A Finite Element Model for Describing the Effect of Muscle Shortening on Surface EMG

A finite-element model for the generation of single fiber action potentials in a muscle undergoing various degrees of fiber shortening is developed. The muscle is assumed fusiform with muscle fibers following a curvilinear path described by a Gaussian function. Different degrees of fiber shortening are simulated by changing the parameters of the fiber path and maintaining the volume of the muscle constant. The conductivity tensor is adapted to the muscle fiber orientation. In each point of the volume conductor, the conductivity of the muscle tissue in the direction of the fiber is larger than that in the transversal direction. Thus, the conductivity tensor changes point-by-point with fiber shortening, adapting to the fiber paths. An analytical derivation of the conductivity tensor is provided. The volume conductor is then studied with a finite-element approach using the analytically derived conductivity tensor. Representative simulations of single fiber action potentials with the muscle at different degrees of shortening are presented. It is shown that the geometrical changes in the muscle, which imply changes in the conductivity tensor, determine important variations in action potential shape, thus affecting its amplitude and frequency content. The model provides a new tool for interpreting surface EMG signal features with changes in muscle geometry, as it happens during dynamic contractions

Student review of doctor-patient communication skills training in a South African undergraduate medical programme

Background. Barriers to the training of doctor-patient communication in the South African (SA) context have been well explored through qualitative research at several SA medical schools. However, this aspect of training has not been reviewed in a systematic way by a large number of students. A student review of doctor-patient communication skills training in the undergraduate medical programme of a medical school in SA was obtained to improve training and identify further research needs. Objective. To investigate doctor-patient communication skills training in the undergraduate programme of a medical school in SA to identify shortcomings and further research needs. Methods. A descriptive, cross-sectional design was used. Data were collected through an anonymous questionnaire based on Harden’s extended vision of the curriculum. Printed anonymous questionnaires, distributed to all the fourth- and fifth-year undergraduate medical students, were analysed quantitatively. Open-ended questions were analysed qualitatively using grounded theory. Results. The sample comprised 106/132 fifth-year students (response rate 80.3%) and 65/120 fourth-year students (response rate 54.2%). Frequent training in history-taking was reported by >75% of students, while >60% reported infrequent training in breaking bad news. More than 50% of participants indicated that senior doctors seldom or never modelled patient-centred communication in the clinical teaching milieu. Students preferred experiential learning to didactic methods. Conclusion. Medical students want to see patient-centred communication unequivocally modelled in the clinical setting. A greater emphasis on practical training in context-specific communication skills is required. Positive role-modelling is needed in the clinical environment

Injury-related South African mortality in children, 1981 - 1985

Data on all registered deaths in children < 15 years in the RSA (excluding Transkei, Bophuthatswana, Venda and Ciskei) were analysed for 1981 - 1985. Variations in age, sex and population group pattern for different causes of injury were evaluated. Injury accounted for 8% of deaths in children < 15 years and was the leading cause of death between the ages of 5 years and 14 years (accounting for 43% of deaths). Motor vehicle accidents were the most important cause of injury deaths in all age groups except < 1 year, when accidental choking and suffocation resulted in more deaths. Drowning accounted for 19% of injury deaths and burns for 11%. In 14% of injury deaths it was not determined if the injury was accidental or purposefuUy inflicted. In all age and population groups deaths among boys outnumbered girls. The impact and pattern of injury varied considerably between age and population groups and reasons for these findings are discussed

The prevalence of skin scars in patients previously given intramuscular diclofenac injections attending the Pain Clinic at Universitas Academic Hospital, Bloemfontein, South Africa

Intramuscular (IM) diclofenac rarely causes scarring (reported incidence <0.05%). Some patients attending the Pain Clinic at Universitas Academic Hospital, Bloemfontein, South Africa, presented with scars that had developed after IM diclofenac injections. We investigated the prevalence of scars in patients at the clinic and how the injections had been obtained. Patients attending the clinic over a period of 9 months who said they had received diclofenac (N=131) were included. Information was collected using a questionnaire and physical examination. Data obtained from 118 patients who were certain that they had received diclofenac were analysed. Ninety-three patients (78.8%) indicated they had not been warned about the possibility that a diclofenac injection could result in scarring. Scarring had occurred in 10 patients (8.5%). Two-thirds of the patients who had obtained diclofenac from a pharmacy had never had a prescription for it. Four patients had required medical treatment for an ulcer or abscess, of whom two had undergone surgery. The risk of skin lesions associated with IM diclofenac is higher than reported previously. Contrary to regulations, diclofenac injections were often dispensed to patients without a prescription

