The Physicist's Guide to the Orchestra

An experimental study of strings, woodwinds (organ pipe, flute, clarinet, saxophone and recorder), and the voice was undertaken to illustrate the basic principles of sound production in music instruments. The setup used is simple and consists of common laboratory equipment. Although the canonical examples (standing wave on a string, in an open and closed pipe) are easily reproduced, they fail to explain the majority of the measurements. The reasons for these deviations are outlined and discussed.Comment: 11 pages, 10 figures (jpg files). Submitted to European Journal of Physic

Endemic goitre in a rural community of KwaZulu-Natal

CITATION: Benade, J. G. et al. 1997. Endemic goitre in a rural community of KwaZulu-Natal. South African Medical Journal, 87:310-313.The original publication is available at http://www.samj.org.zaObjective. To quantify the prevalence of goitre and iodine deficiency. Setting. Ndunakazi, a rural community of approximately 8 000 people in KwaZulu-Natal. Design. A cross-sectional community-based survey and a school-based survey. Participants. The 127 mothers and 114 children aged 6 -11 years, selected during the cross-sectional survey, and 304 children aged 6 -14 years, from the school-based survey. Methods. Urinary iodine levels and thyroid size were determined and categorised according to guidelines proposed jointly by the WHO, UNICEF and the ICCIDD. Z-score anthropometric indicators were calculated, and mid-year exam marks of goitrous and non-goitrous pupils for Zulu and mathematics were compared. Results. In school-aged children, both surveys demonstrated a goitre prevalence in the 20 - 29.9% range and a median urinary iodine level in the 2 - 4.9 ug/dl range, indicating iodine deficiency of moderate severity. Goitrous subjects scored consistently worse in their Zulu exam papers than those without goitre. Stunting was not more prevalent than in the rest of KwaZulu-Natal. Iodised salt was not available in any of the three community shops. Conclusion. This level of iodine deficiency in children can adversely affect their neuropsycho-intellectual development. Factors contributing to deficient iodine intake in Ndunakazi are present in many rural areas, and South Africa cannot afford to be overly confident about the apparent absence of iodine deficiency as a public health problem.Publisher’s versio

The effect of parenteral nnutrition with lipovenous or intralipid on the fatty acid composition of plasma and erythrocyte membrane lipids in very-low-birthweight infants

No Abstract

Intonation and Compensation of Fretted String Instruments

In this paper we present mathematical and physical models to be used in the analysis of the problem of intonation of musical instruments such as guitars, mandolins and the like, i.e., we study how to improve the tuning on these instruments. This analysis begins by designing the placement of frets on the fingerboard according to mathematical rules and the assumption of an ideal string, but becomes more complicated when one includes the effects of deformation of the string and inharmonicity due to other string characteristics. As a consequence of these factors, perfect intonation of all the notes on the instrument can never be achieved, but complex compensation procedures are introduced and studied to minimize the problem. To test the validity of these compensation procedures, we have performed extensive measurements using standard monochord sonometers and other basic acoustical devices, confirming the correctness of our theoretical models. In particular, these experimental activities can be easily integrated into standard acoustics courses and labs, and can become a more advanced version of basic experiments with monochords and sonometers.Comment: Improved version, with minor changes. 25 pages, including 6 figures and 2 tables. Accepted for publication in the American Journal of Physics (AJP

Reproducing Musical Instrument Components from Manufacturers’ Technical Drawings using 3D Printing: Boosey & Hawkes as a Case Study

This paper demonstrates how component musical instrument parts can be recreated from manufacturers’ technical drawings using 3D printing. While the application of this technology is not new, previous approaches have usually involved Computer Tomography scanning of extant models. Instead we used surviving technical drawings of clarinet mouthpieces originally manufactured by Boosey & Hawkes. We demonstrated that this non-invasive technique can be used to 3D print musical component parts if the original plans survive, even when extant parts do not. We also demonstrated through qualitative feedback from professional musicians that hand finishing of 3D printed mouthpieces remains essential for skilled performers

Obesity in South Africa: Challenges for government and health professionals

OBJECTIVES: To review data on the prevalence, causes and health consequences of obesity in South Africa and propose interventions to prevent and treat obesity and related outcomes. METHODS: Data from existing literature were reviewed with an emphasis on changing eating and activity patterns, cultural factors, perceptions and beliefs, urbanisation and globalisation. Results of studies on the health consequences of obesity in South Africans are also reviewed. RESULTS: Shifts in dietary intakes and activity patterns to higher fat intakes and lower physical activity are contributing to a higher prevalence of obesity. Few overweight black women view themselves as overweight, and some associate thinness with HIV/AIDS. Glucose and lipid toxicity, associated with insulin resistance, play roles in the pathogenesis of the co-morbid diseases of obesity. Elevated free fatty acids in the black population predispose obese black patients to type 2 diabetes. CONCLUSION & RECOMMENDATIONS: Obesity prevention and treatment should be based on education, behaviour change, political support, intersectoral collaboration and community participation, local actions, wide inclusion of the population, adequately resourced programmes, infiltration of existing initiatives, evidence-based planning, and proper monitoring and evaluation. Interventions should have the following components: reasonable weight goals, healthful eating, physical activity and behavioural change. Genes and mutations affecting susceptibility to the development of co-morbidities of obesity and vulnerable periods of life for the development of obesity should be prioritised. Prevention should be managed in community services, identification of high-risk patients in primary healthcare services and treatment of co-morbid diseases in hospital services

Caracterização da qualidade acústica de salas de aula para prática e ensino musical

Resumo O músico necessita perceber adequadamente o som nos recintos destinados ao estudo e prática musical, o que é possível quando estes locais estão acusticamente preparados e permitem o desenvolvimento e aprimoramento da percepção sonora musical. Neste trabalho três salas de estudo e três salas de aula coletiva, destinadas ao ensino e prática de Música de uma universidade, foram caracterizadas acusticamente através da opinião dos músicos usuários e de medições da sua resposta impulsiva. As salas descritas pelos músicos como secas tiveram, nas bandas de frequência de oitava de 500 a 1000 Hz, um Tempo de Reverberação em torno de 0,3 segundos, entre 14 e 22 dB de Clareza e entre 88% a 96% de Definição. As salas caracterizadas como reverberantes tiveram um tempo ao redor de 1,5 segundos, Clareza de 1 dB e Definição de 40%. A opinião dos músicos permitiu compreender as preferências da qualidade acústica das salas e as informações fornecidas pelos músicos se mostraram coerentes com os dados das medições