The contribution of viruses to lower respiratory tract disease in sub-Saharan Africa where human immunodeficiency virus may exacerbate respiratory infections is not well defined. No data exist on some of these viruses for Southern Africa. Comprehensive molecular screening may define the role of these viruses as single and co-infections in a population with a high HIV-AIDS burden. To address this, children less than 5 years of age with respiratory infections from 3 public sector hospitals, Pretoria South Africa were screened for 14 respiratory viruses, by PCR over 2 years. Healthy control children from the same region were included. Rhinovirus was identified in 33% of patients, RSV (30.1%), PIV-3 (7.8%), hBoV (6.1%), adenovirus (5.7%), hMPV (4.8%), influenza A (3.4%), coronavirus NL63 (2.1%), and OC43 (1.8%). PIV-1, PIV-2, CoV-229E, -HKU1, and influenza B occurred in <1.5% of patients. Most cases with adenovirus, influenza A, hMPV, hBoV, coronaviruses, and WU virus occurred as co-infections while RSV, PIV-3, and rhinovirus were identified most frequently as the only respiratory pathogen. Rhinovirus but not RSV or PIV-3 was also frequently identified in healthy controls. A higher HIV sero-prevalence was noticed in patients with co-infections although co-infections were not associated with more severe disease. RSV, hPMV, PIV-3, and influenza viruses had defined seasons while rhinovirus, adenovirus, and coronavirus infections occurred year round in this temporal region of sub-Saharan Africa.

The experience with cutaneous tuberculosis at Ga-Rankuwa Hospital is reviewed. A total of 92 cases of skin tuberculosis was seen over the past 12 years. All recognized forms of cutaneous tuberculosis were encountered, plus some forms which were difficult to classify. Lupus vulgaris was the most common true infection and papulonecrotic tuberculid the most common tuberculid. The classification and pathogenetic mechanisms are briefly discussed.

Respiratory syncytial virus (RSV) may cause severe lower respiratory tract disease in premature infants. Prolonged viral shedding has been reported in patients with underlying immunosuppressive disorders, such as human immunodeficiency virus 1 (HIV-1) infection. During March to May 2006, 23 preterm pediatric patients developed nosocomial pneumonia in a district hospital in the Gauteng Province of South Africa due to RSV infection. The patients were identified using routine diagnostic testing. All had been admitted with their mothers to a Kangaroo Mother Care (KMC) ward from birth--a low care unit for the management of stable low birth weight infants. The HIV-1 seroprevalence among the mothers to these infants was 52.6%, translating to a 52.6% perinatal exposure. A multiplex nested RT-PCR was used to subtype RSV positive nasopharyngeal aspirates. Sequencing and phylogenetic analysis of part of the G-protein gene was used for molecular epidemiological analysis of the outbreak. In total, 19 of the 23 RSV positive specimens could be PCR amplified and sequenced. The subtype A, GA5 genotype was identified in 14 specimens and the BA genotype, a new subtype B genotype not previously recognized in South Africa, in seven. One patient had an infection with both genotypes. Phylogenetic analysis demonstrated eight separate introductions. Two of the strains identified in this outbreak were identical to strains circulating in a general pediatric ward of this hospital during the preceding month. Inadequate infection control measures by health care providers and mothers to children in KMC units may increase potentially the risk of severe RSV infection in a population group with compounded risk factors.

Abstract:The splitting tensile test is a much used method to determine the tensile strength of concrete. The conventional test procedure is known to have a number of limitations related to size effect and boundary conditions. Furthermore, it has been reported to be impossible to determine the tensile strength of Fibre Reinforced Concrete (FRC) using the standard splitting tensile test method. The objective of this paper is to present a methodology to obtain a close estimate of the true tensile strength of FRC from an adjusted tensile splitting test procedure. Splitting tests were performed on cylindrical specimens of four FRC mixes. The transversal deformation perpendicular to the load direction was recorded during the tests. The experimental load-deformation curves thus obtained have two peaks, an initial one as a result of the tensile stresses at the centre of the specimen and a second peak due to secondary cracking outside the loading axis. The tensile strength can be calculated from the first peak which represents the elastic limit state for the material. The method is validated through numerical simulation of the splitting tests using a cohesive crack approach. It is concluded that it is possible to obtain a close estimate of the true tensile strength of FRC using the procedure developed in the paper.

Current management techniques for the maintenance of mine haul roads, such as ad hoc blading, scheduled blading and even maintenance management systems, have shortcomings in complex mining environments. This paper investigates the possibility of using the response of haul trucks to aid the management of haul road maintenance. The question arises as to whether truck response data can be used to recognize road defects at specific locations, in terms of type and size. This is important since different defect types require different road maintenance strategies. A modeling methodology based on dynamic equilibrium of the unsprung mass of a haul truck is proposed and investigated.

In this paper a simple, but effective methodology to simulate opening mode fracture in high performance fibre reinforced concrete is presented. To obtain the specific fracture energy of the material, load-deflection curves from three point bending (TPB) experiments are extrapolated. The proposed extrapolation technique is an adaptation of an approach originally developed for plain concrete. The experimental part of the paper includes a size effect study on TPB specimens. The post crack behaviour of the material is modelled using a cohesive softening function with crack tip singularity. Numerical simulation of the experiments is performed by means of an embedded discontinuity method. The simulation provides satisfactory predictions of the fracture behaviour of the material and the size-effect observed in the experiments.

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Full-scale heavy vehicle simulator (HVS) testing of pavements incorporating granular layers indicated that granular materials behave elasto-plastically when subjected to repeated traffic loading. Elasto-plastic behaviour implies that permanent deformation takes place with every load repetition, although traffic loading normally induces stresses well below the failure stress of the material as defined bythe Mohr–Coulomb failure envelope. In the development of design a method for granular layers, cognizance should therefore be taken of the permanent deformation that occurs with each load repetition. In this Paper, the development ofa design method for limiting rutting granular layers developed from data obtained through full-scale HVS testing and using the principle of S–N curves, is described. HVS data indicated that the model generally used to describe the relation between permanent strain development and number of load repetitions does not give reliable estimates of the permanent deformation at large numbers of load repetitions. The design method described here recognizes the elasto-plastic behaviour of granular materials and uses an improved model to describe the relation between permanent deformation development and number of load repetitions. This design method was found to give reasonable predictions of the loading capacity of in-service low volume roads comprising mainly granular layers