Hollow-fibre membrane for sample introduction in a flow-injection system : Determination of carbon disulphide in air

A hollow-membrane fibre is used for the introduction of gaseous compounds into a flow-injection system. The sampling system consists of a certain length of asymmetric hollow-fibre membrane in which an acceptor stream is stopped for a fixed period of time. The analyte permeates from the surrounding environment through the membrane and is accumulated in the acceptor solution, then pumping is resumed. The method is tested for the determination of carbon disulphide in ambient air. The detection range of the method is from 3 to at least 30 mg l−1

Use of the hunt filter to optimize the determination of impulse-response functions of individual component parts of flow-injection manifolds

The dispersion behaviour of the various individual parts making up a flow-injection manifold can be expressed by means of impulse-response functions. These functions can be determined by deconvolution of the response curves obtained with and without the part concerned. Special attention is paid to a procedure to decrease the influence of noise. It is shown that good results can be obtained with a Hunt filter which operates in the Fourier domain

Impulse/response functions of individual components of flow-injection manifolds

The dispersion behaviour of the various individual parts making up a flow-injection manifold is often difficult to establish because it is virtually impossible to obtainthe required very small injection and detection volumes. It is shown that it is possible, under suitable experimental conditions, to find the impulse/response functionof each component by means of a deconvolution process of the response functions have been established, the response function of any arrangement can be predicted by convoluting the impulse/response functions of all the individuaol parts involved. Convolution and deconvolution were done in the Fourier domain, by using a fast FT algorithm

Impulse-response functions of several detectors used in flow-injection analysis

A procedure for the determination of the impulse-response function of a detector is given. Its application to photometers, ion-sensitive field effect transistors, a potentiometric detector at constant current and a voltammetric detector shows that the impulse-response function can be used to obtain specific information about the performance of the detector in the manifold. This function clearly shows the contribution of the detector to the peak broadening and how the detector generates the final signal from the presented concentration profile. From this information one could derive improvements to the detector, such as changing the construction of the detector cell, minimizing the influence of other parts of the manifold or adapting the attached electronics

A Method for Greatly Reduced Edge Effects and Crosstalk in CCT Magnets

Iron-free CCT magnet design offers many advantages, one being the excellent field quality and the absence of multipole components. However, edge effects are present, although they tend to integrate out over the length of the magnet. Many modern accelerator applications, however, require that these magnets are placed in an area of rapidly varying optics parameters, so magnets with greatly reduced edge effects have an advantage. We have designed such a magnet (a quadrupole) by adding multipole components of the opposite sign to the edge distortions of the magnet. A possible application could be the final focus magnets of the FCC-ee, where beam sizes at the entry and exit point of the magnets vary by large factors. We have then used this technique to effectively eliminate cross talk between adjacent final focus quadrupoles for the incoming and outgoing beams.Comment: Poster presented at MT25,25th International Conference on Magnet Technology, Amsterdam, August 27 - September 1, 201

Out-of-hospital critical case time intervals occuring in the Greater Johannesburg Metropolitan area, Gauteng, as recorded in a paramedic clinical learning database

Background. Out-of-hospital time intervals are often used to assess Emergency Medical Service (EMS) system performance. In addition, these time intervals are linked to patient outcome in certain time-dependent pathologies such as stroke, out-of-hospital cardiac arrest (OHCA) and myocardial infarction. There are a number of variables that are thought to influence these time intervals such as the number of interventions performed and the transport distance to hospital. Objective. This Johannesburg-based study assessed out-of-hospital critical case time intervals as recorded in a paramedic student clinical learning database. Methods. This retrospective study analysed 19742 cases that were attended to by paramedic students and their clinical supervisors. Of the total number of cases, 1360 critical cases were deemed to meet inclusion criteria in the Greater Johannesburg Metropolitan (GJM) area over the eight-year period under review. Results. Eight hundred and fifty six “trauma” cases and 504 “medical” cases were analysed. The mean response time interval was 10.67 minutes (95% CI:10.48;10.86). Of the critical cases assessed, the mean on-scene time interval was 26.69 minutes (95% CI:26.23;27.15). Generally, critical cases in Johannesburg had longer total incident time intervals (53.53 minutes 95% CI:52.90;54.15) when compared to international data. Conclusions. This study found that when compared to international trends, patients who are critically-ill locally experience similar response time intervals when compared to certain data. On-scene time intervals are comparatively extended. In addition, it was also found that in increase in the number of on-scene interventions led to an increase in on-scene time intervals

Validation of a strand-level CICC-joint coupling loss model

Calculating the coupling losses in cable-in-conduit conductor (CICC) joints requires a large amount of numerical effort, which is why the numerical system is often reduced by grouping strands together. However, to better understand the loss behaviour, and eventually the stability mechanism in such joints, a full-sized model working on the level of individual strands is more desirable. For this reason, the numerical cable model JackPot-AC has been expanded to also simulate the coupling losses in a CICC joint. This model has been verified with AC loss measurements on a mock-up joint, which was subjected to an applied harmonic field at different angles. The mock-up joint consisted of two sub-sized CICCs connected by a copper sole. For additional verification the AC loss of one of these conductors and the copper sole was also measured separately. The results of the simulation agree with the measurements, and the model therefore proves to be a useful analytical tool for examining the coupling loss in CICC joint

Editorial: Understanding persistent postoperative pain in South Africa

No Abstrac

Roofline-aware DVFS for GPUs

Graphics processing units (GPUs) are becoming increasingly popular for compute workloads, mainly because of their large number of processing elements and high-bandwidth to off-chip memory. The roofline model captures the ratio between the two (the compute-memory ratio), an important architectural parameter. This work proposes to change the compute-memory ratio dynamically, scaling the voltage and frequency (DVFS) of 1) memory for compute-intensive workloads and 2) processing elements for memory-intensive workloads. The result is an adaptive roofline-aware GPU that increases energy efficiency (up to 58%) while maintaining performance

Emergency care practitioners’ views on the use of ultrasound in pre-hospital acute care settings

Background: Ultrasound may assist in the detection of life-threatening conditions and evolving pathologies. South African emergency care practitioners (ECPs) working in pre-hospital contexts have historically not used ultrasound to diagnose and treat patients. However, recently published clinical practice guidelines from the Health Professions Council of South Africa (HPCSA) suggest that ultrasound be considered as an adjunct in the provision of pre-hospital emergency care. Our study investigated ECPs’ views and perceptions of introducing ultrasound to their scope of practice. Method: A qualitative prospective approach was followed, using semi-structured interviews with a purposefully selected sample of practising ECPs to investigate and describe their views and perceptions of the use of ultrasound in local pre-hospital emergency care contexts. The interviews were audio recorded and transcribed. Transcripts were critically read before being manually coded to identify core themes and categories. Results: ECPs recognise the potential value of ultrasound for a subset of patients within specific pre-hospital contexts. Concerns around the introduction of ultrasound as a diagnostic adjunct included the potential to create delays in treatment and transportation. Implementation challenges included cost implications and the need for additional education and training. Conclusion: ECPs practising in South African pre-hospital acute care contexts support the use of ultrasound, provided they are adequately trained, and its use does not lead to delays in treatment and arrival at receiving facilities. Additional training on the use of ultrasound may be necessary for ECPs. Further research is required to explore the benefits of ultrasound concerning patient-specific outcomes and the associated costs in resource-constrained pre-hospital emergency care settings