The use of a geographical information system (GIS) to evaluate the distribution of tuberculosis in a high-incidence community

CITATION: Beyers, N. et al. 1996. The use of a geographical information system (GIS) to evaluate the distribution of tuberculosis in a high-incidence community. South African Medical Journal, 86(1):40-44.The original publication is available at http://www.samj.org.zaObjective. To determine the geographical distribution of tuberculosis in the two Western Cape suburbs with the highest reported incidence of tuberculosis. Design. Descriptive illustrative study. Setting. Two adjacent Western Cape suburbs covering 2.42 km2 with a population of 34 294 and a reported tuberculosis incidence of > 1 000/100 000. Subjects. All patients notified as having tuberculosis over a 10-year period (1985-1994). Interventions. None. Outcome measure. The geographical distribution of the cases was determined using a geographical information system (GIS) and the National Population Census (1991). Results. One thousand eight hundred and thirty-five of the 5 345 dwelling units (34.3%) housed at least 1 case of tuberculosis during the past decade and in 483 houses 3 or more cases occurred. These cases were distributed unevenly through the community, with the tuberculosis incidence per enumerator subdistrict (ESD) varying from 78 to 3 150/100 000 population. Conclusion. In a small area with a high incidence of tuberculosis, the cases are spread unevenly through the community and there are certain houses where tuberculosis occurs repeatedly. This information should be used to direct health services to concentrate on certain high-risk areas.Publisher’s versio

Updated recommendations for the management of upper respiratory tract infections in South Africa

Background. Inappropriate use of antibiotics for non-severe upper respiratory tract infections (URTIs), most of which are viral, significantly adds to the burden of antibiotic resistance. Since the introduction of pneumococcal conjugate vaccines in South Africa in 2009, the relative frequency of the major bacterial pathogens causing acute otitis media (AOM) and acute bacterial rhinosinusitis (ABRS) has changed. Recommendations. Since URTIs are mostly viral in aetiology and bacterial AOM and ABRS frequently resolve spontaneously, these recommendations include diagnostic criteria to assist in separating viral from bacterial causes and hence select those patients who do not require antibiotics. Penicillin remains the drug of choice for tonsillopharyngitis and amoxicillin the drug of choice for both AOM and ABRS. A dose of 90 mg/kg/d is recommended for children, which should be effective for pneumococci with high-level penicillin resistance and will also cover most infections with Haemophilus influenzae. Amoxicillin-clavulanate (in high-dose amoxicillin formulations available for both children and adults) should be considered the initial treatment of choice in patients with recent antibiotic therapy with amoxicillin (previous 30 days) and with resistant H. influenzae infections pending the results of studies of local epidemiology (β-lactamase production ≥15%). The macrolide/azalide class of antibiotics is not recommended routinely for URTIs and is reserved for β-lactam-allergic patients.Conclusion. These recommendations should facilitate rational antibiotic prescribing for URTIs as a component of antibiotic stewardship. They will require updating when new information becomes available, particularly from randomised controlled trials and surveillance studies of local aetiology and antibiotic susceptibility patterns.

SDSS J160043.6+074802.9: a very rapid sdO pulsator

We report the serendipitous discovery of the Sloan Digital Sky Survey star, SDSS J160043.6+074802.9 to be a very rapid pulsator. The variation is dominated by a frequency near 8380 microHz (period = 119.33 s) with a large amplitude (0.04 mag) and its first harmonic at 16760 microHz (59.66 s; 0.005 mag). In between these frequencies, we find at least another 8 variations with periods between 62 and 118 seconds and amplitudes between about 0.007 and 0.003 mag; weaker oscillations might also be present. Preliminary spectrograms from the performance verification phase of the Southern African Large Telescope indicate that SDSS J160043.6+074802.9 is a spectroscopic binary consisting of an sdO star and a late-type main-sequence companion. This makes it the first unambiguous detection of such an sdO star to pulsate, and certainly the first found to exhibit multi-frequency variations.Comment: 7 pages, 6 figures (figure 4 at reduced resolution, original available on request). Accepted for publication in MNRA

Development of intuitive rules: Evaluating the application of the dual-system framework to understanding children's intuitive reasoning

This is an author-created version of this article. The original source of publication is Psychon Bull Rev. 2006 Dec;13(6):935-53 The final publication is available at www.springerlink.com Published version: http://dx.doi.org/10.3758/BF0321390

Drivers of advanced stage at breast cancer diagnosis in the multicountry African breast cancer – disparities in outcomes (ABC-DO) study

