33 research outputs found
Traumatic superior mesenteric arteriovenous fistula
No full textCITATION: Du Toit, D.F & Rademan, F. 1987. Traumatic superior mesenteric arteriovenous fistula - a case report. S Afr Med J, 71(9):587-588.The original publication is available at http://www.samj.org.zaENGLISH ABSTRACT: In a case of traumatic superior mesenteric arteriovenous fistula resulting from a stab wound in the abdomen clinical signs of high-output cardiac failure or portal hypertension were absent. Selective angiography was useful in confirming and locating the fistula. The patient made a good recovery after resection of the aneurysm and fistula and insertion of a prosthetic graft.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaarPublisher’s versio
Splenic rupture caused by a cricket ball. A case report
No full textCITATION: Du Toit, D.F. & Rademan, F. 1987. Splenic rupture caused by a cricket ball - a case report. S Afr Med J, 71(12):796.The original publication is available at http://www.samj.org.zaENGLISH ABSTRACT: A 14-year-old boy presented with a ruptured spleen after being injured by a cricket ball during a match. A typical picture of splenic rupture with intra-abdominal haemorrhage was evident on admission to hospital. At emergency laparotomy splenorrhaphy was not feasible because of a deep hilar laceration and splenectomy was performed.Publisher’s versio
The simulation of a transient leaching circuit
No full textThesis (PhD (Process Engineeering))--University of Stellenbosch, 1995.The hydrometallurgical leaching of sulphide concentrates was introduced in the
1950's. Generally the leaching mechanisms of these processes are not understood
fundamentally. The reasons for this are the inherently complex nature of sulphide
chemistry and that the sulphide concentrates usually consist of highly intergrown
sulphide minerals. The leaching kinetics of sulphide concentrates where only one
metal-sulphide mineral occurs have been investigated intensively, but not for
sulphide concentrates with more than one metal-sulphide mineral. The behaviour of
these mixed metal-sulphide minerals has mostly been investigated on plant scale to
qualitatively determine the leaching trends of the process. The consequence of the
relatively unKnown leaching mechanism and kinetics is that these processes are not
controlled efficiently.
This study was conducted on the acid-oxygen pressure leaching of Ni-Cu matte (the
first stage leach process at the Ni-Cu refinery of Impala Platinum Ltd.). As a first step
to improve the control efficiency of the process, the process must be stabilised.
Therefore, an off line computer simulation program is proposed to control the
repulping section of the plant that has previously been controlled solely by an
operator. Controlling the repulping section is very important, because conditions exist
in the repulping tanks for leaching to occur. This causes perturbations in the pulp
entering the pressure leach autoclave. Due to the fast reaction kinetics of the matte
in the pressure leach autoclave the perturbations entering the autoclave will influence
the performance of the acid-oxygen pressure leach process. The simulation program
was tested on the plant and indicated that considerable improvement in the stability
of the operation could be achieved.
In obtaining a better understanding of the behaviour of this process, it is essential
that key variables and trends are identified. A methodology is proposed to analyse
and model this ill-defined and poorly understood process from historical data by
v
artificial neural networks (ANN), inductive learning by decision trees and statistical
techniques. The back propagation neural network, learning vector quantization neural
network and the decision trees yielded comparable classification rates between 73%
and 84%, and could serve as a basis for the adjustment of operating conditions to
improve the efficiency of the process. The relative importance of the process
variables is determined by a method of sensitivity analysis and together with the
statistical mean, the effect of an increase or decrease in the variable on the process
is quantified. These results are substantiated by experimental findings.
A leaching mechanism for the acid-oxygen pressure leach of Ni-Cu matte is
postulated. The leaching sequence of the nickel and copper sulphides is Ni3Sr Ni7S"
NiS-Ni3S4, and CU2S-CU31SWCU1.BS-CUS, respectively. Ni7Sa and CU31 S1a are
intermediate nickel and copper sulphide phases that form during the leaching
process. Ni alloy has a galvanic effect on the sulphide minerals which inhibits the
overall leaching rate and results in the formation of H2S and the intermediate nickel
and copper sulphides (Ni7Sa and CU31 S1a). A semi-empirical kinetic model was
developed based on the chemical reaction rate expressions of the leaching
mechanism. This model can accurately simulate the batch leaching process for
variations in the oxygen partial pressure, oxygen flowrate, temperature, particle size,
initial acid concentration and pulp density. A sensitivity analysis on the model
indicated that for a matte with a lower initial Ni alloy content the leaching rate of
nickel is much faster.Doctora
Klankproduksie : 'n ondersoek na die spraak- en sangstem
No full textThesis (MA)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: Actors and singers mainly use their voices as theatrical communication
instruments. The production of sound - for singing, speech and other
derivatives - makes use of the same physiological mechanics. This indicates
that the anatomical components are applicable to all of the the above
mentioned. The goal of exploring the anatomy and physiology of the voice
mechanics is to enhance the artist's and the theoretic's awareness of the
dynamic process. Even though it does not replace technical training in voice
production, it is still of cardinal importance.
