Describe algunos temas teóricos que involucran técnicas experimentales para encontrar los valores de algunos parámetros ópticos no lineales. El estudio de los efectos ópticos no lineales nos proporciona una riqueza de información sobre la interacción de la intensidad de la radiación con la materia, asimismo nos proporciona nuevas tecnologías que pueden ser usadas para realizar las tareas que son más difíciles o imposibles con la óptica lineal. Ejemplos de tales tecnologías emergentes, son up-conversión, la conversión de frecuencia óptica en la que la radiación coherente que es generada por un láser en una parte del espectro es convertida en otra radiación coherente en una región espectral completamente diferente. En esta forma la radiación coherente se hace disponible en otros regímenes espectrales que son inaccesibles por los láseres comerciales. La aplicación de la óptica no lineal a la espectroscopia, ha sido desarrollada para aumentar el espectro y la resolución espectroscópica. / Tesis

Trabajo de Investigación Requisito para optar al Título de Cirujano Dentista / El dolor constituye una de las principales causas de consulta odontológica. Entre los múltiples fármacos que existen en la actualidad para el manejo del dolor, sea éste tanto agudo como crónico, los analgésicos antiinflamatorios no esteroidales (AINEs) constituyen una de las herramientas más utilizadas por los profesionales. Considerando que su uso esta asociado a diversos efectos secundarios, se hace necesario buscar métodos para potenciar su efecto analgésico disminuyendo al mismo tiempo los efectos indeseables, siendo el uso combinado de AINEs una estrategia para lograrlo. En el presente trabajo se evaluó la actividad analgésica producida por dos AINEs, dexketoprofeno y naproxeno, en el test de las contorsiones abdominales o writhing test, siendo evaluados en forma aislada y en combinación. Se utilizaron ratones, a los cuales se les administró vía intraperitoneal ambas drogas combinadas en relación 1:1, 1:3 y 3:1 y en proporciones fijas de 1/2, 1/4, 1/8 y 1/16 de las DE25 y DE50 de cada AINE. Se determinó por análisis isobolográfico la naturaleza de la interacción entre ambos, siendo esta de tipo sinérgico, excepto en la combinación 1:3. Este hallazgo tiene importancia clínica, por su proyección en el tratamiento farmacológico del dolor, incidiendo a través de nuevas combinaciones farmacológicas, en un beneficio para los pacientes.