Breast cancer (BC) survival rates in sub-Saharan Africa (SSA) are low in part due to advanced stage at diagnosis. As one component of a study of the entire journey of SSA women with BC, we aimed to identify shared and setting-specific drivers of advanced stage BC. Women newly diagnosed in the multicountry African Breast Cancer–Disparities in Outcomes (ABC-DO) study completed a baseline interview and their stage information was extracted from medical records. Ordinal logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for advanced stage (I, II, III, IV) in relation to individual woman-level, referral and biological factors. A total of 1795 women were included from Nigeria, Uganda, Zambia, and the multiracial populations of Namibia and South Africa, 1091 of whom (61%) were stage III/IV. Stage was lower in women with greater BC knowledge (OR 0.77 (95% CI: 0.70, 0.85) per point on a 6 point scale). More advanced stage was associated with being black (4.00 (2.79, 5.74)), having attended <secondary education (1.75 (1.42, 2.16)), having never heard of BC (1.64 (1.31, 2.06)), an unskilled job (1.77 (1.43, 2.20)) and pregnancy in the past 3 years (30% of ≤45 year olds) (1.63 (1.15, 2.31)), and were mediated through delays to diagnosis: symptom duration of ≥ 1 year (OR 2.47 (1.93, 3.15)). These findings provide further evidence that late-stage BC in SSA is largely attributed to modifiable factors and strategies to improve BC education and awareness in women and the health system should be intensified

Multiyear and multisite photometric campaigns on the bright high-amplitude pulsating subdwarf B star EC 01541-1409

We present follow-up observations of the pulsating subdwarf B (sdB) star EC 01541–1409 as part of our efforts to resolve pulsation spectra for use in asteroseismological analyses. This paper reports on data obtained from a single-site campaign, during 2008, and a multisite campaign, during 2009. From limited 2008 data, we were able to clearly resolve and pre-whiten 24 periods. A subsequent multisite campaign spanning nearly 2 months found over 30 individual periodicities most of which were unstable in amplitude and/or phase. Pulsation amplitudes were found to the detection limit, meaning that further observations would likely reveal more periodicities

Residensiele mobiliteit van blankes in die Kaapstadse metropolitaanse gebied

Proefskrif (Ph. D.) -- Universiteit van Stellenbosch, 1978.Full text to be digitised and attached to bibliographic record

The geographical distribution of diagnostic medical and dental X-ray services in South Africa

CITATION: Walters, N. M., Zietsman, H. L. & Bhagwandin, N. 1998. The geographical distribution of diagnostic medical and dental X-ray services in South Africa. South African Medical Journal, 88(3):383-389.The original publication is available at http://www.samj.org.zaAim. The aim of this study was threefold, viz.: (/) to evaluate the availability and accessiblity of medical and dental X-ray services in South Africa; (//) to evaluate geographical information systems (GIS) as a tool for management of health care technologies; and (Hi) to guide policy and develop a process to provide optimal utilisation of X-ray services in South Africa. Methods. Information supplied by the Department of Health on licensed X-ray equipment was integrated with census data and processed with GIS. Four key areas were assessed, viz. distribution, accessibility, age and availability of X-ray services in South Africa. Results. The analysis shows a vast inequity in the distribution of X-ray services on a provincial as well as a district level, although on the national level the distribution of X-ray services meets the World Health Organisation criteria. Conclusion. GIS is a useful tool in evaluating and planning of essential health services/techniques. However, care must be taken in interpreting the data on a macro level, as this masks vast inequities on the district level. Recommendations. The indicators of coverage should be expanded, similar reports should be prepared for the nine provinces, and these data should be integrated into the clinic planning programme. Radiological services should be added to and managed as part of an essential district health care technology package.Publisher’s versio

Evaluating image classification techniques on ASTER data for lithological discrimination in the Barberton Greenstone Belt, Mpumalanga, South Africa

