The history of paediatric trauma care in Cape Town

Trauma is a leading cause of morbidity, mortality and disability in childhood. In most developed countries where 18% of the population are in the age group 0 - 15 years, injury exceeds all other causes of childhood mortality. In the developing countries of Africa, however, children aged 0 - 15 years constitute 43% of the population and trauma has an even bigger impact on child health.There is an erroneous perception that trauma is not a major health problem in Africa, derived from undue emphasis on mortality statistics alone. Yet, the impact of trauma ought to be measured not only in terms of death, but also the tremendous morbidity and disability caused by injuries, and their socioeconomic consequences

Unconventional magnetism in all-carbon nanofoam

We report production of nanostructured carbon foam by a high-repetition-rate, high-power laser ablation of glassy carbon in Ar atmosphere. A combination of characterization techniques revealed that the system contains both sp2 and sp3 bonded carbon atoms. The material is a novel form of carbon in which graphite-like sheets fill space at very low density due to strong hyperbolic curvature, as proposed for ?schwarzite?. The foam exhibits ferromagnetic-like behaviour up to 90 K, with a narrow hysteresis curve and a high saturation magnetization. Such magnetic properties are very unusual for a carbon allotrope. Detailed analysis excludes impurities as the origin of the magnetic signal. We postulate that localized unpaired spins occur because of topological and bonding defects associated with the sheet curvature, and that these spins are stabilized due to the steric protection offered by the convoluted sheets.Comment: 14 pages, including 2 tables and 7 figs. Submitted to Phys Rev B 10 September 200

Ablation of solids by femtosecond lasers: ablation mechanism and ablation thresholds for metals and dielectrics

The mechanism of ablation of solids by intense femtosecond laser pulses is described in an explicit analytical form. It is shown that at high intensities when the ionization of the target material is complete before the end of the pulse, the ablation mechanism is the same for both metals and dielectrics. The physics of this new ablation regime involves ion acceleration in the electrostatic field caused by charge separation created by energetic electrons escaping from the target. The formulae for ablation thresholds and ablation rates for metals and dielectrics, combining the laser and target parameters, are derived and compared to experimental data. The calculated dependence of the ablation thresholds on the pulse duration is in agreement with the experimental data in a femtosecond range, and it is linked to the dependence for nanosecond pulses.Comment: 27 pages incl.3 figs; presented at CLEO-Europe'2000 11-15 Sept.2000; papers QMD6 and CTuK11

A cross-cultural examination of the relationships among human resource management practices and organisational commitment: an institutional collectivism perspective

Previous research has shown that human resource management (HRM) practices vary across cultures. However, little research has empirically compared the effects of various HRM practices on firm-level or individual-level outcome variables across cultures. Drawing upon psychological contract theory and the literature on cultural values, the present study examined the effects of three organisational-level HRM practices on individual organisational commitment in a survey of 2424 individuals in 120 organisations located in four countries and three industries. Based upon the GLOBE study, we classified the four countries into two groups – high versus low institutional collectivism. The results of our hierarchical linear modelling (HLM) analyses found significant differences in the effects of organisational-level HRM on individual organisational commitment across cultures for two of the three HRM practices included in our model: training and teamwork. We also found partial support for differences across cultures for the effects of the third HRM practice: employee involvement in decision making. Overall, our results support the utility of theoretical and empirical models that address multiple levels of analyses to better understand the mechanisms through which the HRM-performance link takes place across national cultures

Application of two phosphorus models with different complexities in a mesoscale river catchment

The water balance and phosphorus inputs of surface waters of the Weiße Elster catchment, Germany, have been quantified using the models GROWA/MEPhos and SWAT. A comparison of the model results shows small differences in the mean long-term total runoff for the entire study area. All relevant pathways of phosphorus transport were considered in MEPhos with phosphorus inputs resulting to about 65% from point sources. SWAT focuses on agricultural areas and estimates a phosphorus input of about 60% through erosion. The mean annual phosphorus input from erosion calculated with SWAT is six times higher than the estimation with MEPhos due to the differing model concepts. This shows the uncertainty contributed by the modelling description of phosphorus pathways

Integrating water quality models in the High Level Architecture (HLA) environment

International audienceHLA (High Level Architecture) is a computer architecture for constructing distributed simulations. It facilitates interoperability among different simulations and simulation types and promotes reuse of simulation software modules. The core of the HLA is the Run-Time Infrastructure (RTI) that provides services to start and stop a simulation execution, to transfer data between interoperating simulations, to control the amount and routing of data that is passed, and to co-ordinate the passage of simulated time among the simulations. The authors are not aware of any HLA applications in the field of water resources management. The development of such a system is underway at the UFZ -Centre for Environmental Research, Germany, in which the simulations of a hydrodynamic model (DYNHYD), eutrophication model (EUTRO) and sediment and micro-pollutant transport model (TOXI) are interlinked and co-ordinated by the HLA RTI environment. This configuration enables extensions such as (i) "cross-model" uncertainty analysis with Monte Carlo Analysis: time synchronisation allows EUTRO and TOXI simulations to be made after each successive simulation time step in DYNHYD, (ii) information transfer from EUTRO to TOXI to compute organic carbon fractions of particulate matter in TOXI, (iii) information transfer from TOXI to EUTRO to compute extinction coefficients in EUTRO and (iv) feedback from water quality simulations to the hydrodynamic modeling