In most rural areas, reliance on traditional medicine and food is high and this is attributed to both economic and cultural factors. The edible stink-bug (Encosternum delegorgueiSpinola), local name “thongolifha” is consumed by the Venda tribe in Limpopo Province of South Africa. Thongolifha is important to the Venda tribe in terms of culture, nutrition and economical value. They eat it raw or cooked with porridge or as a snack. The edible stink-bug is sold at the Thoyandou open market and provides valuable income for the harvesters. Many insects have been reported to contain good source of proteins minerals and vitamins. In terms of medicinal value, insects have also been used in folk medicine in the past by various cultures to treat many ailments such as stroke, asthma, cold, etc. Some insects are also known to sequester compounds from their host plant and use them for its defensive mechanism. The host plant for thongolifha was identified as Dodonaea viscosa Jacq. var. angustifolia which has been reported to have antibacterial activity. The aim of this study was to investigate the possible interaction between the thongolifha and its host plant Dodonaea viscosa. Since thongolifha is so important to the Venda tribe and its nutritional value was never analysed before it was also relevant to determine its nutritional composition. Nutritional components of thongolifha such as the proteins, fats, amino acids and carbohydrates contents were detected by using standardized methods. Thongolifha contained 35.2% protein, 50.6% fat and 7.63 g/100 g carbohydrate with an energy content of 2599 kJ/100 g. These results compare well to nutritional values of other edible insects such as termites (41.8% protein and 44.3% fat) and wasps (31% protein and 62% fat).The mopane worm has higher protein content (63.5%) and a lower fat content of (18%). Mineral content of thongolifha (1.2 g/100 g) was found to be at a comparable level to other bugs such as the Acantocepphala declivis (1.0 g/100g). Analysis of essential amino acids varied from 0.82 mg/100 g (threonine) and 1.32 mg/100 g (valine). The nutritional composition of thongolifha is acceptable and thongolifha is not just a traditional delicacy but also contributes as a diet supplement of the Venda tribe. Between 680 and 3400 of thongolifha will however have to be consumed to supply the daily nutritional needs for the essential amino acids phenylalanine and methionine. Analysis for antibacterial activity of thongolifha was carried out after extracting with solvents of varying polarities, separation by thin layer chromatography (TLC) and bioautography against four nosocomial bacteria; Gram-negative; Escherichia coli and Pseudomonas aeruginosa; Gram positive; Staphylococcus aureus and Enterococcus faecalis. Bioautography results of the thongolifha extracts revealed some activity against S. aureus and E. faecalis. Evaluation of the minimal inhibitory concentration (MIC) by using a serial dilution microplate method indicated low antibacterial activity (MIC > 2.5 mg/ml). Thongolifha therefore does not contain antibacterial compounds but there may be present in a low concentration or the serial dilution microplate method does not work well with insects extracts. Some insects contain peptides as antibacterial compounds. Spraying thongolifha extracts chromatograms with several spraying reagents indicated that these antibacterial compounds were not peptides Methanol crude leaf extracts of D. viscosa was reported in the literature to have antibacterial activity against S. aureus however the results were obtained by using the agar diffusion method which does not provide convincing quantitative results. In our study we extracted components from D. viscosa using solvents of varied polarities to evaluate its antibacterial and antioxidant activities. Dichloromethane and acetone extracted more compounds with good antibacterial activity against S. aureus, E. faecalis, E. coli and P. aeruginosa. The average MIC values varied from 0.04 to 0.28 mg/ml, indicating excellent to good antibacterial activity. The antioxidant activity using the DPPH Spectrophotometric assay gave the EC50 of the extracts of 212 ± 4 to 469 ± 9 µg/ml. As expected, the more polar crude extracts, ethyl acetate and acetone demonstrated higher activity compared to other extracts. This was supported by the TLC qualitative assay showing more yellow bands in these extract on TLC chromatograms after spraying with 0.2% DPPH in methanol. To determine whether thongolifha has sequestered compounds from the host plant, D. viscosa, a serial exhaustive extraction was performed in order to extract components from the crude extracts of both insect and the host plant by using various solvents and separating the extracts on TLC plates by using various eluant systems. After the TLC chromatograms were sprayed with vanillin-sulphuric acid to reveal separated components, there were few similarities of components from both insect and host plant. This could mean that either a sequestered plant compounds are present in low quantities in the insect extract, that insect may have metabolized the sequestered compounds or alternatively that the insect might not have sequestered the compounds from the host plant at all. It should be kept in mind that the stink-bugs feed by sucking sap from the host plant. By using bioassay-guided fractionation based mainly on silica gel chromatography, four compounds (5-hydroxy-3,74’-trimethoxyflavone (1); 5,7-dihydroxy-3,6,4’-trimethoxyflavone (2); 5,7,4’-trihydroxy-3,6-dimethoxyflavone (3); and 4’-O-methylkaempferol (4) where isolated from dichloromethane fraction of a crude D. viscosa leaf extract, acetone crude leaf extract yielded only one compound, Kaempferol (5). Compounds 1, 2, 3 and 5 where previously isolated from D. viscosa whereas compound 4 was isolated for the first time from D. viscosa. Compounds 4 is not a novel compound because it was previously isolated from other plants species such as the Lens culinaris. Compounds 3, 4 and 5 have good antibacterial activity against E. coli and E. faecalisat MIC values of 15.63 µg/ml and 31.25 µg/ml respectively. In addition, the DPPH quantitative assay has demonstrated that Compounds 4 and 5 have strong antioxidant activities (EC50 = 35.1 ± 0.85 and 75.5 ± 1.76 µM respectively) but lower than L-ascorbic acid (EC50 = 13.5 ± 0.28 µM) used as a standard antioxidant agent. The antibacterial and antioxidant activity of most of the isolated compounds were not known previously. Investigation of structure antibacterial-activity relationship in the isolated compounds did not yield a clear correlation. When investigating the possible interaction between the insect and the host plant, bioautography assay has shown compounds with antibacterial activity against S. aureus (Rf 0.79) E. faecalis (Rf 0.66) when separated with CEF eluent system. Some of the isolated compounds from D. viscosa leaf extracts had an Rf of 0.79 (5, 7-dihydroxy-3, 6, 4’-trimethoxyflavone) and Rf 0.61 (5, 7, 4’-trimethoxxyflavone) when separated with CEF eluent system. These findings indicate that thongolifha may have sequestered the two compounds from D. viscosa leaves, but this possibility has to be confirmed. This study has indicated that thongolifha is good source of protein, vitamins, minerals and amino acids; however we have not found evidence of significant antibacterial activity of thongolifha. If fresh material of thongolifha can be analysed in future work the probability of finding medicinal properties may be greater. On the other hand, D.viscosa. crude leaf extracts have demonstrated strong antibacterial and antioxidant activities; although isolated compounds have shown moderate level of activities. Because practically all antibacterial compounds based on bioautography have been isolated, it is clear that in the crude dichloromethane extract some synergism must have taken place because the antibacterial activity on a mass basis was nearly as good as the isolated compound without removing >90% of non active compounds. / Thesis (PhD (Paraclinical Science))--University of Pretoria, 2006. / Paraclinical Sciences / PhD / unrestricted

