Die radio in Afrika

Omvang van radio-uitsendings in en na Afrika. — Redes vir die versnelde tempo van uitbreiding. — Radio as die geskikste massa-kommunikasiemiddel vir Afrika. — Faktore wat die verspreiding bemoeilik. — Skouspelagtige toename in luistertalle.Toe Plinius, wat in die jaar 79 oorlede is, in sy „Historia Naturalis” verklaar het dat daar altyd iets nuuts uit Afrika afkomstig is, kon hy nouliks voorsien het dat die „iets" negentien eeue later in die lug sou setel wat hierdie reuse-vasteland oorspan — ’n Babelse spraakverwarring en ’n ongekende, verbete woorde-oorlog in die etergolwe, onder meer daarop bereken om die harte en hoofde van derduisendes te verower

The deteriorating nutrient status of the Berg River, South Africa

The upper catchment area of the Berg River in the Western Cape, South Africa, supplies most of Cape Town and its suburbs with freshwater, in addition to providing water for irrigation purposes along the middle and lower reaches of the river. This study investigates the nutrient status of the Berg River and long-term trends therein. It is shown that inorganic nitrogen and phosphorus levels increase downstream by a factor of more than 10, in response to anthropogenic inputs. Similarly, nutrient levels fluctuate seasonally by more than an order of magnitude, in response to input from diffuse and point sources of pollution. These changes of more than 1 000% far exceed the 15% maximum change stipulated by the South African water quality guidelines for aquatic ecosystems. Total phosphorus levels indicate that hypertrophic conditions prevail at least episodically at all of the Berg River monitoring stations and most of the time at some of them. Additionally, river water phosphate levels show a dramatic increase over the past 20 years. There is also strong evidence that the trophic status of the Berg River is very sensitive to reduced river runoff. The implication is that the construction of the new Berg River Dam in the upper catchment area of the Berg River will exacerbate the existing situation, threatening ecosystem services, human health and lucrative agricultural activities.Keywords: Berg River, eutrophication, nutrients, nitrate, phosphat

Seasonal and interannual variability in phytoplankton biomass on the southern African continental shelf: evidence from satellite-derived pigment concentrations

Surface ocean phytoplankton biomass variability on the southern African continental shelf area is investigated using coastal zone colour scanner data for the period 1979–1986. Coherent interannual trends in surface ocean chlorophyll for both the west coast Benguela and the south coast Agulhas Bank areas correspond with sea surface temperature records, rather than with local records of upwelling-favourable winds. This finding implies that interannual variability in phytoplankton biomass, in contrast to the well-established seasonal cycle, is associated with large-scale oceanic circulation features and forcing mechanisms, rather than with localized upwelling events. The most probable causative mechanism is suggested to be anomalous advective fluxes of warm surface water into areas typically of high biomass deriving from the Agulhas Current retroflection in the south. Studyingvariability in phytoplankton biomass on the continental shelf in the context of large-scale oceanic circulation features is important to understanding long-term trends in productivity and fisheries resources

Recognition of neotype specimens for species described from the Arnot Pipe, Banke, Namaqualand, South Africa

Important palynological studies were completed by Scholtz (1985) on material from the Arnot Pipe on the farm Banke in Namaqualand, Northern Cape Province. The results comprised a rare record of early Tertiary vegetation in southern Africa. The body of Scholtz’s research consisted of systematic, descriptive palynology including the description of one new genus and fifteen new species. Ongoing research into South Africa’s Tertiary palynology requires that the type specimens from Arnot be used for comparative purposes. However, the microscope slides on which they were founded were not available for examination. Another set of slides, representing two of the seven samples taken at Arnot, was used to search for neotype specimens to replace the missing holotypes. Specimens representing all fifteen new species were found, but were often badly preserved, obscured by debris or trapped between air bubbles as the condition of the decade-old microscope slides had deteriorated. Only specimens in good condition were selected as neotypes, and comprehensively illustrated. Four of Scholtz’s new species were transferred to alternative, more applicable, genera.The Council's Research Committe, University of the Witwatersrand; National Science Foundatio

Has monitoring failed the Olifants River, Mpumalanga?