By being in possession of a worthy knowledge of the voice and body as an
instrument of unity, singers and actors can challenge their instruments to the
maximum. In this way professional vocal artists can finally come into contact
with their humanness to create a mature character on stage.
The correct body posture, breathing methods, resonance and articulation play
an important role in ensuring good projection. Successful projection and
resonance can only take place if the whole of the sound production instrument
is working in a physiologically correct manner.
Research has been done on the leading theater theorists' expectations of the
regarding voice production. It was specifically their opinions that initiated the
modern approach to sound production in terms of speech and singing in the
modern theatre. A sound production experiment, focusing on the challenge of
the human voice, was staged as a theatre production, and was analysed. The
presentation was predominantly based on the ideas of the directors. These
ideas were discussed in the previous chapter.
This study explores the phsyiological mechanism that produces sound to
promote the creative commerce with sound.AFRIKAANSE OPSOMMING: Akteurs en sangers gebruik hoofsaaklik hulle stemme as 'n teatrale
kommunikasie-instrument. Die produksie van klank - vir sang, spraak en
ander geluide - spruit uit dieselfde fisiologiese meganika. Dit dui daarop dat
dieselfde anatomiese komponent vir bogenoemde van toepassing is. Die
verkenning van die anatomie en fisiologie van die stem-meganika het ten doel
om die kunstenaar en teoretikus se bewustheid van die dinamiese proses uit
te brei. Hoewel dit geensins die tegniese opleiding in stemgebruik vervang
nie, is dit steeds van kardinale belang.
Deur oor'n waardige kennis van die stem en liggaam as eenheids-instrument
vir die teaterkunstenaar te beskik, kan sangers en akteurs hul instrumente tot
die uiterstes uitdaag. Op hierdie manier kom 'n professionele stemgebruiker
uiteindelik in aanraking met sy/haar potensiaal en kan sodoende 'n
volwaardige karakter op die verhoog skep word. Die korrekte
liggaamshouding, asemhalingsmetode, resonansie en artikulasie speel 'n
kardinale rol in goeie projeksie. Suksesvolle projeksie en resonansie kan
slegs geskied indien die hele klankproduksie-instrument op 'n
natuurwetmatige wyse in werking is.
Daar is ook navorsing gedoen oor die toonaangewende teaterteoretici se
verwagtinge t.o.v. stemproduksie. Dit was juis hierdie persone se opinies wat
die huidige aanwending van klankproduksie in terme van spraak en sang in
die moderne teater geïnisieer het. 'n Klankproduksie-eksperiment (wat
gefokus is op die uitdaging van die menslike stem) is in die vorm van 'n
teaterproduksie gedoen waarin die uitgangspunte van die regisseurs wat in die
vorige hoofstuk bespreek is, prakties ondersoek is.
Die juiste doel van hierdie studie is dus om 'n ondersoek te loods na die
fisiologiese meganisme wat klankproduksie by die menslike stem tot gevolg het, en uiteindelik die kreatiewe omgang met klank in terme van die spraaken
die verwante sangstem te promoveer.Master
Anticancer activity and mechanism of action of plant extracts on squamous cell carcinoma
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Industrial brine characterisation and modelling
No full textIncludes abstract.Includes bibliographical references.Industrial wastewater contains many soluble inorganic and organic components and solid particles. This study focused on inorganic industrial hypersaline brines. Chemical engineering presents a variety of mechanical, thermal, biological and chemical processes capable of treating hypersaline brines to the standard required by legislation. However, some of these technologies are inefficient, costly and outdated and are not applicable in solving modern brine accumulation problems
Quadratus lumborum block for analgesia after caesarean section: a randomised controlled trial
No full textESRA19-0521 Quadratus lumborum block (QLB) for postoperative analgesia after caesarean section: a randomised controlled trial
No full textQuadratus Lumborum Block for Analgesia After Cesarean Section: A Randomized Controlled Trial
No full text