No abstract available / Dissertation (MEd)--University of Pretoria, 2011. / Education Management and Policy Studies / unrestricted

This study examines the importance of a central agency such as The Presidency in the administration of intergovernmental relations (IGR) in South Africa. Further to this broad objective, is the need to develop a definitional framework for IGR, particularly within the context of the unitary-federal system. The study contends that the mechanism for an IGR system in emerging democracies should be obligatory and driven through constitutional provisions and arrangements. The historical-political evolution of the South African Constitution has demonstrated the importance of a central agency in regulating IGR mechanisms. This study was able to trace historical precedents ranging from the British Imperial Council era, through to the Apartheid era, the President’s Council and The Presidency of the current democratic government of South Africa. In order to provide clarity on the importance of a high profile office within an IGR co-ordination infrastructure, the study utilised the authority relationship models, which strategically present a new paradigmatic shift in theoretical constructs. These models identified and explored the viabilities in the procurement of significant relationships between and amongst spheres of government. In clarifying the emerging cooperative governance paradigm, a terminological compromise for federalism in South Africa was posted. The study also provides a distinguished hierarchy-defining route between spheres and tiers of government as an important notation for consideration. Since models are abstractions of reality, the study establishes that the political coherency of IGR constructs could be considered as a direct function of a normative environmental infrastructure. The study examines factors influencing IGR. Principal to these is the party political system and the character of the Head of State. The study argues that the degree to which the ruling political coalition/party is centralised impacts directly on the ability of sub-national governments to interrelate. The study found that IGR reform should be based on the following conditionalities that involve IGR as a human activity, which should accommodate varied socialisation values. The study further attempts to promote the notion that IGR, as a political activity, should be flexible enough to accommodate constituency-serving tendencies, which are reminiscent of new and emerging political environments. Furthermore, as a technocratic activity, IGR should accommodate the reality of it being a terrain of contestation between elected and appointed officials. At the same time, it could act as a relational barometer that could be functional in nature and allow everyone in government to be an IGR practitioner. Whilst the study has left unanswered questions, it has laid the basis upon which emerging democratic dispensations should approach IGR. More specifically, the IGR definition presented in this study, has called for a disengagement process with the federal/unitary view of IGR. This study exemplifies the need for continuous debate in Public Administration as it provides a critical knowledge base for society to expand future intellectual discussions on IGR reforms in new and emerging democracies. / Thesis (DAdmin)--University of Pretoria, 2004. / School of Public Management and Administration (SPMA) / unrestricted