Water quality monitoring in the Olifants River catchment, Mpumalanga, is evaluated using river water dissolved sulphate levels, one of the best indicators of pollution related to acid mine drainage. Assessment of long-term water quality records shows that monitoring has not been carried out systematically. In that it fails one of the most fundamental criteria of good environmental monitoring practices. At some monitoring stations sampling frequency has been scaled down from approxi-mately weekly to monthly intervals over time, despite evidence for increasing and problematic levels of pollution. At the Loskop Dam dissolved sulphate levels have increased more than 7-fold since the 1970s evidently due to increasing levels of pollution within the Little Olifants River catchment. At 4 of the 7 long-term monitoring stations river water sulphate levels exceed the 100 mg/. threshold value for aquatic ecosystem health most of the time for the duration of the record, and all of the time since about 2001. At these stations river water sulphate levels also exceed the 200 mg/. threshold for humanconsumption 27 to 45% of the time, for the duration of the long-term record. These observations necessitate more frequent and improved monitoring, not evidently reduced efforts. A major concern is the location of a recently re-opened copper mine outside Phalaborwa, just upstream from the confluence of the Ga-Selati River and the Olifants River. Levels of copper sulphate, highly toxic to aquatic species, should be urgently investigated as a probable cause of recent fish and crocodile deaths in the Kruger National Park. In river systems subject to intensive mining activity, such as the Olifants River, toxicconstituents such as copper, arsenic, chrome-VI, etc., currently not routinely measured by the Department of Water Affairs(DWA) need to be included in monitoring efforts as a matter of urgency. This will require drastic improvements in current water quality monitoring efforts, including the acquisition of modern analytical instrumentation

The palynology of tertiary sediments from a palaeochannel in Namaqualand, South Africa.

Main articleA site in amaqualand, Western Cape Province, has yielded a diverse and well-preserved pa lynoflora. The site consists of a quarry, exposing a palaeochannel containing fluviatile sands, silts and clays with accompanying peat horizons. This paper presents a qualitative account of the pollen and pore assemblages extracted from the peats. Ang iosperms were dominant both in terms of the number of individuals and the recognised types. Identification were made where possible with reference to published illustrations and descriptions. There was a total of 69 palynomorph types, including spores, gymnosperm and angiosperm pollen.Non

Prevalence and characteristics of erectile dysfunction in black and mixed race primary care populations of the Cape Flats and Helderberg Basin area of the Western Cape, South Africa

Objective: To estimate the prevalence of erectile dysfunction (ED) among users of primary care in a Black and Mixed Race urban population in the Western Cape, and to describe any associated health and psychosocial factors. Design: Cross-sectional survey by interviewer administered questionnaire. Setting: Two primary care medical centres, 40km apart, in Cape Town metropolitan area. Serve different ethnic groups, with no cross-contamination between them. Study period: March-June 1999 Patients: 833 Males (35-70 years old) attending these health centres for primary care. Systematic selection of all attendees. Main outcome measures: Prevalence of ED and presence of associated health and psychosocial factors. Describe patient demographics, physical attributes, sexual relationships. Results: Results of 730 males with current sexual partners: Mean ages 48 years (SD:7 years) all; 46 years (SD:9 years) Black group; 51 years (SD: 9 years) Mixed Race group. All degrees of ED prevalence: All 77.1% (95% CI: 74.0-80.2), Black 76.4% (95% CI: 71.8-80.4) and Mixed Race 77.7% (95% CI: 72.8-82.0). Significantly associated diseases: hypertension, diabetes, gastrointestinal and heart disease. Alcohol consumption (younger patients), smoking (older patients) significantly related to ED. Males with ED: more sexual partners than males without ED. More than 90% choose primary care physician/ generalist as primary ED care-giver. Conclusions: ED is very common in both study groups. Primary care workers must be prepared to manage associated risk factors and health implications. ED sufferers in this population may also be at higher risk for sexually transmitted diseases due to multiple sexual partners. (SA Fam Pract 2003;45(1):14-20) Keywords: erectile dysfunction, impotence, prevalence, black

