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

Catchment management-model evaluation : verifying data for the implementation of the water release module of the WAS program

Published ArticleThe Water Administration System (WAS) is designed to be a management tool for irrigation schemes and water offices that want to manage their water accounts and supply to clients through canal networks, pipelines and rivers. The ultimate aim of WAS is to optimize irrigation water management and minimize management-related distribution losses in irrigation canals. This research project focus on the implementation of the water release module of the WAS program at the Vaalharts irrigation scheme. WAS consists of four modules that are integrated into a single program that can be used on a single PC, a PC network system (in use currently at Vaalharts) or a multi-user environment. These modules can be implemented partially or as a whole, depending on the requirements of the specific scheme or office. The four modules are an administration module, a water request module; water accounts module and a water release module. The first three modules are already implemented at Vaalharts, while module four is implemented only partially. This module links with the water request module and calculates water releases for the main canal and all its branches allowing for lag times and any water losses and accruals. Any researcher in this field should first understand where water comes from and how it will be utilized before any calculations are attempted. Only then manipulation of the release volume can commence. To precisely calculate this water release, accurate data is needed to ensure that the correct volume of water is released into the canal network. This can be done by verifying existing data with field data. To optimize the management of the irrigation scheme the fully implemented WAS program need to be installed and running at the scheme. A series of data and calculation verification needs to be executed. The exercise will show the adequacy and correctness of the available database WAS uses to do the release calculation from. This will ensure improved management of the irrigation scheme, catchment and water resource sustainability. It is planned that the information generated from this project will be used in the compilation of an integrated catchment management information system, currently underway in the school of Civil Engineering and Built Environment at the Central University of Technology, Free State, South Africa

The Physiological Effects Of a Mid-shift feed of sucrose

When men work continuously at a moderate (1'0 litres/ min oxygen consumption) or hard rate (1'5 litres/ min oxygen consumption) for 6 hours, the respiratory quotient falls from 0·94 to 0·80. In classical concepts this ind:cates that 68% of the caloric requirement comes from carbohydrate initially and that only 30% comes from that source at the end of the work period. This change in metabolism is associated with an increase in oxygen consumption and heart rate, indicating that the men were being less effective mechanically towards the end of the work period when they were using predominantly fat metabolism. A mid-shift feed of 100 and of 200 g of sucrose in water .caused an immediate rise in RQ and a higher level of RQ than in the fasting men which persisted for the rest of the work period. This was associated with a lower rate of oxygen consumption than in the fasting state. Whife there may be some doubt about the immediate increase in RO being due to a shift towards carbohydrate metabolism after' the ingestion of sucrose, there can be little doubt that this is the case from the end of the first hour onwards, after the ingestion of sucrose. The doubt about whether the rapid increase in RQ after the ingestion of sucrose is due to a change from fat to carbohydrate metabolism or whether it is due to an alteration in blood insulin level following the ingestion of sucrose could be resolved by ingesting HC sucrose and studying the output of HC CO, in expired air. In view of the practical importance to industry of showing whether or not carbohydrate given during a mid-shift feed is actually metabo'ized during the remainder of the shift, a study with HC sucrose appears to be fully justified; its scientific value in solving the above problems is not in doubt

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

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

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

Preferences for services in a patient’s first six months on antiretroviral therapy for HIV in South Africa and Zambia (PREFER): research protocol for a prospective observational cohort study

Study protocol and supplementary files for protocol manuscript in Gates Open Research.BACKGROUND: For patients on HIV treatment in sub-Saharan Africa (SSA), the highest risk for loss from care consistently remains the first six months after antiretroviral (ART) initiation, when patients are not yet eligible for most existing differentiated service delivery (DSD) models. To reduce disengagement from care during this period, we must gain a comprehensive understanding of patients’ needs, concerns, resources, and preferences for service delivery during this period. The PREFER study will use a sequential mixed-methods approach to survey a sample of patients in South Africa and Zambia 0-6 months after ART initiation to develop a detailed profile of patient characteristics and needs. PROTOCOL: PREFER is an observational, prospective cohort study of adult patients on ART for ≤6 months at 12 public sector healthcare facilities in Zambia and 18 in South Africa that aims to inform the design of DSD models for the early HIV treatment period. It has four components: 1) survey of clients 0-6 months after ART initiation; 2) follow up through routinely collected medical records for <12 or <24 months after enrollment; 3) focus group discussions to explore specific issues raised in the survey; and 4) in South Africa only, collection of blood samples self-reported naïve participants to assess the prevalence of ARV metabolites indicating prior ART use. Results will include demographic and clinical characteristics of patients, self-reported HIV care histories, preferences for treatment delivery, and predictors of disengagement. CONCLUSIONS: PREFER aims to understand why the early treatment period is so challenging and how service delivery can be amended to address the obstacles that lead to early disengagement from care and to distinguish the barriers encountered by naïve patients to those facing re-initiators. The information collected by PREFER will help respond to patients’ needs and design better strategies for service delivery and improve resource allocation going forward.Bill & Melinda Gates Foundation, INV-031690 to Boston Universit