Shortcomings In The Estimation Of Clay Fraction By Hydrometer

Published ArticleThe estimation of clay fraction is important for predicting the engineering properties of a soil. SANS 3001 GR3 (SANS 2011) specifies a procedure for clay fraction determination using a hydrometer. It has long been suspected that there may be flaws in this approach. Some of the possible sources of error have been suggested, but little or no change has been made in the standard procedures for assessment of clay fraction in well over half a century. This paper deals with a microscopic examination of some typical South African clayey soils to assess the adequacy of dispersion and possible consequences for clay fraction determination in currently specified hydrometer procedures. Clays are examined both with and without dispersant, and with and without labelling of clay minerals using an exchangeable cation dye

Clinical experience with amikacin, a new aminoglycoside antibiotic

CITATION: Theron, F. P. & De Kock, M. A. 1977. Clinical experience with amikacin, a new aminoglycoside antibiotic. South African Medical Journal, 51(21):746-8.The original publication is available at http://www.samj.org.za[No abstract available]Publisher’s versio

Dental caries and oral hygiene patterns in Afrikaans- and English-speaking white high school pupils from upper and lower socio-economic areas of Johannesburg and environs

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Patterns of Striped order in the Classical Lattice Coulomb Gas

We obtain via Monte Carlo simulations the low temperature charge configurations in the lattice Coulomb gas on square lattices for charge filling ratio $f$ in the range $1/3 < f < 1/2$. We find a simple regularity in the low temperature charge configurations which consist of a suitable periodic combination of a few basic striped patterns characterized by the existence of partially filled diagonal channels. In general there exist two separate transitions where the lower temperature transition ($T_p$) corresponds to the freezing of charges within the partially filled channels. $T_p$ is found to be sensitively dependent on $f$ through the charge number density $\nu = p_{1}/q_{1}$ within the channels.Comment: 4 pages, 8 figure

Bosonization in d=2 from finite chiral determinants with a Gauss decomposition

We show how to bosonize two-dimensional non-abelian models using finite chiral determinants calculated from a Gauss decomposition. The calculation is quite straightforward and hardly more involved than for the abelian case. In particular, the counterterm $A\bar A$, which is normally motivated from gauge invariance and then added by hand, appears naturally in this approach.Comment: 4 pages, Revte

A discussion of Adrio Konig's views on the evil one, evil and evil powers

Peer reviewedThe article investigates demonic evil as a historic theme in König’s theology, a theme that has been important to him but which, for the most part, has come to the fore indirectly. His high regard for Scripture and of what is said in the Bible about God and Jesus has also led him to take references to demonic powers seriously. Implications of his approach to these issues and his theology on the subject, as it has grown over three decades, are discussed. Some biographical data are linked to his theological viewpoints on these issues.Church History Society of Southern Afric

Comparison in the incidence of anorectal malformations between a first- and third-world referral center

PURPOSE : Aim of study was to evaluate the differences in incidence and presentation of anorectal malformations (ARMs) between selected Pediatric Surgery Divisions in the Republic of South Africa (ZAR) and Italy. METHODS : A retrospective cohort study involved analysis of clinical records of patients with ARM born between 2005 and 2012. Type of ARM, maternal age, birth weight, gestational age, presence of associated anomalies and delayed diagnosis were analyzed. RESULTS : 335 patients were included in this study. Of note, statistically significant differences between the African and European patient groups were observed in a male predominance in the ZAR patient population. In addition, female recto-perineal fistulas were diagnosed in significantly more Italian patients than in ZAR. Furthermore, a more advanced maternal age and a lower gestational age was noted in the European cohort with a minimal delay in initial diagnosis as opposed to the African counterpart. Both centers reported recto-perineal fistula as the most common malformation in male patients. CONCLUSION : With the exception of perineal fistulas in females, the incidence of specific subtypes of ARMs was similar in the two groups. This may be of importance when extrapolating European study conclusion to the South African setting.http://link.springer.com/journal/3832016-08-31hb201

The South African Tuberculosis Care Cascade: Estimated Losses and Methodological Challenges

Background: While tuberculosis incidence and mortality are declining in South Africa, meeting the goals of the End TB Strategy requires an invigorated programmatic response informed by accurate data. Enumerating the losses at each step in the care cascade enables appropriate targeting of interventions and resources. / Methods: We estimated the tuberculosis burden; the number and proportion of individuals with tuberculosis who accessed tests, had tuberculosis diagnosed, initiated treatment, and successfully completed treatment for all tuberculosis cases, for those with drug-susceptible tuberculosis (including human immunodeficiency virus (HIV)–coinfected cases) and rifampicin-resistant tuberculosis. Estimates were derived from national electronic tuberculosis register data, laboratory data, and published studies. / Results: The overall tuberculosis burden was estimated to be 532005 cases (range, 333760–764480 cases), with successful completion of treatment in 53% of cases. Losses occurred at multiple steps: 5% at test access, 13% at diagnosis, 12% at treatment initiation, and 17% at successful treatment completion. Overall losses were similar among all drug-susceptible cases and those with HIV coinfection (54% and 52%, respectively, successfully completed treatment). Losses were substantially higher among rifampicin- resistant cases, with only 22% successfully completing treatment. / Conclusion: Although the vast majority of individuals with tuberculosis engaged the public health system, just over half were successfully treated. Urgent efforts are required to improve implementation of existing policies and protocols to close gaps in tuberculosis diagnosis, treatment initiation, and successful treatment completion

Scheduling with genetic algorithms

In many domains, scheduling a sequence of jobs is an important function contributing to the overall efficiency of the operation. At Boeing, we develop schedules for many different domains, including assembly of military and commercial aircraft, weapons systems, and space vehicles. Boeing is under contract to develop scheduling systems for the Space Station Payload Planning System (PPS) and Payload Operations and Integration Center (POIC). These applications require that we respect certain sequencing restrictions among the jobs to be scheduled while at the same time assigning resources to the jobs. We call this general problem scheduling and resource allocation. Genetic algorithms (GA's) offer a search method that uses a population of solutions and benefits from intrinsic parallelism to search the problem space rapidly, producing near-optimal solutions. Good intermediate solutions are probabalistically recombined to produce better offspring (based upon some application specific measure of solution fitness, e.g., minimum flowtime, or schedule completeness). Also, at any point in the search, any intermediate solution can be accepted as a final solution; allowing the search to proceed longer usually produces a better solution while terminating the search at virtually any time may yield an acceptable solution. Many processes are constrained by restrictions of sequence among the individual jobs. For a specific job, other jobs must be completed beforehand. While there are obviously many other constraints on processes, it is these on which we focussed for this research: how to allocate crews to jobs while satisfying job precedence requirements and personnel, and tooling and fixture (or, more generally, resource) requirements