Role of ultrasound in the evaluation of rotator cuff muscle quality

The evaluation of the quality of rotator cuff muscles has become an important part of the preoperative ultrasound examination. Ultrasound is accurate in the evaluation of rotator cuff integrity, but has been found to be insufficient compared to magnetic resonant imaging (MRI) in the evaluation of rotator cuff muscle quality. Complete tears of the rotator cuff lead to muscle atrophy and fatty infiltration, these changes are known to be important negative prognostic factors with regard to the anatomical and functional results after tendon repair. Several classifications and grading systems have been described for computed tomography (CT) and MRI. A number of studies have been directed at the ultrasound assessment of muscle atrophy and fatty infiltration of the rotator cuff, however, no quantitative method or grading systems have been established. At present MRI is the preferred choice for evaluation of rotator cuff fatty infiltration and muscle atrophy in clinical practice. Ultrasound is widely available, cost effective and safe; the aim of this literature review is to investigate if there is a role for ultrasound in the examination of rotator cuff muscle quality.http://www.ajol.info/journal_index.php?jid=153&ab=ajpher

RKKY interaction in one-dimensional flat band lattices

We study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between two classical magnetic impurities in one-dimensional lattice models with flat bands. As two representative examples, we pick the stub lattice and the diamond lattice at half filling. We first calculate the exact RKKY interaction numerically and then compare our data to results obtained via different analytical techniques. In both our examples, we find that the RKKY interaction exhibits peculiar features that can directly be traced back to the presence of a flat band. Importantly, these features are not captured by the conventional RKKY approximation based on non-degenerate perturbation theory. Instead, we find that degenerate perturbation theory correctly reproduces our exact results if there is an energy gap between the flat and the dispersive bands, while a non-perturbative approach becomes necessary in the absence of a gap

Experimental and numerical investigation of an air-to-water heat pipe-based heat exchanger

An experimental and analytical investigation was conducted on an air-to-water heat exchanger equipped with six wickless heat pipes (thermosyphons) charged with water as the working fluid. The flow pattern consisted of a double pass on the evaporator and condenser sections. The six thermosyphons were all made from carbon steel, measured 2m in length and were installed in a staggered arrangement. The objectives of the reported experimental investigation were to analyse the effect of multiple air passes at different air inlet temperatures (100 to 250°C) and air mass flow rates (0.05 to 0.14kg/s) on the thermal performance of the heat exchanger unit including the heat pipes. The results were compared with a CFD model that assumed the heat pipes were solid rods with a constant conductivity. The conductivity of the pipes was extracted from modifications of correlations available in the literature based around the theory of Thermal Resistance. The results proved to be very accurate within 10% of the experimental values

Issues in public health: Unnatural deaths, alcohol bans and curfews: Evidence from a quasi-natural experiment during COVID-19

Background. Coronavirus disease-19 (COVID-19) restrictions, particularly relating to the sale of alcohol and hours of curfew, have had a marked effect on the temporal pattern of unnatural deaths in South Africa. Methods. Death data were collected over 68 weeks from January 2020 to April 2021, together with information on the nature of restrictions (if any) on the sale of alcohol, and hours of curfew. Data were analysed using a simple ordinary least square (OLS) regression model to estimate the relative contribution of restrictions on the sale of alcohol and hours of curfew to the pattern of excess unnatural deaths. Results. The complete restriction on the sale of alcohol resulted in a statistically significant reduction in unnatural deaths regardless of the length of curfew. To the contrary, periods where no or limited restrictions on alcohol were in force had no significant effect, or resulted in significantly increased unnatural deaths. Conclusion. The present study highlights an association between alcohol availability and the number of unnatural deaths and demonstrates the extent to which those deaths might be averted by disrupting the alcohol supply. While this is not a long-term solution to addressing alcohol-related harm, it further raises the importance of implementing evidence-based alcohol control measures

