effects beyond the standard DMFT.Comment: 4 pages, 3 figure

"The corporate university" training and learning solution for a South African airline industry.

The training and development of employees in the airline industry usually take place within a decentralized structure and may result in fragmented and costly initiatives. To improve the current practice a corporate university (CU) model to be implemented in the airline is proposed. For the purpose of the study qualitative interviews were held, human documents were studied and participant observation and the views of employees of the South African airline industry were sought regarding training in general and CUs in particular. The study revealed support for the CU concept because it would encourage continuous learning at all levels in the organisation and would place emphasis on both employee and organisational needs

Observations on the biochemical changes in gonads and other organs of Uca annulipes, Portunus pelagicus and Metapenaeus affinis (Decapoda: Crustacea) during the reproductive cycle

The fluctuations in biochemical constituents such as water, nitrogen, non-protein nitrogen, protein, lipid and glycogen in gonad, muscle and hepatopancreas have been followed in 3 decapod crustaceans, Uca annulipes (Latreille), Portunus pelagicus (Linnaeus) and Metapenaeus affinis (Milne-Edwards). The water and ash content of the entire body show no systematic fluctuation in relation to the annual reproductive cycle. The water content of the ovary diminishes as it matures. In the ovary of these crustaceans, the lipid fluctuated greatly in relation to the reproductive cycle. The maturing ovary contains more lipid than an immature or spent ovary per unit tissue weight. The changes in the biochemical constituents in the testis are not so pronounced as in the ovary, since the testicular cycle is often drawn-out and almost continuous in these crustaceans. There is an inverse relationship between water content and lipid content of the hepatopancreas; the greater the fat content, the lesser the water content. The hepatopancreas in these crustaceans is apparently a storage organ and contains much lipid and glycogen. At the height of the breeding season, when gonad production is intense, there is an indication of the mobilisation of at least a part of the lipid from hepatopancreas to gonad

Expression of DC-SIGN and DC-SIGNRs in placentas of HIV-positive patients

Background. Human dendritic cell-specific intracellular adhesion molecule-3 (ICAM3)-grabbing non-integrin (DC-SIGN) is a mannose-binding lectin that initiates interaction between dendritic cells and resting T-lymphocytes. DC-SIGN is highly expressed in placental tissue on dendritic cells and Hofbauer cells, and it is suggested that HIV may become adsorbed to DC-SIGN on Hofbauer cells as part of the mechanism of mother-to-child HIV transmission. A possible mechanism of transfer of the virus from the Hofbauer cells to the fetus is the subsequent adsorption to DC-SIGN-related molecules (DC-SIGNRs), present on immediately adjacent capillary vascular endothelium. However, data on DC-SIGN and DC-SIGNR expression in the placenta are few. Methods. Forty term placentas from HIV-positive mothers and 21 term placentas from HIV-negative mothers underwent immunohistochemistry staining for DC-SIGN and DC-SIGNR expression. Five random sets of 10 villi were assessed, and the average number of positive cells were counted in each case. In addition, where possible, maternal and cord blood viral loads and maternal CD4+ counts were performed in the HIV-positive group only. Results. The median maternal CD4+ count was 377 cells/μl and 27% of participants had undetectable viral loads; the median detectable viral load was 3.72 log. Most (97%) of the cord bloods tested in infants from HIV-positive mothers had lower than detectable viral loads. HIV-positive cases had significantly greater expression of both DC-SIGNRs (median values in HIV-positive cases, 14.5 positive cells/10 villi (pc/10villi), compared with 11 pc/10villi in HIV-negative cases, p=0.020) and DC-SIGN (median value in HIV-positive cases, 26.5 pc/10villi, compared with 23 pc/10villi in HIV-negative cases, p=0.037). DC-SIGNR expression was also noted in Hofbauer cells and decidual macrophages in addition to endothelium (reported currently). There was no difference in expression of DC-SIGN and DC-SIGNRs in patients with or without chorioamnionitis, but there was an inverse relationship between DC-SIGN and DC-SIGNR expression and maternal CD4+ counts in HIV-positive cases. Conclusion. Both DC-SIGN and DC-SIGNR expression were higher in placentas from HIV-positive mothers compared with HIV-negative cases. These lectins may be potential new therapeutic targets for preventing vertical transmission of HIV

A screening method for banana weevil (Cosmopolites sordidus Germar) resistance using reference genotypes

The banana weevil (Cosmopolites sordidus Germar) is a serious pest in most banana-growing areas of the world. Host-plant resistance is considered to be the most feasible and sustainable method for itscontrol. However, a quick and effective method for screening banana genotypes for resistance against the banana weevil to facilitate selection and/or development of resistant genotypes is lacking. The objective of the study was to develop an early screening method for weevil resistance by using a set of reference genotypes. Three susceptible genotypes (‘Atwalira’, ‘Namwezi’ and ‘Kibuzi’) and three resistant genotypes (‘Calcutta 4’, ‘Yangambi Km5’ and ‘TMB3x1968-2’) were used in screen-houseexperiments to assess weevil resistance/susceptibility. Healthy plantlets of the above genotypes were established in buckets in a screen house. Ten adult weevils (5 females and 5 males) were introduced at the base of each plant and the bucket was covered with a weevil-proof mesh. Weevil damage of the corms was estimated as a percentage at 35 and 60 days after the weevil introduction by estimating the peripheral and cross-section corm damage. The resistant genotypes had significantly lower (p < 0.05)peripheral and total cross-section corm damage, and less larvae than the susceptible genotypes. These results indicated that these genotypes can be used as reference genotypes in evaluating resistance or susceptibility against the banana weevil. These experiments were completed in five to seven months, depending on the source of planting material, as compared to field-screening experiments for the banana weevil that can take up to three or more years

A preliminary study of the effects of aircraft noise on families who reside in close proximity to an airport

Background: The use of air transportation has grown in the last century, escalating the noise exposure of families residing in close proximity to airports. The audiological effects need to be assessed to determine the impact of this increase on children and young adults living near to airports in South Africa. Method: Hearing patterns for these individuals were compared to those residing 30 km away from the airport. Sixty people, between the ages of 12-30 years, were assessed. Participants completed a questionnaire and were subjected to a diagnostic audiological test battery and tested using diagnostic distortion product otoacoustic emissions (DPOAEs). Results: Participants residing in close proximity to the airport presented with a notch configuration in the high frequencies, as opposed to those who lived further away. DPOAEs indicated a change in hearing in the high frequencies between the test populations. The positive relationship between the pure tone results and the DPOAEs strengthens the claim that aircraft noise has an effect on the hearing patterns of individuals living near to airports. Participants also experienced annoyance resulting from such noise. Conclusion: The results highlight the need for investigation into the hearing of individuals who reside in close proximity to airports. Comprehensive studies will be informative and beneficial to the field of audiology in South Africa. The highlighted health and safety issues require in-depth study to formulate a stronger argument for monitoring the hearing of families who are exposed to aircraft noise.Keywords: aircraft noise exposure, hearing patterns, distortion product otoacoustic emissions (DPOAEs