Community-based care of stroke patients in a rural African setting

Background. To develop a community-based model of stroke care, we assessed discharge planning of stroke patients, available resources and continuity of care between hospital and community in a remote rural setting in South Africa. We sought to determine outcomes, family participation and support needs, and implementation of secondary prevention strategies.Methods. Thirty consecutive stroke patients from the local hospital were assessed clinically (including Barthel index and modified Rankin scores) at time of discharge and re-assessed 3 months after discharge in their homes by a trained field worker using a structured questionnaire.Results. Two-thirds of all families received no stroke educationbefore discharge. At discharge, 27 (90%) were either bed- or chair-bound. All patients were discharged into family care as there was no stroke rehabilitation facility available to the community. Of the 30 patients recruited, 20 (66.7%) were alive at 3 months, 9 (30%) had died, and 1 was lost to follow-up. At 3 months, 55% of the remaining cohort were independently mobile compared with 10% at discharge. Of the 20 surviving patients, 13 (65%) were visited by home-based carers. Only 45% reported taking aspirin at 3 months.Conclusions. The 3-month mortality rate was high. Most survivors improved functionally but were left with significant disability. Measures to improve family education and the level of home-based care can be introduced in a model of stroke care attempting to reduce carer strain and reduce the degree of functional disability in rural stroke patients

A Human Torque Teno Virus Encodes a MicroRNA That Inhibits Interferon Signaling

Rodney P. Kincaid, James M. Burke, Jennifer C. Cox, Christopher S. Sullivan, The University of Texas at Austin, Molecular Genetics and Microbiology, Austin, Texas, United States of AmericaEthel-Michele de Villiers, Division for the Characterization of Tumorviruses, Deutsches Krebsforschungszentrum, Heidelberg, GermanyTorque teno viruses (TTVs) are a group of viruses with small, circular DNA genomes. Members of this family are thought to ubiquitously infect humans, although causal disease associations are currently lacking. At present, there is no understanding of how infection with this diverse group of viruses is so prevalent. Using a combined computational and synthetic approach, we predict and identify miRNA-coding regions in diverse human TTVs and provide evidence for TTV miRNA production in vivo. The TTV miRNAs are transcribed by RNA polymerase II, processed by Drosha and Dicer, and are active in RISC. A TTV mutant defective for miRNA production replicates as well as wild type virus genome; demonstrating that the TTV miRNA is dispensable for genome replication in a cell culture model. We demonstrate that a recombinant TTV genome is capable of expressing an exogenous miRNA, indicating the potential utility of TTV as a small RNA vector. Gene expression profiling of host cells identifies N-myc (and STAT) interactor (NMI) as a target of a TTV miRNA. NMI transcripts are directly regulated through a binding site in the 3′UTR. SiRNA knockdown of NMI contributes to a decreased response to interferon signaling. Consistent with this, we show that a TTV miRNA mediates a decreased response to IFN and increased cellular proliferation in the presence of IFN. Thus, we add Annelloviridae to the growing list of virus families that encode miRNAs, and suggest that miRNA-mediated immune evasion can contribute to the pervasiveness associated with some of these viruses.This work was supported by grants RO1AI077746 from the National Institutes of Health, RP110098 from the Cancer Prevention and Research Institute of Texas, a Burroughs Wellcome Investigators in Pathogenesis Award to CSS, a UT Austin Powers Graduate Fellowship to RPK, a UT Austin Institute for Cellular and Molecular Biology fellowship, and the DKFZ for EMdV. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Molecular BiosciencesMicrobiologyEmail: [email protected]