Decoherence due to elastic Rayleigh scattering

We present theoretical and experimental studies of the decoherence of hyperfine ground-state superpositions due to elastic Rayleigh scattering of light off-resonant with higher lying excited states. We demonstrate that under appropriate conditions, elastic Rayleigh scattering can be the dominant source of decoherence, contrary to previous discussions in the literature. We show that the elastic-scattering decoherence rate of a two-level system is given by the square of the difference between the elastic-scattering \textit{amplitudes} for the two levels, and that for certain detunings of the light, the amplitudes can interfere constructively even when the elastic scattering \textit{rates} from the two levels are equal. We confirm this prediction through calculations and measurements of the total decoherence rate for a superposition of the valence electron spin levels in the ground state of $^9$Be$^+$ in a 4.5 T magnetic field.Comment: 5 pages, 3 figure

A Survey of the quality of nursing care in several health districts in South Africa.

BACKGROUND: South Africa is currently focusing strongly on human resource development. The purpose of this study was to describe and compare the quality of nursing service and care in three health districts in the KwaZulu Natal Province. To identify deficiencies which could be addressed by education and training, it might be useful to measure the quality of care given by nurses. METHODS: From March to August 2002 a survey was done in six hospitals and six clinics in three health districts of the KwaZulu-Natal province of South Africa. Five different aspects of care was evaluated; hand-over from one nursing shift to another, implementation of universal precautions, patient satisfaction, nursing records, management of chronic illnesses. All these aspects were evaluated using checklists based on record reviews or direct observation, except for patient satisfaction, which was evaluated by questionnaires. RESULTS: The average scores on the different aspects varied from 11% (for nursing records) to 73% (for management of chronic diseases). Specific problems became evident. In one district three out of four hand-overs between shifts of nurses scored less than 50%. In all three districts the use of protective gear scored low (43%). While the average score for management of chronic illnesses were high at 73%, the blood pressures of only 23% was within the target range, and the blood sugar of only 38% of patients were controlled. Patient satisfaction averaged 72% across the three districts. CONCLUSION: The quality of care measurements identified specific training needs, but other management strategies are probably also indicated

Trapped-ion probing of light-induced charging effects on dielectrics

We use a string of confined $^{40}$Ca$^+$ ions to measure perturbations to a trapping potential which are caused by light-induced charging of an anti-reflection coated window and of insulating patches on the ion-trap electrodes. The electric fields induced at the ions' position are characterised as a function of distance to the dielectric, and as a function of the incident optical power and wavelength. The measurement of the ion-string position is sensitive to as few as $40$ elementary charges per $\sqrt{\mathrm{Hz}}$ on the dielectric at distances of order millimetres, and perturbations are observed for illumination with light of wavelengths as long as 729\,nm. This has important implications for the future of miniaturised ion-trap experiments, notably with regards to the choice of electrode material, and the optics that must be integrated in the vicinity of the ion. The method presented can be readily applied to the investigation of charging effects beyond the context of ion trap experiments.Comment: 11 pages, 5 figure

English medium of instruction: A situation analysis

The majority of learners in southern Africa receive their education through the medium of a second language, English. Although teachers of English play a crucial role in helping learners to acquire language skills in the medium of instruction, we argue that subject content teachers' lack of attention to the teaching of the four language skills may be a raison d'être for learners' lack of academic achievement. A situation analysis conducted among three study populations examined the extent to which subject content teachers took responsibility for the teaching of language skills in the content classroom, as well as possible reasons for not doing so. It also shed some light on the amount of language teaching that actually took place in a content classroom. The aim of the situation analysis was to determine whether there was a need for a specialised training course for English second language medium of instruction teachers.South African Journal of Education Vol. 27 (1) 2007: pp. 69-8

Scalable ion traps for quantum information processing

We report on the design, fabrication, and preliminary testing of a 150 zone array built in a `surface-electrode' geometry microfabricated on a single substrate. We demonstrate transport of atomic ions between legs of a `Y'-type junction and measure the in-situ heating rates for the ions. The trap design demonstrates use of a basic component design library that can be quickly assembled to form structures optimized for a particular experiment

Case Report

The illegal practice of combining organophosphates (OPs) with other compounds such as carbamates and pyrethroids, creating ‘streetpesticides’, is common in South Africa. These agents contain mostly unknown quantities of unregulated toxins and contribute to atypicaland unpredictable clinical presentations following human ingestion. We present such a case in a patient with intentional rodenticideingestion. The initial presentation in the emergency department was a classic cholinergic toxidrome, and clinical resolution was achievedafter provision of atropine. This was followed 12 hours later by an acute decompensation resulting from an apparent sympatheticallydriven episode of autonomic instability and acute pulmonary oedema requiring immediate respiratory and haemodynamic support. In ourdiscussion, we explore this secondary decompensation and suggest various pathophysiological explanations for this atypical clinical coursefollowing what had appeared to be OP poisoning. The patient was discharged home after a total of 6 days in hospital