The purpose of this study is to determine the factors impacting on ethical behaviour in organisations. More specifically the purpose of this study is to a) identify the factors impacting on ethical behaviour in organisations within a theoretical framework, specifically focusing on the South African context and b) to make certain recommendations to address the factors identified as impacting on ethical behaviour in organisations. To achieve these goals the study was designed in two phases. The first phase entails a theoretical inquiry with the aim of understanding the concepts of ethics as well as ethical and unethical behaviour, to identify the factors impacting on ethical behaviour in organisations, to provide practical recommendations to address these factors and provide a background to the second phase. The second phase consists of an empirical inquiry with the aim to identify the factors impacting on ethical behaviour in organisations based on the data gathered through a survey designed for this purpose. For each phase there is a separate discussion of the research methodology employed to achieve the objectives of that phase. A mostly qualitative research methodology was employed for the first phase while quantitative research was utilised during the second phase. The first phase contains two chapters each devoted to a separate topic. Chapter 3 unpacks the concept of ethics while chapter 4 looks at various models that identify factors impacting on ethical behaviour in organisations and recommendations to address these factors. Chapter 3 also contains the definition and discussion of the concept of ethics as it relates to the purpose of this study, whereas chapter 4 also contains practical recommendations to address the specific factors identified as impacting on ethical behaviour in organisations. Chapter 5 contains the discussion of the research methodology for the empirical inquiry and presents the results thereof. In the last section of chapter 5 conclusions are made w.r.t the results of the study, the research quality is evaluated and recommendations are made for future research in this field. Some of the more salient conclusions of the study are: -- Ethics can be defined as the principles or standards that govern good and right behaviour. -- The entire population identified seven factors as impacting on ethical behaviour in organisations amongst which: leader or manager behaviour, code of conduct, values, beliefs, referent others, reward systems and parental influence. -- Results of the literature analysis indicated that there were six factors impacting on ethical behaviour in organisations, which include: referent others, leader or manager behaviour, reward systems, code of conduct, organisational culture and the individuals level of moral development. -- The results of the theoretical inquiry and empirical inquiry indicate that there are four factors in total that were identified in both phases of the inquiry as having an impact on ethical behaviour in organisations which are: referent others, leader or manager behaviour, reward systems and a code of conduct. / Dissertation (MCom (Human Resources Management))--University of Pretoria, 2004. / Human Resource Management / unrestricted

Owing to the crippling nature of arthritis, surgeons have been trying for well over a century to successfully treat this debilitating disease particularly when attacking the hip joint. In the early 1970s, Sir John Charnley started with total hip replacement as a solution to this ever-increasing problem. Many different designs were developed but all the designs revolved around a femoral stem, femoral head and acetabular component. Independent of the design, longevity of the implant remains a problem. The major cause of replacements, according to various hip registers, is due to aseptic loosening resulting from osteolysis. According to these registers, the average in-vivo life of a hip replacement is approximately 12 years. The main aim of this study was to determine the root cause of mechanical failure of the acetabular cups and to determine the origin of the excessive amount of ultra-high molecular weight polyethylene (UHMWPE) wear debris floating in the joint resulting in osteolysis. During the study, various techniques were used to investigate the acetabular components to try to establish the root cause of mechanical failure. These techniques included: 1. Visual inspection 2. Investigation making use of dye penetrant spray 3. Investigation under stereo microscope 4. Investigation making use of a scanning electron microscope 5. Electrophoresis 6. Mass-spectrometric analysis 7. Analysis of the synovial fluid on high-frequency linear-oscillation machine (SRV). The wear debris retrieved from the scar tissue surrounding the joints of a number of patients was also analysed. Apart from the obvious defects such as mechanical damage due to impingement, the main defect on which this study focuses is the wear patches found on the inside of the acetabular components. The wear areas were presented as areas where the surface layer of the UHMWPE was ripped off by adhering to the rotating femoral head. This type of failure is possible if localised overheating takes place resulting in the material either adhering to the rotating femoral head or the material being squeezed out under the prevailing pressure. Both these mechanisms were confirmed by the wear debris retrieved from the scar tissue, being either droplets of UHMWPE or whisker-like wear products. To confirm the existence of elevated temperatures the brown discolouring on the inside of the acetabular cups was analysed, making use of electrophoresis, mass-spectrometric analysis and scanning electron microscope recordings. In this part of the study, it was confirmed that localised temperatures on the bearing surface had reached at least 60°C during in-vivo service. This temperature was confirmed by inserting a thermocouple just under the surface of an acetabular cup and then measuring the temperature while in-vitro testing was taking place on a hip simulator. The wear debris as retrieved was also duplicated in laboratory experiments while the temperature on the surface of an acetabular cup was monitored. It was established that wear particles similar in shape and size were formed at temperatures in excess of 90°C. At temperatures above 50°C the UHMWPE had visually shown extensive increase in creep, indicating that at these temperatures the material softens sufficiently for this type of debris to be generated The overheating as described can also only occur if there is a lack of lubrication in the bearing couple. The synovial fluid from 12 patients was retrieved during revision surgery. This synovial fluid was then tested on a high-frequency linear-oscillation machine (Optimol SRV test machine) to determine the lubricity characteristics of the synovial fluid as retrieved. It was discovered that the load-carrying capability of the synovial fluid did not comply with the minimum requirements for a fluid to function as a lubricant. The final conclusion of this study is that excessive amounts of wear debris are generated due to the localised overheating of the bearing couple as a result of insufficient lubrication. The localised heat build-up results in excessive amounts of wear debris being generated and deposited in the joint area resulting in osteolysis. / Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2005. / Mechanical and Aeronautical Engineering / unrestricted