Nutritional status of young school-going and pre-school children

A series of experiments was undertaken to investigate the feasibility of enriching maize meal with nicotinic acid and riboflavin. First the necessary level of enrichment was established and then the efficacy of such enrichment of maize was tested in the field on children and young adults. This report deals with the results of an experiment designed to establish whether such an enrichment scheme would have any detrimental effects on young growing children with marginal protein calorie malnutrition. As in the previous experiments, a marked improvement in the nicotinic acid and riboflavin status was found in the experimental group. These biochemical findings were in conformity with the improvement in clinical status found. Moreover, such enrichment did not have any noticeable adverse effects. The hypothesis that vitamin enrichment could cause growth stimulation, and thus aggravate an existing marginal protein deficiency state, could not in any way be substantiated. The enrichment of maize meal with riboflavin and nicotinic acid during milling has been shown conclusively to be highly effective in improving the vitamin nutritional status while at the same time not harming the protein nutritional status of young children. Since tho:! previous experiments proved it to be economically and technologically feasible, it is now strongly r::commended that such an enrichment scheme be introduced on a national basis with the least possible delay.S. Afr. Med. J., 48, 1641 (1974

Diagnostic accuracy of GeneXpert MTB/RIF in musculoskeletal tuberculosis: High sensitivity in tissue samples of HIV-infected and HIV-uninfected patients

Background. GeneXpert MTB/RIF is useful for the diagnosis of pulmonary TB in adults, but there is limited evidence on its usefulness in extrapulmonary TB.Objectives. To investigate the diagnostic accuracy of GeneXpert MTB/RIF in HIV-infected and HIV-uninfected patients with suspected musculoskeletal TB.Methods. A prospective study of patients with suspected musculoskeletal (bone and joint) TB was undertaken. The diagnostic accuracy of GeneXpert MTB/RIF was compared with the reference standards of culture and histopathology.Results. A total of 206 biopsies from 201 patients (23% HIV-infected) were evaluated. The sensitivity and specificity of GeneXpert MTB/RIF was 92.3% (84/91) and 99.1% (114/115), respectively. GeneXpert MTB/RIF detected 8.8% more cases than culture (84/91 (92.3%) v. 76/91 (83.5%), respectively; p=0.069). GeneXpert MTB/RIF also detected all 4 multidrug-resistant TB cases and an additional 2 rifampicin-resistant cases in culture-negative samples. The sensitivity of GeneXpert MTB/RIF in HIV-infected patients was 96.9% (31/32) v. 89.6% (43/48) in HIV-uninfected patients (p=0.225).Conclusion. GeneXpert MTB/RIF is an accurate test for the detection of TB in tissue samples of HIV-infected and HIV-uninfected patients with suspected musculoskeletal TB. A positive GeneXpert MTB/RIF result should be regarded as microbiological confirmation of TB.

Results of a cluster randomised controlled trial to reduce risky use of alcohol, alcohol-related HIV risks and improve help-seeking behaviour among safety and security employees in the Western Cape, South Africa

Objective: To test the effectiveness of a programme aimed at reducing the risky use of alcohol and alcohol-related HIV risk and increase help-seeking behaviour among a sample of municipal employees in the Western Cape Province, South Africa. Methods: A clustered randomised controlled trial was conducted in 2011–2012 among 325 employees. The eight hour intervention, Team Awareness (TA), addressing behavioural risk among employees was administered to 168 employees in the intervention arm and the 157 employees in the control arm who received a one-hour wellness talk. Results: The results show that TA had the greatest impact on risky drinking practices and hangover effects. There was a significant group × time interaction (F (1, 117) = 25.16, p < 0.0001) with participants in the intervention condition reducing number of days on which they engaged in binge drinking. There was also a significant time effect with participants in the intervention condition reducing the likelihood of going to work with a hangover (F (1,117) = 4.10, p = 0.045). No reduction in HIV-related risk behaviours were found. Conclusions: This intervention study was able to demonstrate a modest but significant reduction in risky drinking practices and hangover effects. This provides encouraging evidence for the effectiveness of interventions that address risky use of alcohol among employed persons, further providing a launch pad for strengthening and replicating future RCT studies on workplace prevention, especially in developing country settings. Clinical Trial Registration Number: Pan-African Control Trial Registry (201301000458308)