Thesis (MSc (Geography and Environmental Studies))--University of Stellenbosch, 2005.81 Leaves printed on single pages i-xi, preliminary pages and numbered pages 1- 70. Includes bibliography, list of tables and list of figures.Digitized at 300 dpi color PDF format (OCR), using KODAK i 1220 PLUS scanner.ENGLISH ABSTRACT: Geological field mapping is often limited by logistical and cost constraints as well as the scope and extent of observations possible using ground-based mapping. Remote sensing offers, among others, the advantages of an increased spectral range for observations and a regional perspective of areas under observation. This study aimed to determine the accuracy of a collection of image classification techniques when applied to ASTER reflectance data. Band rationing, the Crosta Technique, Constrained Energy Minimization, Spectral Correlation Mapping and the Maximum Likelihood Classifier were evaluated for their efficiency in detecting and discriminating between greenstone and granitoid material. The study area was the Archaean Barberton Greenstone Belt in the eastern Mpumalanga Province, South Africa. ASTER reflectance imagery was acquired and pre-processed. Training and reference data was extracted from the image through visual inspection and expert knowledge. The training data was used in conjunction with USGS mineral spectra to train the five classification algorithms using the ERDAS's software package. This resulted in abundance images for the target materials specified by the training data. The Maximum Likelihood Classifier produced a classified thematic map. The reference data was used to perform a rigorous classification accuracy assessment procedure. All abundance images were thresholded to varying levels, obtaining accuracy statistics at every level. In so doing, threshold levels could be defined for every abundance image in such a way that the reliability of the classification was optimized. For each abundance image, as well as for the output map of the Maximum Likelihood Classifier, user's- and producer's accuracies as well as kappa statistics were derived and used as comparative measures of efficiency between the five techniques. This information was also used to assess the spectral separability of the target materials. The Maximum Likelihood Classifier outperformed the other techniques significantly, achieving an overall classification accuracy of 81.1% and an overall kappa value of 0.748. Greenstone rocks were accurately discriminated from granitoid rocks with accuracies between 72.9% and 98.5%, while granitoid rocks showed very poor ability to be accurately distinguished from each other. The main recommendations from this study are that thermal infrared and gamma-ray data be considered, together with better vegetation masking and an investigation into object orientated techniques.AFRIKAANSE OPSOMMING: Geologiese veldkartering word algemeen beperk deur logistiese en koste-verwante faktore, sowel as die beperkte bestek waartoe waarnemings met veld-gebasseerde tegnieke gemaak kan word. Afstandswaarneming bied, onder andere, 'n vergrote spekrale omvang vir waarnemings en 'n regionale perspektief van die area wat bestudeer word. Hierdie studie was gemik daarop om die akkuraatheid van 'n versameling beeld-klassifikasie tegnieke, toegepas op ASTER data, te bepaal. Bandverhoudings, die Crosta Tegniek, "Constrained Energy Minimization", Spektrale Korrellasie Kartering, en Maksimum Waarskynlikheid Klassifikasie is evalueer op grond van hul vermoë om groensteen en granitoied-rotse op te spoor en tussen hulle te onderskei. Die studiegebied was die Argalese Barberton Groensteengordel in die oostelike Mpumalanga Provinsie in Suid Afrika. 'n ASTER refleksie beeld is verkry, waarop voorverwerking uitgevoer is. Opleidings- en verwysingsdata is van die beeld verkry deur visuele inspeksie en vakkundige kennis. Die opleidingsdata is saam met VSGO mineraalspektra gebruik om die vyf klassifikasie algoritmes met behulp van die ERDAS sagteware pakket op te lei. Die resultaat was volopheidsbeelde vir die teikenmateriale gespesifiseer in die opleidingsdata. Die Maksimum Waarskynlikheid algoritme het 'n geklassifiseerde tematiese beeld gelewer. Met behulp van die verwysingsdata is 'n streng akkuraatheidstoetsing prosedure uitgevoer. Vir alle volopheidsbeelde is 'n reeks drempelwaardes gestel, en by elke drempelwaarde is akkuraatheidsstatistieke afgelei. Op hierdie manier kon 'n drempelwaarde vir elke volopheidsbeeld vasgestel word sodat die drempelwaarde die betroubaarheid van die klassifikasie optimeer. Vir elke volopheidsbeeld, asook vir die tematiese kaart verkry van die Maksimum Waarskynlikheid klassifikasie, is gebruikers- en produsent-akkuraathede en kappa statistieke bereken. Hierdie waardes is gebruik as vergelykende maatstawwe van akkuraatheid tussen die vyf tegnieke, asook van die spektrale skeibaarheid van die onderskeie teikenmateriale. Die Maksimum Waarskynlikheid klassifikasie het die beste resultate gelewer, met 'n algehele klassifikasie akkuraatheid van 81.1%, en 'n gemiddelde kappa waarde van 0.748. Groensteenrotse kon met hoë akkuraathede van tussen 72.9% en 98.5% van granitoiedrotse onderskei word, terwyl granitoiedrotse 'n swak vermoë getoon het om van mekaar onderskei te word. Die belangrikste aanbevelings vanuit hierdie studie is dat termiese uitstralingdata asook gamma-straal data geimplimenteer word. Beter verwydering van plantegroei en 'n studie na die lewensvatbaarheid van objekgeorienteerde metodes word ook aanbeveel

Surface temperature measurement from space : a case study in the South Western Cape of South Africa

CITATION: Sandham, L. A. & Zietsman, H. L. 1997. Surface temperature measurement from space : a case study in the South Western Cape of South Africa. South African Journal of Enology & Viticulture, 18(2):25-30, doi:10.21548/18-2-2250.The original publication is available at http://www.journals.ac.za/index.php/sajevThis paper reports on the use of Landsat Thematic Mapper (TM) thermal infrared (TIR) and Transformed Normalised Difference Vegetation Index (TNDVI) data to map summer surface temperature distribution in a portion of the South Western Cape (South Africa). It adopts a ground truth calibration approach, as a possible solution for alleviating the paucity of spatial temperature data. Means and standard deviations of the TIR and transformed NDVI of all pixels within a radius of 120 m around each ground truth point were regressed on spatially collocated surface-observed temperature data. Linear multiple regression analysis showed that mean TIR and standard deviation of TNDVI were effective in accounting for 43 % of variation in surface temperature. The regression equation was used to generate a temperature map at a spatial resolution of 30 m, showing good agreement with expected mesoscale spatial temperature patterns in terms of general climatic principles. The temperature map provides a useful tool for depicting and assessing the spatial variation in daily temperatures, providing information currently unavailable to the fruit-producing farmers in the South Western Cape.http://www.journals.ac.za/index.php/sajev/article/view/2250Publisher's versio