In this study we evaluated the validity of well-known human electrocardiographic markers of myocardial pathology in Dorper sheep. These markers are all properties of PVC`s, namely the duration of the QRS complex of PVC`s, the presence of notching of the QRS complex of PVC`s and change in the ST segment of PVC`s. It was shown that these three electrocardiographic phenomena correlate with myocardial pathology in the hearts of Dorper sheep. We also described a new electrocardiographic indicator of myocardial pathology in the hearts of Dorper sheep, namely an increase in the frequency of cardiac memory T waves, induced by PVC`s, as a new electrocardiographic surrogate for myocardial pathology. This study was possible, because we knew from a pilot study that our specific method of inducing right ventricular PVC`s is known to induce structural alterations in the myocardium of Dorper sheep. The guidewire was situated in the right ventricle and we examined the histological appearance of only the left ventricle, in order to exclude any possible changes caused by the wire itself. Although this study was not designed to answer the question of whether PVC`s can be a cause of, rather than a consequence of, structural myocardial disease, it is an important method, because in this way every wether serves as it`s own histological control for electrocardiographic changes. We started with normal Dorper wethers, induced right ventricular PVC`s and these PVC`s had certain characteristics, as described in chapter 3. We know what the normal histological appearance of Dorper wethers are and the electrocardiographic appearance of PVC`s in the normal heart. At the end of the study certain changes appeared in the PVC`s, namely the QRS duration increased, notching appeared and the ST segment disappeared. Furthermore, at this stage the histological appearance of the left ventricle resembled that of myocarditis. At the end of the study (abnormal myocardial histology) we also noted an increase of 42 % in the incidence of cardiac memory T waves following PVC`s, when compared to the beginning of the study (normal myocardial histology). What might the reason be for the abnormal left ventricular histology ? As this study was not designed to answer that question this is open to debate. It might be the anaesthetic, the wire itself or the PVC`s. As already discussed we induced right ventricular PVC`s and afterwards we examined the left ventricles, therefore these histological alterations cannot be a direct consequence of the guidewire itself. It is suggested that it will be worthwhile to explore the possibility that PVC`s may be a cause of myocardial disease and that it is not always a consequence of established myocardial disease. / Thesis (PhD (Human Physiology))--University of Pretoria, 2006. / Physiology / unrestricted

Korean-German composer Isang Yun received international recognition as one of the successful and leading twentieth-century composers. Despite Yun’s lasting fame, some of his works remain lesser known such as all three of his violin concerti. Yun’s main compositional techniques in his violin concerti are abundant ornamentations and articulations that imitate the sound of Korean folk instruments but played on the violin. Without acknowledging Korean folk music performance practices and folk instruments, a violinist cannot accurately deliver what Yun’s music expressed. The fact that Yun’s Violin Concerto No. 3 imitates Korean string instruments, haegeum or komungo, it must be explained how Korean ornamentations are played and can be incorporated on the violin. The purpose of this paper is to provide these answers as well as technical suggestions regarding abundant ornamentations, frequent dynamic and articulation changes, as well as fingerings and bowings. It is hoped that this study will help violin performers to understand Yun’s Concerto No. 3 and encourage more frequent performances of it.

No description available.