Evaluation of the phytoestrogenic activity of Cyclopia genistoides (honeybush) methanol extracts and relevant polyphenols

The original publication is available at http://pubs.acs.org/Unfermented C. genistoides methanol extracts of different harvestings and selected polyphenols were evaluated for phytoestrogenic activity by comparing binding to both ER subtypes, transactivation of an ERE-containing promoter reporter, proliferation of MCF-7-BUS and MDA-MB-231 breast cancer cells, and binding to SHBG. The extracts from one harvesting of C. genistoides (P104) bound to both ER subtypes. All extracts transactivated ERE-containing promoter reporters via ERβ but not via ERα. All extracts, except P122, caused proliferation of the estrogen-sensitive MCF-7-BUS cells. Proliferation of MCF-7-BUS cells was ER-dependent as ICI 182,780 reversed proliferation. Physiologically more relevant, extracts antagonized E2-induced MCF-7-BUS cell proliferation. Furthermore, all extracts, except P122, induced proliferation of the estrogen-insensitive MDA-MB-231 cells, suggesting that the extracts are able to induce ER-dependent and ER-independent cell proliferation. Binding to SHBG by extracts was also demonstrated. These results clearly show that C. genistoides methanol extracts display phytoestrogenic activity and act predominantly via ERβ. HPLC and LC-MS analysis, however, suggests that the observed phytoestrogenic activity cannot be ascribed to polyphenols known to be present in other Cyclopia species. © 2007 American Chemical Society.Publishers' versio

On-the-fly memory compression for multibody algorithms.

Memory and bandwidth demands challenge developers of particle-based codes that have to scale on new architectures, as the growth of concurrency outperforms improvements in memory access facilities, as the memory per core tends to stagnate, and as communication networks cannot increase bandwidth arbitrary. We propose to analyse each particle of such a code to find out whether a hierarchical data representation storing data with reduced precision caps the memory demands without exceeding given error bounds. For admissible candidates, we perform this compression and thus reduce the pressure on the memory subsystem, lower the total memory footprint and reduce the data to be exchanged via MPI. Notably, our analysis and transformation changes the data compression dynamically, i.e. the choice of data format follows the solution characteristics, and it does not require us to alter the core simulation code

Age of diagnosis of congenital hearing loss: Private v. public healthcare sector

Background. The age of diagnosis of congenital hearing loss is one of the most important determinants of communication outcome. A previous study by the lead author had evaluated the performance of the public health services in Bloemfontein, South Africa (SA), in this regard. This study aimed to examine whether the private health services in the same city were any better.Objective. To determine whether the age of diagnosis of congenital hearing loss (CHL) in children seen in the private healthcare sector in Bloemfontein, Free State Province, SA, was lower than that in the public healthcare system in the same city.Methods. A comparative study design was utilised and a retrospective database review conducted. Data obtained from this study in the private healthcare sector were compared with data from a previous study in the public healthcare sector using the same study design.Results. Forty-eight children aged <6 years with disabling hearing impairment (DHI) were identified in the private healthcare sector during the study period; 33/47 (70.2%) did not undergo hearing screening at birth. The median age of diagnosis of DHI in the private healthcare sector was 2.24 years, and this was statistically significantly lower than the median age of diagnosis of 3.71 years in the public healthcare sector (p<0.0001; 95% confidence interval (CI) 0.99 - 2.0). The median age of diagnosis of CHL in the private healthcare sector was 3.01 years in children who were not screened at birth, and 1.25 years in those who were screened at birth. This difference was statistically significant (p<0.01; 95% CI 0.72 - 2.47). We also compared the median age of diagnosis of CHL in children from the private healthcare sector who were not screened at birth (median 3.01 years) with that in children in the public healthcare sector (median 3.71 years). This difference was statistically significant (p<0.01; 95% CI 0.41 - 1.56).Conclusions. Children in the Free State are diagnosed with CHL at a younger age in the private healthcare sector than in the public healthcare sector. With the social and economic benefits of early intervention in cases of DHI well established internationally, SA healthcare providers in both the public and private sectors need to develop screening, diagnostic and (re)habilitation services for children with hearing impairment